Re: Why MSDP?

["Stephen Sprunk" <ssprunk@cisco.com>]

Thus spake "Ali Boudani" <aboudani@irisa.fr>
> > One reason: the timescales for change of active source indications
> > are much different than BGP was designed to carry.  BGP wants to
> > carry data that doesn't change very often, e.g. see route dampening.
> > Sources can come and go at an arbitrary rate, so the rate of change
> > of the information is potentially much higher.
>
> can you specifie more, why should the timescales for change active
> source indications are much different.???

BGP route advertisements are measured in days or months; MSDP source
advertisements are measured in seconds.

Also, the traffic patterns for the two are completely different.  BGP
only needs updates when networks (dis)connect to each other or when
there is a critical link failure -- things that are fairly rare and
relatively long-lived.  MSDP needs an SA for every new mcast flow
originated, and they can be as small as a single packet and rarely last
more than a few hours.

S

     |          |         Stephen Sprunk, K5SSS, CCIE #3723
    :|:        :|:        Network Design Consultant, ANS
   :|||:      :|||:       RCDN2 in Richardson, TX
.:|||||||:..:|||||||:.    Email: ssprunk@cisco.com