The MPLS WG Archive

["chetan kumar s" <chetan.kumar@wipro.com>]

On Wed, 18 Jul 2001, Vikas D wrote:

Hi Vinod,
        LSR will not try to establish multiple sessions for the multiple
adjacencies under no conditions. The requirement for "An LSR MUST
advertise the same transport address in all Hellos" is due to the fact if
the LSR advertises diff transport address in diff hello adjacencies, the
role of the LSR will not be defined same on all adjacencies, it may be
active on one while on the other it may be passive. Now when the LSR is
passive on other adjacencies, the peer may try to establish the session,
which may result in setting up multiple session.

Hope this clears ur doubts..
Thanks
Chetan S


> All,
> 
> A small doubt in Section 2.5.2, "Transport Connection
> Establishment"
> of LDP RFC.  It says:
> 
>              .............snip..................
>  "An LSR MUST advertise the same transport address in all Hellos that
>   advertise the same label space.  This requirement ensures that two
>   LSRs linked by multiple Hello adjacencies using the same label
> spaces
>   play the same connection establishment role for each adjacency."
>              .............snip....................
> 
> 
> 
> Now, under what circumstances would two LSRs, having multiple
> hello adjacencies , using same label spaces on all adjacencies
> try to establish multiple TCP sessions?
> 
> Is this not already precluded by the following rule in the same
> section (Sec 2.5.2 of RFC 3036):
> 
>              .............snip..................
>  "  1. If LSR1 does not already have an LDP session for the exchange
>        of label spaces LSR1:a and LSR2:b it attempts to open a TCP
>        connection for a new LDP session with LSR2."
>              .............snip..................
> 
> 
> Thanks
> - Vikas
> 
> 
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