ROUTE PRINT under Vista 2

[NFI]

Hello,

can anybody tell me what the "On-Link" options means under the Gateway heading when you run ROUTE PRINT under Vista, please?

As far as I can make out from reading the MS documentation, it's some sort of dynamic option for referring to the gateway when you don't know it's IP address? I can't quite understand what that means, though
Any help will be much appreciated,

Thanks,

Paul

 

[burtsbees]

The default route---it routes from 0.0.0.0 to 0.0.0.0 via the outgoing interface. Your gateway has routes to and from your LAN, but it must go to ITS own next hop to find things like Google and such---it does not have that info in its routing table. The default route says "If a request from the LAN is initiated to somewhere I don't know about, just send the request to my next hop---that will know how to get there".

Burt

 

[NFI]

Hiya,

thanks for that - 0.0.0.0 is every address in the current subnet, isn't it? I'm not sure what you mean by routing from 0.0.0.0 to 0.0.0.0 Why would the gateway not have routing information to the next hop for internet access?

Thanks,

Paul

 

[burtsbees]

The edge router only knows how to get to its next hop---the routers at the ISP that run BGP (usually) will have routing tables with thousands and thousands of entries---not your edge router. The 0.0.0.0 0.0.0.0 means that the edge router forwards packets to any address with any mask to its outgoing interface or its next hop. I misinformed about the 0.0.0.0 being from and the other 0.0.0.0 being to---it is any address (0.0.0.0) with any mask (0.0.0.0). For example, in a Cisco router, the command to add a default route is
ip route 0.0.0.0 0.0.0.0 s0/0
assuming serial 0/0 is the outgoing interface, or
ip route 0.0.0.0 0.0.0.0 121.121.121.1
assuming the next hop is 121.121.121.1
That tells the router "I can get to any address with any mask that I do not know about by forwarding these packets I do not have routes for out my outgoing interface, or my next hop, however my default route is configured".

Burt

 

[NFI]

I see,

thanks for all of that - it's much appreciated,

Paul