Router Default Gateway Failover

[agrayson]

I was recently told that because we have 2 internet connections with 2 vendors that we needed to configure our network for internet access failover...one ISP goes down then trafic routed to the other ISP...I looked at using BGP but this is a private network and that would be costly and very time consuming to do but I sure there is a easier way like helper addresses or something.....suggestions please

Thanks

Al

[Richard Burts]

We could give better answers if we knew more about your environment. For example you refer to your network as aprivate network but we do not know if you are using Provider Independent address space, Provider Supplied address space, or private address space with NAT on traffic going to the ISPs. This would make a difference on which solution makes the most sense for your situation.

I will point out that most of the discussion is likely to focus on how you get traffic out to the ISPs, but for effective redundancy you also need to think about how traffic is going to get back to you in the case of failure of one of your ISPs.

HTH

Rick

[agrayson]

Rick

I am sorry and I need to clarify. I use private IP space Network connected to 2 ISPs protected by 2 Firewalls. I have 2 primary sites ...NS and SS. NS is COX for internet and SS is with USLEC. I have firewalls at each site and CORE routers. The NS FW connects to a COX router for internet access and the SS connects to USLEC through my edge router....IE ....NS-INTERNET..COX RT...NS FW...NS Core RT-.-.-.-SS Core RT....SS FW...SS RT....USLEC Internet. I did a successful manual default route change on the core routers to point either to the NS or the SS core routers and I maintain internet connections but the ISP will not provide timely info the internet circuit is down and I do not have access to the NS COX router. BGP with ASN and ISP cooperation is too costly so I am trying to find a different solution at hte same time I need to find a way to monitor the ISP/Internet connections to now when they go down. I have posted here before with the same issue but we can not afford the BGP solution...I was looking at some kind of PBR but most of the results I found point to a interface being down and if I can not monitor that interface becasue its the vendors router ...well what do I do???Thanks

[Richard Burts]

Al

This response does help clarify some aspects of your situation. I sympathesize with your position. I understand that you wish there were some simple solution like helper addresses, or HSRP, or Policy Based Routing that you could use to gain redundancy. But I do not believe that there is any simple solution that works for you.

I believe that your message indicates that you recognize that there are at least two parts of your problem: how do you recognize that there is a problem, and how do you respond when there is a problem. I believe the first part is the most difficult part - how do you know when there is a problem. Typically solutions to this involve some kind of dynamic protocol between you and the Service Provider. If there is no dynamic protocol you might try to create some kind of monitoring process (from some edge device periodically try to reach some destination (or set of destinations) that is beyond the provider) that could detect when you have lost connectivity through that provider.

HTH

Rick

[a.ajose-adeogun]

I have a similar scenario but my own case is that i have two routers each connected to my LAN and pointing to one ISP each, (2 ISP altogether) i need to load balance between the two such that when internet access goes not on one, the other router automatically takes over. Can i possibly use the Gateway load balancing protocol? pls i will appreciate your kind response on this. Thanks

[a.ajose-adeogun]

In addition to this, i want to configure NAT on the two routers on my LAN and want to avoid using BGP. Can GLBP work for me?

Thanks

[scottosan · Accepted solution]

A better solution for redundancy/failover may be to get like a 3550 switch running eigrp to do load balancing between the 2 edge routers (redistributing internally to eigrp). Without knowing what your current configs are on each of the isp routers I can not be more specific. The advantage of this would be that if the ISP side interface remains up/up while not recieving any BGP updates, then the 3550(or what ever device you use) would no see that path as a viable gateway.

[a.ajose-adeogun]

Thanks for your advice. i will get back to you on this. Regards,

Oyeyemi

[agrayson]

Thanks..sorry for the late reply....My problem is I have 2 seperate sites/subnets...I going to try to use IGRP and or EIGRP...good luck...unless I can get my org to buy off on the BGP stuff

[gabrieloyeyemi]

I think you can exploit the possiblity of using Policy based routing, where you internal LAN is sub-divided into 2 such that a particular ip address range goes to the internet via one ISP and the other range through the second ISP.

On the other hand you can still use the GLBP option in case you have two proxy server in place. Each proxy is connected to an ISP.

This are cost effective techniques.good luck.

Gabriel Oyeyemi