nanog mailing list archives
Re: What's the point of prepend communities?
From: William Herrin <bill () herrin us>
Date: Thu, 26 Oct 2017 15:14:38 -0400
On Thu, Oct 26, 2017 at 3:05 PM, William Herrin <bill () herrin us> wrote:
On Thu, Oct 26, 2017 at 2:47 PM, Jason Lixfeld <jason+nanog () lixfeld ca> wrote: You'd only use communities like that if you want to signal the ISP to deprioritize your advertisement on a particular peer or set of peers but not others. That's when you're getting fancy. It's not the norm. The norm is you want to deprioritize one of your paths as a whole. Maybe that link has less capacity or is enough better connected that it would always override your other links unless you detune it a little. I mean, you could tell the ISP to prepend everything based on a community, assuming they support such a community, but why would you? That needlessly makes things more complicated.
Ah, I see. I completely misread your question. The answer you may be looking for is that the ISP can be more subtle about which of their peers gets your prepend. Maybe you want to prefer ISP A for your overseas traffic but prefer ISP B for your domestic traffic. ISP A can design a community tag that causes your advertisement to be prepended but only when sent to domestic peers. Still not a relic but not a primary knob. Regards, Bill Herrin -- William Herrin ................ herrin () dirtside com bill () herrin us Dirtside Systems ......... Web: <http://www.dirtside.com/>
Current thread:
- What's the point of prepend communities? Jason Lixfeld (Oct 26)
- Re: What's the point of prepend communities? William Herrin (Oct 26)
- Re: What's the point of prepend communities? Jason Lixfeld (Oct 26)
- Re: What's the point of prepend communities? Christopher Morrow (Oct 26)
- Re: What's the point of prepend communities? Job Snijders (Oct 26)
- Re: What's the point of prepend communities? Jason Lixfeld (Oct 26)
- Re: What's the point of prepend communities? Rob Foehl (Oct 28)
- Re: What's the point of prepend communities? Jason Lixfeld (Oct 26)
- Re: What's the point of prepend communities? William Herrin (Oct 26)
- Re: What's the point of prepend communities? William Herrin (Oct 26)
- RE: What's the point of prepend communities? Naslund, Steve (Oct 26)
- Re: What's the point of prepend communities? William Herrin (Oct 26)
- Re: What's the point of prepend communities? Brett Frankenberger (Oct 26)
- Re: What's the point of prepend communities? Steve Dodd (Oct 28)
- Re: What's the point of prepend communities? Leo Bicknell (Oct 26)
- Re: What's the point of prepend communities? Clinton Work (Oct 26)
- RE: What's the point of prepend communities? Naslund, Steve (Oct 26)
- Re: What's the point of prepend communities? Leo Bicknell (Oct 30)
- Re: What's the point of prepend communities? Michael Hallgren (Oct 30)
- Re: What's the point of prepend communities? Mike Hammett (Oct 29)
- Re: What's the point of prepend communities? Brett Frankenberger (Oct 29)