ASR9K 10 Giga Loss signal and Lacp

[mcagiola]

Hi all, I'm facing on two different behavior about LACP due to Remote Fault loss signal on a 10 Gigabit.

The topology is simple, I have one ASR9K and one Huawei device, they are connected using 2 tengigabit and are configured with lacp port-channel. One interface is active and the other is stand-by.

If the customer plug off the TX on the active link on the ASR9K, the device immediately switch the port role, the port that was in stand-by is switched on active role.

If the customer plug off the RX on the active link on the ASR9k, the device wait the lacp timeout, after that switch the port role.

This behavior was observed only with ASR connected to a Huawei device, if the connection is between ASR and Juniper or Ericsson device, the behavior is ever the same, that ASR switch the role of the port immediately.

Why this behavior?

As I know the standard of 10 Gigabit, in case of a fault on RX link, the device with the TX "active" send a RF signal, and the remote device should put in shut the gigabit. Is that correct?

Thanks.

Marco.

[Aleksandar Vidakovic]

hi Marco,

correct. The device "B" that detects signal loss on Rx should signal back to the peer via its Tx that there was a LOS. Without that, the device "A" has no way of knowing that "B" has a LOS on Rx, so the only mechanism that remains is the LACP timeout.

/Aleksandar

[mcagiola]

Hi Aleksandar, in this case the device B is ASR9K, and its mean that our device never send a RF to the remote host, whatever the vendor is. In case of a fault on TX of the ASR9K we observed that the port is immediately shut and the lacp port role switch, it means that the remote host sent a RF to ASR9K... or because the ASR have an "internal" physical protocol that shut the port even if the RX is up?! The first behavior was observed only with Huawei.

Thanks for your support.

Marco.

[Adam Vitkovsky · Accepted solution]

If it works with ASR->other vendors, then I’d assume the RF is being sent on TX by ASR9k in reaction to RX failure detection.

And to me it looks like the Huawei box can’t actually interpret the RF correctly.

Do you see ASR doing switchover to backup as soon as the RX is pulled?

–I would expect the ASR interface to go down right away(unless you have carrier-delay down > 0 configured under the 10GE interface?).

adam

[mcagiola]

Hi Adam, yes the ASR9K shut the port immediately.

Thanks for you support!!

Best regards.

Marco

[quanle]

Hi team,

Sorry for bringing this up, been searching the issue and found this only post.

I have a similar case with a simple topology: ASR 9K – (TenGigE directly connected) – ASR 903.

When the TX fiber is pulled off on the ASR 903, the port is shutdown on the ASR9K side, but stay up on the ASR903 side.

When the RX fiber is pulled off on the ASR 903, the port is shutdown on both side.

Is this an interwork problem between the ASR9K and ASR903 i.e the ASR903 somehow can’t understand the RF signal from the ASR9K correctly?