Hot standby on Internet router

[Nikos Nicolaides]

Hello team,

I want to implement a failover scenario on an internet router. Currently the setup is shown in drawing 1. There is only 1 router (default gateway) in which connects to the internet with the other interface.

The new network design is as following: The routers will be a part of a HSRP pair in the inside interface, and the link to the internet will be on the first router only. When the first router fails, the administrator has to manually switch the link to the internet from the first router to the second.

Is there a way to automate this process with SLA or something? The ideal scenario will be no manual user intervention.

[gatlin007 · Accepted solution]

What kind of media/encapsulation are your internet circuits?  If they utilize an end-to-end encapsulation such as PPP you can simply have HSRP track the status of the internet interface and dynamically adjust the HSRP priority based on whether or not a particular internet circuit is available.

Consider using a simple dynamic routing protocol between your routers and the service provider to inject a default route to your internet circuits.  This would ensure fail over as the absence of a default route would make the opposing router attractive; consider RIPv2, OSPF or EIGRP for this simple application.

Lastly I would consider IP SLA.


Chris

[Nikos Nicolaides]

Hi Christopher,

On the internet connection is ADSL (and in some other examples Metro Ethernet). So PPP is out of the question. The other thing is that in some implementations the subnet mask is not /29 but a normal /30 point-to-point line.