internet router

[carl_townshend]

On an internet router, how does this get back to my default router, we have loads of differnet networks that all go through the internet router, but I want to know how they get back to my default router ?

[amit-singh]

Carl,

Your internet router will have a route pointing to your defualt router for each of the subnet you want to reach or access.

If you have routes only in one direction say from your default router to ypur internet router but your internet router doesnot have routes back to your defualt router for each subnet then it will not work. So you need routes in both the direction from A-B and also from B-A.

HTH,

-amit singh

[carl_townshend]

So if we are using natting, the router here is on the 10.0.0.0 network, if other networks connect through this for example the 172.19.0.0 network, what will need to be natted ?

[mehrdad]

each service provider which has AS number connect together through BGP protocol, in fact BGP (Border Gateway Protocol) create loop-free interdomain routing between autonomous systems.each service provider announce ip addresses which belong to itself by BGP protocol,due to this annoncment and BGP, every routesr which have AS number, will be aware about those ip addresses and their routes so reachability will take place between networks which are annonced.

when you send a packet to the internet through your service provider and when it received to destination, the destination service provider aware about specify path that should be sent to you because it use BGP (has AS number) or default gateway to a service provider which is using BGP protocol, be aware some other routers exist between two ends service providers which are using BGP as well, you can see them by trace route facility.

Hope this help

Regards,

Mehrdad