[c-nsp] Load Balancing of Unequal Ethernet Bandwidth

[Ben Steele]

Alternatively if you are using BGP, have a look at BGP Link Bandwidth
http://www.cisco.com/en/US/docs/ios/12_2t/12_2t2/feature/guide/ftbgplb.html

On Mon, Feb 16, 2009 at 5:32 PM, Tony <td_miles at yahoo.com> wrote:

>
> Hi Andy,
>
> What do you run as IGP then so that we can help you out ?
>
> If static routes, then you can do it using by having multiple routes that
> are to the same destination.
>
> eg. on 2x serial links you might have:
>
> serial1 = 200Mbps (10.1.1.1/30)
> serial2 = 100Mbps (10.1.1.5/3)
>
> You would then add static routes like this:
>  ip route x y serial1
>  ip route x y 10.1.1.2
>  ip route x y serial2
>
> This way when you do "show ip route x" you would see something like:
>
> * directly connected via serial1
>      Route metric is 0, traffic share count is 1
> * directly connected via serial2
>      Route metric is 0, traffic share count is 1
> *  10.1.1.2
>      Route metric is 0, traffic share count is 1
>
> Your router would then divide the traffic into three with one third going
> to each of the destinations configured. The fact that two of those
> destinations are the same link means that two thirds will go down your
> 200Mbps link and one third down your 100Mbps link.
>
> This is fairly basic and doesn't scale very well, but will work.
>
>
> regards,
> Tony.
>
>
> --- On Mon, 16/2/09, Andy Saykao <andy.saykao at staff.netspace.net.au>
> wrote:
>
> > From: Andy Saykao <andy.saykao at staff.netspace.net.au>
> > Subject: Re: [c-nsp] Load Balancing of Unequal Ethernet Bandwidth
> > To: "Ben Steele" <illcritikz at gmail.com>
> > Cc: cisco-nsp at puck.nether.net
> > Date: Monday, 16 February, 2009, 5:39 PM
> > Hi Ben,
> >
> > When I googled around, there were many discussions abvout
> > using the
> > variance command with eigrp but we don't run eigrp
> > internally as our
> > IGP.
> >
> > This is a typical setup where we need to upgrade some of
> > our links, so
> > we might upgrade 50M on the second leg and end up with a
> > situation where
> > the first leg is100M and the second leg is 150M. As you may
> > know, some
> > providers aren't so flexible so you can't just
> > upgrade 25M on each leg
> > because they increment by 50M per leg only. Hence my
> > question if it was
> > possible to load balance across unequal ethernet circuits
> > without buying
> > additional bandwidth for both circuits.
> >
> > Thanks.
> >
> > Andy
> >
> >
> > ________________________________
> >
> > From: Ben Steele [mailto:illcritikz at gmail.com]
> > Sent: Monday, 16 February 2009 5:29 PM
> > To: Andy Saykao
> > Subject: Re: [c-nsp] Load Balancing of Unequal Ethernet
> > Bandwidth
> >
> >
> > You could do this with variance in eigrp, just add variance
> > 2 into the
> > eigrp config and it will load balance on a 2:1 ratio, if
> > your links are
> > equally matched in terms of latency you can look at
> > enabling per-packet
> > load sharing on the 2 egress interfaces to get an even more
> > granular
> > distribution, this can wreck some havoc with unequal paths
> > and out of
> > sequence packets though, however if equally similar in
> > characteristics
> > then performance is usually very good.
> >
> > Ben
> >
> >
> > On Mon, Feb 16, 2009 at 4:01 PM, Andy Saykao
> > <andy.saykao at staff.netspace.net.au> wrote:
> >
> >
> >        Is it possible to aggregate and then load balance unequal
> > ethernet
> >       circuits like so:
> >
> >       I have two ethenet circuits on my Cisco router. Both have
> > equal
> > costs to
> >       the next hop.
> >
> >       Ethernet Circuit #1- 200M
> >       Ethernet Circuit #2 - 100M
> >
> >       Can I aggregate both ethernet circuits so that the total
> > amount
> > of
> >       bandwidth available to the next hop is is 300M?
> >       Can I then load balance it so both circuits are equally
> > utilized?
> >
> >       For example...
> >
> >       * If I have 150M of traffic flowing to the next hop then
> > the
> > router
> >       would spread the load across both links like so:
> >
> >       100M through Ethernet Circuit #1.
> >       50M through Ethernet Circuit #2.
> >
> >       * The formula to use for this would be something like:
> >
> >       Utilization / Total Bandwidth = percentage of utilization
> > required per
> >       link
> >       150/300 = 0.5
> >
> >       0.5 x bandwidth of Ethernet #1 = 0.5 x 200 = 100M
> >       0.5 x bandwidth of Ethernet #1 = 0.5 x 100 = 50M
> >
> >       * If there was a total of 250M of traffic flowing to the
> > next
> > hop, and
> >       applying the formula above, the router would work out that
> > the
> > load
> >       distributed across both ethernet links would be:
> >
> >       166M through Ethernet Circuit #1.
> >       84M through Ethernet Circuit #2.
> >
> >       Any ideas???
> >
> >       Thanks.
> >
> >       Andy
>
>
>
>
>
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