Frame-Relay & PPP transitivity

[sboukef]

Hello

A customer has a main office and two branch offices A and B.

Branch office A is connected to the main office via a leased line and a ppp encapsulation.

Branch office B (like several other offices) is connected to the main office via a frame-relay connection.

No subinterfaces are configured on the serial interface of the central router.

Static mappings between frame-relay dlcis and remote IP addresses are configured at both end of the connection.

Static routing is configured properly and each remote site can ping the main site LAN.

This is the problem : The two remote offices cannot see each other. Is there a need to configure subinterfaces on the main office or could the problem come from somewhere else ?

Thank you for your help.

[Harold Ritter]

It sounds like a routing issue and has nothing to do with whether you are using a subinterface or not.

When you say the two remote offices don't see each other, do you mean you can't ping from the router in one sitte to the other.

Try an extended ping using the LAN interface IP address from Branch Office A to B. You have to bear in mind that by using the regular form of ping the ip address of the WAN interfaqce is used as the source address and would require additional static routes to be configured on the remote sites.

Hope this helps,

[sboukef]

In fact, the ping does not work from office A LAN to office B LAN.

The same routing configuration works properly when pinging between sites both connected to the main office via ppp.

Thank you again.

[thisisshanky]

Have you added static routes on Office A (and vice versa) as follows

To reach HO lan use HO router wan ip as next hop

To reach Office B lan use HO router wan ip as next hop

To reach Office B wan use HO router wan ip as next hop

OR

Default route with HO router as next hop

If you have done the configuration as above, office A LAN should be able to ping Office B LAN and vice versa.

[Harold Ritter]

Unless you configured default routing at the remote sites, you are not using the same routing configuration when pinging the central site and the remotes sites. Could you please include your static routes configured at the central and remote sites.

Thanks,

[Kevin Dorrell]

I am confused by the singular of "... on the serial interface of the central router ...". I presume the central site has a router with two serial interfaces, one of which receives the leased line, and one the Frame Relay connections.

I think it would be helpful to see the configuration of the central router. I can imagine any number of configuration problems that might result in the symptoms you describe. Also, does each branch office have a default route via the central office, or at least specific routes to the other offices? It might be useful to see the configs of the branch offices too.

Kevin Dorrell

Luxembourg

[sboukef]

By "the serial interface of the central router", I meant the serial interface on which Frame-Relay is configured.

The router configurations and the network map are attached.

[thisisshanky]

Try pinging from lan of Site A to Site B (or vice versa) you will be able to ping back and forth with the existing configuration. What you are trying to do is trying to ping from the router at Site A and Site B to their respective LANS. When you try to ping from the router, the source address of the packet will be wan (serial) interface IP address. Either remote site router does not know how to reach the wan subnets (192.168.101.0 and 192.168.31.0)

On Site A, add the route

ip route 192.168.31.0 255.255.255.0 192.168.101.1

On Site B, add the route

ip route 192.168.101.0 255.255.255.0 192.168.31.1

Hope that helps!

[sboukef]

That'a exactly what I cannot do : pinging from lan to lan. I am not pinging from the routers...

[thisisshanky]

Ok!

Have you checked default gateway on the PC's in question ?

Can you do an extended ping from the router (say at Site A) to a PC in site B ?

type ping and hit enter and follow the options and specify the extended options to yes, and specify source address as 10.3.10.1 (ethernet interface ip address)

[sboukef]

That's it :

Adding routes to router A WAN on router B and vice versa made the ping work from LAN to LAN.

I tried to delete the mapping :

"frame-relay map ip 192.168.31.2 16 broadcast"

and I also deleted the routes to the WANs I have just added and it worked !

I guess the problem was in the Frame-Relay mapping.