[c-nsp] 2960 -> 4948 - no more drops :)

Reuben Farrelly reuben-cisco-nsp at reub.net
Sat Feb 16 19:42:19 EST 2013

The 2960 is a floor/access switch - and at the low end of the range.  It 
isn't positioned or designed to be used in the type of bursty traffic 
environment that the OP was using it for.

This is a classic example of when a Gig port in name is not a Gig port 
in throughput, ie it may link up at that speed but you'd be lucky to get 
the rated throughput in all but ideal circumstances.  Unfortunately the 
concepts around buffers, drops and architecture, and what makes a 2960 
different from a 4948 or ME series switch (because they all have 'Gig' 
ports - but a big price difference) are still concepts foreign to many 
engineers - more so in enterprise land than service provider land, IMHO.

I doubt it's an attempt at guerrilla marketing.  It's no real surprise 
that once upgrading to a switch that was designed for the purpose that 
performance and output drops improved significantly.


On 17/02/2013 11:25 AM, Alex Pressé wrote:
> Not sure if guerrilla marketer trying to get readers to google this
> fantastic switch...
> On Sat, Feb 16, 2013 at 5:14 PM, CiscoNSP_list CiscoNSP_list <
> cisconsp_list at hotmail.com> wrote:
>> Hi Rob (Sorry for not replying inline, but hotmail screws the formatting)
>> We did try tuning qos buffers (It did improve the drops, but they were
>> still significant), and we also tried disabling mls qos (Still saw
>> significant drops)....Im really interested to know why there is such a
>> difference between the two platforms....i.e. is it buffers/how they are
>> allocated, architectural differences or combination of both?
>> Cheers.
>>> Date: Sun, 17 Feb 2013 00:27:31 +0100
>>> Subject: Re: [c-nsp] 2960 -> 4948 - no more drops :)
>>> From: robhass at gmail.com
>>> To: cisconsp_list at hotmail.com
>>> CC: cisco-nsp at puck.nether.net
>>>> We recently upgraded a 2960G(Only doing L2) that was hitting
>> ~500Mb/sec on one port, and we were seeing 40,000+ output drops (5Min) -
>> Since the swap to the 4948, we see zero output drops. Is the difference in
>> performance purely buffer size?  I *think* the 2960 has 1.9Mb (Per ASIC)
>> and the 4948 has 16Mb (total?)?

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