[c-nsp] ME3600x buffer calculations- revisited

[Waris Sagheer (waris)]

Hi Julie,

Replies inline [Waris]


From: Julie Rudolph <Julie.Rudolph at cdw.com<mailto:Julie.Rudolph at cdw.com>>
Date: Tuesday, December 24, 2013 4:17 PM
To: "cisco-nsp at puck.nether.net<mailto:cisco-nsp at puck.nether.net>" <cisco-nsp at puck.nether.net<mailto:cisco-nsp at puck.nether.net>>
Subject: [c-nsp] ME3600x buffer calculations- revisited

Hello:

My questions key off of this thread:  http://www.gossamer-threads.com/lists/cisco/nsp/172513.  I just seek a bit more clarification.  Wondering if anyone knows the answers to the following 2 questions:


1)      When using queue-limit percent, does this mean the switch will take that as a percentage of the 18MB of packet buffer for the ASIC serving the Gig ports on the switch?  Moreover, does it mean that the switch will dynamically allocate buffers to where they are needed, with the switch allocating the associated buffers to the busy interfaces (but not above the percentage of buffer that was specificied for that class(es) in question?

[Waris] That's correct. There is no per port buffers. Buffer allocation is done dynamically by an intelligent allocator based on the interface requirement and configuration.

2)      If I have 20 interfaces on the same asic (the one with 18MB available buffer) with QOS classes that each have the max of 2Mbytes specified as the queue-limit and those limits exceed 18MB, what will happen?

[Waris] Configuration oversubscription is supported since we assume not all the queues are oversubscribed at the same time.

3)      Lastly, has anyone ever had to configure queue-limits on the TenGig interfaces (i.e the default queue-limits weren't enough)?

[Waris] I have seen many providers who have changed the default queue-limit on 10Gig.

Thanks,
Julie
_______________________________________________
cisco-nsp mailing list  cisco-nsp at puck.nether.net<mailto:cisco-nsp at puck.nether.net>
https://puck.nether.net/mailman/listinfo/cisco-nsp
archive at http://puck.nether.net/pipermail/cisco-nsp/