Fibre Channel (SAN)

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Contributor
Posts: 32
Registered: ‎06-09-2012

C3 Discards

Dear Techies,

Iam quite new to SAN. Please do help me in understanding the below scenerio...Many thanks to you all...


Here's a snapshot of an existing SAN environment...
If we've couple of fabrics in Site A and another 2 fabrics in Site B.Lets Say F0, F1 in Site A & F0 & F1 in Site B connected by a Backbone switches at both the ends. Both the F0's connected to Backbone fabric-0 and, F1's on both the sides connected to Backbone fabric F1 conveying there's no interconnection between edge fabrics in both site A and Site B.Now the question is...

Will the C3 discard errors generated in any of the switch ports in edge fabrics F0 in Site A&B gets propagated to edge fabrics F1 in Site A & B???????????

Thanks,

Rakesh.

External Moderator
Posts: 4,906
Registered: ‎02-23-2004

Re: C3 Discards

rakesh,

--->>> Will the C3 discard errors generated in any of the switch ports in edge fabrics F0 in Site A&B gets propagated to edge fabrics F1 in Site A & B???????????

disc c3 = Class 3 frames discarded:

This affects the receiving link: The number of Class 3 frames discarded. Class 3 frames can be discarded due to timeouts or invalid or unreachable destinations. This counter increment during normal operation. It can also be used to show the effect of port congestion, means good frames from consecutive S-ID's and D-ID's not being directly routed port to port, but instead an exception frame is routed through the internal port (that normally should not happen with a port to port routing on the ASIC, but it does when the D-ID port suffers a buffer full condition and cannot accept any more frames). Also, if the destination is blocked due to high ISL workload (means that is: a long time with BB Credit Buffer = 0), that can cause buffer full conditions, therefore the S-ID port may (in extreme circumstances) meet a timeout condition and therefore the disc c3 counter will increase.

These errors are in the sum for the LLI = "Low Level Interface" errors.

TechHelp24

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