topic RE: ELRP ingress port = egress port in ExtremeSwitching (EXOS/Switch Engine)

ELRP ingress port = egress port

eyeV — Thu, 20 Nov 2014 18:21:00 GMT

Hi everybody!

I configured standalone ELRP-client on my SummitStack (two x480). So, after a couple of days I saw strange log messages...

ELRP.Report: Slot-1: [CLI:Default:2] LOOP DETECTED : 35590 transmited, 23 received, ingress slot:port (1:7) egress slot:port (1:7)ELRP.Report: Slot-1: [CLI:Default:2] LOOP DETECTED : 35550 transmited, 5 received, ingress slot:port (1:4) egress slot:port (1:4)It happens periodically, but only on stack. I have nine standalone x480 switches and ELRP works correctly on it. I've never seen this situation on it at any rate.

Can anybody suggest me something?

RE: ELRP ingress port = egress port

PARTHIBAN_CHINN — Thu, 20 Nov 2014 18:37:00 GMT

there must be loop .
could you trace it down by following below steps
1.see what devices are conencted to 1:4 and 1:7
2.If it is a switch ---run elrp on that switch to indentify the loop.
Most possible cause are phones connecting to edge swicth are looped back within the ports in phone.
Have seen this problem for the past 10 years.
if you find thats the issue.
then the remedy on edge switch is to enable bpdu-restrict /edge safegurad features.

RE: ELRP ingress port = egress port

eyeV — Thu, 20 Nov 2014 18:52:00 GMT

Ok. Thanks for this hint!

RE: ELRP ingress port = egress port

davidj_cogliane — Wed, 13 Jan 2016 20:28:00 GMT

We see this with some older Cisco phones when switches get rebooted. After some research we found the Cisco phones are designed with a closed circuit that can loop back edp packets before the phone is powered up. We are currently forced to go through the switches after reboots and enable the ports that are disabled due to these "phantom loops".

Has anyone seen ports reported as elrp disabled but actually be active?

RE: ELRP ingress port = egress port

Drew_C — Wed, 13 Jan 2016 20:28:00 GMT

The phone will still be powered by the switch but could have its data connection disabled by ELRP. Are you sure that's not what you're seeing?

RE: ELRP ingress port = egress port

davidj_cogliane — Wed, 13 Jan 2016 20:28:00 GMT

Last time I saw this we disabled the port and re-enabled it to get it to clear out of the elrp. I have also seen the ports because stuck in the disabled state. After hours today I plan to try disabling the port and re-enabling it.

I guess I was trying to find out if this is a known reported bug.

Thanks,

RE: ELRP ingress port = egress port

Drew_C — Wed, 13 Jan 2016 20:28:00 GMT

If there is a known issue, it's one that I don't recall seeing. Just because I don't recall it doesn't mean there isn't an issue though.
Instead of disabling/re-enabling, you can try the

restart port

command since that's a little quicker (note it won't reset inline-power, just the link).

RE: ELRP ingress port = egress port

davidj_cogliane — Wed, 13 Jan 2016 20:28:00 GMT

Wow,

This bring back bad memories.

In the interest of providing complete resolution.

We discovered that these older Cisco phones have a physical loop that opens when they receive power. The behavior we saw appeared to be the result of the data link coming up before power could get there to open the loop. As a result the elrp frames made it back to the switch and disabled the port.