Subject: (ION) nhrp: fwd-ing requests across nbma?

From: "Paul Henri" <[email-masked]>
Date: 30 Jan 1998 10:37 EST

Hi,

I have a question about nhs operation when the co-resident router has
interfaces on dissimilar nbma networks. Suppose this [transit] router
has atm and frameRelay interfaces; Can the nhs fwd an nhrp resolution
request rx-ed on the frameRelay interface out the atm interface?
Consider the following:

nhc <----------> nhs <----------> nhs <----------> nhc
     frameRelay          atm           frameRelay

                  ^
                  |
             Can this nhs fwd the request?
             If the nhc's are on the same logical frameRelay network
             they may be able to establish an svc despite the fact
             that the routed path traverses an atm section.

Thanks,
pdh
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Paul Henri
[email-masked]
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From: Joel Halpern <[email-masked]>
Date: Fri, 30 Jan 1998 11:17:08 -0500 (EST)

>              that the routed path traverses an atm section.

No. 
In fact, if an NHS has two physical interfaces, even if they are the same
type, it MUST not forward the NHRP request unless it is also the switch,
and can therefore KNOW that they really are the same NBMA.  
So, the answer is no unless the NHS is also the SVC interworking unit in
the picture you have drawn.

(We have not specified the NHRP handling for FR SVCs, and for SVCs which
span ATM and FR, but those aught to work.  There are some interesting
encapsulation questions underneath that may need to be explored.)

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