Default Route(s)

gatornation 19 years ago

Hello, I have 4 sites on a private sprint provided mpls network. Each site has it's own internet connection. I would like to advertise each site's default route to provide a backup in case a site looses it's internet connection. Sprint has to configure the PE routers to advertise this default route and I am redistributing static routes via eigrp.

So each router has something like ip route 0.0.0.0 0.0.0.0 x.x.x.x 1

Question is, when the routers start learning default routes of other routers how will a site get to the internet. Will learned default routes have an implicit higher cost than the locally defined routes even though the all have a cost of 1?

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Walter Roberson 19 years ago

Keep in mind that when you redistribute routes from one protocol to another, there is a cost translation. It has been a number of years since I looked at this, but if memory serves, a static route cost of 1 does not correspond to the lowest cost available through eigrp. I seem to recall that the cost translation offsets are adjustable.

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gatornation 19 years ago

Ok, so is that what the "90" number is when I do a show ip route x.x.x.x on a particular network. If so that is a good thing. I wouldn't want a site using the backup when it's internet connection is working...

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anybody43 19 years ago

The "90" number is the "Adminsitrative Distance" look it up on cco.

If two equally specific routes are available to the router then the one with the lower adimn. dist. wins.

In order to get assistnace you need to provide more information.

What routing protocol are Sprint offering to use to send you the default route? Do you publish any internet services such as ftp, http, email? Does yor internet access use NAT?

There is a method that you can use independently of the ISP as long as you are not publishing any services e.g. -email server.

You can use "ping based routing" to get web browsing working.

Cisco officially call it SAA routing - sort of.

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It's late here now and I am going to finish but have a look at the above and at

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Vincent, who posts here, has some very nice papers on the site and a good looking book that he has written that covers your topic in depth.

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