[c-nsp] 10G Aggregation?

[John Gill]

Not to mince your words Nick, you have good points.  Buffering is a very 
significant consideration, especially if you have a mix of 1G and 10G or 
you expect a lot of many-to-one patterns.

I do want to mention that the key differentiators of the 5548 vs. 4500X 
buffering that 5548 uses ingress buffering and is cut-through vs. shared 
tx store and forward.  However there is no sharing on the 5548 ports 
(But some models of Fabric Extenter [n2k] can).  The ingress buffer 
architecture can scale very well for short bursts from many interfaces 
at the same time, since each packet is stored on it's own ingress 
virtual output queue.

Regards,
John Gill
cisco



On 7/17/12 3:58 PM, Nick Hilliard wrote:
> On 17/07/2012 17:02, Garry wrote:
>>  From a price- and performance-view, you may want to take a look at the
>> Nexus 5500 series ... depending on what all you want to do with your
>> core switch, it will not only outperform the 4500 (and even 6500)
>> series, but will most likely be quite a bit cheaper ... eg. 5548 has 32
>> built-in SFP/SFP+ ports with one expansion slot for additional 16
>> SFP/SFP+ ports. If you need L3, make sure you don't forget to get the L3
>> card (which pushes up to 160Gbit/s)
>
> Just be careful that the buffering on each of these switches is sufficient
> for your needs.  Neither is over-endowed with huge buffers, but depending
> on your requirements, this may not be a serious issue (or an issue at all).
>
> By way of reference, the 4500X has 32M shared buffers per box, but it's a
> store-n-forward switch, whereas the 5548 has as more complicated mixture of
> shared and per-port dedicated buffers which are much smaller - but that's
> ok because it's a cut-thru (unless you're doing 10G -> 1G downsizing in
> which case it reverts to store-n-forward).
>
> I.e. make sure you understand the design architecture of these switches
> before making a decision to choose one over the other.
>
> Nick
>
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