Source routing

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06-03-2004
failure_to

Source routing

hi

RFC specifies that if client uses source routing option then TCP server must use reverse route for all the segments on that connection.
But if client specifies strict source routing,how can server successfully return data segments using the same route?
For example,if client(172.9.1.3) specifies that segment should go trought intermediate router(172.9.1.1) to reach final destination(146.3.4.1).When packet gets to final destination,server will reverse the recorded route.But that would mean that it would have to specify 172.9.1.1 as a hop to final destination(172.9.1.3).
But what if server's routing table doesn't contain an entry for 172.9.1.1,so it doesn't know that router with IP 146.3.4.4 also uses IP of 172.9.1.1?

-Also,does source routed packet carrie the same source IP address through all of its hops?

thank you for your help
06-04-2004
EvBladeRunnervE

Quote:

But what if server's routing table doesn't contain an entry for 172.9.1.1,so it doesn't know that router with IP 146.3.4.4 also uses IP of 172.9.1.1?

please make it clearer, I can't figure out if you are saying what if the router doesnt have its own IP in the router, or that you are wondering how does the router know it also has a interface to connect to the network IP 146.3.4.1 is on?

Quote:

-Also,does source routed packet carrie the same source IP address through all of its hops?

are you sure you have read the IP RFCs? there is a tutorial one that gives the long answer I am giving you : yes.
06-04-2004
failure_to

I did some searching and found out that when datagram passes trought all listed hops,each hop replaces its listed address with IP of its outgoing interface.That answered my questions

Quote:

please make it clearer, I can't figure out if you are saying what if the router doesnt have its own IP in the router, or that you are wondering how does the router know it also has a interface to connect to the network IP 146.3.4.1 is on?

I didn't know that each hop replaced IP with one from its outgoing interface so I was puzzled how would server find out trough wich routers datagrams must travel to get back to client.Since each hop would have two interfaces and server may not be aware of the other interface...

:)English ain't my strongest point