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OSPF Default Route

OSPF Default Route

EMES
New Contributor
We recently had a network event where a card in our core switch would not lock OSPF neighbors. I ended up rebooting this card and was able to restore services. However, I am confused why the network didn't alter the default route in the rest of our routers to redirect traffic. I have attached a simple diagram, red routers are ospf and green routers include BGP. My problem was the link between the green routers and when I tried to get traffic in a peer on the north side(north is up, right?!?) destined for a customer attached via BGP on the south peer, it goes from green to the red just north of it, once it got there, it didn't have a route in it's table for that southern peer, it only has the default route.

So...should it recalculate the default route or should I see a route in the routing table on that first hop away from the green so it doesn't use the default route. The default route is viable so I'm not sure that truly needs recalculated. I do have the following commands on the south BGP router:

enable ospf export e-bgp ExportToBGP
enable ospf export i-bgp ExportToBGP

that policy just states that all networks are accepted:
permit;
cost 2;
cost-type ase-type-1;

b6b5185bcf1b4b12bb5362994ae538e9_RackMultipart20161230-121280-uycgoo-routers_inline.png

13 REPLIES 13

I posted another reply below, let me know if there is anything else I can share. thanks again for your help!

EMES
New Contributor
what is the best way for me to share this data with the two of you?

Tripathy__Priya
Extreme Employee
Apart from what Stephane has to say whether any loopbacks of these green routers are redistributed into OSPF or not. We can also need to identify the default route injection if taking place or not. Actually Default route is injected to OSPF domain only if that router has a default route in it. Also Router will originate a default route only if it has the routes permitted in route-map.

Stephane_Grosj1
Extreme Employee
On that red router north the upper green, do you have A, B and C prefix? I mean, are the BGP prefixes redistributed in your IGP?

So, if I understand correctly, the traffic load-balancing is performed by your customer, via AS-Path prepending? You do not control your exit point with local-preference?

The point here is that none of your green router was down, nor the BGP links. So their advertisements were still correct. Are you sure the loopbacks of the green routers are redistributed into OSPF? Not via a static route on the directly connected link between them (for example)?

sorry for the delay here. A bit of an amateur mistake, not sure it should have any effects but maybe not the best way about it. We have a peer with a customer on both routers using private AS and private IP space, nothing except the E peers use public IP's so in order to cut down on static routes or matching private IP spacing I have a single /30 with the customer protected with EAPS...one interface on their router and one interface on our BGP Router. Is there a way I can message that info to you or is it best to just pull the output and clean it of any data I don't want published? RIB Meaning you want the whole routing table?
GTM-P2G8KFN