[c-nsp] Few questions regarding fixed vs modular and when which is better.

[James Slepicka]

This is more or less what I do as well and I'm pretty happy with it.  
Cabinets have 48-port patch panels tied over to a relay rack.  In one 
cabinet, the first half of the ports go to switch A, the other half to 
switch B.   Same thing in the second cabinet, except A/B are reversed, 
so each pair of cabinets shares a pair of switches.  It's effectively a 
top-of-rack design, except that the switches are located at the end of 
the row.  See http://slepicka.net/physicaldesign.png to get an idea of 
what I'm talking about.  Access layer switches are 4948-10GEs w/ dual 
power supplies connected to 6506s w/ 6704-10GEs in the distribution layer.

The biggest benefit of this config is that cable management is a snap 
and it's really easy to replace a switch if you need to.  Instead of 
messing around with a switch and a ton of cables at the top of the 
cabinet, I only need to move around a bunch of 1 foot cables in the 
rack.  I suppose the same thing could be done in the cabinet at the 
expense of additional space.  A ports are always the primary, and B's 
are backup.  With a 10Gb link to the distribution layer, that means I'm 
running at about 2.4:1 oversubscription assuming everything is happy.  
Downsides are that cabling can be expensive (all that CAT-6 vs. some 
fiber) and that it's tough for the server guys to figure out what 
switch/port they're plugging into at times.

I do hope that Cisco doesn't EOL the 4948-10GE without releasing a 
switch with similar features in a 1U form factor.

James


Shane Short wrote:
> I've had pretty good success doing this in the past, however, I've run 
> double the density and split it over two racks.
> Ie, 24 Servers per rack, so a 48port switch per rack, with 48 ties 
> between the rack to tie it all together, each server would hit the 
> switch in it's own rack, then tie over to the adjacent rack.
>
> Idea generally behind this was to have the servers/switches on 
> opposing phases to eliminate power problems, without having to get 
> Dual Power supplies in the switches themselves.
>
> -Shane
>
>
> On 29/08/2008, at 6:45 PM, Dean Smith wrote:
>
>> Surely 2 basic Switches - With Servers dual homed across giving you
>> independent uplinks to the core, dual control planes and dual power etc
>> gives far better resilience at the price point than a simple switch 
>> with an
>> extra PSU ?
>>
>> -----Original Message-----
>> From: cisco-nsp-bounces at puck.nether.net
>> [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Gert Doering
>> Sent: 29 August 2008 08:34
>> To: Pete Templin
>> Cc: cisco-nsp at puck.nether.net
>> Subject: Re: [c-nsp] Few questions regarding fixed vs modular and 
>> when which
>> is better.
>>
>> Hi,
>>
>> On Thu, Aug 28, 2008 at 10:56:51AM -0500, Pete Templin wrote:
>>> Have you looked at their product line lately?  I attended one of their
>>> LAN Switching Update events, and learned a lot about their new
>>> products, such as 1U 3560E models with 24 or 48 10/100/1000 ports and
>>> two X2 10G uplinks and dual power.  Might that suffice?
>>
>> Still "full L3" with the L3 price tag.
>>
>> Something like a 2960G-24TC with dual power would be cool.
>>
>> gert
>>
>> -- 
>> USENET is *not* the non-clickable part of WWW!
>>
>> //www.muc.de/~gert/
>> Gert Doering - Munich, Germany
>> gert at greenie.muc.de
>> fax: +49-89-35655025
>> gert at net.informatik.tu-muenchen.de
>>
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