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Re: Same global address on Multiple Interface of an IP6 node



> Can a single global address (say 2222::1111) be configured on multiple
> interfaces of a single ip6 node.

Yes, it can.  There are a few ways to accomplish this.  If all the 
interfaces are on the same lan, then you could have a "primary" and a 
"backup" interface.  If the interfaces are on different lans, you can run 
a dynamic routing protocol and advertise the address as being reachable 
through each physical interface on a node.  In this case, the address 
isn't really configured on the multiple interfaces per-se (you instead 
have a "virtual" interface which is assigned the IP address), but the 
result is any interface on the node may be used.  There are other methods 
which may be used as well.

> If so is there any specific purpose for doing that ??

Redundancy.  If one interface goes down, traffic will automatically switch 
to the another interface without disrupting existing connections.

> What about link-local address, how would it be used, if single link 
local
> address is configured on multiple interface of a same node.

I'm not sure it is particularly useful.  Link-local addresses are really 
intended to be used for bootstraping, configuration discovery, route table 
maintenance, and the like.  Most, if not all, of these protocols work on a 
per-interface basis.  I suppose it could allow an interface to act as a 
"hot standby" for another interface, automatically switching over if the 
primary interface fails.  But this would only work if the interfaces are 
on the same physical lan.  If they are on different lans, then the two 
interfaces are in different link-local scope zones and are treated as 
unique addresses.

Roy
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