[37157] in North American Network Operators' Group
BGP Question: Problems with connectivity when using local prefere
daemon@ATHENA.MIT.EDU (Devon True)
Thu May 3 21:30:44 2001
Message-ID: <CA03BBAFD1BE6E428888E19CDF9544A225D2AE@exchange.xodiax.org>
From: Devon True <dtrue@xodiax.com>
To: "'nanog@merit.edu'" <nanog@merit.edu>
Date: Thu, 3 May 2001 21:28:14 -0400
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All:
We are running BGP4 between Sprint and UUNet. We are using route-maps to add
local preferences to certain AS numbers to force traffic out Sprint rather
than UUNet. One of the AS's we force out Sprint is AS3356 (Level3).
Our CTO has a DSL line from a local provider. When he traceroutes from his
DSL connection, he goes across the DSL provider, Level3, and stops at UUNet.
When I run a traceroute to his DSL IP, I go across UUNet, Level3, and stop
at the DSL provider's router.
Here is the AS path that my traceroute takes: AS701 -> AS3356 -> AS12050
Here is the AS path that his traceroute takes: AS12050 -> AS3356 -> AS701
We are forcing Level3 routes out our Sprint connection, but AS12050 routes
go out UUNet (no local-preference change).
When I took out Level3's AS from our route-map, thus sending Level3 routes
out UUNet, everything worked fine. He could reach us and I could him. Any
ideas why?
Devon
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<META NAME=3D"Generator" CONTENT=3D"MS Exchange Server version =
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<TITLE>BGP Question: Problems with connectivity when using local =
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<P><FONT SIZE=3D2>All:</FONT>
</P>
<P><FONT SIZE=3D2>We are running BGP4 between Sprint and UUNet. We are =
using route-maps to add local preferences to certain AS numbers to =
force traffic out Sprint rather than UUNet. One of the AS's we force =
out Sprint is AS3356 (Level3). </FONT></P>
<P><FONT SIZE=3D2>Our CTO has a DSL line from a local provider. When he =
traceroutes from his DSL connection, he goes across the DSL provider, =
Level3, and stops at UUNet. When I run a traceroute to his DSL IP, I go =
across UUNet, Level3, and stop at the DSL provider's router.</FONT></P>
<P><FONT SIZE=3D2>Here is the AS path that my traceroute takes: AS701 =
-> AS3356 -> AS12050</FONT>
<BR><FONT SIZE=3D2>Here is the AS path that his traceroute takes: =
AS12050 -> AS3356 -> AS701</FONT>
</P>
<P><FONT SIZE=3D2>We are forcing Level3 routes out our Sprint =
connection, but AS12050 routes go out UUNet (no local-preference =
change).</FONT>
</P>
<P><FONT SIZE=3D2>When I took out Level3's AS from our route-map, thus =
sending Level3 routes out UUNet, everything worked fine. He could reach =
us and I could him. Any ideas why?</FONT></P>
<P><FONT SIZE=3D2>Devon</FONT>
</P>
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