Redistributed default route from multiple locations with EIGRP

[jeff.vargas]

I've got a problem I'm trying to resolve and I haven't figured out the right metrics for this. I'm hoping someone can help. I have two connections to the Internet from two separate locations. The entire internal network is routed via EIGRP and a default route to 0.0.0.0 is redistributed via EIGRP from site1. The two locations are connected with a DS3/45Mbps. Everything works fine at this point and Site2 picks up the default as an external EIGRP route as it should, but my desire is to add a second default route out of Site2 in case I lose my DS3 connecting site1 and site2. So basically I want to have that second 0/0 route in my routing table but I only want it to be preferred if the first 0/0 route is unavailable. I'm enclosing a VISIO which may help.

[jheckart]

I would suggest utilizing floating static routes.

On site1, you should add another static route with a higher AD pointing to 10.227.1.1. On site2, you should do the same by add a static with a higher AD pointing to 10.224.1.1.

[jeff.vargas]

Floting static doesn't work. I tried adding: ip route 0.0.0.0/0.0.0.0 10.227.1.1 50. The distibution layer off of the Core @ site 2 sends all traffic out Site 2 PIX.

Thanks for the support.

[CSCO10408957]

Your method is correct but wrong parameter.

Core @ site 1 redistribute static.

Core @ site 2 receive external EIGRP route with 170 administrative distance.

So, You should set the value over 170 not 50.

About Administrative Distance:

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094195.shtml

[Richard Burts]

Jeff

I believe that there are a couple of options that could work for you. If it was OSPF instead of EIGRP you could redistribute one site as an E1 route and the other redistribute as an E2 route and the preference would be automatic. But EIGRP does not have this possibility.

Probably the best way to get what you want is to redistribute with a different default metric at site 2. If you redistribute static at site 1 with a sufficiently low delay in the default metric and redistribute static at site 2 with a sufficiently high delay in the default metric then everyone will prefer the default from site 1. But if the default from site 1 gets withdrawn then the default route from site 2 will be used.

HTH

Rick

[jeff.vargas]

I've tried the following to no avail. Is this correct:

Site1:

router eigrp 1

redistribute static metric 100000 1 255 1 1500

network 10.0.0.0

Site2:

router eigrp 1

redistribute static metric 50000 1 255 1 1500

network 10.0.0.0

[Richard Burts]

Jeff

You have manipulated a difference in bandwidth to create some difference. While it seems that it should work you should bear in mind that the advertised bandwidth is the lowest bandwidth of any link along the path. I suspect that advertising over the serial link which connect site 1 and site 2 eliminates the difference that you create. If you manipulate the delay as I suggested it is more likely to be effective since the advertised delay is the sum of all delays along the path. So advertising over the serial between site 1 and site 2 will not affect any difference in delay.

I have thought about this some more and I believe that there is another issue to consider. On the core of site 2 it is learning a default from EIGRP and it has a static which it is redistributing. A normal static route always takes precedence over any dynamically learned route. So core 2 is going to want to forward out its Internet link (not what you want). I believe that we do in fact need to consider floating static on core 2 (and a normal static on core 1). I suggest that you configure a floating static on core 2 specifying an administrative distance of 250 (higher than any dynamic learned route. After you configure this it would be helpful if you would post the output of show ip route 0.0.0.0 and post the output of show ip eigrp topology 0.0.0.0 0.0.0.0

HTH

Rick

[jeff.vargas]

Rick,

I had tried a floating static on core 2 of 171. Basically 1 higher than a dynamic external EIGRP route and traffic still flowed from site 2 out intenet link 2. I will try 250 and see if that makes a difference. I won't be able to try this for awhile as I will need a maintenence window. Do you have an e-mail address so I can send you the ouput when I do get a chance to try this again?

Thanks,

-Jeff

[Richard Burts]

Jeff

My email address is available from my NetPro profile and is rburts@netcraftsmen.net. I will be glad to take a look at your output when it is available.

I am surprised that a floating static using 171 did not work. If it did not work then I am not confident that a distance of 250 will work, but it may be worth trying. I like this value because it is obvious and is higher than any dynamic routing protocol.

Would you be able to post (or to send to me) the output of show ip route 0.0.0.0 and the output of show ip eigrp topology 0.0.0.0 0.0.0.0 from core 2?

HTH

Rick