The Routing Over Large Clouds Mailing List Archive by date

[jhalpern@us.Newbridge.com (Joel Halpern)]

I was just re-reading the NHRP draft, and thinking about some routing issues.
I am concerned about the use of the Source NBMA and Source Protocol Address
fields in the request.

Two cases come to mind:
1) The routing protocol is BGP.  The outward path does not have a policy
   restriction on shortcuts, but the assymettric reverse path does.  
   (Someone is being very "careful" about what paths they advertise.)  As 
   currently defined, the destination can learn the sources ATM address,
   and attempt to establish the VC to him anyway, avoiding the fact that 
   an NHRP request in the reverse direction would hit a policy terminator
   who would respond with his own address.
2) The station issuing the query is doing so on behalf of a bridge-like
   device which is the actual ingress to the ATM.  (Yes, there is some
   clever layering here.  Come to MPOA for fun and confusion.)  As such,
   the internetwork source address is the routing entity issuing the 
   query request.  However, in order to cause VCs to match up properly,
   the ATM level source address is that of the bridge-like device which
   will make use of this information.  Therefore,
   A) caching this pairing will not produce good information
   B) sending the response over an existing short-cut will be problematic.

Comments?
Thank you,
Joel M. Halpern				jhalpern@newbridge.com
Newbridge Networks Inc.