Path Mtu Discovery For Ipv6; Ipv6 Neighbor Discovery; Ipv6 Neighbor Solicitation And Advertisement Messages - Cisco AP776A - Nexus Converged Network Switch 5020 Configuration Manual

Cisco mds 9000 family cli configuration guide - release 4.x (ol-18084-01, february 2009)

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Configuring IPv6 for Gigabit Ethernet Interfaces

S e n d d o c u m e n t a t i o n c o m m e n t s t o m d s f e e d b a c k - d o c @ c i s c o . c o m

Path MTU Discovery for IPv6

As in IPv4, path MTU discovery in IPv6 allows a host to dynamically discover and adjust to differences

in the MTU size of every link along a given data path. In IPv6, however, fragmentation is handled by the

source of a packet when the path MTU of one link along a given data path is not large enough to

accommodate the size of the packets. Having IPv6 hosts handle packet fragmentation saves IPv6 router

processing resources and helps IPv6 networks run more efficiently.

In IPv4, the minimum link MTU is 68 octets, which means that the MTU size of every link along a given

data path must support an MTU size of at least 68 octets.

In IPv6, the minimum link MTU is 1280 octets. We recommend using an maximum transmission unit

(MTU) value of 1500 octets for IPv6 links.

The IPv6 neighbor discovery process uses ICMP messages and solicited-node multicast addresses to

determine the link-layer address of a neighbor on the same network (local link), verify the reachability

of a neighbor, and keep track of neighboring routers.

A value of 135 in the Type field of the ICMP packet header identifies a neighbor solicitation message.

Neighbor solicitation messages are sent on the local link when a node wants to determine the link-layer

address of another node on the same local link. (See

link-layer address of another node, the source address in a neighbor solicitation message is the IPv6

address of the node sending the neighbor solicitation message. The destination address in the neighbor

solicitation message is the solicited-node multicast address that corresponds to the IPv6 address of the

destination node. The neighbor solicitation message also includes the link-layer address of the source

OL-18084-01, Cisco MDS NX-OS Release 4.x

47-7.) When a node wants to determine the

Cisco MDS 9000 Family CLI Configuration Guide

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