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Re: Communities BCP [was: RE: BGP Path Filtering]
From: Danny McPherson <danny () tcb net>
Date: Fri, 16 May 2003 16:16:04 -0600
On 5/16/03 4:01 PM, "Stephen J. Wilcox" <steve () telecomplete co uk> wrote:
Hmm.. assuming you're interconnecting at multiple points with the same ASN they will probably want to indicate to you where to send traffic to them using MEDs, if you go stripping them out you lose that info, check the peering policy.. this may put you in breach. Even without a breach of policy the MED will help find the best path to a route thats identical at two points and if you take it out you lose that.
Perhaps folks are foolish enough to put "MUST accept MEDs" in a bilateral peering agreement (note that if money is attached the circumstance change, but routing breaks all the same). They should be cautious, however, not only are MEDs the most obvious trigger for persistent route oscillation, they _very often break with aggregation (unless you're foolish enough to accept more-specifics as well!) and if compared between multiple ASes (or even in the same AS) often turn your "cold-potato routing" into "mashed-potato-routing" because of disjoint policies between different domains, or downright stupid MED-derivation mechanisms. Not intending to turn this into an MED rant, but more than a few of us have experienced brokenness on account of MEDs in the past .. NANOG and IDR WG archives have addressed these concerns a number of times. -danny
Current thread:
- BGP Path Filtering Mark Radabaugh (May 15)
- Re: BGP Path Filtering Brian Wallingford (May 15)
- Re: BGP Path Filtering Jay Ford (May 15)
- Communities BCP [was: RE: BGP Path Filtering] Deepak Jain (May 16)
- Re: Communities BCP [was: RE: BGP Path Filtering] Daniel Golding (May 16)
- Re: Communities BCP [was: RE: BGP Path Filtering] Joe Abley (May 16)
- Re: Communities BCP [was: RE: BGP Path Filtering] Jay Ford (May 16)
- Re: Communities BCP [was: RE: BGP Path Filtering] Danny McPherson (May 16)
- Re: Communities BCP [was: RE: BGP Path Filtering] Stephen J. Wilcox (May 16)
- Re: Communities BCP [was: RE: BGP Path Filtering] Danny McPherson (May 16)
- Re: Communities BCP [was: RE: BGP Path Filtering] Richard A Steenbergen (May 16)
- Re: Communities BCP [was: RE: BGP Path Filtering] Guy Tal (May 16)
- Re: Communities BCP [was: RE: BGP Path Filtering] Leo Bicknell (May 16)
- Re: Communities BCP [was: RE: BGP Path Filtering] Danny McPherson (May 16)
- Re: Communities BCP [was: RE: BGP Path Filtering] Danny McPherson (May 16)
- Re: Communities BCP [was: RE: BGP Path Filtering] Stephen J. Wilcox (May 16)
- Re: Communities BCP [was: RE: BGP Path Filtering] Guy Tal (May 16)
- Communities BCP [was: RE: BGP Path Filtering] Deepak Jain (May 16)