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Webcast-Catalyst9k
New Member

Balance Internet Traffic on Multihome Frame

I would to use CEF to balance traffic to my 2 ISP's that are on a multihost WAN. How could one setup CEF to work across 2 sites that all additional sites have 512k DLCI's into? (Am I stuck with BGP?) Also, the entire 12 site network is running great on EIGRP.

Right now, I just point half the group to one ISP and the rest to the other with static routes. (Not very efficient)

The design plan is to have the sites be failover for each other and loadbalance traffic. There is a T1 between the 2 sites with the ISP links. The ISP links are both T1's as well.

Here's a "stick" drawing that might help..

1751 (ISP)

|

|

PIX 515e (v6.x)

|

|

1700 (DLCI to other sites, EIGRP)

|

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(WAN)----1750 at other sites (1 DLCI to ea ISP Host, EIGRP)

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3725 (DLCI to other sites, EIGRP)

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PIX 515e (v6.x)

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1751 (ISP)

Thanks

Mike

3 REPLIES
Gold

Re: Balance Internet Traffic on Multihome Frame

You should be able to advertise a default from both sites with ISP connections through EIGRP. I would condition the default on the state of the connection to the ISP, which would get you failover. Since each remote site would have two defaults, they would load shar between them (as long as you have your metrics set up so they are equal cost).

:-)

Russ.W

New Member

Re: Balance Internet Traffic on Multihome Frame

That sounds like what I'm after, but do you know of any examples I could look at? I tried a similar approach once before, but found that most of the traffic was moving to one site and very little was going the other.

Gold

Re: Balance Internet Traffic on Multihome Frame

I don't know of any.... Assuming you're not going to be receiving a default from the ISP through BGP, something like this should work:

Router A

! connection to first ISP

!

ip route 0.0.0.0 0.0.0.0

!

router eigrp xxx

redistribute static metric 10000 1 255 1 1500

Router B

! connection to second ISP

!

ip route 0.0.0.0 0.0.0.0

!

router eigrp xxx

redistribute static metric 10000 1 255 1 1500

If you are seeing more traffic exit one way than the other, then you should probably adjust your metric on the redistritbute static commands above so the less used path is more preferred. I'd do this in small steps--major changes will just shift all the traffic one direction or the other.

On the inbound side, your options are going to depend on what address space you're using, and if you're nat'ing or not, etc. Generally, inbound load sharing is difficult to achieve, just because of the way internet routing works--especially if you are not running BGP with the ISPs. The most fundamental thing you need to check is to make certain both ISPs are advertising your address space (if you're using one address space), and that neither of them are aggregating the address space into a larger block.

:-)

Russ.W

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