Low-cost improvement on a poor man's Internet loadbalance?

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Sep 26th, 2006
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To achieve Internet loadbalance and redundancy, we currently connect to SBC (T1/Frame Relay) and TimeWarner (Cable) for Internet access. Between the edge routers (2600/2500) and our ASA firewall, we position a 3rd router as loadbalancer using CEF, RIP2, PBR (for outgoing) and a pair of default routes. At the cost of three old routers, it has worked very well for us. We do, however, have the following two limitations:

1. Our CEF loadbalance is connection based (can't use packet-based because we only have a class-C space, not big enough to be on the internet routing table). Therefore, we cannot loadbalance according to available bandwidth on both uplinks.

2. The dynamic routing setup only detects immediate link failures. It cannot detect performance degration on a particular link or a remote upstream failure. When an ISP has problems, our users experience random Internet problems because they may be redirected to go through the ISP with problems.

Does anyone have any experience with a low-cost solution, like Linksys RV-082, Xincom XC-DPG502, and Zyxel Zywall 70?

As to No.2, I am thinking about writing a script for our net monitoring software to test for link speed to certain popular web sites and shut down an Internet link if it gets too slow.

But I'd don't want to "reinvent the wheel" if there is a low-cost solution out there already.


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Overall Rating: 4 (2 ratings)
DANIEL WANG Wed, 09/27/2006 - 11:01
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That's exactly what we need. Thank you very much!

I checked the platform requirement. It requires 2600XM and up. We have to buy 2 or 3 XMs. I wonder if I can do with only one. I am just not sure with NAT, master controller and everything else on one router, whether it is going to perform well. I had to use three routers because NAT and CEF didn't work well in the one-router topology.

Did you actually have experience using OER? What's the memory requirement for the edge router and master controller if I need to optimize loadbalance on all of our Internet destinations? The documentation says you can do with just 64MB if you have only a few destination prefixes (like connecting to several remote locations within the enterprse.)

I will rate your comment.

Thanks a lot!


jackyoung Wed, 09/27/2006 - 17:13
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It is good that it suits for you. I am sorry that I did not configure and verify it at the moment due to no resources.

What I believe the memory consumption will not be high be the CPU loading may be a bit higher.

IMO, the memory also related to the routing table size. If you only using default route or partial BGP for the routing. It will be fine. If you are going to have full Internet routing table, then min. 256MB is required. The 64MB requirement is for the OER feature only and not including any additional services.

What the existing router CPU loading ? If it is not high then it is fine to try. Moreover, why not purchase 28xx model that is much higher performance than 26xxXM.

There are three models in the OER, If you have spare router, you can try it one-by-one, i.e. start the testing at minimum hardware then depends on the requirement to increase the router.

However, you can also compare the cost to implement additional routers for this feautre and implement a single external box to load-sharing the link. It because a single load-sharing box will be much simpler but lead to another brand and require additional management.

Hope this helps.

DANIEL WANG Mon, 10/02/2006 - 11:09
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Sorry for the late reply. I thought the Master Controller had to remember many prefixes and their performance stats in OER. No, we don't use BGP at all. We only use two floating default routers with CEF for loadbalance.

Our 2500 router (for cable) is frequently overhwelmed. The 2600 T1 router cpu load peaks at 30-40% with an average of 10-20%.

2800 is out of the budget for now.


jackyoung Mon, 10/02/2006 - 16:48
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IC, if only two floating / static routes, it will be fine for 2600 router. However, the loading is already 30%-40%, I believe it is caused by the throughput. Try to simplier the config. e.g., remove unused commands and simplier the ACL, etc.

I suggest to test it in the lab first to obtain any cpu loading increasment then select the right platform. You can also consider 18xx platform that it is even much faster than 26xx. Check below link for the router performance, it gives hint on router selection and cost/performance ratio.


Hope this helps.

DANIEL WANG Tue, 10/03/2006 - 05:39
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That PDF is very helpful. I will check into the 1800 series. Cost is a main concern. We are thinking about trying out the 2 router scenario with a 3rd as backup or addition if 2 routers can't handle the task very well.

Thank a lot. I will report back when we get it implemented. There are some other solutions, but if difference in cost is not huge, I will go with Cisco any time.

jackyoung Tue, 10/03/2006 - 16:50
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You're welcome. Please feel free to let us know your solution then I may able to comment it. ;)


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