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Cross-Platform Release Notes for Cisco IOS Release 12.0S
OL-1617-14 Rev. Q0
Caveats
Resolved Caveats—Cisco IOS Release 12.0(33)S3
• CSCsx08901
Symptoms: The following message is received from the standby RP:
SEC 8:Jan 13 23:11:09.991: SPA CHOCX ALARM MSG:
spa_chocx_update_sonet_ctrlr_alarm_status : mib is NULL plugin = 0xA7357E4 line_id =
0 SEC 8:Jan 13 23:11:09.991: -Traceback= 20E8FC 929F50 929E1C 929D64 928B58 928A98
9335D8 4FAA38 4C09E0 362A84 35EED8 35EF30 2F92DC Jan 13 23:11:10.987 UTC:
%SONET-4-ALARM: SONET 14/2/0: SLOS Jan 13 23:11:10.987 UTC: %CONTROLLER-5-UPDOWN:
Controller SONET 14/2/0, changed state to down SEC 8:Jan 13 23:11:10.991:
spa_chocx_update_sonet_ctrlr_alarm_status : mib is NULL plugin = 0xA7357E4 line_id =
0 SEC 8:Jan 13 23:11:10.991: -Traceback= 20E8FC 929F50 929E1C 929D64 928B58 928A98
9335D8 4FAA38 4C09E0 362A84 35EED8 35EF30 2F92DC
Conditions: This symptom is observed after the framing on the chstm1 SPA card is changed.
Workaround: There is no workaround.
• CSCsx10140
Recent research (1) has shown that it is possible to cause BGP sessions to remotely reset by injecting
invalid data, specifically AS_CONFED_SEQUENCE data, into the AS4_PATH attribute provided
to store 4-byte ASN paths. Since AS4_PATH is an optional transitive attribute, the invalid data will
be transited through many intermediate ASes which will not examine the content. For this bug to be
triggered, an operator does not have to be actively using 4-byte AS support.
The root cause of this problem is the Cisco implementation of RFC 4893 (4-byte ASN support) -
this RFC states that AS_CONFED_SEQUENCE data in the AS4_PATH attribute is invalid.
However, it does not explicitly state what to do if such invalid data is received, so the Cisco
implementation of this RFC sends a BGP NOTIFICATION message to the peer and the BGP session
is terminated.
RFC 4893 is in the process of getting updated to avoid this problem, and the fix for this bug
implements the proposed change. The proposed change is as follows:
“To prevent the possible propagation of confederation path segments outside of a confederation,
the path segment types AS_CONFED_SEQUENCE and AS_CONFED_SET [RFC5065] are
declared invalid for the AS4_PATH attribute. A NEW BGP speaker MUST NOT send these path
segment types in the AS4_PATH attribute of an UPDATE message. A NEW BGP speaker that
receives these path segment types in the AS4_PATH attribute of an UPDATE message MUST
discard these path segments, adjust the relevant attribute fields accordingly, and continue
processing the UPDATE message.”
The only affected version of Cisco IOS software that supports RFC 4893 is Cisco IOS
Release 12.0(32)S12, released in December 2008.
(1) For more information please visit:
http://www.merit.edu/mail.archives/nanog/msg14345.html
• CSCsx23456
Symptoms: The standby reloads on a Cisco 7500 series router.
Conditions: The symptom is observed when IMA PA is configured on a Cisco 7500 series router and
where RPR+ is configured. It is seen when an OIR is done on the VIP where IMA PA is sitting.
Workaround: There is no workaround.
• CSCsx23559
Symptoms: With a nested policy map, when EF traffic is sent at police rate or above police rate, BFD
flaps. The BFD timer is set to 999 ms*3, while the EF traffic average latency is only 50 to 70
microseconds.
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