[j-nsp] "Invalid VCs" error message on ATM interface

William Phang phangjk at hotpop.com
Wed Jun 9 00:53:49 EDT 2004


Why the "Invalid VCs" happen?. This is the explanation:

It goes up every time you receive a cell for a non-configured VC If
connected to an ATM switch, this routinely happens to reserved VCIs 5,16,18
etc being probed by the switch, so no harm here. Furthermore, until very
recently, JUNOS ATM PIC firmware was unable to register those cells
separately for interfaces on the same PIC.This means the counter could go up
on the wrong port

The source of the problem is in the chip. The microcode for the SAR chip to
increment this counter and one counter is maintained per chip, not per port.

The 'Invalid VCs" should never increase only in one case - when _both_ PIC
ports are connected to another router.

We have seen a lot of this problem and have working with JTAC. But it seems
very hard to solve since this is hardware bug.

Don't worry it will not impact to performance. I have test it.


William Bong

-----Original Message-----
From: juniper-nsp-bounces at puck.nether.net
[mailto:juniper-nsp-bounces at puck.nether.net] On Behalf Of Patrick Liu
Sent: Wednesday, June 09, 2004 4:04 AM
To: juniper-nsp at puck.nether.net
Subject: [j-nsp] "Invalid VCs" error message on ATM interface


We are seeing the "Invalid VCs" as input errors on an ATM interface of M10.
The error number is increasing randomly. We have tried to work with the
transport provider to identify the issue. They have indicated that they
shouldn't send cells with non-existent VC over to us. We have also tried to
turn on the monitoring on that interface. It doesn't give us too much
information. Does anyone out there have better ways / ideas to troubleshoot

Thanks in advance.
juniper-nsp mailing list juniper-nsp at puck.nether.net

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