Re: Final rolc minutes

[Andrew Smith <[e-mail]>]

> From [e-mail] Mon Apr 29 12:21:41 1996
> Date: Mon, 29 Apr 1996 14:59:40 +0500
> From: [e-mail] (Joel Halpern)
> To: [e-mail]
> Subject: Re: Final rolc minutes

Joel,

> 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?

1) I guess "learning" and "routing" don't mix too well ...
2) Don't do that!

> Thank you,
> Joel M. Halpern				[e-mail]
> Newbridge Networks Inc.
> 

Andrew


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