VoIP again

RouterOS Wireless Networking
1

Ok, I know there are alot of posts about this, and I think I have read them all, but I haven’t found a good answer just yet.

I have a few customers on Vonage, and we also resell our own branded VoIP service. We just upgraded all of our towers from AP-1000’s to RB532/SR-2’s and have seen dramatic improvements in service quality, however, the VoIP seems to have become worse.
Originally before the upgrade, our customers complained about random cut outs in audio, or echoing, and etc. now it is very “choppy” kind of like a CD skipping, it is a constant momentary cutout.
I know SIP is hard to classify and prioritize, but are there any working configurations out there that might help? Any suggestions on settings that would help this improve?
I know the ToS values for our branded service as well as the vonage, and can prioritize based on this, but this only helps on the upstream traffic. What can be done to give the stream priority inbound to the customer?

Can someone provide a detailed configuration example they have had luck with.

Thanks in advance!

2

You could prioritise the traffic based on where it is going to (vonage / your service) and were it is comming from. Either change the ToS or use queueing or both! Will not catch all VOIP traffic but you can add to the rules as you find out what voip companies people are using. This is just theory btw I’m planning to do something like this on my network if VOIP gets bad, at the moment it is fine

3

I am looking into that, there are just soo many IP’s used by vonage and our provider as well, that it makes it a headache.. but that might be my only option i guess.

4

I have build a mangle rule, based on tcp/ip package contents. then i build a address list from that.

I use the following rule

/ip firewall mangle chain=prerouting in-interface=ether2 content=SIP/2.0 action=add-src-to-address-list address-list=sip address-list-timeout=1h

But my question is howto use TOS correct

5

what do you mean be how to use it correct? there is a way to define it in the mangel rule, or do you mean how do you find the right value?

6

Also, I am unsure of how to properly configure the priorities, meaning how do I set it up so that VoIP or SIP in this case, gets priority over everything else.

7

We have messed with this for awhile. SIP itself is easy to spot but that is just the handshaking. Vonage seems to use random ports above 10000 for the actual conversation. But so does lots of other stuff.

Our best solution was to set everything else at a lower priority. That will sort of leave voip to run free. Some gets missed. Kinda backwards way to approach the problem.

We use http://www.testyourvoip.com to check things.

I’m hoping that the MT detection method for p2p could be applied to voip traffic in an upcoming version.

Mike

8

Nice site.. ill use it for sure

When you say give everything else a lower priority, you mean you just define all the possible services and etc, and set them lower, and then let the voip and a few other undefined flows be higher?
interesting approach… can you give an example by chance? I understand there might be alot, but just a simplified example would help me understand it better.

9

The way I have made it, wich is sort of reversed since I have my VOIP servers internally is to connection mark all traffic coming from a specific server/IP OR going to the same IP, tag all packets with that connection mark with a proper VOIP tag and then put them in the top-prio queue

Some code


add chain=prerouting src-address=192.168.2.41 action=mark-connection \
    new-connection-mark=voip-con passthrough=yes comment="" disabled=no
add chain=prerouting dst-address=192.168.2.41 action=mark-connection \
    new-connection-mark=voip-con passthrough=yes comment="" disabled=no
add chain=prerouting connection-mark=voip-con action=mark-packet new-packet-mark=voip \
    passthrough=no comment="" disabled=no

Basically you should be able to do the same, just use the Voange server IP and your own to service IP to tag the connections and then mark up the associated packets with a voip packet mark.

Hope this helps some

/Jörgen

10

To look inside the packet!

Later i have rules to bypass traffic which comes and goes to the host in the address list

11

I finally got it! :unamused: sometimes it takes a smack in the head.. it seems to work just like you said.. i just didn’t understand at first.
I had to play with how to identify the actual packets i wanted to, but once that was figured out the rest was just as you said.

Thanks!

12

Earlier, someone mentioned the control ports vs the transaction ports of VoIP and how difficult it would be to manage ports 10000+ for voice. MT does do this, but some of the SIP firewall software is intelligent enough to track spawned ports and then prioritize them as well as the original ports. For example, when SIP starts its session on 5060/5061 the firewall watches for the spawned ports from that session and increases their priority. When the call terminates, the temporary priority is dropped for the spawned ports. You can actually do this for any port with some of the firewalls and not just voice. Rather interesting type of on-the-fly QoS. It allows you to manage multimedia much easier without prioritizing P2P or other unwanted traffic.

This OTF port management would be a great addition to MT’s firewalling. Of course just adding easy SIP management would be great too.

Steve