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Hi, I wonder if anyone can discuss with me about buffer size in ICX ?

New Contributor II
Hi, I wonder if anyone can discuss with me about buffer size in ICX ? 
I am not much clear on how to size the buffer?


Contributor III
To what buffer size are you referring?

Which ICX are you referring?

Here is some info that describes a 6610.

The other models may have a different, but similar architecture.


As far as MTU goes, the Ethernet_II is set to 1500 by default, but you can change it.

Many thanks for prompt help. Yep, They are ICX-6610 and also ICX-7250.

In summary, I would test the performance of egress port against (different buffer sizes). It seems that ICX enables buffer sizing, but it is not clear at all in the configuration guide.

For example, one command like: qd-buffer 0 1 y, another command like qd-descriptor 0 1 y.  Please note above 0 means device number, 1 means any 1Gb port, y means buffer size (in terms of number of buffers).

Here, I got confused! The commands are not clear, why we must allocate all 1Gb ports the same buffer size, what are the descriptors, why do we need to allocate y for descriptors.    

Many thanks!
Best Regards,


RUCKUS Team Member
Hello, ICX 6610 and 7250 use two different chipset and the cmd line to tweak the buffer profiles may not be the same. But to give a perspective, queue buffers are used to control the total number of packets that can be queued in the outbound transmit for the port and descriptor points to one or more packet buffers. 'y' refers to the numbers of buffers to allocate against a device number and port type.

These commands provide the capability to allocate additional egress buffering and descriptors to handle momentary bursty traffic periods, especially when other priority queues may not be in use, or may not be experiencing heavy traffic.

If you need assistance in tweaking these values, Please open a tac case so our technical team can evaluate your requirement and suggest accordingly.

New Contributor II
Hi Jijo Panangat,

Thanks for your explanation and time.

In the default mode, ICX-6610 supports 8 queues. And my understanding that normal traffic will be scheduled through q0 (that appears as TC0 in the switch console if I am right) as long as this traffic has not marked or explicitly assigned to higher priority queue. 

That said, then we can set the buffer size of each egress port queue. For example, qd-buffer 0 1 y 0, will allocate y buffers for TC0 or q0. My concern is that max limit is 128 buffers for q0 as in the Egress buffer limits Table, but it still accepts larger number. Is this larger configured number ( > 128) still be taken by the switch?

The second query, when we configure TC0, Will that be for any egress port, in our example any 1Gb? because I still not understand why is not available to configure different buffer sizes among the 1Gbps egress ports and also different buffer sizes among TC0 of different ports.

Any comments on this are highly appreciated!

Thank you.