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From: colin on 30 Mar 2010 17:35
Hi NG,

i need some advice/comments on finding an assumpted L2 Loop via software...
instead of tracking it with shutting down the redundancy the hard way..

Setup of szenario:

3550 gi0/2 -- gi2/2 4506 -- PrtChan -- PrtChan -- 6509


Cat 4506 and Cat 6509 play HSRP whereby the 6509 is always the prio 105 of
all configured vlans.

On the Cat 3550, witch is only attached to the 4506 via gi2/2, i get
following messages:

Mar 30 14:16:10: %ETHCNTR-3-LOOP_BACK_DETECTED: Keepalive packet loop-back
detected on GigabitEthernet0/2.
Mar 30 14:16:10: %PM-4-ERR_DISABLE: loopback error detected on Gi0/2,
putting Gi0/2 in err-disable state
Mar 30 14:16:11: %LINEPROTO-5-UPDOWN: Line protocol on Interface
GigabitEthernet0/2, changed state to down
Mar 30 14:16:12: %LINK-3-UPDOWN: Interface GigabitEthernet0/2, changed state
to down

Thats the 3550 gone to Err-Dis!

on the 4506 i get following logs:
23 08:39:53: %C4K_EBM-4-HOSTFLAPPING: Host 18:A9:05:62:4E:DA in vlan 100 is
flapping between port Gi2/6 and port Po10
Mar 23 08:39:53: %STANDBY-3-DUPADDR: Duplicate address 192.168.6.3 on
Vlan60, sourced by 000e.383e.483f
Mar 23 08:39:54: %C4K_EBM-4-HOSTFLAPPING: Host 18:A9:05:62:4E:DA in vlan 100
is flapping between port Gi2/6 and port Po10
Mar 23 08:39:54: %C4K_EBM-4-HOSTFLAPPING: Host 00:D0:03:EA:E0:0A in vlan 110
is flapping between port Po10 and port Gi2/6
Mar 23 08:39:54: %C4K_EBM-4-HOSTFLAPPING: Host 18:A9:05:62:4E:DA in vlan 100
is flapping between port Gi2/6 and port Po10
Mar 23 08:39:54: %C4K_EBM-4-HOSTFLAPPING: Host 00:D0:03:EA:E0:0A in vlan 99
is flapping between port Gi2/6 and port Po10
Mar 23 08:39:54: %C4K_EBM-4-HOSTFLAPPING: Host 00:00:00:00:FE:01 in vlan 100
is flapping between port Po10 and port Gi2/6
Mar 23 08:39:54: %C4K_EBM-4-HOSTFLAPPING: Host 00:D0:03:EA:E0:0A in vlan 200
is flapping between port Po10 and port Gi2/6
Mar 23 08:39:54: %C4K_EBM-4-HOSTFLAPPING: Host 00:1E:0B:C3:23:78 in vlan 100
is flapping between port Po10 and port Gi2/6
Mar 23 08:39:54: %C4K_EBM-4-HOSTFLAPPING: Host 00:0E:7F:FD:58:B0 in vlan 100
is flapping between port Po10 and port Gi2/6
Mar 23 08:39:55: %C4K_EBM-4-HOSTFLAPPING: Host 00:D0:03:EA:E0:0A in vlan 99
is flapping between port Po10 and port Gi2/6
Mar 23 08:39:55: %C4K_EBM-4-HOSTFLAPPING: Host 00:90:FB:24:BA:00 in vlan 100
is flapping between port Gi2/6 and port Po10
Mar 23 08:39:55: %C4K_EBM-4-HOSTFLAPPING: Host 00:1F:29:69:9D:6E in vlan 100
is flapping between port Gi2/6 and port Po10
Mar 23 08:39:55: %C4K_EBM-4-HOSTFLAPPING: Host 00:D0:03:EA:E0:0A in vlan 100
is flapping between port Gi2/6 and port Po10
Mar 23 08:55:58: %C4K_EBM-4-HOSTFLAPPING: Host 00:50:56:83:45:A3 in vlan 100
is flapping between port Po10 and port Gi6/5
Mar 23 08:56:59: %C4K_EBM-4-HOSTFLAPPING: Host 00:50:56:83:45:A3 in vlan 100
is flapping between port Po10 and port Gi6/5

the interessting one i guess is this:
Mar 23 08:39:53: %STANDBY-3-DUPADDR: Duplicate address 192.168.6.3 on
Vlan60, sourced by 000e.383e.483f

when i issue the following on the 4506

asw03#sh mac-address-table | i 000e.383e.483f
12 000e.383e.483f static ip,ipx,assigned,other Switch
30 000e.383e.483f static ip,ipx,assigned,other Switch
50 000e.383e.483f static ip,ipx,assigned,other Switch

it sees its own mac addr, what a surprise!
so i do guess i got some bad things happening on L2, loopin all over.


------------------------------------------------------------
as i just tried following within a complete seperate lab:

3560 fa0/2 -- fa0/1 3550 from 3550 to itself from fa0/47 to fa0/48
(looped)

on the 3550 i configured: no spanning-tree vlan 1-999 making sure
it runs as if i would use some unmanaged switch, thereby creating a loop on
it self.

within this LAB it was a pretty ugly szenario, since i actually thought the
3560 on fa0/2 would track it and STP would go into the Blocking state on
fa0/2, but it did NOT.
so the hole thing looped and flashed like an x-mas tree on fa0/2 aswell of
course on the 3550.

so i am considering in order to find the loop to go and take the approach
via storm-control, thereby issuing the action trap mode, in order not to
shutdown my hole network.

on my Distribution Trunks/Uplinks towards the Access-Switches:

storm-control broadcast level pps 500
storm-control multicast level pps 500
storm-control action trap

i guess this should give me an idea from witch link i get alot of
broadcasts..

i still can't explain why my 3550 in the real world setup went down with
Err-Dis, since it is single attached to the 4506....

so if you got other idea's how to track L2 Loops without pulling out the
redundancy until it stops, feel free to contact me and send me youre advice.

Thank you
colin











From: Thrill5 on 31 Mar 2010 20:57
This problem has nothing to do with spanning tree. A very long time ago
(probably around 2001 or 2002) I had a similar problem on 3550's and after
much troubleshooting I found it was software bug on the 3550's. The
workaround was issuing a "no keepalive" on each of the uplink interfaces on
the 3550's. After a quick search, I found a reference to this bug id
CSCea46385.


"colin" <colin.cant(a)solnet.ch> wrote in message
news:4bb26e8d$0$158$fb624d75(a)newsspool.solnet.ch...
> Hi NG,
>
> i need some advice/comments on finding an assumpted L2 Loop via
> software... instead of tracking it with shutting down the redundancy the
> hard way..
>
> Setup of szenario:
>
> 3550 gi0/2 -- gi2/2 4506 -- PrtChan -- PrtChan -- 6509
>
>
> Cat 4506 and Cat 6509 play HSRP whereby the 6509 is always the prio 105 of
> all configured vlans.
>
> On the Cat 3550, witch is only attached to the 4506 via gi2/2, i get
> following messages:
>
> Mar 30 14:16:10: %ETHCNTR-3-LOOP_BACK_DETECTED: Keepalive packet loop-back
> detected on GigabitEthernet0/2.
> Mar 30 14:16:10: %PM-4-ERR_DISABLE: loopback error detected on Gi0/2,
> putting Gi0/2 in err-disable state
> Mar 30 14:16:11: %LINEPROTO-5-UPDOWN: Line protocol on Interface
> GigabitEthernet0/2, changed state to down
> Mar 30 14:16:12: %LINK-3-UPDOWN: Interface GigabitEthernet0/2, changed
> state to down
>
> Thats the 3550 gone to Err-Dis!
>
> on the 4506 i get following logs:
> 23 08:39:53: %C4K_EBM-4-HOSTFLAPPING: Host 18:A9:05:62:4E:DA in vlan 100
> is flapping between port Gi2/6 and port Po10
> Mar 23 08:39:53: %STANDBY-3-DUPADDR: Duplicate address 192.168.6.3 on
> Vlan60, sourced by 000e.383e.483f
> Mar 23 08:39:54: %C4K_EBM-4-HOSTFLAPPING: Host 18:A9:05:62:4E:DA in vlan
> 100 is flapping between port Gi2/6 and port Po10
> Mar 23 08:39:54: %C4K_EBM-4-HOSTFLAPPING: Host 00:D0:03:EA:E0:0A in vlan
> 110 is flapping between port Po10 and port Gi2/6
> Mar 23 08:39:54: %C4K_EBM-4-HOSTFLAPPING: Host 18:A9:05:62:4E:DA in vlan
> 100 is flapping between port Gi2/6 and port Po10
> Mar 23 08:39:54: %C4K_EBM-4-HOSTFLAPPING: Host 00:D0:03:EA:E0:0A in vlan
> 99 is flapping between port Gi2/6 and port Po10
> Mar 23 08:39:54: %C4K_EBM-4-HOSTFLAPPING: Host 00:00:00:00:FE:01 in vlan
> 100 is flapping between port Po10 and port Gi2/6
> Mar 23 08:39:54: %C4K_EBM-4-HOSTFLAPPING: Host 00:D0:03:EA:E0:0A in vlan
> 200 is flapping between port Po10 and port Gi2/6
> Mar 23 08:39:54: %C4K_EBM-4-HOSTFLAPPING: Host 00:1E:0B:C3:23:78 in vlan
> 100 is flapping between port Po10 and port Gi2/6
> Mar 23 08:39:54: %C4K_EBM-4-HOSTFLAPPING: Host 00:0E:7F:FD:58:B0 in vlan
> 100 is flapping between port Po10 and port Gi2/6
> Mar 23 08:39:55: %C4K_EBM-4-HOSTFLAPPING: Host 00:D0:03:EA:E0:0A in vlan
> 99 is flapping between port Po10 and port Gi2/6
> Mar 23 08:39:55: %C4K_EBM-4-HOSTFLAPPING: Host 00:90:FB:24:BA:00 in vlan
> 100 is flapping between port Gi2/6 and port Po10
> Mar 23 08:39:55: %C4K_EBM-4-HOSTFLAPPING: Host 00:1F:29:69:9D:6E in vlan
> 100 is flapping between port Gi2/6 and port Po10
> Mar 23 08:39:55: %C4K_EBM-4-HOSTFLAPPING: Host 00:D0:03:EA:E0:0A in vlan
> 100 is flapping between port Gi2/6 and port Po10
> Mar 23 08:55:58: %C4K_EBM-4-HOSTFLAPPING: Host 00:50:56:83:45:A3 in vlan
> 100 is flapping between port Po10 and port Gi6/5
> Mar 23 08:56:59: %C4K_EBM-4-HOSTFLAPPING: Host 00:50:56:83:45:A3 in vlan
> 100 is flapping between port Po10 and port Gi6/5
>
> the interessting one i guess is this:
> Mar 23 08:39:53: %STANDBY-3-DUPADDR: Duplicate address 192.168.6.3 on
> Vlan60, sourced by 000e.383e.483f
>
> when i issue the following on the 4506
>
> asw03#sh mac-address-table | i 000e.383e.483f
> 12 000e.383e.483f static ip,ipx,assigned,other Switch
> 30 000e.383e.483f static ip,ipx,assigned,other Switch
> 50 000e.383e.483f static ip,ipx,assigned,other Switch
>
> it sees its own mac addr, what a surprise!
> so i do guess i got some bad things happening on L2, loopin all over.
>
>
> ------------------------------------------------------------
> as i just tried following within a complete seperate lab:
>
> 3560 fa0/2 -- fa0/1 3550 from 3550 to itself from fa0/47 to fa0/48
> (looped)
>
> on the 3550 i configured: no spanning-tree vlan 1-999 making
> sure it runs as if i would use some unmanaged switch, thereby creating a
> loop on it self.
>
> within this LAB it was a pretty ugly szenario, since i actually thought
> the 3560 on fa0/2 would track it and STP would go into the Blocking state
> on fa0/2, but it did NOT.
> so the hole thing looped and flashed like an x-mas tree on fa0/2 aswell of
> course on the 3550.
>
> so i am considering in order to find the loop to go and take the approach
> via storm-control, thereby issuing the action trap mode, in order not to
> shutdown my hole network.
>
> on my Distribution Trunks/Uplinks towards the Access-Switches:
>
> storm-control broadcast level pps 500
> storm-control multicast level pps 500
> storm-control action trap
>
> i guess this should give me an idea from witch link i get alot of
> broadcasts..
>
> i still can't explain why my 3550 in the real world setup went down with
> Err-Dis, since it is single attached to the 4506....
>
> so if you got other idea's how to track L2 Loops without pulling out the
> redundancy until it stops, feel free to contact me and send me youre
> advice.
>
> Thank you
> colin
>
>
>
>
>
>
>
>
>
>
>


From: colin on 1 Apr 2010 04:19
Hey Thrill,

you just saved me alot of time!!

BIG THANK YOU!

Regards
Colin


"Thrill5" <nospam(a)somewhere.com> schrieb im Newsbeitrag
news:hp0r21$i9n$1(a)news.eternal-september.org...
> This problem has nothing to do with spanning tree. A very long time ago
> (probably around 2001 or 2002) I had a similar problem on 3550's and after
> much troubleshooting I found it was software bug on the 3550's. The
> workaround was issuing a "no keepalive" on each of the uplink interfaces
> on the 3550's. After a quick search, I found a reference to this bug id
> CSCea46385.
>
>
> "colin" <colin.cant(a)solnet.ch> wrote in message
> news:4bb26e8d$0$158$fb624d75(a)newsspool.solnet.ch...
>> Hi NG,
>>
>> i need some advice/comments on finding an assumpted L2 Loop via
>> software... instead of tracking it with shutting down the redundancy the
>> hard way..
>>
>> Setup of szenario:
>>
>> 3550 gi0/2 -- gi2/2 4506 -- PrtChan -- PrtChan -- 6509
>>
>>
>> Cat 4506 and Cat 6509 play HSRP whereby the 6509 is always the prio 105
>> of all configured vlans.
>>
>> On the Cat 3550, witch is only attached to the 4506 via gi2/2, i get
>> following messages:
>>
>> Mar 30 14:16:10: %ETHCNTR-3-LOOP_BACK_DETECTED: Keepalive packet
>> loop-back detected on GigabitEthernet0/2.
>> Mar 30 14:16:10: %PM-4-ERR_DISABLE: loopback error detected on Gi0/2,
>> putting Gi0/2 in err-disable state
>> Mar 30 14:16:11: %LINEPROTO-5-UPDOWN: Line protocol on Interface
>> GigabitEthernet0/2, changed state to down
>> Mar 30 14:16:12: %LINK-3-UPDOWN: Interface GigabitEthernet0/2, changed
>> state to down
>>
>> Thats the 3550 gone to Err-Dis!
>>
>> on the 4506 i get following logs:
>> 23 08:39:53: %C4K_EBM-4-HOSTFLAPPING: Host 18:A9:05:62:4E:DA in vlan 100
>> is flapping between port Gi2/6 and port Po10
>> Mar 23 08:39:53: %STANDBY-3-DUPADDR: Duplicate address 192.168.6.3 on
>> Vlan60, sourced by 000e.383e.483f
>> Mar 23 08:39:54: %C4K_EBM-4-HOSTFLAPPING: Host 18:A9:05:62:4E:DA in vlan
>> 100 is flapping between port Gi2/6 and port Po10
>> Mar 23 08:39:54: %C4K_EBM-4-HOSTFLAPPING: Host 00:D0:03:EA:E0:0A in vlan
>> 110 is flapping between port Po10 and port Gi2/6
>> Mar 23 08:39:54: %C4K_EBM-4-HOSTFLAPPING: Host 18:A9:05:62:4E:DA in vlan
>> 100 is flapping between port Gi2/6 and port Po10
>> Mar 23 08:39:54: %C4K_EBM-4-HOSTFLAPPING: Host 00:D0:03:EA:E0:0A in vlan
>> 99 is flapping between port Gi2/6 and port Po10
>> Mar 23 08:39:54: %C4K_EBM-4-HOSTFLAPPING: Host 00:00:00:00:FE:01 in vlan
>> 100 is flapping between port Po10 and port Gi2/6
>> Mar 23 08:39:54: %C4K_EBM-4-HOSTFLAPPING: Host 00:D0:03:EA:E0:0A in vlan
>> 200 is flapping between port Po10 and port Gi2/6
>> Mar 23 08:39:54: %C4K_EBM-4-HOSTFLAPPING: Host 00:1E:0B:C3:23:78 in vlan
>> 100 is flapping between port Po10 and port Gi2/6
>> Mar 23 08:39:54: %C4K_EBM-4-HOSTFLAPPING: Host 00:0E:7F:FD:58:B0 in vlan
>> 100 is flapping between port Po10 and port Gi2/6
>> Mar 23 08:39:55: %C4K_EBM-4-HOSTFLAPPING: Host 00:D0:03:EA:E0:0A in vlan
>> 99 is flapping between port Po10 and port Gi2/6
>> Mar 23 08:39:55: %C4K_EBM-4-HOSTFLAPPING: Host 00:90:FB:24:BA:00 in vlan
>> 100 is flapping between port Gi2/6 and port Po10
>> Mar 23 08:39:55: %C4K_EBM-4-HOSTFLAPPING: Host 00:1F:29:69:9D:6E in vlan
>> 100 is flapping between port Gi2/6 and port Po10
>> Mar 23 08:39:55: %C4K_EBM-4-HOSTFLAPPING: Host 00:D0:03:EA:E0:0A in vlan
>> 100 is flapping between port Gi2/6 and port Po10
>> Mar 23 08:55:58: %C4K_EBM-4-HOSTFLAPPING: Host 00:50:56:83:45:A3 in vlan
>> 100 is flapping between port Po10 and port Gi6/5
>> Mar 23 08:56:59: %C4K_EBM-4-HOSTFLAPPING: Host 00:50:56:83:45:A3 in vlan
>> 100 is flapping between port Po10 and port Gi6/5
>>
>> the interessting one i guess is this:
>> Mar 23 08:39:53: %STANDBY-3-DUPADDR: Duplicate address 192.168.6.3 on
>> Vlan60, sourced by 000e.383e.483f
>>
>> when i issue the following on the 4506
>>
>> asw03#sh mac-address-table | i 000e.383e.483f
>> 12 000e.383e.483f static ip,ipx,assigned,other Switch
>> 30 000e.383e.483f static ip,ipx,assigned,other Switch
>> 50 000e.383e.483f static ip,ipx,assigned,other Switch
>>
>> it sees its own mac addr, what a surprise!
>> so i do guess i got some bad things happening on L2, loopin all over.
>>
>>
>> ------------------------------------------------------------
>> as i just tried following within a complete seperate lab:
>>
>> 3560 fa0/2 -- fa0/1 3550 from 3550 to itself from fa0/47 to fa0/48
>> (looped)
>>
>> on the 3550 i configured: no spanning-tree vlan 1-999 making
>> sure it runs as if i would use some unmanaged switch, thereby creating a
>> loop on it self.
>>
>> within this LAB it was a pretty ugly szenario, since i actually thought
>> the 3560 on fa0/2 would track it and STP would go into the Blocking state
>> on fa0/2, but it did NOT.
>> so the hole thing looped and flashed like an x-mas tree on fa0/2 aswell
>> of course on the 3550.
>>
>> so i am considering in order to find the loop to go and take the approach
>> via storm-control, thereby issuing the action trap mode, in order not to
>> shutdown my hole network.
>>
>> on my Distribution Trunks/Uplinks towards the Access-Switches:
>>
>> storm-control broadcast level pps 500
>> storm-control multicast level pps 500
>> storm-control action trap
>>
>> i guess this should give me an idea from witch link i get alot of
>> broadcasts..
>>
>> i still can't explain why my 3550 in the real world setup went down with
>> Err-Dis, since it is single attached to the 4506....
>>
>> so if you got other idea's how to track L2 Loops without pulling out the
>> redundancy until it stops, feel free to contact me and send me youre
>> advice.
>>
>> Thank you
>> colin
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>
>


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