Thanks Tom, Fred
From: Tom Samplonius [mailto:[email protected]] Sent: Wednesday, August 17, 2016 12:42 AM To: Templin, Fred L <[email protected]> Cc: [email protected] Subject: Re: [quagga-users 14392] BGP path selection based on IGP metric? “metric” is not something communicated via the BGP protocol. I think you want to research LOCAL_PREF. You could map the local metric, into BGP LOCAL_PREF values, and send that to BPG peers. Depending on what you are doing, MED, may also be a possible solution. But what you are seeing, which is the first learned route is the route uses, is typical BGP behaviour when multiple equal BGP routes are received Tom On Aug 16, 2016, at 10:00 AM, Templin, Fred L <[email protected]<mailto:[email protected]>> wrote: Hello, I have three BGP routers on a shared IPv6 link and using link-local only addressing. Router A (fe80::1) peers with Routers B (fe80::2) and C (fe80::3), but B and C do not peer with each other. Router A receives prefix advertisements from B and C, but does not distribute prefixes learned from B to C and vice-versa (it black-holes them). Router B advertises the prefix 2001:db8:5::/64 with metric 1024 to router A. At a later time, Router C then advertises the same prefix with metric 1 to router A. However, router A continues to consider B as the best next hop for the prefix even though the metric advertised by router C was lower. It seems to be due to the fact that router B advertised the prefix first, but I want router A to prefer router C based on the lower metric as a higher precedence than age. Is there a way to configure quagga to use metric as the higher precedence for best path selection? See below for the BGP table information for router A: Thanks – Fred [email protected]<mailto:[email protected]> n8# sh ipv6 bgp BGP table version is 0, local router ID is 10.0.4.2 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal, r RIB-failure, S Stale, R Removed Origin codes: i - IGP, e - EGP, ? - incomplete Network Next Hop Metric LocPrf Weight Path *> 2001:db8:1::/64 fe80::2 1024 0 2 ? *> 2001:db8:2::/64 fe80::3 1024 0 3 ? * 2001:db8:5::/64 fe80::3 1 0 3 ? *> fe80::2 1024 0 2 ? Total number of prefixes 3 n8# _______________________________________________ Quagga-users mailing list [email protected]<mailto:[email protected]> https://lists.quagga.net/mailman/listinfo/quagga-users
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