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VoIP UDP and PPPoE Clients

Posted: Sat Sep 16, 2006 1:25 am
by airstream
Hi all, we have a MT network that works well for internet service, we have many customers who connect via PPPoE to the main MT connected to the internet.

My problem is I cannot get SIP or UDP for that matter to traverse from a clients PC with an active PPPoE connection to pass UDP packets correctly. If I use btest I get 4 - 5 Mb/s to the main MT termination the PPPoE, but I cannot get UDP to test.

Set up is: station>12Km>MT APWlan1>MT APWlan2>(EOIP)station>Main MT(EOIP)

Customers have a ethernet connection to a station on thier roof, that connects to a MT on a hill, the customer wlan interface is bridged to an EoIP tunnel that connects through another wlan interface to our main MT 15Km away.

All is working well, I can get a PPPoE connection, surf the internet from the clients home, and bandwidth test TCP both ways but not UDP?

Any ideas?

Posted: Mon Sep 18, 2006 3:57 pm
by HarvSki
Have you firewalled UDP? If you use Torch on the PPPoE interface and watch the traffic you may be able to see what is going on.

Posted: Tue Sep 19, 2006 12:18 pm
by sten
normal udp packets does not have Dont-Fragment flag set, routeros udp packets do have Dont-Fragment flag set. Ergo, routeros udp packets wont work like normal udp packets because they would be dropped and "fragmentation-needed-but-DF-set" icmp messages will be generated all over the place.

Could this explain your phenomena? Try btest with smaller udp packets.

Posted: Tue Sep 26, 2006 1:35 am
by airstream
Thanks Harvski and sten for your tips, however the Bandwidth test for UDP seems not to work. I have no firewalling for UDP and I have tried all sort of of UDP packet sizes etc with little success.

However I did manage to get VoIP UDP datagrams to pass through MT after I mangled them to have TOS 184 and mark the packets to pass through a queue with the priority of 1.

Seems to fix the VoIP very well, but still a mystery as to the bandwidth test utility although it is not important in its own merely found it wouldnt work while trying to get VoIP working.

Cheers

Posted: Tue Sep 26, 2006 1:55 am
by HarvSki
Maybe the test server is broken... I've got one that is (or appears to be) on 2.8.x but everything else is fine so I dont worry about it.

Posted: Tue Sep 26, 2006 8:25 am
by sten
Thanks Harvski and sten for your tips, however the Bandwidth test for UDP seems not to work. I have no firewalling for UDP and I have tried all sort of of UDP packet sizes etc with little success.

However I did manage to get VoIP UDP datagrams to pass through MT after I mangled them to have TOS 184 and mark the packets to pass through a queue with the priority of 1.

Seems to fix the VoIP very well, but still a mystery as to the bandwidth test utility although it is not important in its own merely found it wouldnt work while trying to get VoIP working.

Cheers
Wow, you didnt say your isp's pppoe concentrator was firewalling with ridicules rules. UDP bandwidth testing often works poorly when using mt windows bandwidth tester.

Posted: Mon Oct 16, 2006 1:16 am
by airstream
Wow, you didnt say your isp's pppoe concentrator was firewalling with ridicules rules. UDP bandwidth testing often works poorly when using mt windows bandwidth tester.
Indeed this was only a temporary fix and no the foolish firewall rules have been replaced with finer tuned mangle rules specifically for the VoIP. I'd agree the bandwidth testing utility can be a hit or miss thing trying UDP over hops running on M$.