Fibre Channel (SAN)

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Occasional Contributor
Posts: 5
Registered: ‎04-16-2008

How to discover latency or stress test specific ISL links?

I'm new to this so forgive me if my nomeclature isn't correct. I am currently trying to get up to speed unfortunately training is out of the budget for now.

I am trying to discover the latency on a specific trunk to a remote site. With TCP/IP this is easy, send a ping and you get the response time in milliseconds. With fibre I am unsure how to accomplish this task. Any help is appreciated.

Background: 3 Brocade 48000's. 1 in a local data center (another in a box waiting to be installed) and 2 in a remote data center. Currently I have geographically separate paths to the remote data center and I will have full redundancy once I install the 2nd 48000 in my local data center. I have an existing 4gb trunked CWDM solution and we just brought up our redundant 4GB CWDM link and I would like to verify the latency between the directors. This information will be used to quantify choices for Sync or ASync replications of data between our primary and remote sites as well as general troubleshooting.

I did clear my counters on the local and remote trunks and ran the spinfab command at the remote director. No errors were noted in 6GB+ of data transfer but this still does not let me know what the latency time is. I have no hosts connected to this new remote director on the redundant CWDM link so I can't transfer any data to anything other than the switch currently.

Thank you in advance for any assistance.

Occasional Contributor
Posts: 21
Registered: ‎04-18-2006

Re: How to discover latency or stress test specific ISL links?

Hey,

Have a look to fcping

Olivier

Occasional Contributor
Posts: 5
Registered: ‎04-16-2008

Re: How to discover latency or stress test specific ISL links?

Thank you for the pointer. I'll keep digging into it but so far it seems like this tests host to frame. I was hoping to test switch port to switch port. I did find that the Brocade 48k w/5.3.0b firmware have fcping as a standard command but thier parameter requirements are different than the GNU versions of fcping. I understand what the -h output of this command is telling me but there is something wrong with the way I am doing it as I am unable to ping remote ports. From the switch I get "incorrect source wwn" and with the GNU version of fcping the host either see's no ports via the -D/-d output or I am only able to ping the wwn of the card that has been zoned in for that host. So much to learn and no training or mentor to learn from :-/. Gotta love new corporate america.

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