udp packets not forward

[blue4cisco]

we are running client - server application in which server send message using destination port 1010 to client. we are using services of different ISP to route our packet upto destination that's ok . Now one of our new ISP's using DSL to connect our clients , And thr (DSL ISP) our udp packets not reaching upto our clients. what could be problem in routes or access list. we can access all router of isp. please tell me how do i cheke where udp packet are blocking.

[mheusinger]

Hi,

First I would traceroute from the server to the client in question.

With an extended traceroute from a Cisco router you can even use UDP packets with destination port 1010. This assures you to be as close as possible to your client-server communication.

This should allow you to localize the problem to one or two routers.

Then I would investigate all involved router interfaces for access-lists possibly blocking your traffic. I would not consider an ISP ACL to be the most likely cuprit for your problems though.

Are you sure it is not a NAT problem with your DSL access or personal firewalls on the clients?

Hope this helps! PLease rate all posts.

Regards, Martin

[blue4cisco]

ok our ISP using NATTING, what can be problem thr can u tell me , we are not using firewall at cleint end as well.

[mheusinger]

Hi,

In a typical DSL scenario your router gets one internet IP for communication. All your client hosts have private IPs. To be able to communicate with other hosts on the internet your router replaces the private IP (source IP) in each packet with its official IP address. To be able to deliver the return traffic it keeps those translations in a table, the NAT table.

If there is no entry in the NAT table the router does not know, which internal IP to place in the packet arrivig with the official IP and thus drops the packet.

That could cause your communication to fail.

A possible workaround would be to use f.e. VPN tunnels and avoid NAT for your internal traffic. Or maybe the application can be modified/configured to be "NAT aware and compliant".

Regards, Martin

[blue4cisco]

let me clear you more, as we are a lottery operator so we hv to fulsh the result on every 15 minutes on client screen/machine using UDP protocol port 1010. our retiler r getting result but for that they hv to reboot their application on each 15 minutes.(so result is reaching thr but after rebooting the machine)it happning with DSL user only. our other user using gprs/CDMA dialup no problem thr result is printed on screen at right time no rebooting.

i may send u Nat configuretion if u needed.

guess

[mheusinger]

Hi,

you could create a static NAT/PAT entry to allow it to work in the NAT router.

Regards, Martin

[cisconoval]

Chk with your ISP that they have enabled the UPD traffic for your line.

I face like this problem after that ISP has enabled the UPD traffic and now its working fine.

[foxbatreco]

hii,

i feel the probs could be at your config end..try to create a static mapping for the udp applications coz as such no isp's would block traffic for udp . let me know once thru..