Cisco Nexus 7000 Series - Configuring Ipv6; Virtualization Support

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Cisco Nexus 7000 Series NX-OS Unicast Routing Configuration Guide, Release 4.x
OL-20002-02
Chapter 3 Configuring IPv6
Information About IPv6
Figure 3-14 IPv6 Neighbor Discovery—Neighbor Redirect Message
Note A router must be able to determine the link-local address for each of its neighboring routers in order to
ensure that the target address (the final destination) in a redirect message identifies the neighbor router
by its link-local address. For static routing, you should specify the address of the next-hop router using
the link-local address of the router. For dynamic routing, you must configure all IPv6 routing protocols
to exchange the link-local addresses of neighboring routers.
After forwarding a packet, a router sends a redirect message to the source of the packet under the
following circumstances:
• The destination address of the packet is not a multicast address.
• The packet was not addressed to the router.
• The packet is about to be sent out the interface on which it was received.
• The router determines that a better first-hop node for the packet resides on the same link as the
source of the packet.
• The source address of the packet is a global IPv6 address of a neighbor on the same link or a
link-local address.
Virtualization Support
IPv6 supports Virtual Routing and Forwarding instances (VRFs). VRFs exist within virtual device
contexts (VDCs). By default, Cisco NX-OS places you in the default VDC and default VRF unless you
specifically configure another VDC and VRF. For more information, see the Cisco Nexus 7000 Series
NX-OS Virtual Device Context Configuration Guide, Release 4.x and see Chapter 14, “Configuring
Layer 3 Virtualization.”
Router B Router A
Host H
IPv6 packet
Neighbor redirect packet definitions:
ICMPv6 Type = 137
Src = link-local address of Router A
Dst = link-local address of Host H
Data = target address (link-local
address of Router B), options
(header of redirected packet)
Note: If the target is a host, the target
address is equal to the destination
address of the redirect packet and
the options include the link-layer
address of the target host (if known).
Subsequent IPv6 packets
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