[j-nsp] 802.3ad Question

[Bit Gossip]

I had 2x T320 configured each with a bundle of 3x 10GE and traffic was
split correctly 33% 33% 33%

These has been in place for several years and across several Junos
releases.

On Thu, 2010-01-14 at 02:57 -0300, alexi wrote:
> Hello Stefan:
> 
> Thanks for your answer, this was a costumer question that i think camed from
> the way how load balancing in Cisco using Ether Channel was done , in that
> case you had a fixed number of 8 values so the hashing algorithm (using the
> source ip , mac ... etc) gives you one of those fixed values. So each one of
> the links in a bundle was identified with one or several of those values ...
> so in this case you can only have perfect load balance if you are using 2, 4
> or 8 links ... any other combination gives you a not even distribution ...
> 
> this is explained here :
> http://www.cisco.com/en/US/tech/tk389/tk213/technologies_tech_note09186a0080094714.shtml
> 
> I don´t know how this goes in 802.3ad  in Juniper ...what do you think ? ,
> 
> have you ever seen examples of good load balancing using 3 , 5 or 6 links in
> a bundle ?
> 
> BR
> Alexi
> 
> 
> On Thu, Jan 14, 2010 at 2:04 AM, Stefan Fouant <
> sfouant at shortestpathfirst.net> wrote:
> 
> > > -----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
> >
> >
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