-----Original Message----- From: owner-nanog@merit.edu [mailto:owner-nanog@merit.edu] On Behalf Of Saku Ytti Sent: Thursday, September 21, 2006 9:12 AM To: nanog@merit.edu Subject: Lucent GBE (4 x VC4) clues needed
(oops technical question in nanog, wearing my asbestos suit)
Consider this topology
GSR - 3750 --(GE over 4xVC4) - NSE100 - NSE100 --(GE over 4xVC4) -- 3550 - GSR
All other fibres are dark fibres, except marked.
When we ping either NSE100 <-> GSR leg, when there is no background traffic there is no packet loss. If there is even few Mbps, lets say 10Mbps of background traffic we get 1-5% packet loss on 1500 bytes, and bit less packet loss on small packets. As background traffic increases packet loss quickly increases.
We tried to replace (GSR-3750) with 7600, but same issue persisted.
We've measured both Lucent GBE legs with having loop in other end and pushing tests from EXFO and Smartbits gear through the loop, no errors can be detected in RFC tests.
There isn't very much that can be configured in the Lucent, and we've tried pretty much every setting. We've tried to set autonego on and off in every gear in the path, without any changes to observed behaviour. We've also tried to use use 1xVC4, without any changes to the behaviour. All VC4's in given leg are using same path. Even though we test the packet loss pinging from router link to router link, same packet loss is experienced for transit traffic also. We've tried to turn PXF off in NSE100. Packets between NSE100 <-> NSE100 over dark fibre are not lost.
We're pretty much utterly without clues. All I can think off is some obscure IFG issue, that is, NSE100 would have less than perfect timing for IFG which would confuse Lucent regarding what is part of which frame. Does stuff like this really happen?
NSE100 drops bad IP packets in PXF and there is only shared counter, so I can't tell if I get CRC for IP, I just loose the packets. But IS-IS is not handled in PXF, and I get %CLNS-4-LSPCKSUM and %CLNS-3-BADPACKET messages over both Lucent legs, but not between the NSE100's. So I assume the packets are not dropped, but broken.
I swear next time I'll complain about some political issue, thanks, -- ++ytti
Silly question (considering that you stated that IS-IS is borked also, which is not handled by PXF - but did you try disabling PXF? There's a reason why Cisco discontinued every product that "features" it. It's broken.