lan emulation, ip switching and label switching › ~jain › bnr › ftp › b_ipsw.pdf · raj...
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Raj Jain1
LAN Emulation, IPLAN Emulation, IPSwitchingSwitching
and Label Switchingand Label SwitchingRaj Jain
Professor of Computer and Information SciencesThe Ohio State University
http://www.cis.ohio-state.edu/~jain/
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Raj Jain2
q LAN Emulationq Classical IP over ATMq Next Hop Resolution Protocol (NHRP)q Multiprotocol over ATM (MPOA)q IP Switching (Ipsilon)q Tag Switching (CISCO)q Multi-protocol label switching (MPLS)
OverviewOverview
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Raj Jain3
IP Forwarding:FundamentalsIP Forwarding:Fundamentals
q IP routers forward the packets towards the destinationsubnet
q On the same subnet, routers are not required.
q IP Addresses: 164.56.23.34Ethernet Addresses: AA-23-56-34-C4-56ATM : 47.0000 1 614 999 2345.00.00.AA....
To: 164.56.23.34 From: 164.56.43.96
A CR RR R
164.56.43 164.56.23
B
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Raj Jain4
LAN EmulationLAN Emulation
q LAN Emulation driver replaces Ethernet driver andpasses the networking layer packets to ATM driver.
q Each ATM host is assigned an Ethernet address.
q LAN Emulation Server translates Ethernet addressesto ATM addresses
q Hosts set up a VC and exchange packets
q All software that runs of Ethernet can run on LANE
ATM
IP
Ethernet
IP
LANE
ATM
IP
LANE
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Raj Jain5
LAN EmulationLAN EmulationLAN Emulation Server
ATM client BBridge
2. Client sendsmessages onthe VC
1. Client getsrecipient'saddress fromLES and sets-up a VC.
Broadcast/Unknown Server (BUS) Non-ATM client
4. Messages for non-ATMclients are forwardedthrough bridges
3. Messages forATM clients aredelivered directly.Switches
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Raj Jain6
ATM Virtual LANsATM Virtual LANsq Physical View
q Logical View
ATMSwitch
ATMSwitch
LANEServer B
LANEServer B
LANEServer A
LANEServer A
RouterRouterA1A1
B1B1
A2A2
B2B2
RouterRouterA1A1
A2A2
B1B1
B2B2
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Raj Jain7
IP Over ATMIP Over ATM
IP
ATM
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Raj Jain8
Classical IP Over ATMClassical IP Over ATM
q ATM stations are divided in to Logical IP Subnets(LIS)
q ATMARP server translates IP addresses to ATMaddresses.
q Each LIS has an ATMARP server for resolution
q IP stations set up a direct VC with the destination orthe router and exchange packets.
Router
A1
A2 B1
B2
ATMARPServer
ATMARPServer
LIS 1 LIS 2
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Raj Jain9
IP Multicast over ATMIP Multicast over ATMq Multicast Address Resolution Servers
(MARS)
q Internet Group Multicast Protocol (IGMP)
q Multicast group members send IGMP join/leave messages to MARS
q Hosts wishing to send a multicast send aresolution request to MARS
q MARS returns the list of addresses
q MARS distributes membership update informationto all cluster members
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Raj Jain10
Next Hop Resolution ProtocolNext Hop Resolution Protocolq Routers assemble packets ⇒ Slow
q NHRP servers can provide ATM address for the edgedevice to any IP host
q Can avoid routers if both source and destination areon the same ATM network.
ATM Network HostHost
NHRPServer
NHRPServer
NHRPServer
NHRPServer
Bridge
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Raj Jain11
Multiprotocol Over ATMMultiprotocol Over ATMq MPOA= LANE + “NHRP+”
q Extension of LANE
q Uses NHRP to find the shortcut to the next hop
q No routing (reassembly) in the ATM network
Next Hop Address Resolution
LAN Emulation
Multiprotocol Over ATM
Routing
Bridging
Multicast Address Resolution Server
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Raj Jain12
MPOA (Cont)MPOA (Cont)q LANE operates at layer 2
q RFC 1577 operates at layer 3
q MPOA operates at both layer 2 and layer 3 ⇒ MPOA can handle non-routable as well asroutable protocols
q Layer 3 protocol runs directly over ATM⇒ Can use ATM QoS
q MPOA uses LANE for its layer 2 forwarding
RNHS NHS
H HELAN1 ELAN2
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Raj Jain13
IP SwitchingIP Switchingq Developed by Ipsilon
q Routing software in every ATMswitch in the network
q Initially, packets are reassembled by the routingsoftware and forwarded to the next hop
q Long term flows are transferred to separate VCs.Mapping of VCIs in the switch ⇒ No reassembly
R R
SS
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Raj Jain14
IP Switching (Cont)IP Switching (Cont)q Flow-oriented traffic: FTP, Telnet, HTTP, Multimedia
q Short-lived Traffic: DNS query, SMTP, NTP, SNMP,request-response Ipsilon claims that 80% of packetsand 90% of bytes are flow-oriented.
q IP switching implemented as a s/w layer over an ATMswitch
q Ipsilon claims their Generic Switch ManagementProtocol (GSMP) to be 2000 lines, and Ipsilon FlowManagement Protocol (IFMP) to be only 10,000 linesof code
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Raj Jain15
Tag SwitchingTag Switchingq Proposed by CISCO
q Similar to VLAN tags
q Tags can be explicit or implicit L2 header
L2 Header Tag
q Ingress router/host puts a tag. Exit router strips it off.
H
R
R
R H
H
HUntaggedPacket Tagged packet
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Raj Jain16
Tag Switching (Cont)Tag Switching (Cont)q Switches switch packets based on labels.
Do not need to look inside ⇒ Fast.
q One memory reference compared to 4-16in router
q Tags have local significance⇒ Different tag at each hop (similar to VC #)
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Raj Jain17
Tag Switching (Cont)Tag Switching (Cont)q One VC per routing table entry
R164.107/16
<3>
R164.107/16
<2>
164.107/16<64>
164.107/16<5>
R164.107/16
<3>
643
2
5 3
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Raj Jain18
Alphabet SoupAlphabet Soupq CSR Cell Switched Router
q ISR Integrated Switch and Router
q LSR Label Switching Router
q TSR Tag Switching Router
q Multi layer switches, Swoters
q DirectIP
q FastIP
q PowerIP
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Raj Jain19
MPLSMPLSq Multiprotocol Label Switching
q IETF working group to developswitched IP forwarding
q Initially focused on IPv4 and IPv6.Technology extendible to other L3 protocols.
q Not specific to ATM. ATM or LAN.
q Not specific to a routing protocol (OSPF, RIP, ...)
q Optimization only. Labels do not affect the path.Only speed. Networks continue to work w/o labels
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Raj Jain20
Label FormatLabel Formatq Labels = Explicit or implicit L2 header
q TTL = Time to live
q CoS = Class of service
q SI = Stack indicator
L2 Header Label
Label CoS SI TTL20b 3b 1b 8b
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Raj Jain21
Label StacksLabel Stacksq Labels are pushed/popped
as they enter/leave MPLS domain
q Routers in the interior will use Interior GatewayProtocol (IGP) labels. Border gateway protocol (BGP)labels outside.
L2 Header Label 1 Label 2 Label n...
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Raj Jain22
MPLS: IssuesMPLS: Issuesq Loop prevention, detection, survival
q Multicast:Multiple entries in label information base
q Multipath: Streams going to the same destination butdifferent sources/port # may be assigned separatelabels.
q Host involvement: Label-enabled hosts will avoid firsthop reassembly
q Security: Label swapping may be terminated beforefirewall
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Raj Jain23
SummarySummary
q LANE allows current applications to run on ATMq Classical IP allows ARP using ATMARP serversq NHRP removes the need for routing in an ATM netq MPOA combines LANE and NHRP
q IP Switching: Traffic-based, per-hop VCs,downstream originated
q Tag switching: Topology based, one VC per route
q MPLS combines various features of IP switching,CSR, Tag switching, ARIS
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Raj Jain24
Summary (Cont)Summary (Cont)
LANE RFC1577 IP Switch
NHRP CSR
Tag
ARIS
MARS
MPOA
MPLS
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Raj Jain25
Key ReferencesKey Referencesq See http://www.cis.ohio-state.edu/~jain/refs/
ipoa_ref.htm and http://www.cis.ohio-state.edu/~jain/refs/ipsw_ref.htm
q "A Framework for Multiprotocol Label Switching",11/26/1997, http://www.internic.net/internet-drafts/draft-ietf-mpls-framework-02.txt
q Multiprotocol Label Switching (mpls) working groupat IETF. Email: [email protected]
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Raj Jain26
References (Cont)References (Cont)q ATM Forum, "MPOA V1.0," July 1997,
ftp://ftp.atmforum.com/pub/approved-specs/af-mpoa-0087.000.doc
q RFC 2332, "NBMA Next Hop Resolution Protocol(NHRP)", ftp://ftp.isi.edu/in-notes/rfc2322.txt ,2/6/98.
q RFC 2225, "Classical IP and ARP over ATM,"1/20/94, ftp://ftp.isi.edu/in-notes/rfc2225.txt
q LAN Emulation over ATM v1.0 Specification (Jan1995), ftp://ftp.atmforum.com/pub/approved-specs/af-lane-0021.000.ps