default routes, default-network, default-gateway

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Sep 9th, 2008
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Hi,

I don't know the difference between a default route, an ip default-network and an ip default-gateway. In which cases do I need them?

any help would be appreciated.

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Mark Yeates Tue, 09/09/2008 - 07:29
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ccnpninja,


A default route, also known as the gateway of last resort, is the network route used by a router when no other known route exists for a given IP packet's destination address.


Unlike the ip default-gateway command, you can use ip default-network when ip routing is enabled on the Cisco router. When you configure ip default-network the router considers routes to that network for installation as the gateway of last resort on the router.



The 'ip default-gateway' command is used to enter your router's default gateway, just as you would do on your normal Windows machine. This command does not differ from your everyday 'gateway' used in all devices required to access hosts outside the local network.


HTH,

Mark

satish_zanjurne Tue, 09/09/2008 - 07:37
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1.Default Route :- marked as * , when router ends up finding the way for networks not listed in the routing table, it sends those packets to default route , if it is present.


2.default-network :- apart from using ip route 0.0.0.0 0.0.0.0 XXXXX , to create the default route. "ip default-network" command is used to generate candidate route for default route.


3.deault-gateway : mostly used in L2 switches to point the way out of subnet/vlan/segment.Mostly points to the Router Interface connected to access/L2 swicth..


HTH...rate if helpful...

ccnpninja Tue, 09/09/2008 - 09:39
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Satish,

I understand that if there's no default route on the router, the "default-network" will create a default route? can you explain further by a example of a routing table?

Nagendra Kumar ... Tue, 09/09/2008 - 20:57
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Try with the below topology,


R1------------R2------

10.0.0.0 11.0.0.0


In R2, if you configure "ip default-network 11.0.0.0" command.


11.0.0.0 network will be marked as default candidate network in R1 as below,


D* 11.0.0.0/8


HTH,

Nagendra

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