[c-nsp] "Core/AGG" switch for small DC

[Jeremy Bresley]

On 3/26/2015 11:35 AM, CiscoNSP List wrote:
>> For a datacentre, I'd pay attention to buffering. Cisco stackables tend
>> to have tiny buffers (not sure about 3950), which may or may not be a
>> problem for an agg switch, depending on your traffic patterns and link
>> speeds, and whether the device does cut-through switching.
>>
>> How many ports and of what media/speed do you want? Do you need any DCB
>> / FCoE stuff? Layer 2 or layer 3?
>
> Purely L2, all eth...Id like 2 separate agg boxes, but dual links from TOR switches, to 2 "independent" switches would be difficult (i.e. how to have all vlans go to both switches, and handle a failure of one of them "automatically"...all the cust vlans are trunked up to ME's and ASR's for L3.
>
If you've been happy with the 4948s, I'd look at the 4500X as a possible 
aggregator for them.  16/32 ports of 1/10G (plus 8 on an expansion 
module), support for all the optics and twinax options (with a few 
caveats for ZR optics, but shouldn't be an issue within a DC).

They do support VSS, and it's been stable for us for ~18 months running 
10 floors worth of heavy users from closet 4507R+E's via 20Gb 
port-channels as well as a large port-channel via EWDM boxes to our 
data-center.  Mixed L2/L3 on ours, and other than having to order some 
3rd party PDU cables (C15s on these, not C13s, same as the PoE 3560X's) 
they've been great for our use case.  We've got another pair running in 
a colo space for circuit handoffs, and they've been rock solid boxes for 
us.  They're basically a Sup7E from a 4500E with 16/32 ports of 10G 
built into a 1U chassis, same code image and feature support as you'd 
have on those.

The other option for a more traditional data-center switch would be the 
Nexus 5500/5600 lines.  These are NX-OS rather than the IOS-XE of the 
4500X so there is a learning curve there if you aren't familiar with it, 
but are 90% of the functionality you'd get out of a Nexus 7000/7700 
device in a 1-3U package.  The 5500/5600s do VPC which allows you 
dual-active forwarding and are a cut-through instead of traditional 
store and forward switch.  The 5600s also have 40Gb ports available and 
would allow you to use FEX's to replace some of the TOR 4948s and have 
all management from one central point (can configure master/slave for 
configs on the 5Ks in VPC mode, so you configure both switches as one 
unit, same with VSS on the 4500X's).  The 5500/5600 are more limited on 
their optics support (don't support any CWDM/DWDM or ER/ZR optics), but 
are a solid data-center/TOR switch.

I've worked with both of these for several years, let me know if you 
have any specific questions about either of them.

Jeremy "TheBrez" Bresley
brez at brezworks.com