SPAN port without a down link

[psafarik]

Hi all,

please advise. I have the optical SPAN port on C4948 connected to monitoring device. But the monitoring device doesn't send the link light back to the SPAN port (because it is not needed, the data flows from SPAN port to monitoring device only).

So the monitoring device uses only one optical fiber from TX port of SPAN port to RX port of the monitoring device. But the SPAN port on C4948 doesn't send data to monitoring device unless receiving a link light on its RX fiber.

How can I configure the SPAN port to send data to monitoring device without a need of light on its RX pin ?

Thanks in advance

Petr Safarik

petr.safarik@o2.com

[Eugene Lau]

Hi Petr,

You might be able to try disabling autonegotion if this is a Gig port. Autonegotiation is part of the 1000BaseX IEEE standard and is used to diagnose L1 issues. In this case, it's non-standard, so disabling autoneg could help.

If this is an IOS 4948

-> under interface

#Speed nonegotiate

A side note - typically with a SPAN monitor port, no traffic is switched from this port unless ingress keywords are specified. This means that even if the monitoring device did try to send traffic, it would be dropped at the port. This can be verified through the software configuration guide of your IOS version.

HTH

Eugene