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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: BGP - weight
On Feb 14, 2004, at 5:23 AM, Sven Huster wrote: Dumb question: If I apply a equal weight to all our transit/peers, will that affect route announcements to iBGP or eBGP peers anyhow? Yes, given that it's a local parameter (i.e., not BGP, per se, though it does impact what's installed in the BGP RIB and what's subsequently advertised to your peers), you'll likely begin preferring more routes via eBGP learned peers per subsequent attributes in the best path selection algorithm (e.g., MED, AS_PATH, even LOCAL_PREF) won't be considered. We got a very simple setup: - 2 routers on the border to transit/peers (that's were i want to set the weight) - 1 edge router to customers - core router running BGP as well What I want to achieve is that traffic leaves through the border router it arrived, rather than have it bounced around. Perhaps you should first look at other reasons why this may be occurring (e.g., accepting MEDs from one peer and not the other, accepting MEDs from both but different policies are employed to derive their values, AS_PATH "suggests" a better path, etc..) -- then comes preference for eBGP over iBGP. We had some recent issues were it looks like the core got "out of sync" with the border (looks more like a sw issue than just convergence delay) and packets bounced back and forth between them. This could be any of a number of things.. Without more information I'd be hesitant to start tweaking knobs. I know this doesn't solve the cause but the before digging for the initial reason I want a quick workaround. "Weight" is a very influential parameter. I'm not a big fan of configuring routing policies that are entirely local to a system, for obvious reasons. But I do suspect it would accomplish what you're trying to achieve. -danny
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