cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
684
Views
5
Helpful
1
Replies

ip route??

abhi-adte
Level 1
Level 1

Hi,

What happen if I configure the IP route 0.0.0.0 0.0.0.0 0.0.0.0 no entry in routing table but what it happen??    

Please help...

1 Reply 1

Peter Paluch
Cisco Employee
Cisco Employee

Hello Abhinay,

Nothing will happen, the route will not be inserted into the routing table because of the following two reasons:

  1. Any route that recursively loops back to itself, either directly or over a set of different routes, will be removed from the routing table. There is a process in IOS that checks the routing table every minute, and if a recursive routing entry is detected in the routing table, it will be removed. Your route is recursively looped into itself directly - the next-hop IP address of this network is inside this very network.
  2. For every route that is defined using the next-hop IP address, the next-hop IP address must be resolvable in the routing table, otherwise the next-hop IP is considered unreachable and the route will be declared unusable. However, a default route will never be used to resolve a next-hop IP address. In other words, there must be a more specific match for a next-hop IP address in the routing table than the default route. As the only reasonable match for the next-hop IP address 0.0.0.0 can be the default route itself, no other entries in the routing table will match. As a result, the next-hop IP address is considered unreachable and the route cannot be inserted into the routing table.

Best regards,

Peter

Getting Started

Find answers to your questions by entering keywords or phrases in the Search bar above. New here? Use these resources to familiarize yourself with the community:

Innovations in Cisco Full Stack Observability - A new webinar from Cisco