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forwarding UDP broadcast not working

Hi everyone,

We've a client/server application based on a Sybase database. It's parcel software of DHL called Easylog 6.1.

The client app needs to connect to a DB server.

When the client and server are on the same vlan, everything works fine. But i need to seperate them by vlans.

Wireshark reveals that the software uses UDP broadcasts to search for the server. the client issues the start:

source               Destination          Protocol     Source port               Dest. port     UDP          "different everytime"     2638

When they're connected, the transmission is done over TCP.


UDP port: 2638

client vlan: 192.168.21.x /24

DB server: /24

I've tried with IP-helper address on the receiving inteface, in conjunction with ip forward-protocol UDP 2638 - Doesn't work.

When i do ip helper-address there's udp communication between the client and server, but the source UDP port changes everytime. - doesn't work also.

i've tried with IP-directed broadcast, but i'm not sure how to build the ACL regarding the source and destination, and where to place it...

The story about UDP flooding specified in this link

i don't really understand.

Someone have experience with this?

thanks in advance

Community Member

Re: forwarding UDP broadcast not working [Solved]

Hi everyone,

The problem is solved. While the originating application sends UDP broadcasts to find the server, you can also specify the host address in the ODBC connection.

Open the corresponding ODBC DSN

Go to the tab Network.

enable checkbox TCP/IP

fill in: host=ipaddress:portnumber

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