cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
2218
Views
15
Helpful
1
Replies

" ip default Network "

jonk34567
Enthusiast
Enthusiast

What does " ip default-network " command do ? what diffrence between that and "ip default gateway "

1 Accepted Solution

Accepted Solutions

Peter Paluch
Cisco Employee
Cisco Employee

Hello,

The ip default-gateway is a command to define a default gateway for a Cisco IOS-based router or a switch that operates in the host mode. A router or a switch operates in the host mode if it is configured with no ip routing command and has no routing table as a result. For Catalyst switches such as 2950, 2960, 3550, 3560, or 3750, the host mode is the default mode. Routers operate in routed mode by default. If the device operates in routed mode, the ip default-gateway command can be configured but will be ignored. In that case, the default gateway can be configured with ip route 0.0.0.0 0.0.0.0 or by ip default-network.

The ip default-network is a deprecated and old command whose purpose was to designate a known classful network as being already located in the "outside world", and so the route to that network would be also considered a default route. If you had a classful network in your routing table that was marked as a candidate default network using the ip default-network, then all packets with an unknown destination would be sent down the same path as packets for the candidate default network. This command should not be used anymore as it only works with classful networks, does not cooperate well with routing protocols, and is very cumbersome to use.

You might be interested in reading the following document as well:

https://www.cisco.com/c/en/us/support/docs/ip/routing-information-protocol-rip/16448-default.html

Feel welcome to ask further!

Best regards,
Peter

View solution in original post

1 Reply 1

Peter Paluch
Cisco Employee
Cisco Employee

Hello,

The ip default-gateway is a command to define a default gateway for a Cisco IOS-based router or a switch that operates in the host mode. A router or a switch operates in the host mode if it is configured with no ip routing command and has no routing table as a result. For Catalyst switches such as 2950, 2960, 3550, 3560, or 3750, the host mode is the default mode. Routers operate in routed mode by default. If the device operates in routed mode, the ip default-gateway command can be configured but will be ignored. In that case, the default gateway can be configured with ip route 0.0.0.0 0.0.0.0 or by ip default-network.

The ip default-network is a deprecated and old command whose purpose was to designate a known classful network as being already located in the "outside world", and so the route to that network would be also considered a default route. If you had a classful network in your routing table that was marked as a candidate default network using the ip default-network, then all packets with an unknown destination would be sent down the same path as packets for the candidate default network. This command should not be used anymore as it only works with classful networks, does not cooperate well with routing protocols, and is very cumbersome to use.

You might be interested in reading the following document as well:

https://www.cisco.com/c/en/us/support/docs/ip/routing-information-protocol-rip/16448-default.html

Feel welcome to ask further!

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: