Re: [HSSG] 40G MAC Rate Discussion
On Tue, 3 Apr 2007, Shimon Muller wrote:
> Nothing magic about 40Gb for servers, just as there is nothing magic
> about a 10x scaling factor, except for tradition. 40Gb happens to be in
> the right ballpark for server needs in that timeframe, and it will be at
> the right cost.
I represent a customer view here.
My coworkers who run servers seem to have no problem with link aggregation
and they have a history with four port FE cards and they're now doing LAG
with gig ports when they need it. The only 10GE attached servers we have
exist in the network lab for cheap packet generation.
Myself, being a network engineer, I see operational problems with more
than 4 links in a LAG but 4 is quite ok. I therefore see little reason for
a 40G server speed, as this can be solved by 4*10GE LAG. A 10x scaling
factor makes sense because 10 links in a LAG starts to create operational
problems with proper load balancing, how you manage them both physically
and logically, and a host of other problems that is better solved on the
hardware layer.
I see more reason for a 40G optical standard that basically extends the
OC192 10GE WAN PHY standard to OC768 as this would enable ethernet to be
carried in current state of the art DWDM systems. This would of course be
a moot point if we think that most DWDM vendors will have a 100GE DWDM
transponder by the time the 100GE standard is ready, and a 40GE OC768
compatible standard would take the same amount of time to implement as the
100GE variant.
I do think that it should be taken into account that a 100GE standard will
be carried over DWDM, and mechanisms should be implemented for
fast-failure-detection, mostly of the "there is a one-way fiber
break"-variant and the "the BER is high so the link is not good". This is
perhaps something that should be discussed in another thread...
--
Mikael Abrahamsson email: swmike@swm.pp.se