Subject: Re: NHRP question

From: Tim Salo <[email-masked]>
Date: Fri, 21 Nov 1997 15:02:29 -0600 (CST)

> Date: Thu, 20 Nov 1997 11:48:16 -0800
> From: [email-masked] (Rajeev Gupta)
> To: [email-masked]
> Subject: Re: NHRP question
> 	[...]
> Routing of ATM connections to anycast addresses occurs based on
> PNNI, which finds the topologically closest ATM endpoint within
> the specified scope of the anycast address. Since this is completely
> independent of L3 (IP) addressing and routing mechanisms, it is
> upto the network administrator to assign L3 (IP) and ATM (unicast
> and anycast) addresses appropriately and to configure the NHCs
> with the correct (anycast) ATM address of serving NHSs.

It's too bad we don't have a rule about not requiring a human to
coordinate the configurations of two seperate systems in order
for things to work.

> Even if the NHC establishes a connection to the "wrong" NHS, the
> NHS will typically forward the resolution request to the correct
> NHS (assuming that L3 routing is working correctly and the routing
> tables in routers/NHSs are consistent) which will then send the
> resolution reply to the NHC.A

Assuming that, for example, the ATM network isn't supporting multiple
virtual private networks, (perhaps all using 10.x.x.x addresses).

-tjs

---

From: Joel Halpern <[email-masked]>
Date: Fri, 21 Nov 1997 17:24:52 -0500 (EST)

Clearly, VPNs is one obvious granularity where distinct anycast addresses
would be needed.  That is equally true with the LANE anycast address for
connecting to the LECS.  No-one objects to the fact that the spec does not
call that out as a case where anycast can not be used.  If an ATM
infrastructure is shared by several administrative organizations, anycast
can only be used for things which transcend individual organizations or
where they are willing to coordinate data.  So?

Anycast is a mechanism designed to make things work better/simpler in many
customer configurations.  It does not work for all cases.  It was put in
because it was obviously workable and useful sometimes.  I would actually
say that it is probably useable in "most" likely deployments.  But not
all.

There may be other cases we did not think of where it does not work.

Yours,
Joel M. Halpern                         [email-masked]
Newbridge Networks Inc.