All about ip default-network

[bhattunagaraju]

Hi Peter,

1.Can you let me know the exact difference bet. default route with ip default-network and a static default route.

2. Do we need to use ip default-network along with a RP or not required?

3. If one edge router (Router A) receives an RIP route to network 10.0.0.0 from some other router that connects to different subnets in 10.0.0.0/8, how the routing needs to be implemented on other routers in the n/w below Router A, so that they will send the traffic to 10.0.0.0?

4. How would be the RT entries on all the routers interpreted- Router A, B, C?

Note: assuming B & C directltly connected to A on FR.

[arvind_data]

1.  ip default-network  -- for L2 devices

    static default route  -- For L3 Devices

2  not Required 

[arvind_data]

1.  ip default-network  -- for L2 devices

    static default route  -- For L3 Devices

2  not Required 

[cadet alain]

Hi,

1. 

ip default-network  -- for L2 devices     INCORRECT  ip default-gateway is for L2 device

There are multiple  ways of advertising a candidate default route in EIGRP or RIP but the preferred way in RIP should be using the default-information originate command and in EIGRP to  configure a static default route and redistribute in EIGRP.

A static default route is a static route as its name implies so it has nothing to do with the ip default-network command

2.  No it's not mandatory you can do as I explained above and for OSPF the command is default-information originate, you can't redistribute a static default route.

3. could you rephrase points 3 and 4 along with a diagram

Regards.

Alain

[Peter Paluch]

Hello Nag,

Please do not hesitate to address your queries to all members of this community, not just to me

Arvind, I have to disagree with you. For L2 devices that do not have their own IP routing table, the command to define the default gateway's IP address is the ip default-gateway command.

Both ip default-network and static default route are usable only on devices that have their own IP routing table, as they enter or manipulate entries in the routing table.

1.) Regarding the difference between the static default route and the ip default-network command, I strongly suggest reading this document first:

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094374.shtml

It explains the concepts very nicely. Of course, if there are remaining questions or any uncovered issues, please feel welcome to ask further.

2.) I am afraid I do not know what is the "RP" acronym in your question. Can you be more specific?

3.) and 4.) Can you please draw a quick sketch of your network? It would help to understand your question better.

Best regards,

Peter