ipv6 introduction · ipv6 header l simpler l40 bytes (fixed size) lonly twice bigger than the older...
TRANSCRIPT
�.- Little bit of history�.- IPv6 Header�.- IPv6 Neighbor Discovery (ND)
Today’s content
�.- Little bit of history
Today’s content
� 1969 – Start of ARPANET� 1981 – IPv4 definitions and the RFC 791� 1983 – ARPANET adopts TCP/IP � 1990 – First studies about IPv4 address exhaustion� 1993 – Internet begins to be commercially exploited
- Increased discussion about a possible address depletion and the increase of the addess routing tables
Internet and the TCP/IP protocols
IPv4 Address exhaustion
� IPv4 = 4.294.967.296 addresses (*)� Initial distribution policy directions
§ Class Ao IBM o HPo AT&To MIT
§ Class B§ Class C§ Reserved Addresses
o DoDo US Armyo USPSo ........
IPv4 = 4.294.967.296 addresses NOT FULLY TRUE
IPv4 Address Exhaustion
Palliative Solutions§1992 - IETF started ROAD working group (ROuting and ADdressing).
§CIDR (RFC 4632)§End use of “classes” = appropriately sized blocks§Network addresses = prefix/length§Routing aggregation = the growth in the size of the routing tables
§DHCP§Dynamic address assignment
§NAT + RFC 1918 (Address Allocation for Private Internets)§Enable to connect an entire network with only one public address
Proposed solutions
N A T (Network Address TranslationAdvantages
• Reduces the need of public internet addresses• Facilitates the internal network address numbering• Hides the network topology• Only allows the packet entry to our network as a response to a request from the network
Disadvantages• Breaks the internet point-to-point model• Hinder the functioning of a number of applications• Not scalable• Increase the process load in the traduction device• False sense of security• Unable to trace the path of the packet• Prevents the use of security mechanisms such as IPSec• Limits of HW & SW
Solutions
Palliative Solutions: Fall of only 14%
Solutions
The measures discussed above generate more time to develop a new version of the IP protocol
•1992 - IETF make the IPng working group (IP Next Generation)•Main questions:
•Escalability•Security•Network configuration and management•QoS support•Movility•Routing policies•Transition
Solutions
Definitive solution
Solutions
Protocols closelyevaluated
•1998 Defined in RFC 2460 (now RFC 8200)•128 bits for addressing•Base header simplified•Extension headers•Flow identification data (QoS).•IPSEC mechanisms built into the protocol•Performs packet fragmentation/reassembly on the source and destination•NAT is not necessary, allowing point-to-point mechanisms that facilitate network configuration•....
IPv6
IPv4 Header
It’s integrated by 12 fixed fields. It may contain options or not, therefore it’s size can vary from 20 to 60 Bytes.
IPv6 Header
l Simplerl40 Bytes (fixed size)lOnly twice bigger than the older versionl
l More flexiblelExtensions through additional headersl
l More efficientlHeader overhead is minimizedlPacket processing cost is reduced
IPv6 Header
l Six fields from the IPv4 header were removed
IPv6 Header
l Six fields from the IPv4 header were removedl Four fields had it’s name and it’s location changed
1 12
2
3
3 4
4
IPv6 Header
l Six fields from the IPv4 header were removedl Four fields had it’s name and it’s location changedl The Flow Label field was enlarged
IPv6 Header
l Six fields from the IPv4 header were removedl Four fields had it’s name and it’s location changedl The Flow Label field was enlargedl Three fields were unchanged
IPv6 Header
more
lIt uses five types of ICMPv6 messages:lRouter Solicitation (RS) – ICMPv6 type 133;lRouter Advertisement (RA) – ICMPv6 type 134;lNeighbor Solicitation (NS) – ICMPv6 135;lNeighbor Advertisement (NA) – ICMPv6 type 136;lRedirect - ICMPv6 Type 137
lA value of 255 is set to the Hop Limit field.lIt can contain options:
lSource link-layer address.lTarget link-layer address.lPrefix Information.lRedirected header.lMTU
Neighbor Discovery
Neighbor Discovery (NS)lLink layer address discovering
lIt determines the link layer addressing of neighbors on the same link.lReplaces the ARP protocol.lIt uses multicast address “solicited-node” instead of broadcast.lThe host sends a NS message informing his MAC address and requests that of the neighbor.
lLink layer address discoveringlIt determines the link layer addressing of neighbors on the same link.lReplaces the ARP protocol.lIt uses multicast address “solicited-node” instead of broadcast.
lThe host sends a NS message informing his MAC address and requests that of the neighbor.lThe neighbor answers by sending a NA message informing his MAC address.
Neighbor Discovery (NA)
l Router and neighbor discoveringlFinds neighboring routers on the same link.lDetermines prefixes and parameters related to the address auto configuration.lIn IPv4, this function is held by the ARP request.lRouters send RA messages to the multicast address “all-nodes”
Neighbor Discovery (RA)
Hosts inquire with Router Solicitation messages to locate routers on an attached linkRouters which forward packets not addressed to them generate Router Advertisements immediately upon receipt of this message rather than at their next scheduled time
l.- Hosts will send to the ‘All Router IPv6 Multicast Address’ (FF02::2) l.- All layer 3 multicast addresses have a corresponding layer 2 mac address (33:33:xx:xx:xx:xx) where xx:xx:xx:xx are the last 32 bits of the layer 3 multicast address)
Router Solicitation (RS)
https://www.slideshare.net/kriz5/cisco-i-pv6labandtechtorialworkshop-v0
lRedirectlIt sends Redirect messages.lIt redirects a host to a more appropriate first hop router.lIt informs the originator host that the destination is on the same link.lThis mechanism is the same as the existing one in IPv4.
Neighbor Discovery (redirect)
Paquete IPv6
Somewhereelse
