EIGRP - Default Gateway

Answered Question
Jun 21st, 2010

Existing setup   - Multi-site MPLS network running BGP with Internet links setup as DMVPN running EIGRP for backup.

We are bringing up some smaller sites using only EIGRP and need to advertise the default gateway from the hub.  It appears the summary address is what I need ? Any help is greatly appreciated .

I have this problem too.
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Correct Answer by Muhammad Zeesha... about 6 years 5 months ago

This is because you have static default route which is preferred due to smaller administrative distance and installed in the routing table.

If you need that a default route from the Hub via the DMVPN tunnel then you must remove the other default route and as a replacement enter the specific route for the Hub tunnel source (physical address) so that tunnel can be created. As of know the tunnel endpoints are using the default route but since you need the default route via the tunnel itself you must enter specific routes to each tunnel endpoints.

Thanks

Zeeshan Sanaullah

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Jerry Ye Mon, 06/21/2010 - 10:53

Yes, you can do that with summary route. What kind of help do you need? Setting up summary route is pretty straight forward

interface tunnel x

ip summary-address eigrp xx 0.0.0.0 0.0.0.0

xx is the AS EIGRP AS number.

HTH,

jerry

gizbri Mon, 06/21/2010 - 11:03

Thanks Jerry. Is this done on the hub and propagated out or do I do this on each spoke site ?

Muhammad Zeesha... Mon, 06/21/2010 - 11:31

Yes this is done on Hub. But you need to consider that all routes will be suppressed and only the default route will be advertised when you originate a default route with the ip summary-address eigrp command.

You can also originate a default route without suppressing other routes using the following commands

ip route 0.0.0.0 0.0.0.0 x.x.x.x next hop
!
router eigrp 100
redistribute static
default-metric 10000 1 255 1 1500


There is also a third method in which you manually create a static default route on spoke routers which points to the hub tunnel interface IP address as the next-hop

Hope this help, Please rate helpful posts

Thanks & Regards

Zeeshan Sanaullah
gizbri Mon, 06/21/2010 - 12:22

Thank you for the info. The second method appears to be the best solution. I added it on  the "hub" router here is the current EIGRP config:

router eigrp 1

redistribute connected metric 1 1 255 1 1 route-map only10

redistribute static

network 192.168.10.0

default-metric 10000 1 255 1 1500

no auto-summary

!

Would the route-map or no auto-summary interfere with this ?

Muhammad Zeesha... Mon, 06/21/2010 - 23:33

No auto-summary will not interfere. And neither will route-map as it is applied with redistribute connected command while the default route is redistributed with redistribute static command.

Please rate helpful posts,

Thanks

Zeeshan Sanaullah

gizbri Tue, 06/22/2010 - 09:24

Thanks Zeeshan - This isnt working, yet. It looks like it's getting to the spoke router ,but its it using the default local route. Any ideas ?

Here is the output from the spoke:

cnc-1861#sh ip eigrp topology 0.0.0.0
IP-EIGRP (AS 1): Topology entry for 0.0.0.0/0
  State is Passive, Query origin flag is 1, 0 Successor(s), FD is 4294967295
  Routing Descriptor Blocks:
  192.168.10.1 (Tunnel0), from 192.168.10.1, Send flag is 0x0
      Composite metric is (2816256/256256), Route is External
      Vector metric:
        Minimum bandwidth is 1000 Kbit
        Total delay is 10010 microseconds
        Reliability is 255/255
        Load is 14/255
        Minimum MTU is 1400
        Hop count is 1
      External data:
        Originating router is 192.168.10.1
        AS number of route is 0
        External protocol is Static, external metric is 0
        Administrator tag is 0 (0x00000000)
        Exterior flag is set

Correct Answer
Muhammad Zeesha... Tue, 06/22/2010 - 10:38

This is because you have static default route which is preferred due to smaller administrative distance and installed in the routing table.

If you need that a default route from the Hub via the DMVPN tunnel then you must remove the other default route and as a replacement enter the specific route for the Hub tunnel source (physical address) so that tunnel can be created. As of know the tunnel endpoints are using the default route but since you need the default route via the tunnel itself you must enter specific routes to each tunnel endpoints.

Thanks

Zeeshan Sanaullah

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