Learning new ip route and adding to Routing Table

Answered Question
May 14th, 2007
User Badges:

IP Routing question. New host route 192.168.20.181 is learned by my router. The network 192.168.20.0/24 is new and does not exist on the network. OSPF is the routing protocol on the router and the router tries to add this to the routing table - see debug output below. I have 2 questions:-

1. Can someone confirm that the router sees that this is a /32 host route and tries to add this to the RT but why does it also delete 192.168.20.0 - is it because this is a Class C address?


May 14 11:00:40 UTC: RT: add 192.168.20.181/32 via 19.50.100.1, ospf metric [110/20]

.May 14 11:00:40 UTC: RT: add 192.168.20.181/32 via 19.50.100.2, ospf metric [110/20]

.May 14 11:00:50 UTC: RT: del 192.168.20.181/32 via 19.50.100.1, ospf metric [110/20]

.May 14 11:00:50 UTC: RT: del 192.168.20.181/32 via 19.50.100.2, ospf metric [110/20]

.May 14 11:00:50 UTC: RT: delete subnet route to 192.168.20.181/32

.May 14 11:00:50 UTC: RT: delete network route to 192.168.20.0


Question 2.

Also, the route apparently is originating from a next-hop 3rd party router. This company have a static route for 192.168.20.0/24 configured on this box. OSPF is configured on this router and they do have a redistribute static route-map Test but the route-map Test does not include this network. Is there any chance that the OSPF process is redistributing all statics into OSPF rather than the specific Test Route map?

Correct Answer by Harold Ritter about 9 years 11 months ago

Mary,


1) As we remove the subnet (192.168.20.181/32)from the routing table we also remove the majornet (192.168.20.0/24) used in the IOS internal data structures.


2) Not if the route-map is configured properly.


Hope this helps,

  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 5 (1 ratings)
Loading.
Correct Answer
Harold Ritter Mon, 05/14/2007 - 05:02
User Badges:
  • Cisco Employee,

Mary,


1) As we remove the subnet (192.168.20.181/32)from the routing table we also remove the majornet (192.168.20.0/24) used in the IOS internal data structures.


2) Not if the route-map is configured properly.


Hope this helps,

Actions

This Discussion