Reaching Remote Networks Dynamically
Hey Im R1 and Im using EIGRP to let my neighbors know that Im directly connected to networks: /24 /24 /30 Internet Hey Im R2 and Im using EIGRP to let my neighbors know that Im the gateway to the Internet and that Im directly connected to: /24 /24 /30 Reaching Remote Networks Statically
Hey Im R1 and I know about my 3 directly connected networks. Im also a stub router so to reach any network I do not know about I will use a default static route to R2 Internet Hey Im R2 and I know about my 3 directly connected networks and the Internet. I need to reach the two R1 LANs therefore I will use two static routes to R1. I will also use a default static route to connect to the ISP.. A static route is a manually entered route into the routing table that specifies: The remote network address/mask The next hop router Static Routing Advantages
R1(config)# ip route Dont worry about the syntax right now Media Description: Use the media is from E More secure since they are not advertised over the network. More efficient since they use less bandwidth than dynamic routing protocols. No CPU cycles are used to calculate and communicate routes. Predictable as the path a static route uses to send data always the same. Static Routing Disadvantages
R1(config)# ip route R1(config)# ip route R1(config)# ip route R2(config)# ip route R2(config)# ip route R3(config)# ip route R3(config)# ip route R3(config)# ip route Initial configuration and maintenance is time-consuming. Configuration is error-prone, especially in large networks. Administrator intervention is required to maintain changing route information. Does not scale well with growing networks; maintenance becomes cumbersome. Requires complete knowledge of the whole network for proper implementation. Media Description: Use the media is from E Static Routing Versus Dynamic Routing
Configuration Complexity Generally independent of the network size Increases with network size Topology Changes Automatically adapts to topology changes Administration intervention required Scaling Suitable for simple and complex topologies Suitable for simple topologies Security Less secure More secure Resource Usage Uses CPU, memory, and link bandwidth No extra resources required Predictability Route depends on the current topology Route to destination is always the same When to Use Static Routes
In small networks that are not expected to grow significantly. To route traffic to and from stub networks. A stub network is a network accessed by a single route. When to Use Static Routes A stub router has only one upstream neighbor. Types of Static Routes The following types of IPv4 and IPv6 static routes will be discussed: Standard static route Default static route Summary static route Floating static route A brief explanation of each will follow but we will explain each one in detail. Dont worry about the terms and syntax until we get into the detail. Standard Static Route Standard static routes are useful when connecting to a specific remote network. R2(config)# ip route .2 When to Use Static Routes No need to use a dynamic routing protocol with R1 to reach /24. I can simply use a static route to reach the stub network. .1 Default Static Route Router(config)# ip route [exit-interface | ip-address ] Dont worry about the syntax right now A default static route is a catch-all route that matches all networks that is not in the routing table. It is configured with a /0 quad zero destination address. It creates a Gateway of Last Resort in the routing table When to Use Static Routes Default Static Routes Are Used When
Router# show ip route * - candidate default, U - per-user static route, o - ODR Gateway of last resort is to network List of directly connected networks and remote networks C /24 is directly connected, Serial0/0/0 L /32 is directly connected, Serial0/0/0 S /24 [1/0] via S /24 [1/0] via . . . S* /0 is directly connected, When to Use Static Routes When no other routes in the routing table match the packet destination IP address. In other words, when a more specific match does not exist. A common use is when connecting a company's edge router to the ISP network. When a stub router connects to only one upstream router. Default Static Route Example
All I need to know about are my directly connected networks. For all other networks, I can use a default static route going to R2. Default static routes are also commonly used with edge routers to connect to an ISP. .2 .1 When to Use Static Routes R1(config)# ip route Summary Static Route I have four static routes to reach the remote networks / /16. /16 /24 /16 R1 .2 /16 /16 R1(config)# ip route R1(config)# ip route R1(config)# ip route R1(config)# ip route Media Description: Create the media as indicated. Used to reduce the number of routing table entries. Multiple static routes can be summarized into a single static route if: The destination networks are contiguous and can be summarized into a single network address. The destination networks are all reachable using the same exit interface or next-hop IP address. Summary Static Route But to reduce the size of my routing table, I will replace those four static routes with one summary static route using a /14 subnet mask /16 /24 /16 .2 R1 /16 /16 R1(config)# no ip route R1(config)# no ip route R1(config)# no ip route R1(config)# no ip route R1(config)# R1(config)# ip route Media Description: Create the media as indicated. I can reach the HQ router 10.0.0.0/8 LAN using the private WAN link.
Im using EIGRP to exchange routes between sites. Floating Static Route Private WAN /30 /30 S0/0/0 S0/0/0 .2 .1 /8 Branch HQ S0/0/1 S0/0/1 .242 .226 /29 Internet /29 .241 .225 ISP Media Description: Create the media as indicated. Floating static routes are static routes used to provide a backup path to a primary static or dynamic route, in the event of a link failure. The floating static route is only used when the primary route is not available. However, if that link ever fails, I will use a floating static route connecting to the Internet as a backup. Since EIGRP has an administrativedistance of 90 I will configure the static route with a higher value Floating Static Route Private WAN /30 Branch(config)# ip route S0/0/1 100 /30 S0/0/0 S0/0/0 .2 .1 /8 Branch HQ S0/0/1 S0/0/1 .242 .226 /29 Internet /29 .241 .225 ISP Media Description: Create the media as indicated. Accomplished by configuring the static route with a higher administrative distance than the primary route. Administrative distance represents the trustworthiness of a route. If multiple paths to the destination exist, the router will choose the path with the lowest administrative distance. When to Use Static Routes
In small networks that are not expected to grow significantly. To route traffic to and from stub networks. To configure a catch-all route (i.e., default route) when no other route in the routing table match. To summarize other routes in one route. To make a backup route for a dynamic routing protocol. With a dynamic routing protocol such as a default route (coming) When to Use Static Routes Configuring Standard Static Routes Collecting and Filtering Using Cisco IOS
TSHOOT Slide Collecting and Filtering Using Cisco IOS To help find specific information, troubleshooters need to know how to use filtering techniques effectively. Filtering can be accomplished by using: Additional options / keywords to make the command more specific. Appending a pipe character (|) followed by one of the keywords include, exclude, or begin, and then a regular expression. Use regular expressions for more granular filtering. Adding redirect, tee, and append to show commands. NOTE: These may not work with Packet Tracer and my differ slightly with some IOS versions. Filtering With Additional Options / Keywords
TSHOOT Slide Filtering With Additional Options / Keywords To limit the output, enter a specific IP address, routing protocol or type of route as an option. R1# show ip route ? Hostname or A.B.C.DNetwork to display information about or hostname bgp Border Gateway Protocol (BGP) connected Connected dhcp Show routes added by DHCP Server or Relay eigrp Enhanced Interior Gateway Routing Protocol (EIGRP) isis ISO IS-IS list IP Access list mobile Mobile routes odr On Demand stub Routes ospf Open Shortest Path First (OSPF) profile IP routing table profile rip Routing Information Protocol (RIP) static Static routes summary Summary of all routes supernets-only Show supernet entries only track-table Tracked static table update-queue Queue of RIB updates vrf Display routes from a VPN Routing/Forwarding instance | Output modifiers R1# show ip route To limit the output of the show ip route command, you can enter a specific IP address on the command line as an option. You can also limit output to a specific routing protocol or type of route. Note that if gateway of last resort (default route) is present in the IP routing table, but no entry matches the IP address entered, the router responds with the % Subnet not in table message even though packets for that destination are forwarded using the gateway of last resort. Filtering With Additional Options / Keywords
TSHOOT Slide Filtering With Additional Options / Keywords R1# show ip route Routing entry for /30 Known via "connected", distance 0, metric 0 (connected, via interface) Redistributing via eigrp 1 Routing Descriptor Blocks: * directly connected, via Serial0/0/1 Route metric is 0, traffic share count is 1 R1# To limit the output of the show ip route command, you can enter a specific IP address on the command line as an option. You can also limit output to a specific routing protocol or type of route. Note that if gateway of last resort (default route) is present in the IP routing table, but no entry matches the IP address entered, the router responds with the % Subnet not in table message even though packets for that destination are forwarded using the gateway of last resort. To limit the output to a specific address: | keyword TSHOOT Slide R1# show running-config | ?
appendAppend redirected output to URL begin Begin with the line that matches exclude Exclude lines that match include Include lines that match redirectRedirect output to URL section Filter a section of output tee Copy output to URL R1# show running-config | | keyword Using pipes with include, exclude and begin keywords. s
TSHOOT Slide | keyword Using pipes with include, exclude and begin keywords. R1# show processes cpu | include IP Input %0.15%0.05% 0 IP Input R1# R1# show processes cpu| include IP Input ^ % Invalid input detected at '^' marker. There must always be at least one space preceding and following the pipe operator, otherwise it will not be accepted by the IOS CLI. s S1# show ip interface brief | exclude unassigned Interface IP-AddressOK? Method Status Protocol Vlan YES NVRAMup up S1# S1# show running-config | begin line vty line vty 0 4 transport input telnet ssh line vty 5 15 ! A more generic way of filtering is to use the a pipe operator | with Cisco IOS show commands, followed by one of the keywords include, exclude, or begin, and then a regular expression. Regular expressions are patterns that can be used to match strings in a piece of text. The pattern to be matched is case sensitive. The first example shows only the IP Input CPU process for R1. The second example shows only switch S1 interfaces that have an IP addressed assigned. The third example shows the running config for switch S1 beginning with the first output line that contains the character string line vty. The fourth example illustrates that, when using the pipe operator, there must always be at least one space preceding and following it, otherwise it will not be accepted by the IOS CLI. | keyword and Regular Expressions
TSHOOT Slide | keyword and Regular Expressions Using pipes with section and ^ R1# show running-config | section router eigrp router eigrp 1 network network network no auto-summary R1# R1# show processes cpu | include ^CPU|IP Input CPU utilization for five seconds: 1%/0%; one minute: 1%; five minutes: 1% %0.04%0.00% 0 IP Input Cisco IOS Software Release (12.3(2)T) introduced the section option, to display a specific section of lines from the configuration that matches a particular regular expression and any following associated lines. In the first example, the command show running-config | section router eigrp displays the EIGRP configuration section only. Using section router without the eigrp keyword will display all router sections configured (EIGRP, RIP, OSPF, etc.) . In the second example, the show processes cpu | include ^CPU|IP Input, the ^CPU only matches lines that start with the characters CPU. Lines that do not start with the "CPU" characters do not match the ^CPU regular expression, even if they actually contain the string "CPU" somewhere else. The same line uses the pipe operator | as part of a regular expression to signify a logical OR to also include lines that contain the string IP Input. The ^CPU keyword only matches lines that start with the characters CPU. Lines that do not start with the "CPU" characters do not match the ^CPU regular expression, even if they actually contain the string "CPU" somewhere else. The same line uses the pipe operator | as part of a regular expression to signify a logical OR to also include lines that contain the string IP Input. Topology We will assume all the interface have been configured with an IPv4 address and are in the up/up state. Verify the Routing Table of R1
Notice how R1 only has entries for its directly connected networks. It does not have any knowledge of any networks beyond its directly connected interfaces. For example, R1 has no knowledge of networks: /24 - LAN on R2 /24 - R2 to R3 /24 - LAN on R3 Verify the Routing Table of R1 R1# show ip route | begin Gateway Gateway of last resort is not set /16 is variably subnetted, 4 subnets, 2 masks C /24 is directly connected, Serial0/0/0 L /32 is directly connected, Serial0/0/0 C /24 is directly connected, GigabitEthernet0/0 L /32 is directly connected, GigabitEthernet0/0 R1# Media Description: Create as indicated. Verify the Routing Table of R2
R2 has no knowledge of networks: /24 - LAN on R1 /24 - LAN on R3 R2# show ip route | begin Gateway Gateway of last resort is not set /16 is variably subnetted, 4 subnets, 2 masks C /24 is directly connected, GigabitEthernet0/0 L /32 is directly connected, GigabitEthernet0/0 C /24 is directly connected, Serial0/0/0 L /32 is directly connected, Serial0/0/0 /24 is variably subnetted, 2 subnets, 2 masks C /24 is directly connected, Serial0/0/1 L /32 is directly connected, Serial0/0/1 R2# Media Description: Create as indicated. Verify the Routing Table of R3
R3 has no knowledge of networks: /24 - LAN on R2 /24 R1 to R2 /24 - LAN on R1 R3# show ip route | include C Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP C /24 is directly connected, Serial0/0/1 C /24 is directly connected, GigabitEthernet0/0 R3# Media Description: Create as indicated. Verify Connectivity to R2
R1# ping Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to , timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 12/13/16 ms R1# Media Description: Create as indicated. Verify Connectivity to R3
? R1# ping Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to , timeout is 2 seconds: ..... Success rate is 0 percent (0/5) R1# Media Description: Create as indicated. This network is not in the routing table and there is no IPv4 default route. The ip route Command Parameter Description network-add
ip route network-add subnet {ip-address | exit-intf [ip-address]} [distance] Parameter Description network-add Destination network address of the remote network to be added to the routing table. subnet Subnet mask of the remote network to be added to the routing table. Note: The subnet mask can be modified to summarize a group of networks ip-address Commonly referred to as the next-hop routers IP address. Typically used when connecting to a broadcast media (i.e., Ethernet) . Commonly creates a recursive lookup. exit-intf Use the outgoing interface to forward packets to the destination network. Also referred to as a directly attached static route. Typically used when connecting in a point-to-point configuration. distance Used to create a floating static route by setting an administrative distance that is higher than a dynamically learned route. Media Description: Create as indicated. ip route Command (for IPv4 static routes)
Simpler version : Router(config)# ip route network-address subnet-mask {ip-address | exit-interface} network-address: Destination network address of the remote network subnet-mask: Subnet mask of the remote network One or both of the following parameters must also be used: ip-address: Next-hop routers IP address. (Does not have to be next-hop.) exit-interface: Outgoing or exit interface The following parameters are used: network-address: Destination network address of the remote network to be added to the routing table. (Equivalent to the prefix parameter in the complete syntax.) subnet-mask: Subnet mask of the remote network to be added to the routing table. The subnet mask can be modified to summarize a group of networks. (Equivalent to the mask parameter in the complete syntax.) One or both of the following parameters must also be used: ip-address: Commonly referred to as the next-hop routers IP address. (Equivalent to the ip-address parameter in the complete syntax.) exit-interface: Outgoing interface that would be used in forwarding packets to the destination network. (Equivalent to the interface-type interface-number parameter in the complete syntax.) Note: The ip-address parameter is commonly referred to as the next-hop routers IP address. The actual next-hop routers IP address is commonly used for this parameter. However, the ip-address parameter could be any IP address, as long as it is resolvable in the routing table. This is beyond the scope of this course. Types of Standard Static Routes
Next Hop Static Route (With CEF.. Use this one) ip route network-add subnet ip-address Directly Attached Static Route ip route network-add subnet exit-intf Fully Specified Static Route ip route network-add subnet exit-intf ip-address Next Hop (IPv4) Static Routes
Router(config)# ip route network-address subnet-mask next-hop-ip-address A next hop static route uses an IPv4 address to in the ip route command to specify the next hop router. A next hop static route is recommended to be used over: Directly attached routes Fully specified static routes Directly attached and fully specified static routes should only be used when needed (coming) and CEF is disabled. CEF is enabled by default since IOS 12.2 We will cover directly attached and fully specified static routes, but it is best to use the next hop static route when CEF is enabled. Configure Next Hop Static Routes on R1
R1(config)# ip route R1(config)# ip route R1(config)# ip route R1(config)# Media Description: Create as indicated. Notice: R1 uses the same next-hop IPv4 address for all static routes. Next Hop Might be a Recursive Static Route
A recursive lookup means: 1. A network in the routing table looks for a match with the packets destination IP address. 2. The next-hop address is looked up in the routing table to find an exit-interface. Only recursive if CEF is disabled R1# show ip route | begin Gateway Gateway of last resort is not set /16 is variably subnetted, 5 subnets, 2 masks S /24 [1/0] via C /24 is directly connected, Serial0/0/0 L /32 is directly connected, Serial0/0/0 C /24 is directly connected, GigabitEthernet0/0 L /32 is directly connected, GigabitEthernet0/0 S /24 [1/0] via S /24 [1/0] via R1# Media Description: Create as indicated. Only if CEF disabled 2 1 Cisco Express Forwarding (CEF)
Recursive lookups are not a problem when CEF is enabled CEF is enabled by default beginning with IOS 12.2 CEF provides optimized lookup for efficient packet forwarding by using the FIB and Adjacency tables. Therefore, a next hop static route is resolved in one single lookup when CEF is enabled. With CEF enabled, it is recommended that next-hop routes are used. Alex Zinins Routing Table Principles
I know about my remote networks but it is not my responsibility if R2 and R3 know about their remote networks. Principle 1: Every router makes its decision alone, based on the information it has in its own routing table. R1 has three static routes in its routing table and makes forwarding decisions based solely on the information in the routing table. R1 does not consult the routing tables in any other routers, nor does it know whether those routers have routes to other networks. Making each router aware of remote networks is the responsibility of the network administrator. Principle 1: Every router makes its decision alone, based on the information it has in its own routing table. Principle 2: The fact that one router has certain information in its routing table does not mean that other routers have the same information. Principle 3: Routing information about a path from one network to another does not provide routing information about the reverse, or return, path. Configuring Next Hop Static Routes on R2
R2(config)# ip route R2(config)# ip route R2(config)# end R2# *Feb 21 17:56:16.231: %SYS-5-CONFIG_I: Configured from console by console up R2# show ip route /16 is variably subnetted, 5 subnets, 2 masks C /24 is directly connected, GigabitEthernet0/0 L /32 is directly connected, GigabitEthernet0/0 C /24 is directly connected, Serial0/0/0 L /32 is directly connected, Serial0/0/0 S /24 [1/0] via /24 is variably subnetted, 2 subnets, 2 masks C /24 is directly connected, Serial0/0/1 L /32 is directly connected, Serial0/0/1 S /24 [1/0] via Media Description: Create Syntax Checker. Configuring Next Hop Static Routes on R3
R3(config)# ip route R3(config)# ip route R3(config)# ip route R3(config)# end R3# show ip route /24 is subnetted, 3 subnets S [1/0] via S [1/0] via S [1/0] via /24 is variably subnetted, 2 subnets, 2 masks C /24 is directly connected, Serial0/0/1 L /32 is directly connected, Serial0/0/1 /24 is variably subnetted, 2 subnets, 2 masks C /24 is directly connected, GigabitEthernet0/0 L /32 is directly connected, GigabitEthernet0/0 R3# Media Description: Create Syntax Checker. Directly Attached Static Routes
Router(config)# ip route network-address subnet-mask exit-interface When CEF is not enabled, a directly attached static route avoids the recursive lookup problem on point-to-point networks. It allows the routing table to resolve the exit interface in a single search, instead of two searches. Typically used with point-to-point serial interfaces. Note: Next-hop static routes are recommended when CEF is enabled. Configure Directly Attached Static Routes
R1(config)# ip route s0/0/0 R1(config)# ip route s0/0/0 R1(config)# ip route s0/0/0 R1(config)# Media Description: Create as indicated. This is an alternative method for configuring static routes on a point-to-point network. Static routes with a next-hop address recommended when CEF is enabled. Verify the Routing Table of R1
Note (covered more later): Although the routing table entry indicates directly connected, the administrative distance of the static route is still 1. Only a directly connected interface can have an admin. distance of 0. Verify the Routing Table of R1 R1# show ip route | begin Gateway Gateway of last resort is not set /16 is variably subnetted, 5 subnets, 2 masks S /24 is directly connected, Serial0/0/0 C /24 is directly connected, Serial0/0/0 L /32 is directly connected, Serial0/0/0 C /24 is directly connected, GigabitEthernet0/0 L /32 is directly connected, GigabitEthernet0/0 S /24 is directly connected, Serial0/0/0 S /24 is directly connected, Serial0/0/0 R1# Media Description: Create as indicated. Directly Attached Static Routes on R2
R2(config)# ip route s0/0/0 R2(config)# ip route s0/0/1 R2(config)# ^Z R2# *Feb 21 18:04:37.207: %SYS-5-CONFIG_I: Configured from console by console R2# show ip route Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2 i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2 ia - IS-IS inter area, * - candidate default, U - per-user static route o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP + - replicated route, % - next hop override Gateway of last resort is not set /16 is variably subnetted, 5 subnets, 2 masks C /24 is directly connected, GigabitEthernet0/0 L /32 is directly connected, GigabitEthernet0/0 C /24 is directly connected, Serial0/0/0 L /32 is directly connected, Serial0/0/0 S /24 is directly connected, Serial0/0/0 /24 is variably subnetted, 2 subnets, 2 masks C /24 is directly connected, Serial0/0/1 L /32 is directly connected, Serial0/0/1 S /24 is directly connected, Serial0/0/1 Media Description: Create Syntax Checker. Directly Attached Static Routes on R3
R3(config)# ip route s0/0/1 R3(config)# ip route s0/0/1 R3(config)# ip route s0/0/1 R3(config)# ^Z R3# *Feb 21 18:01:14.055: %SYS-5-CONFIG_I: Configured from console by console R3# show ip route Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2 i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2 ia - IS-IS inter area, * - candidate default, U - per-user static route o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP + - replicated route, % - next hop override Gateway of last resort is not set /24 is subnetted, 3 subnets S is directly connected, Serial0/0/1 S is directly connected, Serial0/0/1 S is directly connected, Serial0/0/1 /24 is variably subnetted, 2 subnets, 2 masks C /24 is directly connected, Serial0/0/1 L /32 is directly connected, Serial0/0/1 /24 is variably subnetted, 2 subnets, 2 masks C /24 is directly connected, GigabitEthernet0/0 L /32 is directly connected, GigabitEthernet0/0 Media Description: Create Syntax Checker. Fully Specified Static Routes
Router(config)# ip route network-address subnet-mask exit-interface next-hop-ip-address A static route with just an exit-interface will not work on multi-access networks such as Ethernet because there may be multiple next-hops. A fully specified static IPv4 route is can be used when: CEF is disabled The exit interface is a mutli-access network (Ethernet) Note: CEF is enabled by default beginning with IOS 12.2, so a static route with a next hop address is recommended. Fully Specified Static Routes on R1
Media Description: Create as indicated. R1(config)# ip route G0/ R1(config)# ip route G0/ R1(config)# ip route G0/ R1(config)# Required when CEF is disabled and on a multi-access network. Verify the Routing Table of R1
R1# show ip route | begin Gateway Gateway of last resort is not set /16 is variably subnetted, 5 subnets, 2 masks S /24 [1/0] via , Gigabitethernet0/1 C /24 is directly connected, Gigabitethernet0/1 L /32 is directly connected, Gigabitethernet0/1 C /24 is directly connected, GigabitEthernet0/0 L /32 is directly connected, GigabitEthernet0/0 S /24 [1/0] via , Gigabitethernet0/1 S /24 [1/0] via , Gigabitethernet0/1 R1# Media Description: Create as indicated. Fully Specified Static Routes on R2
R2(config)# ip route s0/0/ R2(config)# ip route s0/0/ R2(config)# ^Z R2# *Feb 21 18:07:06.915: %SYS-5-CONFIG_I: Configured from console by console R2# show ip route Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2 i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2 ia - IS-IS inter area, * - candidate default, U - per-user static route o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP + - replicated route, % - next hop override Gateway of last resort is not set /16 is variably subnetted, 5 subnets, 2 masks C /24 is directly connected, GigabitEthernet0/0 L /32 is directly connected, GigabitEthernet0/0 C /24 is directly connected, Serial0/0/0 L /32 is directly connected, Serial0/0/0 S /24 [1/0] via , Serial0/0/0 /24 is variably subnetted, 2 subnets, 2 masks C /24 is directly connected, Serial0/0/1 L /32 is directly connected, Serial0/0/1 S /24 [1/0] via , Serial0/0/1 Media Description: Create Syntax Checker. Fully Specified Static Routes on R3
R3(config)# ip route s0/0/ R3(config)# ip route s0/0/ R3(config)# ip route s0/0/ R3(config)# ^Z R3# *Feb 21 18:07:51.319: %SYS-5-CONFIG_I: Configured from console by console R3# show ip route Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2 i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2 ia - IS-IS inter area, * - candidate default, U - per-user static route o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP + - replicated route, % - next hop override Gateway of last resort is not set /24 is subnetted, 3 subnets S [1/0] via , Serial0/0/1 S [1/0] via , Serial0/0/1 S [1/0] via , Serial0/0/1 /24 is variably subnetted, 2 subnets, 2 masks C /24 is directly connected, Serial0/0/1 L /32 is directly connected, Serial0/0/1 /24 is variably subnetted, 2 subnets, 2 masks C /24 is directly connected, GigabitEthernet0/0 L /32 is directly connected, GigabitEthernet0/0 Media Description: Create Syntax Checker. View only static routes in the routing table
R1# show ip route static | begin Gateway Gateway of last resort is not set /16 is variably subnetted, 5 subnets, 2 masks S /24 [1/0] via S /24 [1/0] via S /24 [1/0] via R1# Media Description: Create as indicated. Verify a Specific Entry in the Routing Table
R1# show ip route Routing entry for /24 Known via "static", distance 1, metric 0 Routing Descriptor Blocks: * Route metric is 0, traffic share count is 1 R1# Media Description: Create as indicated. Verify the Static Route Configuration in the running-config
R1# show running-config | section ip route ip route ip route ip route R1# Media Description: Create as indicated. Verify the Static Routing Settings of R2
R2# show ip route static Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2 i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2 ia - IS-IS inter area, * - candidate default, U - per-user static route o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP + - replicated route, % - next hop override Gateway of last resort is not set /16 is variably subnetted, 5 subnets, 2 masks S /24 [1/0] via S /24 [1/0] via R2# R2# show ip route Routing entry for /24 Known via "static", distance 1, metric 0 Routing Descriptor Blocks: * Route metric is 0, traffic share count is 1 R2# show running-config | section ip route ip route ip route Media Description: Create Syntax Checker. Verify the Static Routing Settings of R3
R3# show ip route static Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2 i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2 ia - IS-IS inter area, * - candidate default, U - per-user static route o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP + - replicated route, % - next hop override Gateway of last resort is not set /24 is subnetted, 3 subnets S [1/0] via S [1/0] via S [1/0] via R3# R3# show ip route Routing entry for /24 Known via "static", distance 1, metric 0 Routing Descriptor Blocks: * Route metric is 0, traffic share count is 1 R3# show running-config | section ip route ip route ip route ip route Media Description: Create Syntax Checker. Configuring a Default Static Route
ip route {ip-address | exit-intf [ip-address]} Parameter Description Matches any network address. Matches any subnet mask. ip-address Commonly referred to as the next-hop routers IP address. Typically used when connecting to a broadcast media (i.e., Ethernet) . Commonly creates a recursive lookup. exit-intf Use the outgoing interface to forward packets to the destination network. Also referred to as a directly attached static route. Typically used when connecting in a point-to-point configuration. Media Description: Create as indicated. Configuring a Default Static Route
R1(config)# ip route R1(config)# Media Description: Create as indicated. Commonly used in every network to have at least one route to send packets when the destination IP address doesnt match a more specific route in the routing table. Used along with dynamic routing protocols (later) If a default route is not used and there is not a match in the routing table, then the packet is dropped. Verifying the Routing Table of R1
R1# show ip route static Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2 i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2 ia - IS-IS inter area, * - candidate default, U - per-user static route o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP + - replicated route, % - next hop override Gateway of last resort is to network S* /0 is via R1# Media Description: Create as indicated. Configuring IPv6 Static Routes IPv6 Address Notation One Hex digit = 4 bits 2001:0DB8:AAAA:1111:0000:0000:0000:0100/64 2001 : 0DB8 : AAAA : 1111 : 0000 : 0000 : 0000 : 0100 16 bits 1 16 bits 2 16 bits 3 16 bits 4 16 bits 5 16 bits 6 16 bits 7 16 bits 8 IPv6 addresses are 128-bit addresses represented in: Eight 16-bit segments or hextets (not a formal term) Hexadecimal (non-case sensitive) between 0000 and FFFF Separated by colons Reading and subnetting IPv6 is easier than IPv4! Rule 1:Leading 0s Two rules for reducing the size of written IPv6 addresses. The first rule is: Leading zeroes in any 16-bit segment do not have to be written. 2001 : 0DB8 : 0001 : 1000 : 0000 : 0000 : 0ef0 : bc00 2001 :DB8 :1 : 1000 :0 :0 :ef0 : bc00 2001 : 0DB8 : 010d : 000a : 00dd : c000 : e000 : 0001 2001 :DB8 :10d :a : dd : c000 : e000 :1 2001 : 0DB8 : 0000 : 0000 : 0000 : 0000 : 0000 : 0500 2001 :DB8 :0 :0 :0 :0 :0 :500 If any 16-bit segment has fewer than four hexadecimal digits, it is assumed that the missing digits are leading zeroes. Rule 2: Double colon :: equals 00000000
The second rule can reduce this address even further: Any single, contiguous string of one or more 16-bit segmentsconsisting of all zeroes can be represented with a double colon. FE80 : 0000 : 0000 : 0000 : 0000 : 0000 : 0000 : 0001 FE80 : :1 FE80::1 Second Rule First Rule Network Prefixes IPv4, the prefixthe network portion of the addresscan beidentified by a dotted decimal netmask or bitcount. or /24 IPv6 prefixes are always identified by bitcount (prefix length). Prefix length notation: 3ffe:1944:100:a::/64 bits The address is followed by a forward slash and a decimal number indicating how many of the first bits of the address are the prefix bits. Global Unicast Address (GUA)
Global Routing Prefix Subnet ID Interface ID Range:2000::/ :: to 3FFF::/ :: 001 IANAs allocation of IPv6 address space in 1/8th sections Global unicast addresses are similar to IPv4 addresses Routable Unique Typical Global Unicast Address and Why We Love IPv6!
IPv4 Unicast Address /? Network portion Subnet portion Host portion 32 bits IPv6 Global Unicast Address /48 /64 16-bit Fixed Subnet ID Global Routing Prefix Interface ID 128 bits 64-bit Interface ID =18 quintillion (18,446,744,073,709,551,616) devices/subnet 16-bit Subnet ID = 65,536 subnets 3 1 4 /64 Global Unicast Addresses and the 3-1-4 rule 16 bits 16 bits
/48 /64 16 bits 16 bits 16 bits 16 bits 16 bits 16 bits 16 bits 16 bits Global Routing Prefix Subnet ID Interface ID 3 1 4 2001 : 0DB8 : AAAA : 1111 : 0000 : 0000 : 0000 : 0100 3 + 1 = 4 (/64): 4 2001:0DB8:AAAA:1111:0000:0000:0000:0100/64 2001:0DB8:AAAA:1111::100/64 Subnetting IPv6 and Why We REALLY Love IPv6
Just increment by 1 in Hexadecimal: 2001:0DB8:AAAA:0000::/64 2001:0DB8:AAAA:0001::/64 2001:0DB8:AAAA:0002::/64 2001:0DB8:AAAA:000A::/64 Valid abbreviation is to remove the 3 leading 0s from thefirst shown quartet 2001:0DB8:AAAA:1::/64 3-1-4 Rule Enabling IPv6 Unicast Routing
The ipv6 unicast-routing global configuration command must be configured to enable the router to forward IPv6 packets and participate static/dynamic IPv6 routing. Media Description: Create as indicated. R1(config)# ipv6 unicast-routing R1(config)# Verify the IPv6 Routing Table of R1
Notice how R1 only has entries for its directly connected networks. R1 has no knowledge of networks: 2001:DB8:ACAD:2::/64 - LAN on R2 2001:DB8:ACAD:5::/64 - R2 to R3 2001:DB8:ACAD:3::/64 - LAN on R3 Verify the IPv6 Routing Table of R1 R1# show ipv6 route C :DB8:ACAD:1::/64 [0/0] via GigabitEthernet0/0, directly connected L :DB8:ACAD:1::1/128 [0/0] via GigabitEthernet0/0, receive C :DB8:ACAD:4::/64 [0/0] via Serial0/0/0, directly connected L :DB8:ACAD:4::1/128 [0/0] via Serial0/0/0, receive L FF00::/8 [0/0] via Null0, receive R1# Media Description: Create as indicated. Verify the IPv6 Routing Table of R2
R2 has no knowledge of networks: 2001:DB8:ACAD:1::/64 - LAN on R1 2001:DB8:ACAD:3::/64 - LAN on R3 R2# show ipv6 route C :DB8:ACAD:2::/64 [0/0] via GigabitEthernet0/0, directly connected L :DB8:ACAD:2::1/128 [0/0] via GigabitEthernet0/0, receive C :DB8:ACAD:4::/64 [0/0] via Serial0/0/0, directly connected L :DB8:ACAD:4::2/128 [0/0] via Serial0/0/0, receive C :DB8:ACAD:5::/64 [0/0] via Serial0/0/1, directly connected L :DB8:ACAD:5::2/128 [0/0] via Serial0/0/1, receive L FF00::/8 [0/0] via Null0, receive Media Description: Create as indicated. Verify the IPv6 Routing Table of R3
R3 has no knowledge of networks: 2001:DB8:ACAD:2::/64 - LAN on R2 2001:DB8:ACAD:4::/64 R1 to R2 2001:DB8:ACAD:1::/64 - LAN on R1 R3# show ipv6 route C :DB8:ACAD:3::/64 [0/0] via GigabitEthernet0/0, directly connected L :DB8:ACAD:3::1/128 [0/0] via GigabitEthernet0/0, receive C :DB8:ACAD:5::/64 [0/0] via Serial0/0/1, directly connected L :DB8:ACAD:5::1/128 [0/0] via Serial0/0/1, receive L FF00::/8 [0/0] via Null0, receive R3# Media Description: Create as indicated. Verify Connectivity from R1 to R2
R1# ping 2001:DB8:ACAD:4::2 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 2001:DB8:ACAD:4::2, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 12/30/96 ms R1# Media Description: Create as indicated. Note: The curriculum also uses the ping ipv6 command. The ipv6 is optional. No connectivity from R1 to the R3 LAN
? R1# ping ipv6 2001:DB8:ACAD:3::1 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 2001:DB8:ACAD:3::1, timeout is 2 seconds: % No valid route for destination Success rate is 0 percent (0/1) R1# Media Description: Create as indicated. This network is not in the routing table and there is no IPv6 default route. Configuring an IPv6 Static Route
Router(config)# ipv6 route ipv6-prefix/prefix-length {exit-intf | ipv6-address} Parameter Description ipv6-prefix Destination IPv6 network address of the remote network to be added to the routing table. /prefix-length Prefix length of the remote network to be added to the routing table. Note: Can be modified to summarize a group of networks exit-intf Use the outgoing interface to forward packets to the destination network. ipv6-address Commonly referred to as the next-hop routers IPv6 address. Media Description: Create as indicated. Types of IPv6 Static Routes
Most of parameters are identical to the IPv4 version of the command. ip = ipv4 ipv6 = ipv6 IPv6 static routes can also be implemented as: Standard IPv6 static route Default IPv6 static route Summary IPv6 static route Floating IPv6 static route Types of Standard IPv6 Static Routes
Next Hop Static Route ipv6 route ipv6-prefix/prefix-length ipv6-address Directly Attached Static Route ipv6 route ipv6-prefix/prefix-length exit-intf Fully Specified Static Route ipv6 route ipv6-prefix/prefix-length exit-intf ipv6-address Configure Next Hop Static IPv6 Routes
Media Description: Create as indicated. R1(config)# ipv6 route 2001:DB8:ACAD:2::/ :DB8:ACAD:4::2 R1(config)# ipv6 route 2001:DB8:ACAD:5::/ :DB8:ACAD:4::2 R1(config)# ipv6 route 2001:DB8:ACAD:3::/ :DB8:ACAD:4::2 R1(config)# Verifying an IPv6 Next Hop Route
R1# show ipv6 route C :DB8:ACAD:1::/64 [0/0] via GigabitEthernet0/0, directly connected L :DB8:ACAD:1::1/128 [0/0] via GigabitEthernet0/0, receive S :DB8:ACAD:2::/64 [1/0] via 2001:DB8:ACAD:4::2 S :DB8:ACAD:3::/64 [1/0] C :DB8:ACAD:4::/64 [0/0] via Serial0/0/0, directly connected L :DB8:ACAD:4::1/128 [0/0] via Serial0/0/0, receive S :DB8:ACAD:5::/64 [1/0] L FF00::/8 [0/0] via Null0, receive R1# 1 2 Only necessary if CEF is disabled Media Description: Create as indicated. Configure Next Hop Static IPv6 Routes
R2(config)#ipv6 route 2001:DB8:ACAD:1::/ :DB8:ACAD:4::1 R2(config)#ipv6 route 2001:DB8:ACAD:3::/ :DB8:ACAD:5::1 R2(config)#exit R2# R2#show ipv6 route S :DB8:ACAD:1::/64 [1/0] via 2001:DB8:ACAD:4::1 C :DB8:ACAD:2::/64 [0/0] via GigabitEthernet0/0, directly connected L :DB8:ACAD:2::1/128 [0/0] via GigabitEthernet0/0, receive S :DB8:ACAD:3::/64 [1/0] via 2001:DB8:ACAD:5::1 C :DB8:ACAD:4::/64 [0/0] via Serial0/0/0, directly connected L :DB8:ACAD:4::2/128 [0/0] via Serial0/0/0, receive C :DB8:ACAD:5::/64 [0/0] via Serial0/0/1, directly connected L :DB8:ACAD:5::2/128 [0/0] via Serial0/0/1, receive L FF00::/8 [0/0] via Null0, receive Media Description: Create Syntax Checker. Configure Next Hop Static IPv6 Routes
R3(config)#ipv6 route 2001:DB8:ACAD:2::/ :DB8:ACAD:5::2 R3(config)#ipv6 route 2001:DB8:ACAD:4::/ :DB8:ACAD:5::2 R3(config)#ipv6 route 2001:DB8:ACAD:1::/ :DB8:ACAD:5::2 R3(config)#exit R3#show ipv6 route S :DB8:ACAD:1::/64 [1/0] via 2001:DB8:ACAD:5::2 S :DB8:ACAD:2::/64 [1/0] C :DB8:ACAD:3::/64 [0/0] via GigabitEthernet0/0, directly connected L :DB8:ACAD:3::1/128 [0/0] via GigabitEthernet0/0, receive S :DB8:ACAD:4::/64 [1/0] C :DB8:ACAD:5::/64 [0/0] via Serial0/0/1, directly connected L :DB8:ACAD:5::1/128 [0/0] via Serial0/0/1, receive L FF00::/8 [0/0] via Null0, receive R3# Media Description: Create Syntax Checker. Directly Attached Static IPv6 Routes on R1
Media Description: Create as indicated. R1(config)# ipv6 route 2001:DB8:ACAD:2::/64 s0/0/0 R1(config)# ipv6 route 2001:DB8:ACAD:5::/64 s0/0/0 R1(config)# ipv6 route 2001:DB8:ACAD:3::/64 s0/0/0 R1(config)# This is an alternative method for configuring static routes on a point-to-point network. Next-hop address recommended when CEF is enabled. Verify the Routing Table of R1
R1# show ipv6 route C :DB8:ACAD:1::/64 [0/0] via GigabitEthernet0/0, directly connected L :DB8:ACAD:1::1/128 [0/0] via GigabitEthernet0/0, receive S :DB8:ACAD:2::/64 [1/0] via Serial0/0/0, directly connected S :DB8:ACAD:3::/64 [1/0] C :DB8:ACAD:4::/64 [0/0] L :DB8:ACAD:4::1/128 [0/0] via Serial0/0/0, receive S :DB8:ACAD:5::/64 [1/0] L FF00::/8 [0/0] via Null0, receive R1# Media Description: Create as indicated. Directly Attached Static IPv6 Routes
R2(config)#ipv6 route 2001:DB8:ACAD:1::/64 s0/0/0 R2(config)#ipv6 route 2001:DB8:ACAD:3::/64 s0/0/1 R2(config)#exit R2#show ipv6 route IPv6 Routing Table - default - 9 entries Codes: C - Connected, L - Local, S - Static, U - Per-user Static route B - BGP, R - RIP, I1 - ISIS L1, I2 - ISIS L2 IA - ISIS interarea, IS - ISIS summary, D - EIGRP, EX - EIGRP external ND - ND Default, NDp - ND Prefix, DCE - Destination, NDr - Redirect O - OSPF Intra, OI - OSPF Inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2 ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2 S :DB8:ACAD:1::/64 [1/0] via Serial0/0/0, directly connected C :DB8:ACAD:2::/64 [0/0] via GigabitEthernet0/0, directly connected L :DB8:ACAD:2::1/128 [0/0] via GigabitEthernet0/0, receive S :DB8:ACAD:3::/64 [1/0] via Serial0/0/1, directly connected C :DB8:ACAD:4::/64 [0/0] L :DB8:ACAD:4::2/128 [0/0] via Serial0/0/0, receive C :DB8:ACAD:5::/64 [0/0] L :DB8:ACAD:5::2/128 [0/0] via Serial0/0/1, receive L FF00::/8 [0/0] via Null0, receive R2# Media Description: Create Syntax Checker. Directly Attached Static IPv6 Routes
R3(config)#ipv6 route 2001:DB8:ACAD:2::/64 s0/0/1 R3(config)#ipv6 route 2001:DB8:ACAD:4::/64 s0/0/1 R3(config)#ipv6 route 2001:DB8:ACAD:1::/64 s0/0/1 R3(config)#exit R3#show ipv6 route IPv6 Routing Table - default - 8 entries Codes: C - Connected, L - Local, S - Static, U - Per-user Static route B - BGP, R - RIP, I1 - ISIS L1, I2 - ISIS L2 IA - ISIS interarea, IS - ISIS summary, D - EIGRP, EX - EIGRP external ND - ND Default, NDp - ND Prefix, DCE - Destination, NDr - Redirect O - OSPF Intra, OI - OSPF Inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2 ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2 S :DB8:ACAD:1::/64 [1/0] via Serial0/0/1, directly connected S :DB8:ACAD:2::/64 [1/0] C :DB8:ACAD:3::/64 [0/0] via GigabitEthernet0/0, directly connected L :DB8:ACAD:3::1/128 [0/0] via GigabitEthernet0/0, receive S :DB8:ACAD:4::/64 [1/0] C :DB8:ACAD:5::/64 [0/0] L :DB8:ACAD:5::1/128 [0/0] via Serial0/0/1, receive L FF00::/8 [0/0] via Null0, receive R3# Media Description: Create Syntax Checker. Fully Specified Static IPv6 Routes on R1
Similar to IPv4 topology, a fully specified static IPv6 route is can be used when: CEF is disabled The exit interface is a mutli-access network (Ethernet) CEF is enabled by default beginning with IOS 12.2, so a static route with a next hop address is recommended. In IPv6, a fully specified route is required when the next-hop address is a link-local address. Media Description: Create as indicated. Link-local Unicast 10 bits Remaining 54 bits /64 64 bits Interface ID
xx xxxx Interface ID FE80::/10 EUI-64, Random or Manual Configuration Range:FE80::/ :: to FEBF::/ :: Link-Local Communications
Link-local unicast Link-Local Communications Used to communicate with other devices on the link. Are NOT routable off the link (network). Only have to be unique on the link. Are not included in the IPv6 routing table. An IPv6 device must have at least a link-local address. Used by: Hosts to communicate to the IPv6 network before it has a global unicast address. Routers link-local address is used by hosts as the default gateway address. Adjacent routers to exchange routing updates IOS uses EUI-64 to Create Link-Local Addresses
Wait! Two Link-Locals are the same! G0/0 S0/0/0 G0/1 Router#show interface gigabitethernet 0/0 GigabitEthernet0/0 is up, line protocol is up Hardware is CN Gigabit Ethernet, address is fc c3e0 (bia fc c3e0) Router#show ipv6 interface brief GigabitEthernet0/0 [up/up] FE80::FE99:47FF:FE75:C3E0 2001:DB8:ACAD:1::1 GigabitEthernet0/1 [up/up] FE80::FE99:47FF:FE75:C3E1 2001:DB8:ACAD:2::1 Serial0/0/ [up/up] 2001:DB8:ACAD:3::1 R1# EUI-64 FF:FE = EUI-64 (most likely) Serial interfaces will use a MAC address of an Ethernet interface. Configuring Static Link-Local Addresses
G0/0 FE80::1 Configuring StaticLink-Local Addresses S0/0/0 FE80::1 G0/1 FE80::1 R1 Static addresses are more easily remembered and recognizable. Router(config)#interface gigabitethernet 0/0 Router(config-if)#ipv6 address fe80::1 ? link-localUse link-local address Router(config-if)#ipv6 address fe80::1 link-local Router(config-if)#exit Router(config)#interface gigabitethernet 0/1 Router(config)#interface serial 0/0/0 Router(config-if)# Link-Local Addresses only have to be unique on the link! Exit-interface required when link-local address is used as next-hop address
R1(config)# ipv6 route 2001:db8:acad:2::/64 fe80::2 % Interface has to be specified for a link-local nexthop R1(config)# ipv6 route 2001:db8:acad:2::/64 s0/0/0 fe80::2 R1(config)# fe80::2 can uniquely exist on any interface fe80::2 must be on a directly connected interface (link local) The exit-interface is required to tell the router which exit-interface to use. Verify the Static Route on R1
R1(config)# ipv6 route 2001:db8:acad:2::/64 s0/0/0 fe80::2 R1(config)# end R1#show ipv6 route static | begin 2001:DB8:ACAD:2::/64 S :DB8:ACAD:2::/64 [1/0] via FE80::2, Serial0/0/0 Media Description: Create as indicated. Verify the Routing Table of R1
R1# show ipv6 route static S :DB8:ACAD:2::/64 [1/0] via 2001:DB8:ACAD:4::2 S :DB8:ACAD:3::/64 [1/0] S :DB8:ACAD:5::/64 [1/0] R1# Media Description: Create as indicated. Verify a Specific Entry in the Routing Table
R1# show ipv6 route 2001:db8:acad:3:: Routing entry for 2001:DB8:ACAD:3::/64 Known via "static", distance 1, metric 0 Route count is 1/1, share count 0 Routing paths: 2001:DB8:ACAD:4::2 Last updated 15:28:05 ago R1# Media Description: Create as indicated. Verify the Static Route Configuration
R1# show running-config | section ipv6 route ipv6 route 2001:DB8:ACAD:2::/ :DB8:ACAD:4::2 ipv6 route 2001:DB8:ACAD:3::/ :DB8:ACAD:4::2 ipv6 route 2001:DB8:ACAD:5::/ :DB8:ACAD:4::2 R1# Media Description: Create as indicated. Configuring a Default IPv6 Static Route
Router(config)# ipv6 route ::/0 {ipv6-address | exit-intf} Parameter Description ::/0 Matches any IPv6 prefix regardless of IPv6 mask. ipv6-address Commonly referred to as the next-hop routers IPv6 address. Typically used when connecting to a broadcast media (i.e., Ethernet) . Commonly creates a recursive lookup. exit-intf Use the outgoing interface to forward packets to the destination network. Also referred to as a directly attached static route. Typically used when connecting in a point-to-point configuration. Media Description: Create as indicated. Configuring a Default Static IPv6 Route
Media Description: Create as indicated. R1(config)# ipv6 route ::/0 2001:DB8:ACAD:4::2 R1(config)# Verifying the Routing Table of R1
R1# show ipv6 route static IPv6 Routing Table - default - 6 entries Codes: C - Connected, L - Local, S - Static, U - Per-user Static route S ::/0 [1/0] via 2001:DB8:ACAD:4::2 R1# Media Description: Create as indicated. Verifying Connectivity to the R3 LAN
R1# ping 2001:0DB8:ACAD:3::1 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 2001:DB8:ACAD:3::1, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 28/28/28 ms R1# Media Description: Create as indicated. Classful Addressing Classful Network Addressing
In 1981, RFC 790 and RFC 791 described an IPv4classification system for 3 different sizes of networks. Class A (large), B(medium), and C(small) addresses were defined with a specific format for the high order bits. With classful IP addressing, the subnet mask of a network address could be determined by the first three bits of the address. Media Description: Create as indicated. 0xxxxxxx 10xxxxxx 10 110xxxxx 110 1110xxxx 1110 1111xxxx 1111 Class A Networks 255 .0 1st Octet 2nd Octet 3rd Octet 4th Octet
Always starts with binary 0: 0xxxxxxx Decimal equivalent: 0 127 Network Host Subnet mask 255 .0 Media Description: Create as indicated. Class B Networks 255 .255 .0 1st Octet 2nd Octet 3rd Octet 4th Octet
Always starts with binary 10: 10xxxxxx Decimal equivalent: 128 191 Network Host Subnet mask 255 .255 .0 Media Description: Create as indicated. Class C Networks 255 .255 .0 1st Octet 2nd Octet 3rd Octet 4th Octet
Always starts with binary 110: 110xxxxx Decimal equivalent: 192 223 Network Host Subnet mask 255 .255 .0 Media Description: Create as indicated. Class D and E Class D Multicast addresses begin with 1110.
Multicast addresses are used to identify a group of hosts that are part of a multicast group. Routing protocols, such as RIPv2, EIGRP, and OSPF use designated multicast addresses (RIP = , EIGRP = , OSPF , and ). Class E Reserved IP addresses begin with 1111 These addresses were reserved for experimental and future use. Classful Routing Updates
Classful routing protocols, such as RIPv1, only need to propagate the network address of known routes. Updates do not need to include the subnet mask. The receiving router examined the value of the first octet in the network address. Routing protocols since RIPv1 (and IGRP) are classless. Classless routing protocols send the network address and the subnet mask in the routing update. RIPv2 OSPF EIGRP IS-IS BGP Classful Routing Updates
When R2 receives the update, it applies the receiving interface subnet mask (/24) to the update and adds to the routing table. Media Description: Figure 1: Use the media from E R1 sends an update to R2. It sends because the advertised subnet belongs to the same major classful network as the outgoing interface. Classful Routing Updates
R2 sends an update to R3. R2 summarizes subnets /24, /24, and /24 into the major classful network Media Description: Figure 1: Use the media from E When R3 receives the update it applies the classful mask for a class B network. R3 adds /16 to its routing table. Classful IP Address Allocation = Inefficient
RFCs 790 and 791 resulted in a tremendous waste of address space. Class C(192 223) # of possible networks: 2,097,152 # of Hosts/Net:254 Max. # Hosts: 532,676,608 Class A( ) # of possible networks: 126 # of Hosts/Net:16,777,214 Max. # Hosts: 2,113,928,964 Media Description: Create the media as follows. Class B(128 191) # of possible networks: 16,384 # of Hosts/Net:65,534 Max. # Hosts: 1,073,709,056 Classless Inter-Domain Routing = Efficient
In 1993, RFC 1517 replaced the classful RFCs and classes (A, B, and C) became obsolete. Using CIDR, network updates include a subnet mask (a.k.a. network prefix, or prefix length) such as /8, /19, etc. Class C(192 223) # of possible networks: 2,097,152 # of Hosts/Net:254 Max. # Hosts: 532,676,608 Class A( ) # of possible networks: 126 # of Hosts/Net:16,777,214 Max. # Hosts: 2,113,928,964 Media Description: Create the media as follows. Class B(128 191) # of possible networks: 16,384 # of Hosts/Net:65,534 Max. # Hosts: 1,073,709,056 /8 ( )16,777,216 host addresses /9 ( )8,388,608 host addresses /10 ( )4,194,304 host addresses /11 ( )2,097,152 host addresses /12 ( )1,048,576 host addresses /13 ( )524,288 host addresses /14 ( )262,144 host addresses /15 ( )131,072 host addresses /16 ( )65,536 host addresses /17 ( )32,768 host addresses /18 ( )16,384 host addresses /19 ( )8,192 host addresses /20 ( )4,096 host addresses /21 ( )2,048 host addresses /22 ( )1,024 host addresses /23 ( )512 host addresses /24 ( )256 host addresses /25 ( )128 host addresses /26 ( )64 host addresses /27 ( )32 host addresses /28 ( )16 host addresses /29 ( )8 host addresses /30 ( )4 host addresses /31 ( )2 host addresses /32 ( )Host Route ISPs no longer restricted to three classes. Can now allocate a large range of network addresses based on customer requirements ISPs can now more efficiently allocate address space using any prefix length, starting with /8 and larger (i.e., /8, /9, /10, etc.). Blocks of IP addresses can be assigned to a network based on the requirements of the customer, ranging from a few hosts to hundreds or thousands of hosts. Classless Inter-Domain Routing = Efficient
CIDR also reduces the size of routing tables and manages the IPv4 address space more efficiently using: Route summarization (prefix aggregation) Routes are summarized into a single route to help reduce the size of routing tables such as when one summary static route replaces several specific static route statements. Summary routes can be configured by both static routes and classless routing protocols. Supernetting Summarizes multiple network addresses with a mask that is smaller than the classful mask. Note: A supernet is always a route summary, but a route summary is not always a supernet. Media Description: Create the media as follows. Summarizing Supernet Routes
ISP1 has four customers, and that each customer has a variable amount of IP address space. Customer A /23 RA /23 Customer B /23 RB /23 Media Description: Create the following media. ISP1 ISP2 /22 Customer C /22 RC /21 Customer D /21 RD Summarizing Supernet Routes
The address space of the four customers can be summarized into one advertisement to ISP2 ( /20) This type of route is known as a supernet route. Customer A /23 RA /23 Customer B /23 RB /23 /20 Media Description: Create the following media. ISP1 ISP2 /22 Customer C /22 RC /21 Customer D /21 RD Calculating a Summary Route
List the networks in binary format. Customer A( ): Customer B( ): Customer C( ) : Customer D( ): Calculating a Summary Route
List the networks in binary format. Count the number of far left matching bits. This identifies the prefix length or subnet mask for the summarized route. Copy the matching bits and then add zero bits to the rest of the address to determine subnet prefix. Customer A( ): Customer B( ): Customer C( ) : Customer D( ): /20 Summarizing Routes Creating smaller routing tables makes the routing table lookup process more efficient. Fewer routes to search. Summary CIDR routes can be configured using static routes. If one static route can be used instead of multiple static routes, the size of the routing table is reduced. In many cases, a single static route can be used to represent dozens, hundreds, or even thousands of routes. Media Description: Create the following media. For Example: Six Static Routes (more later)
/16 R1 .1 R1(config)# ip route R1(config)# ip route R1(config)# ip route R1(config)# ip route R1(config)# ip route R1(config)# ip route R1(config)# Media Description: Create the following media. Replaced with One Summary Static Route
R1(config)# no ip route R1(config)# no ip route R1(config)# no ip route R1(config)# no ip route R1(config)# no ip route R1(config)# no ip route R1(config)# R1(config)# ip route Media Description: Create the following media. Classless Routing Updates
R2 summarizes networks /16, /16, /16, and /16, and advertise a supernet summary static route /14 to R3. /14 Media Description: Figure 1: Use the media from E R3 then installs the supernet route /14 in its routing table. Fixed-Length Subnet Masking (FLSM)
/16 subnetted (FLSM) using /24 With FLSM (traditional subnetting), the same number of addresses is allocated for each subnet. If all the subnets have the same requirements for the number of hosts, these fixed size address blocks would be sufficient. However, most often that is not the case. FLSM Example The following network can be subnetted using a /27 subnet mask. This would create subnets with increments of 32, therefore: Building A: /27 Building B: /27 Building C: /27 Building D: /27 This leaves four /27 subnets. Building A /27 Building B /27 Building C /27 Building D /27 Variable-Length Subnet Masking (VLSM)
With VLSM the subnet mask length varies depending on how many bits have been borrowed for a particular subnet, thus the variable part of variable-length subnet mask. VLSM subnetting is similar to traditional subnetting except that subnetting is not a single pass activity. With VLSM, the network is first subnetted, and then the subnets are subnetted again. This process can be repeated multiple times to create subnets of various sizes. VLSM Example The WAN interfaces of the routers are assigned the IP addresses and mask for the /30 subnets (2 hosts). In this example, the last subnet is subnetted into /30 subnets to accommodate WAN interfaces: R1 to R2: /30 R2 to R3: /30 R3 to R4: /30 This leaves 3 /27 and five /30 subnets. Building A /27 Building B /27 Building C /27 Building D /27 VLSM Example Configuring VLSM R1(config)# interface gigabitethernet 0/0
R1(config-if)# ip address R1(config-if)# exit R1(config)# interface serial 0/0/0 R1(config-if)# ip address R1(config-if)# end R1# R3(config)# interface gigabitethernet 0/0 R3(config-if)# ip address R3(config-if)# exit R3(config)# interface serial 0/0/0 R3(config-if)# ip address R3(config)# interface serial 0/0/1 R3(config-if)# ip address R3(config-if)# end R3# R2(config)# interface gigabitethernet 0/0 R2(config-if)# ip address R2(config-if)# exit R2(config)# interface serial 0/0/0 R2(config-if)# ip address R2(config)# interface serial 0/0/1 R2(config-if)# ip address R2(config-if)# end R2# R4(config)# interface gigabitethernet 0/0 R4(config-if)# ip address R4(config-if)# exit R4(config)# interface serial 0/0/0 R4(config-if)# ip address R4(config-if)# end R4# Always satisfy the requirements of the BIGGEST LAN FIRST
VLSM Trick Always satisfy the requirements of the BIGGEST LAN FIRST and then work your way down . Subnetting 10.0.0.0/8 to 10.0.0.0/16 Media Description:
Use the media from E A Subnetting the Subnet 10.1.0.0/16 to 10.1.0.0/24
Media Description: Use the media from E A Subnetting the Subnet 10.2.0.0/16 to 10.2.0.0/24
Media Description: Use the media from E B Subnetting the Subnet 10.3.0.0/16 to 10.3.0.0/28
Media Description: Use the media from E C Subnetting the Subnet 10.4.0.0/16 to 10.4.0.0/20
Media Description: Use the media from E D Route Summarization Summary Static Route Example #1
/16 /16 R1 /16 R1 needs to reach networks /16 through /16. Instead of configuring four separate static routes, summarize the networks and create a summary static route.. /16 Media Description: Create as indicated. Calculating a Route Summary
Media Description: Use the media from E A Calculating a Route Summary
Answer: 14 matching bits = /14 or Media Description: Use the media from E B Calculating a Route Summary
Answer: 14 matching bits = /14 or Media Description: Use the media from E C Answer: One Summary Static Route
/16 /16 /16 .1 R1 /16 R1 /16 R1(config)# ip route R1(config)# Media Description: Create as indicated. Summary Static Route Example #2
/24 /24 /24 /24 /24 R3#show ip route static | begin Gateway Gateway of last resort is not set /24 is subnetted, 3 subnets S [1/0] via S [1/0] via S [1/0] via R3# Media Description: Create as indicated. Summarize the Networks
Media Description: Use the media from E Configure Summary Static Route
/24 /24 /24 /24 /24 R3(config)#no ip route R3(config)#no ip route R3(config)#no ip route R3(config)# R3(config)#ip route Media Description: Create as indicated. Verify the Summary Static Route
/24 /24 /24 /24 /24 R3# show ip route static | begin Gateway Gateway of last resort is not set /22 is subnetted, 1 subnets S [1/0] via R3# Media Description: Create as indicated. Configuring IPv6 Summary Routes IPv6 Route Summarization
2001:DB8:ACAD:2::/64 2001:DB8:FEED:1::/64 2001:DB8:ACAD:1::/64 R1 :2 R1 2001:DB8:ACAD:3::/64 R1 2001:DB8:ACAD:4::/64 R1(config)#ipv6 route 2001:DB8:ACAD:1::/ :db8:feed:1::2 R1(config)#ipv6 route 2001:DB8:ACAD:2::/ :db8:feed:1::2 R1(config)#ipv6 route 2001:DB8:ACAD:3::/ :db8:feed:1::2 R1(config)#ipv6 route 2001:DB8:ACAD:4::/ :db8:feed:1::2 R1(config)# Media Description: Create as indicated. Verify the Routing Table of R1
2001:DB8:ACAD:2::/64 2001:DB8:FEED:1::/64 2001:DB8:ACAD:1::/64 R1 :2 R1 2001:DB8:ACAD:3::/64 R1 2001:DB8:ACAD:4::/64 R1# show ipv6 route static S :DB8:ACAD:1::/64 [1/0] via 2001:DB8:FEED:1::2 S :DB8:ACAD:2::/64 [1/0] S :DB8:ACAD:3::/64 [1/0] S :DB8:ACAD:4::/64 [1/0] R1# Media Description: Create as indicated. Identify Where the Addresses Differ
Media Description: Use the media from E A Convert the Section from Hex to Binary
Media Description: Use the media from E A Count the # of Left-Most Matching Bits
Media Description: Use the media from E A Add Zero Bits Convert the Binary Section Back to Hex
2001:0DB8:ACAD:0000::/61 or 2001:0DB8:ACAD:0::/61 2001:0DB8:ACAD::/61 Media Description: Use the media from E A Configuring an IPv6 Summary Address
2001:DB8:ACAD:2::/64 2001:DB8:FEED:1::/64 2001:DB8:ACAD:1::/64 R1 :2 R1 2001:DB8:ACAD:3::/64 R1 2001:DB8:ACAD:4::/64 R1(config)#no ipv6 route 2001:DB8:ACAD:1::/ :db8:feed:1::2 R1(config)#no ipv6 route 2001:DB8:ACAD:2::/ :db8:feed:1::2 R1(config)#no ipv6 route 2001:DB8:ACAD:3::/ :db8:feed:1::2 R1(config)#no ipv6 route 2001:DB8:ACAD:4::/ :db8:feed:1::2 R1(config)# R1(config)#ipv6 route 2001:DB8:ACAD::/ :db8:feed:1::2 Media Description: Create as indicated. Verify the Summary IPv6 Route
2001:DB8:ACAD:2::/64 2001:DB8:FEED:1::/64 2001:DB8:ACAD:1::/64 R1 :2 R1 2001:DB8:ACAD:3::/64 R1 2001:DB8:ACAD:4::/64 R1# show ipv6 route static S :DB8:ACAD::/61 [1/0] via 2001:DB8:FEED:1::2 R1# Media Description: Create as indicated. Configuring Floating Static Routes Floating Static Route I can reach the HQ router /8 LAN using the private WAN link. Im using EIGRP to exchange routes between sites. Private WAN /30 /30 S0/0/0 S0/0/0 .2 .1 /8 Branch HQ S0/0/1 S0/0/1 .242 .226 Media Description: Create the media as indicated. /29 Internet /29 .241 .225 ISP Floating Static Route However, if that link ever fails, I will use a floating static route connecting to the Internet as a backup. Since EIGRP has an administrativedistance of 90 I will configure the static route with a higher value Private WAN Branch(config)# ip route S0/0/1 100 /30 /30 S0/0/0 S0/0/0 .2 .1 /8 Branch HQ S0/0/1 S0/0/1 .242 .226 Media Description: Create the media as indicated. /29 Internet /29 .241 .225 ISP Advantages and Disadvantages
Backs up multiple interfaces / networks Requires a routing protocol. Encapsulation independent Dependent on convergence times Line protocol status independent Single router backup only Media Description: Create the media as indicated. Configuring a Floating Static Route to R3
Backup Media Description: Create as indicated. R1(config)# ip route R1(config)# ip route R1(config)# Verifying the Routing Table of R1
Only the primary (best) route is in the routing table. The backup route with the higher administrative distance is not in the routing table. Backup Media Description: Create as indicated. R1# show ip route static | begin Gateway Gateway of last resort is to network S* /0 [1/0] via R1# Verify the Path to the R3 LAN
Media Description: Create as indicated. R1# traceroute Type escape sequence to abort. Tracing the route to VRF info: (vrf in name/id, vrf out name/id) msec 4 msec 8 msec msec *12 msec R1# Simulate a Router Failure on R2
X X R2(config)# int s0/0/0 R2(config-if)# shutdown *Feb 21 16:33:35.939: %LINK-5-CHANGED: Interface Serial0/0/0, changed state to administratively down *Feb 21 16:33:36.939: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0/0, changed state to down R2(config-if)# int s0/0/1 R2(config-if)# *Feb 21 16:33:42.543: %LINK-5-CHANGED: Interface Serial0/0/1, changed state to administratively down *Feb 21 16:33:43.543: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0/1, changed state to down Media Description: Create as indicated. Verify the Default Route on R1
X X Primary Media Description: Create as indicated. R1# show ip route static | begin Gateway Gateway of last resort is to network S* /0 [5/0] via R1# Verify the Path to the R3 LAN
If the links come back up, the backup route is removed and the primary route with the lower default administrative distance of 1 is reinstalled into the routing table. X X Media Description: Create as indicated. R1# traceroute Type escape sequence to abort. Tracing the route to VRF info: (vrf in name/id, vrf out name/id) msec 4 msec * R1# Troubleshooting Static Routes Common IOS Troubleshooting Commands
Networks Fail Due to a failed interface. A service provider drops a connection. Links become oversaturated. An administrator enters a wrong configuration. Common IOS Troubleshooting Commands ping traceroute show ip route show ip interface brief show cdp neighbors detail Extended Ping R1# ping 192.168.2.1 source 172.16.3.1
Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to , timeout is 2 seconds: Packet sent with a source address of !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 28/28/28 ms R1# Media Description: Create as indicated. Traceroute R1# traceroute 192.168.2.1 Type escape sequence to abort.
Media Description: Create as indicated. R1# traceroute Type escape sequence to abort. Tracing the route to VRF info: (vrf in name/id, vrf out name/id) msec 4 msec 8 msec msec 12 msec * R1# Verify the Routing table
R1#show ip route | begin Gateway Gateway of last resort is not set /16 is variably subnetted, 5 subnets, 2 masks S /24 [1/0] via C /24 is directly connected, Serial0/0/0 L /32 is directly connected, Serial0/0/0 C /24 is directly connected, GigabitEthernet0/0 L /32 is directly connected, GigabitEthernet0/0 S /24 [1/0] via S /24 [1/0] via R1# Media Description: Create as indicated. Verify Interface Status
R1# show ip interface brief Interface IP-AddressOK? Method Status Protocol Embedded-Service-Engine0/0 unassignedYES unsetadministratively down down GigabitEthernet0/ YES manual up up GigabitEthernet0/ unassignedYES unsetadministratively down down Serial0/0/ YES manual up up Serial0/0/ unassignedYES unsetadministratively down down R1# Media Description: Create as indicated. Directly Connected Cisco Devices
R1# show cdp neighbors Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone, D - Remote, C - CVTA, M - Two-port Mac Relay Device ID Local Intrfce HoldtmeCapabilityPlatformPort ID netlab-cs Gig 0/ S I WS-C2960- Fas 0/1 R Ser 0/0/ R S ICISCO1941 Ser 0/0/0 R1# Media Description: Create as indicated. Troubleshooting Example #1
R1# ping source g0/0 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to , timeout is 2 seconds: Packet sent with a source address of ..... Success rate is 0 percent (0/5) R1# Media Description: Create as indicated. Troubleshooting Example #1
R1# traceroute Type escape sequence to abort. Tracing the route to VRF info: (vrf in name/id, vrf out name/id) msec 4 msec 8 msec msec 12 msec 12 msec msec 8 msec 8 msec msec 16 msec 20 msec msec 16 msec 16 msec msec 20 msec 24 msec Media Description: Create as indicated. Routing Loop! Verify the Routing Table of R2
R2# show ip route | begin Gateway Gateway of last resort is not set /16 is variably subnetted, 5 subnets, 2 masks C /24 is directly connected, GigabitEthernet0/0 L /32 is directly connected, GigabitEthernet0/0 C /24 is directly connected, Serial0/0/0 L /32 is directly connected, Serial0/0/0 S /24 is directly connected, Serial0/0/0 /24 is variably subnetted, 2 subnets, 2 masks C /24 is directly connected, Serial0/0/1 L /32 is directly connected, Serial0/0/1 S /24 [1/0] via R2# Media Description: Create as indicated. Verify the Running Configuration
R2# show running-config | section ip route ip route ip route R2# conf t R2(config)# no ip route R2(config)# ip route R2(config)# Media Description: Create as indicated. Troubleshooting Example #1
R1# ping source g0/0 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to , timeout is 2 seconds: Packet sent with a source address of !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 28/28/28 ms R1# Media Description: Create as indicated.