Load Balancing with two ISPs

Apr 22, 2005 7 Replies

Hello,



I would like to ask if someone knows how to configure load-balancing without using dynamic routing(ospf,bgp,rip). Currently we've to ISP links that does not support dynamic routing. Is there a way we could configure with 2 :



ip route 0.0.0.0 0.0.0.0 ISP1_ip ip route 0.0.0.0 0.0.0.0 ISP2_ip



Our internal network is 192.168.0.0/24. I've searched internet but didn't find any solution. Our router is Cisco_2811 with c2800nm-adventerprisek9-mz.123-11.T3 IOS.



Thx, Mark


From this (and text above it) I can not conclude if you have just 1 ISP and 2 links or 2 ISP's and 2 links. This makes difference.

Two ISPs - Two links : one is 2Mbit async, second 4Mbit sync

/Marek

On 22.04.2005 10:32 marek wrote

What exactly do you mean by that? I'm not aware that you can buy links that prohibit dynamic routing.

Don't do that as this most likely will do round robin packets to ISP1 and ISP2 in the worst case.

I would strongly recommend to make BGP happen. Anything else is broken.

Arnold

Only the 4Mbit link does support BGP, but the second one is low cost and ISP doesn't give us any BGP support. Still the question remains : if any load-balancing is possible with this topology ?

/Marek

On 22.04.2005 12:06 marek wrote

You can always try to nail a pudding at the wall ... but what for? Give your 2nd ISP ++$ and engineer for a prober BGP setup.

If you still want to go the pudding way, I would suggst something along this:

0/1 --> via ISP1, backup via ISP2 128/1 --> via ISP2, backup via ISP1

Observe how it works. If Ok, you are done. If not, refine the splitting (i.e 0/2, 64/2, 128/2, 192/2 or anything else). Do until you are happy.

Arnold

I may be wrong, because I just practised with Cisco routers for a short time but my recent test shows something that may apply to your case.

  1. I do have those two commands set two default gateways line yours, but I use SE 0/0 and SE1/0 as destination instead of fixed IPs.
  2. I use "IP CEF" at config t to enable CEF
  3. I set "ip load-sharing per-packet" for both SEs

Below is the part that directly relates to that setup

[...] ip subnet-zero ip cef ip cef accounting per-prefix ! ! ! no ftp-server write-enable ! modemcap entry usr56k:MSC=&f1s0=1 ! ! ! interface FastEthernet0/0 ip address 192.168.248.1 255.255.255.0 speed auto full-duplex ! interface Serial0/0 ip address 192.168.245.2 255.255.255.252 ip load-sharing per-packet service-module t1 remote-alarm-enable ! interface Serial1/0 ip address 192.168.245.6 255.255.255.252 ip load-sharing per-packet service-module t1 remote-alarm-enable ! [....]

DT

No, I am absolutely wrong. My case is different from yours. My two SEs meet each other at the other end. Yours do not.

Sorry,

DT

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