Dial-up connection disconnects the LAN network

[Hilal Computers]

Dear All,

I have a scenario where, I have created two VLANS (Server - 172.21.1.0/24 and client 172.21.2.0/24) in L3 switch. Intervlan routing enabled. Everything working perfectly.

I have a strange issue, One PC which has 172.21.1.10 IP address connected to LAN , users can RDP to this PC from 172.21.2.x network.. working good.

But this PC has some dial-up connection configured to connect few remote sites. When we establish this dial-up connection , the RDP session from the 172.21.2.x getting disconnected.

If i put 172.21.1.x IP in the client site am not getting disconnected. How to resolve such an issue?

Regards

kajen

[Nicholas Beard]

The reason behind this is likely due to the default gateway changing when the dial up connection is established.  If this is a windows box, perform a "route print" command from the command prompt before and after the dial up connection is established.  If the default gateway changes when the dial up connection is established, return path traffic from the server to the clients for RDP will never be delivered.

The reason it works if you place the client and server in the same VLAN is because the default gateway does not then get used.

Nick

[Hilal Computers]

Hi Nick,

Thanks for your reply. I'll take the "route print" outputs and check. If that is the case, can we add a route in the windows box using route add command ? will it work? We cannot change the VLAN design.

Kajen

[Nicholas Beard · Accepted solution]

Kajen,

Yes you can add a static route from the server quite easily by performing the following from command prompt -

route add 172.21.2.0 mask 255.255.255.0 "SVI address of VLAN" metric 1

This will mean the server will always route traffic destined for 172.21.2.0/24 to the SVI address of the VLAN the server currently resides in.  The switch will then perform the inter-VLAN routing to the client VLAN.

Hope this resolves your problem.

Thanks

Nick

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