STP Loop - Ethernet Channel

Unanswered Question
Aug 9th, 2007
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Dear Community


After added vlan 634 to CoreSwitch1 (CatOS6509), the ethernet channel ports on CoreSwitch1 were disabled due to errors (pls see the log below).


CoreSwitch1>

2007 Aug 08 10:29:31 AEST +10:00 %SPANTREE-2-CHNMISCFG: STP loop - channel 5/1-2 is disabled in vlan/instance 634

2007 Aug 08 10:29:31 AEST +10:00 %SPANTREE-2-CHNMISCFG2: BPDU source mac addresses: 00-09-12-60-d4-44, 00-11-93-38-fd-c9

2007 Aug 08 10:29:31 AEST +10:00 %ETHC-5-PORTFROMSTP:Port 5/1 left bridge port 5/1-2

2007 Aug 08 10:29:32 AEST +10:00 %DTP-5-NONTRUNKPORTON:Port 5/1 has become non-trunk

2007 Aug 08 10:29:32 AEST +10:00 %ETHC-5-PORTFROMSTP:Port 5/2 left bridge port 5/1-2

2007 Aug 08 10:29:32 AEST +10:00 %DTP-5-NONTRUNKPORTON:Port 5/2 has become non-trunk

2007 Aug 08 10:43:15 AEST +10:00 %DTP-5-TRUNKPORTON:Port 5/1 has become dot1q trunk

2007 Aug 08 10:43:19 AEST +10:00 %DTP-5-TRUNKPORTON:Port 5/2 has become dot1q trunk

2007 Aug 08 10:43:21 AEST +10:00 %ETHC-5-PORTTOSTP:Port 5/1 joined bridge port 5/1-2

2007 Aug 08 10:43:24 AEST +10:00 %ETHC-5-PORTTOSTP:Port 5/2 joined bridge port 5/1-2


I did check the config of the ethernet channel, it seems fine to me.


Any idea what caused that?




Pls help.....




kelvin Cheung

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Pavel Bykov Fri, 08/10/2007 - 03:59
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Throughout my experience with etherchannels, they are sometimes very sensitive to changes and go into error mode.


Disabling and reenabling interface solves the problem, but we control which VLANs propagate through it using "switchport trunk allowed vlan XXX,YYY,ZZZ" command.



Please post ethchannel configs of both sides.

cheung.kelvin Sun, 08/12/2007 - 16:11
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Thank you for your help, Pls see the config below:



CoreSwitch1> (enable)


#port channel

set port channel 5/1-2 5


#channelprotocol

set channelprotocol pagp 5



#channelprotocol

set channelprotocol pagp 5


!

#port channel

set port channel 5/1-2 5


set port channel 5/1-2 mode desirable silent


CoreSwitch1> (enable) sh port channel

Port Status Channel Admin Ch

Mode Group Id

----- ---------- -------------------- ----- -----

5/1 connected desirable silent 5 1666

5/2 connected desirable silent 5 1666


Port Device-ID Port-ID Platform

----- ------------------------------- ------------------------- ----------------

5/1 SMG0828A5YX(HTCUDCS2) 2/2 WS-C6509

5/2 SMG0828A5YX(HTCUDCS2) 1/2 WS-C6509

CoreSwitch1> (enable)



+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

CoreSwitch2> (enable)


#channelprotocol

set channelprotocol pagp 2


!

#port channel

set port channel 1/2,2/2 2



set port channel 1/2-4,1/6-24 mode auto silent

set port channel 2/2-4,2/6-24 mode auto silent



CoreSwitch2> (enable)


CoreSwitch2> (enable) sh port channel

Port Status Channel Admin Ch

Mode Group Id

----- ---------- -------------------- ----- -----

1/2 connected auto silent 2 1665

2/2 connected auto silent 2 1665

----- ---------- -------------------- ----- -----

9/1 connected on 102 1666

9/2 connected on 102 1666

9/3 connected on 102 1666

9/4 connected on 102 1666


Port Device-ID Port-ID Platform

----- ------------------------------- ------------------------- ----------------

1/2 SCA052002DL(HTCUDCS1) 5/2 WS-C6509

2/2 SCA052002DL(HTCUDCS1) 5/1 WS-C6509

----- ------------------------------- ------------------------- ----------------

9/1

9/2

9/3

9/4

mohammedmahmoud Fri, 08/10/2007 - 04:03
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Hi,


When doing the configuration, if it is done only on one side (misconfig) it will be err-disabled to prevent any spanning tree loops, and accordingly it is recommended to shutdown the interfaces before doing the configuration. The above feature can be controlled via the "spanning-tree etherchannel guard misconfig" command.


HTH,

Mohammed Mahmoud.


sundar.palaniappan Sun, 08/12/2007 - 19:25
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All ports in an etherchannel group need to have the same attributes i.e. configuration has to be identical to avoid etherchannel or STP issues. One method to avoid etherchannel misconfiguration from impacting the network is to configure 'spanning-tree etherchannel guard misconfig' (as suggested by Mohammed) and this would disable the port(s) when any misconfiguration is detected.


HTH


Sundar

cheung.kelvin Sun, 08/12/2007 - 19:42
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Dear Sundar


Pls see the show version below, I do'nt think I have the 'spanning-tree etherchannel guard misconfig' in CATOS version,


Thank a lots......


CoreSwitch2> (enable) sh ver



WS-C6509 Software, Version NmpSW: 8.3(5)

Copyright (c) 1995-2004 by Cisco Systems

NMP S/W compiled on Dec 13 2004, 18:18:52


System Bootstrap Version: 8.1(3)

System Web Interface Version: Engine Version: 5.3.4 ADP Device: Cat6000 ADP Version: 6.0 ADK: 40

System Boot Image File is 'bootflash:cat6000-sup720cvk9.8-3-5.bin'

System Configuration register is 0x2102


Hardware Version: 3.0 Model: WS-C6509 Serial #: SMG0828A5YX


PS1 Module: WS-CAC-2500W Serial #: ART0825E192

PS2 Module: WS-CAC-2500W Serial #: ART0825E18V

Mod Port Model Serial # Versions

--- ---- ------------------- ----------- --------------------------------------

1 24 WS-X6724-SFP SAL08280DKQ Hw : 2.1

Fw : 8.3(5)

Sw : 8.3(5)

WS-F6700-CFC SAD082705EF Hw : 2.0

Sw :

2 24 WS-X6724-SFP SAL08280DKC Hw : 2.1

Fw : 8.3(5)

Sw : 8.3(5)

WS-F6700-CFC SAD082705JL Hw : 2.0

Sw :

3 48 WS-X6748-GE-TX SAL09148MPA Hw : 2.2

Fw : 8.3(5)

Sw : 8.3(5)

WS-F6700-CFC SAL09148HY8 Hw : 2.0

Sw :

4 48 WS-X6748-GE-TX SAL09148J38 Hw : 2.2

Fw : 8.3(5)

Sw : 8.3(5)

WS-F6700-CFC SAL09148CZS Hw : 2.0

Sw :

5 2 WS-SUP720-BASE SAD08280BR6 Hw : 3.1

Fw : 8.1(3)

Fw1: 8.3(5)

Sw : 8.3(5)

Sw1: 8.3(5)

WS-F6K-PFC3A SAD082707T9 Hw : 2.4

Sw :

6 2 WS-SUP720-BASE SAD09070DK6 Hw : 3.3

Fw : 8.1(3)

Fw1: 8.3(5)

Sw : 8.3(5)

Sw1: 8.3(5)

WS-F6K-PFC3A SAD09070G0H Hw : 2.5

Sw :

7 16 WS-X6516-GE-TX SAD0549024Z Hw : 2.0

Fw : 6.1(3)

Sw : 8.3(5)

8 16 WS-X6516-GE-TX SAD060403X2 Hw : 2.0

Fw : 6.1(3)

Sw : 8.3(5)

9 4 WS-X6066-SLB-APC SAD0825082B Hw : 1.7

Fw :

Sw : 4.1(3)

15 1 WS-SUP720 SAD08260D4V Hw : 2.3

Fw : 12.2(17a)SX4

Sw : 12.2(17a)SX4

16 1 WS-SUP720 SAD09070ET9 Hw : 2.5

Fw : 12.2(17a)SX4

Sw : 12.2(17a)SX4


DRAM FLASH NVRAM

Module Total Used Free Total Used Free Total Used Free

------ ------- ------- ------- ------- ------- ------- ----- ----- -----

5 524288K 138924K 385364K 65536K 39993K 25543K 2048K 366K 1682K


Uptime is 64 days, 20 hours, 17 minutes

CoreSwitch2> (enable)

sundar.palaniappan Sun, 08/12/2007 - 19:57
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Hi


I don't know what the CatOS equivalent of the same command if there indeed one exists. Those error messages that you see clearly indicates there is some inconsistency in how the ports are configured. Can you make sure all the ports on both switches are configured identical in every way and let us know if that helps resolve your problem.


Here's some links for your reference.


http://www.cisco.com/en/US/docs/switches/lan/catalyst5000/catos/5.x/configuration/guide/channel.html#wp1020378


http://www.cisco.com/en/US/tech/tk389/tk213/technologies_tech_note09186a008009448d.shtml


http://www.cisco.com/warp/public/473/127.html


HTH


Sundar

cheung.kelvin Mon, 08/13/2007 - 21:22
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Hi Sunder


Thanks for your help....Sorry to trouble you again. Pls see the 'sh version" and "sh run full". I did put the command 'spanning-tree etherchannel guard misconfig' in, however, I could see it in the config. Do you know why?



R4#sh ver

Cisco Internetwork Operating System Software

IOS (tm) s72033_rp Software (s72033_rp-ADVENTERPRISEK9_WAN-VM), Version 12.2(18)SXF10, RELEASE SOFTWARE (fc1)

Technical Support: http://www.cisco.com/techsupport

Copyright (c) 1986-2007 by cisco Systems, Inc.

Compiled Fri 13-Jul-07 08:58 by kellythw

Image text-base: 0x01020150, data-base: 0x01021000


ROM: System Bootstrap, Version 12.2(17r)S4, RELEASE SOFTWARE (fc1)

BOOTLDR:

HTCUDCR4 uptime is 1 week, 3 days, 22 hours, 51 minutes

Time since HTCUDCR4 switched to active is 1 week, 3 days, 22 hours, 27 minutes

System returned to ROM by Stateful Switchover (SP by reload)

System image file is "sup-bootdisk:s72033-adventerprisek9_wan-vz.122-18.SXF10.bin"



If you require further assistance please contact us by sending email to

[email protected].


cisco WS-C6509-E (R7000) processor (revision 1.3) with 491520K/32768K bytes of memory.

Processor board ID SMC1120000D

SR71000 CPU at 600Mhz, Implementation 1284, Rev 1.2, 512KB L2 Cache

Last reset from s/w reset

Bridging software.

X.25 software, Version 3.0.0.

SuperLAT software (copyright 1990 by Meridian Technology Corp).

TN3270 Emulation software.

2 Virtual Ethernet/IEEE 802.3 interfaces

100 Gigabit Ethernet/IEEE 802.3 interfaces

1917K bytes of non-volatile configuration memory.


65536K bytes of Flash internal SIMM (Sector size 512K).

Configuration register is 0x2102


Patching is not available since the system is not running from an installed image. To install please use the "install file" command


R4#



R4(config)#spanning-tree etherchannel guard misconfig

R4(config)#end


R4#sh run full | in span

spanning-tree mode pvst

R4#


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