[j-nsp] 802.3ad Question

[Stefan Fouant]

> -----Original Message-----
> From: juniper-nsp-bounces at puck.nether.net [mailto:juniper-nsp-
> bounces at puck.nether.net] On Behalf Of alexi
> Sent: Wednesday, January 13, 2010 11:45 PM
> To: mtinka at globaltransit.net
> Cc: juniper-nsp at puck.nether.net
> Subject: Re: [j-nsp] 802.3ad Question
> 
> Hello Mark:
> 
> I am coming back to this question , i would apreciate your help again
> ...
> 
> in the example you mention you said that your bundle is using 3xGE and
> you
> have a pretty fair load balance 1:1:1
> do you know if there is any requirement about having pair numbers or
> power
> of 2 amount of links in a bundle to get a good load balance ?
> 
> I guess that should depend on the hashing algorithm but of course there
> is
> no much info about how it works .... we are interested to have 6xGE in
> a
> bundle ... so , will we get 6Gbps of real throuhput  ...?

The hashing algorithm Juniper uses is proprietary so there isn't much
useable information out that, but in my experience I've never seen anything
along the lines which would require a LAG to be comprised of multiples of 2
links to get an even load balance.  The load balancing tends to get a more
even distribution when you've got a large number of flows.  Assuming a large
number of flows, you should be able to get an even balance across the
component links within the 802.3ad LAG bundle.  You might also want to
consider enabling Layer 4 hashing to get even more granular distribution, if
the source and destinations are sparse, but you're using a large number of
source and destination ports.

HTHs.

Stefan Fouant, CISSP, JNCIE-M/T
www.shortestpathfirst.net
GPG Key ID: 0xB5E3803D