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cat4510re w/Sup7

#sh ip route

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

       E1 - OSPF external type 1, E2 - OSPF external type 2

       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

       ia - IS-IS inter area, * - candidate default, U - per-user static route

       o - ODR, P - periodic downloaded static route

Gateway of last resort is 172.20.100.251 to network 0.0.0.0

    159.181.0.0/16 is variably subnetted, 2 subnets, 2 masks

O E2    159.181.0.0/16 [110/20] via 172.20.2.2, 1d06h, Vlan2

O E2    159.181.240.40/32 [110/7214] via 172.20.2.2, 1d06h, Vlan2

S*   0.0.0.0/0 [1/0] via 172.20.100.251

-I have this route that is causing some hellish issues. This one route with IP 159.181.240.40/32 needs to be removed but I can not seem to figure out how. I know its a route learned through OSPF. Anyone trying to his this particular address is being redirect to 172.20.2.2 which is our backbone to our building accross the street. This address should be going straight through our firewall. Any suggestions please. I tried the following in configT mode...

ip route 159.181.240.40 255.255.255.0 172.20.100.251 ?

After 172.20.20.100.251 its asking for a distance metric. I do not what to do beyond this point??????

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3 REPLIES

cat4510re w/Sup7

Hi Chris ,

What is the network connected to the firewall ? If you set the static as you posted the traffic to host 159.181.240.40 be going to the core.

Dan

Silver

cat4510re w/Sup7

Ok,

Route to 159.181.240/32 is already installed in routing table and learnt via OSPF NSSA external type 2, Not So Stubby Area, has an admin distance of 110.

If you are configuring a static route, define distance metric less than 110, it is safe to say use 100, so the static route gets selected during the route selection process.

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Posted by WebUser Neeraj Jagga from Cisco Support Community App

cat4510re w/Sup7

Not sure if you're familiar with Administrative Distances.

Administrative Distances are used as a "weight" when a router learns multiple paths to the same destination via different means (static route, OSPF, EIGRP, etc...).  Cisco has a default AD for each routing protocol (including static and connected routes) based ostensibly on the "believability" of that protocol to provide the "best" route.  The default for OSPF is 110.

The default for a static route is 1 (it is assumed the admin knows what he/she is doing). You can specify another AD, but that is optional.  So if you enter the command as you have without the ? you will install the static route in the table.  (Higher ADs for static routes can be useful for "floating static routes", for example.)

The router will treat routes to the same network but with different masks as different routes.  Note that (higher) specificity wins by default in routing decisions.

My preference, however, would be to find out how/why the route is coming in via OSPF, and if that is expected behavior.  Do you have the static route installed in another router, and being redistributed via OSPF, by chance?

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

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