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RE: Global BGP - 2001-06-23 - Vendor X's statement...

  • From: Chance Whaley
  • Date: Tue Jun 26 12:36:47 2001


Vendor X released a limited statement to their customers describing the
issue - and their view on it. The large incumbent vendor that we all
know and love has confirmed the issue, and released a "patch" to some of
their customers. Vendor X also went on to state that at no time did
their boxes crash, mis-forward, reset, or have any issue resulting from
the events of the past weekend.

>From Vendor X's statement:

1.	Another vendor's implementation of BGP contained a bug that caused
EBGP peers to leak
	CONFEDERATION information across AS boundaries, interpreted as
malformed AS_PATH
	announcements.

2.	Vendor X's implementation of BGP-4 fully complies with the BGP-4
specification (RFC 1771) and
	accordingly, terminates a BGP session to a BGP peer who forwards
malformed AS_PATH
	announcement.

3.	Unfortunately, this other vendor does not adhere to the standard in
the same manner and as a result,
	malformed AS_PATH announcements are propagated to other BGP peers. This
is contrary to
	RFC 1771. Vendor X believes that these vendors should modify their
implementation to adhere to
	the guidelines as stated per RFC 1771 (see section 6 - BGP Error
Handling).

4.	In light of the events of the past weekend and with input from a
number of the affected service
	providers (point #1 above), Vendor X has concluded that a review of our
BGP implementation is
	unnecessary at this time.


If you happen to be running Vendor X's software and think you may have
experienced the issue you can use the following to verify.

	ssh@vendor-x-119.chi03#sh ip bgp neighbor xxx.xxx.xxx.xx last

	BGP4: 86 bytes hex dump of packet received from neighbor that contains
Error

	ffffffff ffffffff ffffffff ffffffff 00560200
	00003bff ffffffff ffffffff ffffffff ffffff00
	2d0104fd e8005ac0 a8803a10 02060104 00010001
	02028000 02020200 ffffffff ffffffff ffffffff
	ffffffff 001318d0 f20118d0 c10e18d0 f20018d0


.chance
(not speaking for Vendor X in any way shape or form. Just passing along
info that I was sent.)




> -----Original Message-----
> From: owner-nanog@merit.edu [mailto:owner-nanog@merit.edu]On Behalf Of
> lucifer@lightbearer.com
> Sent: Monday, June 25, 2001 9:59 PM
> To: Jared Mauch
> Cc: lucifer@lightbearer.com; Brett Frankenberger; nanog@merit.edu
> Subject: Re: Global BGP - 2001-06-23
>
>
>
> Jared Mauch wrote:
> >
> > On Mon, Jun 25, 2001 at 02:38:32PM -0700,
> lucifer@lightbearer.com wrote:
> > > Can anyone verify whether Cisco still does BGP this way?
> (Propagate, then
> > > kill origionating session). If so, it rather clearly
> answers the question
> > > about how this managed to make it throughout the network...
> >
> > 	I'm fairly sure that is not the case anymore.
> >
> > > (For the record: I'm not trying to Cisco-bash here. All
> vendors have
> > > problems, and when you have a huge market share, your
> problems tend to
> > > show up much more obviously, when they appear. However,
> Cisco does still
> > > have a huge market share, meaning this affected a whole
> lot of people,
> > > if true... so, I'm curious).
> >
> > 	From what I can tell this time it was not ciscos fault.  It
> > appears that the vendor that had the problem just had an issue with
> > a specific "valid" announcement that others propogated to it.
>
> All I can say is that the only report I have had about what caused the
> whole mess to start was a Cisco BugID regarding a mangling
> done by some
> IOS versions on a particular sort of route update that made it invalid
> (or perhaps, "more invalid"). And if Cisco is no longer
> propagating routes
> before shutting down the source session, then we're back to
> wondering how
> this particular issue managed to cause flaps at the same time
> across at
> least 5 "big player" networks that I've had reports about (including 3
> by direct observation), at the same time. This person must
> have some pretty
> impressive connectivity, if they managed to get what appears
> to be well
> over a dozen routers at the absolute minimum, and more likely
> in the range
> of "hundreds" if the rumor volume is at all accurate, to each
> display the
> bug (since, if a bad announcement isn't propagated, it will
> never reach
> anything but the direct peers; thus, this person would have
> to be directly
> peered with every router that anyone saw flapping sessions to
> a customer).
>
> Now, I'll grant, it would be possible to do this, but for them to have
> hit just *our* network, they would have to be on 3 major carries in 3
> states, including some places that a normal class B-type
> announcer just
> isn't terribly likely to have a peering session.
>
> > 	What is interesting is one could use this to see what
> > providers are using vendor "X" at exchange points.
>
> Quite true. Though I suspect that in some cases, this might
> only tell you
> what routing code they use. Making too many inferences is
> probably unwise.
> Especially given the number of folks who thought they knew
> who "X" was,
> only to state their guess and come out wrong...
> --
> **************************************************************
> *************
> Joel Baker                           System Administrator -
> lightbearer.com
> lucifer@lightbearer.com
> http://www.lightbearer.com/~lucifer





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