[c-nsp] DWDM optics on 6500s

[Tim Durack]

We've selected the 6708 for our 10Gig installs. DFCs and good sized
buffers. Lots of availability on the used market. Can be run in
line-rate or over-subscribed mode, which might suit your deployment.

I have hopes for SFP+ linecards to drive 10Gig costs down, but I don't
think much is going to happen until 40Gig/100Gig is the new backbone.

Tim:>

On Mon, Oct 5, 2009 at 4:47 PM, Jeff Bacon <bacon at walleyesoftware.com> wrote:
>> Don't forget they are absurdly under-buffered (16MB per card, compared
>> to 256MB for 6708), and you can easily cause head of line blocking
> with
>> certain traffic profiles. If you want to run anywhere close to line
> rate
>> on them you need to monitor for drops or overruns and be prepared to
>> play the port shuffle game to find an arrangement that works. Passing
> a
>> lot of traffic within the same fabric channel (from port 1<->2, or
>> 3<->4) is the biggest sin, it will start dropping at 7 Gbps.
>
> Well that's wonderfully comforting. Though I really probably only need
> two ports anyway - ring-in and ring-out. Maybe not so bad. I'd consider
> a 720-VS-10G head if I had some confidence that those two ports on the
> sup were actually connected to the fabric.
>
> I don't really need to run line rate - this is more about latency and
> burst capacity than sustained throughput. I have loads that burst from 0
> to 500Mb/sec (then back) in nothing flat, and multiple of those may run
> through the wire at the same time. Or not.
>
> Someone pointed out that the X2 and SFP+ xcvrs don't have much punch,
> and I'm going to be shooting 20-30km through passive MUXes. So that
> might matter.
>
> (This is a bit of a roll-yer-own local metro NYC ring, which I'm doing
> because I can get the wave for not much more than I'd pay for the
> switched gig.)
>
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-- 
Tim:>
Sent from New York, NY, United States