MLPPP over L2TP over Ethernet Channel Groups on Cisco ASR

 

Problem: After upgrading an ethernet port to a channel-group, all MLPPP connections fail on a Cisco ASR 1002-X. The log file looks like this:

Jul 31 2015 07:04:44.801 CEST: Vi4 PPP: Phase is AUTHENTICATING, Authenticated User
Jul 31 2015 07:04:44.801 CEST: Vi4 CHAP: O SUCCESS id 143 len 4
Jul 31 2015 07:04:44.801 CEST: Vi4 PPP: Phase is VIRTUALIZED
Jul 31 2015 07:04:44.802 CEST: Vi6 MLP: Added link Vi4 to bundle xxx
Jul 31 2015 07:04:44.803 CEST: %LINEPROTO-5-UPDOWN: Line protocol on Interface Virtual-Access4, changed state to up
Jul 31 2015 07:04:44.803 CEST: %LINK-3-UPDOWN: Interface Virtual-Access4, changed state to up
Jul 31 2015 07:04:44.805 CEST: %CPPOSLIB-3-ERROR_NOTIFY: SIP0: cpp_cp:  cpp_cp encountered an error -Traceback= 1#795bed15105852c19a9ac138912d7358   errmsg:7F13FA6E0000+121D cpp_common_os:7F13FD6F1000+D8D5 cpp_common_os:7F13FD6F1000+D7D4 cpp_common_os:7F13FD6F1000+19A3E cpp_ifm:7F14106F1000+A198 cpp_mlppp_svr_lib:7F1406B63000+C351 cpp_mlppp_svr_lib:7F1406B63000+1CDC8 cpp_mlppp_svr_smc_lib:7F1406DA1000+2D28 cpp_common_os:7F13FD6F1000+11E6E cpp_common_os:7F13FD6F1000+118AA cpp_common_os:7F13FD6F1000+116EB evlib:7F13FC6D10
Jul 31 2015 07:04:45.152 CEST: Vi6 IPCP: O CONFREQ [REQsent] id 13 len 10
Jul 31 2015 07:04:45.152 CEST: Vi6 IPCP:    Address xxx
Jul 31 2015 07:04:45.152 CEST: Vi6 IPCP: Event[Timeout+] State[REQsent to REQsent]
Jul 31 2015 07:04:47.168 CEST: Vi6 IPCP: O CONFREQ [REQsent] id 14 len 10
Jul 31 2015 07:04:47.168 CEST: Vi6 IPCP:    Address xxx
Jul 31 2015 07:04:47.168 CEST: Vi6 IPCP: Event[Timeout+] State[REQsent to REQsent]

The router continues with “O CONFREQ” but never receives the “I CONFACK”.

Discussion: In this case the router is a L2TP server and handles multiple L2TP/PPP connection. Some of them are multilink PPP connections. The ASR software has a bug that leads to these tracebacks when the L2TP connections are going over an ethernet channel group. We opened a case with Cisco support. After one and a half month we received this answer:

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Apologies for the delay. I was held up on other critical issues and hence was unable to reach out to you earlier. I was able to decode the tracebacks observed during the time of the issue and the issue points to a known software bug as the cause of the problem. Below are more details

CSCua16777 : FMFP-3-OBJ_DWNLD_TO_CPP_FAILED: SIP0: fman_fp_image: MLP bundle
Bug toolkit link : https://tools.cisco.com/bugsearch/bug/CSCua16777/?reffering_site=dumpcr

However the above bug is in closed state with the below release-notes

Symptom: FMFP-3-OBJ_DWNLD_TO_CPP_FAILED: SIP0: fman_fp_image: MLP bundle 8767, link 8766 download to CPP faile
Conditions: LNS MLPPP sessions don't stay up over port-channel
Workaround: MLPPP over port-channel is not supported on ASR1k. Don't use MLPPP over port-channel.
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Dear Cisco! This is no solution. If you define an obvious bug as normal behaviour and the only workaround is “Don’t use..”, your customers will soon remember this:
“Cisco ? Don’t use…”

Solution: “Don’t use Cisco ?”

Version: Cisco ASR 1002-X, IOS XE Version: 03.09.02.S

Update: If I use the link of the bug report, I receive this answer:

Insufficient Permissions to View Bug
This bug contains proprietary information and is not yet publicly available.
Cisco Support Community

Unbelievable !! CSCO: STRONG SELL!

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