Cisco MDS Performance buffers

[jordankatzarov]

Hello,

I want to ask, for what performance buffers are used about?

Are they extensions of the BB_Credits ?

I used the following command for reference:

switch(config-if)# switchport fcrxbbcredit

performance-buffers xx

Thank you and regards,

Jordan

[j.sargent]

Yes, they are extensions of recieve BB_credits. This allows you to give additional credits to the port instead of relying on the switch's built-in algorithm to assign the credits. You probably won't need to mess with this for FC ports, but may wish to for FCIP ports.

To set a port back to its default value and use the built-in algorithm, do:

switchport fcrxbbcredit performance-buffers default

Hope that helps...

[jordankatzarov]

Joshua,

Thank you for answer. Yes I understand, that we use those credits for FCIP ports, but are the performance buffers used if we reached out the BB_credits limit, beacause I know, that we can extend the BB_credits to 3,500 with "extended" BB_credits but with the cost of loosing ports.

Thank you and regards,

Jordan

[j.sargent]

I learned something new while researching this - my understanding was a little off, but I found a doc that explains it fairly well. Look at page 14 of a whitepaper titled "Implementing FCIP SAN Extension in Cisco SAN Environments".

It appears that you do, in fact, use the performance buffers on the ingress FC ports which are separated by an FCIP link.....not on the FCIP interfaces themselves.

Hope that doc helps....for anything deeper, you'll probably have to talk to a Cisco engineer directly.

[jordankatzarov]

Joshua,

Thank you for your answer and attention.Your answer was extremly helpful.

Cheers,

Jordan