From: Brian McGahan (bmcgahan@internetworkexpert.com)
Date: Wed Nov 28 2007 - 15:11:19 ART
It really depends on how you configure it. If OSPFv3 is using
multicast then you don't need a link local mapping to establish adjacency,
however when you learn a prefix it still recurses to the remote link-local
address. This means that you don't need to resolve link-local to learn the
route, but to actually send traffic to the route you do. If OSPFv3 is using
unicast, such as in the network type non-broadcast, the hellos are unicast
to the remote link-local address, which implies that link-local resolution
is required. BGP can work the same way as well.
If you peer with the remote global unicast address in BGP you don't
need a link-local mapping in order to learn routes, but once again the
routes themselves recurse to the remote link-local address, so to actually
send traffic to the prefix you do need the mapping. Likewise you could peer
with the remote link-local address only, which would remove the requirement
for a mapping to the global address, but instead require a mapping to the
remote link-local address.
Design wise the best solution is to always use point-to-point
interfaces for WAN links, then you completely avoid any issues related to
layer 3 to layer 2 resolution. However since we know that the CCIE lab exam
isn't a design test, you'd be better off knowing all 5 out of 4 ways to
configure the technology in question ;)
HTH,
Brian McGahan, CCIE #8593 (R&S/SP/Security)
bmcgahan@internetworkexpert.com
Internetwork Expert, Inc.
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> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Gupta, Gopal (NWCC)
> Sent: Wednesday, November 28, 2007 9:06 AM
> To: keith tokash; ccielab@groupstudy.com
> Subject: RE: IPv6 to DLCI mapping rule of thumb?
>
> As far as I have seen that OSPF requires the DLCI mapping of Link Local
> address to form neighborship and not other protocol
> Gurus any comments please....
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> keith tokash
> Sent: Wednesday, November 28, 2007 19:46
> To: ccielab@groupstudy.com
> Subject: IPv6 to DLCI mapping rule of thumb?
> Importance: Low
>
> Is there a rule of thumb for mapping link-local and/or global ipv6
> addresses to dlcis? I had thought both were necessary, but in a lab
> last night BGP achieved neighbor status without link-local being mapped
> (I was pretty tired).
>
> With a few exceptions, secrecy is deeply incompatible with democracy and
> with science.
> --Carl Sagan
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