# Neighbour Solicitation & Advertisement



## Priyaamaresh (Jun 12, 2012)

Hi,

How to enable Neighbour Solicitation and Neighbour Advertisement messages possible between two unix hosts (AIX and FreeBSD) using link-local IPv6 address? I have already Global address for both unix systems. Ping works only on Global IPv6 address and not on link-local IPv6 address.

Please help.


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## SirDice (Jun 12, 2012)

Keep in mind that link-local addresses are non-routable. Both hosts therefor need to be in the same broadcast domain.


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## Priyaamaresh (Jun 12, 2012)

*Neighbour Solicitation!!*

Hi,

Same broadcast domain needed for neighbour solicitation. Please explain me. Am now just starter of networking.


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## SirDice (Jun 12, 2012)

It means they both need to be on the same network, there cannot be a router between them. 
If you need to traverse one or more routers you'll need to use the global address.


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## Priyaamaresh (Jun 12, 2012)

*Neighbour Solicitation!!!*

Hi,

Both my unix systems are connected via ethernet cable. Hope they are in the same domain. Please reason out why they don't respond to neighbour solicitation.


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## SirDice (Jun 12, 2012)

Do a traceroute6(8) on the global address. If there are any "hops" in between it means there are routers between the two hosts. In that case you can't use the link-local addresses.


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## Priyaamaresh (Jun 12, 2012)

*Neighbour Solicitation!!*

Hi,

I did traceroute6 and got following output:

```
# traceroute6 -s 2010::5ef3:fcff:feb6:59bc 2010::214:5eff:feb8:2abf 64
traceroute6 to 2010::214:5eff:feb8:2abf (2010::214:5eff:feb8:2abf) from 2010::5ef3:fcff:feb6:59bc, 64 hops max, 64 byte packets
 1  2010::214:5eff:feb8:2abf  0.190 ms  0.081 ms  0.078 ms
```
Can you please explain me what they mean to and how to make respond to neighbour solicitation messages?


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## SirDice (Jun 12, 2012)

Ok, this tells me there are no routers in between.

It also tells me neighbor solicitation works, if it didn't work this would fail.


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## Priyaamaresh (Jun 12, 2012)

Could you please tell me about neighbour discovery? Neighbour discovery and neighbour advertisement are they different?


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## SirDice (Jun 12, 2012)

Priyaamaresh said:
			
		

> neighbour discovery and neighbour advertisement are they different?



Neighbor advertisement is just a small part of the neighbor discovery protocol. To some extent it basically replaces ARP (and a few other functions).

http://packetlife.net/blog/2008/aug/28/ipv6-neighbor-discovery/


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