Hi John,
On Nov 12, 2008, at 5:16 PM, John G. Scudder wrote:
GROW folks,
I'll be presenting draft-scudder-bmp-01 ("BGP Monitoring Protocol")
at the meeting in Minneapolis. Long-time GROW fans may remember
that the WG requested to make the -00 version a WG document way back
in 2005. It turned out that there were some major implementation
hurdles with the draft as written and it became moribund and never
did get issued as draft-ietf-grow.
Fast forward to present, there's been significant renewed interest
so we've dusted off the draft and modified the mechanism to make it
more implementor-friendly. I'm hoping that the WG would still,
after the long hiatus, like to adopt the draft.
I'm glad to see this draft has been resuscitated and I do support its
adoption.
A few questions:
1) The draft says the following in Section 2:
---snip---
If the peer is a "Global Instance Peer", this field is zero filled. If
the peer is a "L3VPN Instance Peer", it is set to the route
distinguisher of the particular L3VPN instance that the peer belongs to.
---snip---
I'm a little confused by the second sentence. Is that referring to
the case where a router is doing RFC 4364 "Option A" style eBGP with a
remote peer, or something else?
2) In Section 3, the draft talks about sources of routing information
(Adj-RIB-In or Loc-RIB) sent in Route Monitoring messages. Would it
be useful to have a bit in the BMP "Peer Flags" that indicates if the
path being sent in a RM message was retrieved pre- (Adj-RIB-In) or
post- (Loc-RIB) policies, so the receiver knows which he/she is
looking at?
3) How will BMP cope with BGP flap dampening being enabled on a BMP
source router? In other words, a router (configured as a BMP source)
receives a series of WITHDRAW's & UPDATE's that it is configured to
apply flap dampening on, suppressing re-advertisement of these updates
further into an AS. If the BMP source is forwarding messages from Adj-
RIB-In, would a BMP receiver see all incoming WITHDRAW's & UPDATE's
associated with a "flap" event, (even though these updates would have
been suppressed from further re-advertisement after flap dampening is
applied)? How would, or should, a BMP receiver know that flap
dampening is enabled and/or would be applied?
The reason I ask is perhaps this is more a question of the
'authenticity' of "monitoring data" at a BMP receiver with respect to
formulating what did (or could) have happened with a series of Updates
being propagated further within an AS? Or, perhaps there's another
answer?
-shane
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