Point to Point Ethernet

Wed Jul 8 15:42:10 UTC 2009

On Wed, 8 Jul 2009, William Herrin wrote:

> At the cost of low-volume production run hardware which is A. much more 
> expensive (because of the low volume), B. restricted to a few supported 
> routers and C. less thoroughly tested. I don't see how you come out 
> ahead in that calculation.

The only way to do it would be to make this a standard in the next 
evolution of Ethernet, perhaps 400GE. I don't see this happening though.

But the only REASON to do it, would be to lessen overhead for small 
packets. I don't see how you can not see this.

> My understanding is that 9000 is a standard for GigE and up but for 
> compatibility with earlier ethernets it's not the default. You have to 
> explicitly configure it and you must configure it the same on every host 
> and switch within the broadcast zone. For a point to point link, this 
> should be trivial.

No, IEEE says only 1500 payload MTU. This was discussed in 40GE and 100GE, 
and IEEE left the framesize the same way it's always been.

> I gather from your list that not everything which supports gige also 
> supports jumbo frames but that most things do.

Yes, but that doesn't make it standard. It makes it common.

-- 
Mikael Abrahamsson    email: swmike at swm.pp.se