MLFR Differential Delay Problems

R. Benjamin Kessler rbk at mnsginc.com
Thu Feb 18 21:54:57 CST 2010


Hello NANOGers - 

 

I'm working on a project to migrate a customer from one "Tier 1"
provider to another at 50+ locations (all domestic US sites).  Most of
these connections are 4xT1 multi-link bundles.

 

The old router configuration was MLPPP which was rock-solid for 3 years
(save for the typical "last-mile" circuit issues, fiber-cuts, etc.).
The new carrier uses FRF.16 multi-link Frame Relay vs. MLPPP.

 

We've completed the migration on 10+ sites and all of them are now
reporting errors like the following:

 

Feb 17 21:01:39   /kernel: MFR bundle ls-0/0/0:0 link t1-1/0/0
differential 91.7 ms over yellow differential delay 75 ms

Feb 17 21:01:50   /kernel: MFR bundle ls-0/0/0:0 link t1-1/0/0
differential 115.9 ms over yellow differential delay 75 ms

Feb 17 21:01:50   /kernel: MFR bundle ls-0/0/0:0 link t1-1/0/1
differential 79.0 ms over yellow differential delay 75 ms

Feb 17 21:01:50   /kernel: MFR bundle ls-0/0/0:0 link t1-2/0/1
differential 79.1 ms over yellow differential delay 75 ms

Feb 17 21:01:50   /kernel: MFR bundle ls-0/0/0:0 link t1-1/0/1
differential 97.4 ms over yellow differential delay 75 ms

Feb 17 21:01:50   /kernel: MFR bundle ls-0/0/0:0 link t1-2/0/0
differential 97.5 ms over yellow differential delay 75 ms

Feb 17 21:01:50   /kernel: MFR bundle ls-0/0/0:0 link t1-2/0/1
differential 97.5 ms over yellow differential delay 75 ms

Feb 17 21:01:52   /kernel: MFR bundle ls-0/0/0:0 link t1-1/0/1
differential 97.4 ms over yellow differential delay 75 ms

Feb 17 21:01:52   /kernel: MFR bundle ls-0/0/0:0 link t1-2/0/0
differential 97.5 ms over yellow differential delay 75 ms

Feb 17 21:01:52   /kernel: MFR bundle ls-0/0/0:0 link t1-2/0/1
differential 97.5 ms over yellow differential delay 75 ms

Feb 17 21:01:53   /kernel: MFR bundle ls-0/0/0:0 link t1-1/0/1
differential 90.0 ms over yellow differential delay 75 ms

Feb 17 21:01:53   /kernel: MFR bundle ls-0/0/0:0 link t1-2/0/1
differential 100.0 ms over yellow differential delay 75 ms

 

The customer routers are all Juniper J6350; I believe the Carrier's
routers are all Cisco GSRs.

 

Advanced JTAC says that our configurations are solid and that there are
no known bugs that would exhibit behavior like this.  The carrier is
insisting on performing physical-level tests of the circuits (even
though they're running error free) before they'll engage higher-level
engineers so I'm currently in a holding pattern awaiting those results.

 

My Google-foo is failing me and I'm not able to find any documents that
help explain what may be causing this and how to troubleshoot and find
an eventual solution.

 

I would really appreciate any tips or suggestions from anyone on the
list that may have seen issues like this in the past.

 

Thanks,

 

Ben

 

 




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