The Routing Over Large Clouds Mailing List Archive by date

["Robert G. Cole" <rgc@qsun.att.com>]

Dave,

Re: the NHRP draft, it reads:

>   If the NHRP request is triggered by a data packet, station S may
>   choose to dispose of the data packet while awaiting an NHRP reply in
>  one of the following ways:
>
>     (a)  Drop the packet
>     (b)  Retain the packet until the reply arrives and a more optimal
>          path is available
>     (c)  Forward the packet along the routed path toward D
>
>   The choice of which of the above to perform is a local policy matter,
>   though option (c) is the recommended default, since it may allow data
>   to flow to the destination while the NBMA address is being resolved.
>   Note that an NHRP request for a given destination MUST NOT be
>  triggered on every packet, though periodically retrying a request is
>   permitted.

If the normal routed path over the NBMA travels thru routers A, B, C and D,
where routers B and C are transit routers,  wouldn't this lead to
the generation of three seperate "short cut" link layer connections (in the
case of a connection-oriented NBMA like ATM) for the same packet?
For example, 
    - router A receives a packet and determines that it is to be forwarded
        to its NBMA interface.  it sends a NHRP request and forwards
        the packet to router B,
    - router B receives a packet and determines that it is to be forwarded
        to its NBMA interface.  it sends a NHRP request and forwards
        the packet to router C, etc
    - once the NHRP replies return to routers A, B and C, they each establish
        their own "short cut" connections to D.

If this is indeed the case, then option (c) above should be removed in favor
of one of the remaining two.  Am I missing out on something?

Thanks,

Bob Cole


Robert G. Cole
AT&T Business Multimedia Services, Technical Marketing
rgc@qsun.att.com              +1 908 949 1950 (voice)
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