[NANOG] Larger packets to save power, was: Re: would ip6 help us safeing energy ?

Iljitsch van Beijnum iljitsch at muada.com
Mon May 5 08:07:12 UTC 2008


On 5 mei 2008, at 0:57, Adrian Chadd wrote:

> I'd seriously be looking at making current -software- run more  
> efficiently
> before counting ipv6-related power savings.

Good luck with that.

Obviously there is a lot to be gained at that end, but that doesn't  
mean we should ignore power use in the network. One thing that could  
help here is to increase the average packet size. Whenever I've  
looked, this has always hovered around 500 bytes for internet traffic.  
If we can get jumboframes widely deployed, it should be doable to  
double that. Since most work in routers and switches is per-packet  
rather than per-bit, this has the potential to save a good amount of  
power.

Now obviously this only works in practice if routers and switches  
actually use less power when there are fewer packets, which is not a  
given. It helps even more if the maximum throughput isn't based on 64- 
byte packets. Why do people demand that, anyway? The only thing I can  
think of is DoS attacks. But that can be solved by only allowing end- 
users to send an average packet size of 500 (or 250, or whatever)  
bytes. So if you have a 10 Mbps connection you don't get to send 14000  
64-byte packets per second, but a maximum of 2500 packets per second.  
So with 64-byte packets you only get to use 1.25 Mbps.

I'm guessing having a 4x10Gbps line card that "only" does 14 Mpps  
total rather than 14 Mpps per port would be a good deal cheaper.  
Obviously if you're a service provider with a customer that sends 10  
Gbps worth of VoIP you can only use one of those 4 ports but somehow,  
I'm thinking few people use 10 Gbps worth of VoIP...

Iljitsch

PS. Am I the only one who is annoyed by the reduction in usable  
subject space by the superfluous [NANOG]?




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