IPV6 the work mechanism and principle of neighbor Discovery

IPV6 Neighbor Discovery and static neighbor designation

The topology map still shows the static, manually configured global unicast and link-local addresses on the current topology map.

So what did IPv6 neighbors find?

There is one command:

Show IPv6 neighbor

First on top of the R1, show IPv6 neighbor. It must be straight-connected R2.

I saw the first time all wrong, oh, ca01.1a44.0008 is R2, R1 is the beginning of ca00.

So here, the neighbor you see from this router is actually the link-local address of the direct-attached device, which is definitely not the address of the configured interface 2012::2/64 that unicast address.

Then look at the R2, both R1 and R3 's neighbors.

The meaning of each parameter:

Age:ipv6 life cycle, my understanding is a timer. And ARP that is somewhat similar, after aging, and then trigger resend update message to maintain the neighbor relationship. But the unit here is minutes. Then increment to add up to do the timer.

Link-layer Addr: This actually one eye can see, is to directly the neighbor's a MAC address. 48-bit, same as IPv4.

The Status:reach state means that the neighbour can reach. The stale state (default) means that the neighbor is unreachable within the last 30 minutes.

Interface: Out of interface. from which interface to learn to the address of the end.

Another problem is that the Cisco router supports adding static neighbor table entries to neighbor Discovery tables.

The question is, why is this function? What are the requirements behind this feature?

Cisco implemented the Add static Neighbor table entry because most IPV6 traffic generation devices do not support IPV6 NDP correctly. If a neighbor discovers that the table is not set up in a neighbor table, it cannot send IPV6 traffic to forward through the router. In order to be able to do compatibility, or a fault-tolerant function, this function is very necessary.

Add a static table entry neighbor by command IPv6 neighbor.

Router#ipv6 Neighbor Ipv6-address Interface hw-address

PS: This command is used globally.

Since it is a static table item, then the device must be passive to know that there is this information.

On top of the R1, there is already a R2 neighbor, but the network type is not a point-to-point type.

So I want to add as many as I can, even if the neighbor I added does not exist at all.

R1 before adding a neighbor: