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x440-48p-10G flashing ports

Have a stack of six x440-48p-10G with one x440-48p-10G trunked off of it. All ports on the stack (except switch 1 and 2) are flashing rapidly as if there is a loop, however I cant see any loops through the log or ELRP and network wise everything is working normally (although slow routing between vlans).

11 replies

Userlevel 6
Hey DJ

When did this start? When you do a show port sharing does it show up? are you using LACP? what is happening to the ports on the switch that is trunked off the stack?

Hey Paul, not sure when this started, a show port sharing does not show anything and we are not using lacp. The trunk ports are flashing on both sides as well. Thanks
Userlevel 6
Hey Dj

ok so when you say it is trunked do you mean that the other switch has one link with VLANs tagged to the stack or do you mean that you have two ports LAGed together between the switch and the stack?

is ELRP turned on the port going to the stand alone switch?

Userlevel 7
Slow routing is not normal. Do you have slowpath forwarding happening?
Yes, one link between switches with tagged vlans, no lags are configured. ELRP is not turn on the port going to the stand alone switch
Userlevel 6
can you post the command show stacking and show stacking ports?

It looks like stack ports are blocked:

* Slot-1 75-AMORY-STACK.36 # show stacking stack-portsStack Topology is a Ring
Slot Port Select Node MAC Address Port State Flags Speed
---- ---- ------ ----------------- ----------- ----- -----
*1 1 49 00:04:96:99:b7:89 Operational C- 10G
*1 2 50 00:04:96:99:b7:89 Operational C- 10G
2 1 49 00:04:96:99:b7:8f Operational C- 10G
2 2 50 00:04:96:99:b7:8f Operational C- 10G
3 1 49 00:04:96:99:97:dc Operational C- 10G
3 2 50 00:04:96:99:97:dc Operational C- 10G
4 1 49 00:04:96:99:97:d5 Operational C- 10G
4 2 50 00:04:96:99:97:d5 Operational CB 10G
5 1 49 00:04:96:99:8a:fa Operational CB 10G
5 2 50 00:04:96:99:8a:fa Operational C- 10G
6 1 49 00:04:96:99:97:d7 Operational C- 10G
6 2 50 00:04:96:99:97:d7 Operational C- 10G

* Slot-1 75-AMORY-STACK.34 # show stackingStack Topology is a Ring
Active Topology is a Ring
Node MAC Address Slot Stack State Role Flags
------------------ ---- ----------- ------- ---
*00:04:96:99:b7:89 1 Active Master CA-
00:04:96:99:b7:8f 2 Active Standby CA-
00:04:96:99:97:dc 3 Active Standby CA-
00:04:96:99:97:d5 4 Active Standby CA-
00:04:96:99:8a:fa 5 Active Standby CA-
00:04:96:99:97:d7 6 Active Backup CA-
Userlevel 6
Thanks DJ

I am starting to think that it may not be a loop but maybe a broadcast like storm or some other traffic related issue. After hours can you see if disconnecting the stand alone switch changes anything, or just does it change once users are away from the network.

There are other things that we can look at from the switch perspective but I think that would be best if you did it via a call into GTAC.

Okay, great. Thank you for the help. Ill call in to GTAC when i have a maintenance window.
Userlevel 6
couple of other things to look at... Show port congestion will tell you if indeed any of the ports are being overrun .... Show port xx statistics will show you tx rx packets and break them down so you see how many broadcast frames mcast frames ect. If your broadcast or mcast frames are increasing like crazy then this would effect all ports in the vlan so ports blink almost in sequence...

Before you do these it is a good idea to clear counters...

Sflow is done in hardware and you can set it up and point it to a collector on your network ( good open source one is made by Inmon). Let it run a while and look at what is chattering so much...

Good luck
Userlevel 7
Hi DJ, do you have any new information on this issue?