RE: draft-ietf-l3vpn-mvpn-considerations-05 / Appendix A / sectionA.1.1.3

["NAPIERALA, MARIA H (ATTLABS)" <[e-mail]>]

Thomas,

> 
> Maria,
> 
> NAPIERALA, MARIA H (ATTLABS):
> >>     - ORIGINATOR_ID : updates of the value of this attributes do not
> >> "follow" PE advertisements, as the RR rewrite it when aggregating C-
> >> multicast routes having same NLRI; the advertisements made by
> different
> >> RRs may lead possibly to updates of the value of this attribute,
> given
> >> that each RR would set ORIGINATOR_ID to a value of its own
> >>
>  >
> > Regarding route *aggregation* the draft-ietf-l3vpn-2547bis-mcast-bgp-
> 08 only states the following:
> >
> >     "To further reduce the routing churn due to C-multicast routes
> changes
> >     a Route Reflector that re-advertises a C-multicast route SHOULD
> set
> >     the Next Hop field of the MP_REACH_NLRI attribute of the route to
> an
> >     IP address of the Route Reflector. Likewise, an ASBR that re-
> >     advertises a C-multicast route SHOULD set the Next Hop field of
> the
> >     MP_REACH_NLRI attribute of the route to an IP address of the
> ASBR."
> >
> > It states nothing about setting ORIGINATOR_ID to self on RR.
> 
> It also says:
> 
>       [...] C-multicast routes for a given (S,G) of a given MVPN
> originated by PEs that are clients of
>       a given Route Reflector are aggregated by the Route Reflector.
> [...]
> 

You omitted very important text from the same section 11.4 that precedes the one you quoted, namely:

  "Note that C-multicast routes are "de facto" aggregated by BGP. This
   is because the MCAST-VPN NLRIs advertised by multiple PEs, for a C-
   multicast route for a particular C-S and C-G (or a particular C-* and
   C-G) of a given MVPN are identical."

This is the route aggregation the text you quoted refers to. 

Regarding the routing *churn*, section 11.4 says further down that:

  ”To further reduce the routing churn due to C-multicast routes changes
   a Route Reflector that re-advertises a C-multicast route SHOULD set
   the Next Hop field of the MP_REACH_NLRI attribute of the route to an
   IP address of the Route Reflector."

Which, in fact, doesn’t reduce routing churn. 

Maria