Redudancy through multiple router

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Jan 19th, 2004
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We have a Cisco 3640 router with two T1 interface and configured for BGP between two service providers and we have a cisco pix firewall behind the cisco router. Is there any automatic failover options available incase my cisco 3640 router crashes? Can i have one more cisco 3640 router with same configuration loaded as standy and make it active once the primary router crashes? Is there any equipment that can be placed in between the ISP Jack and the router which splits the connection to both the router and starts sending pockets to the standby router once the active router goes down like a Y cable?


Thanks in Advance


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vcjones Mon, 01/19/2004 - 17:47
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The cleanest way to provide redundancy for your single router is to use a second router and put one T1 on each router. However, you need to examine your situation carefully first, as the router is far from the only single point of failure in your environment... you also need to worry about the hub/switch between the routers and firewall, the firewall, the hub/switch on the user side of the firewall, electrical power, and the physical diversity of your two T1 lines.


Unless you have already paid attention to these factors, your most likely cause of additional downtime is simultaneous failure of both of your T1 lines (which are probably in the same telco cable bundle under the streets between your building and the central office, if not all the way to your wall jacks).


After that, your most likely cause of failure is dead batteries in your UPS (you do have a UPS, if not, move power to the most likely cause of failure).


After that, your most likely cause of failure is human error. You do have processes and procedures in place to control who can change configurations and testing of those configuration changes before putting them into production???


It is very easy to spend a lot of money on redundancy, but you need to invest in planning and understanding to gain significant availabilty increases from the redundancy.


Good luck and have fun!


Vincent C Jones

www.networkingunlimited.com

kjanakiraman Mon, 01/19/2004 - 18:34
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Thanks a lot for your mail. The best way to redudancy is moving the other internet to the other T1 line. Am i correct? I was of the impression that there will be some statefull failover option for the routers like the cisco pix firewall?.

leonard-butler Tue, 01/20/2004 - 13:48
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If I read this email correctly, I assume that you use only one T1 for connectivity and the other for failover using BGP?

If that is in fact the case, you might look into using HSRP over iBGP between two routers. Each router with a single T1 installed and and crossed over for connectivity. We do this same scenario using multiple DS3's and at every aspect, we have a redundant link, switch and interface. The only thing that is lost, is that there is very little load sharing using BGP.

vcjones Tue, 01/20/2004 - 17:39
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> The best way to redudancy is moving the other

> internet to the other T1 line.


I don't understand what you are saying here...


> I was of the impression that there will be some

> statefull failover option for the routers like the

> cisco pix firewall?.


The PIX approach to redundancy has no equivalent in the router world. But you will find that HSRP/VRRP plus routing protocols will get you where you want to be.


Good luck and have fun!


Vincent C Jones

www.networkingunlimited.com

kjanakiraman Tue, 01/20/2004 - 18:10
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Thanks a lot for your reply. I will check with the HSRP/VRRP Options for redudancy.

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