Community discussions

MUM Europe 2020
Frequent Visitor
Frequent Visitor
Topic Author
Posts: 81
Joined: Sun Apr 06, 2014 9:21 pm
Location: Lahore Pakistan

DSCP or normal marking for VoIP on 2 servers

Mon Apr 24, 2017 1:50 am

Hello All,
I would like to get an advice.

I have 2 sites, connected via wireless and have almost 40mbps throughput. both have different networks and both have an asterisk server. Following is a diagram of my network.

(SITE 1) PSTN---->Asterisk1 ( to)-->ether2 Mikrotik (
ether5 Mikrotik
(SITE 2) ether5 Mikrotik
ether2 Mikrotik ( to)---> Asterisk2 (

the scenario is, when user wants to dial to pstn, the call goes from asterisk 2 to mikrotik then to wireless then to mikrotik on the other site and then to mikrotik and then to asterisk 1 and then goes outside. I guess i dont have to define that :-)

Moreover, Internet on site 2 is also provided by this wireless link.

I want to know is, what will be the best practice to prioritize the VoIP so that I can get best voice quality? should I just mark the packets going to and from asterisk(s) or DSCP will be better? (my hard phones can mark DSCP)

Please advice.
Forum Guru
Forum Guru
Posts: 1108
Joined: Fri Mar 24, 2017 11:15 pm
Location: USA

Re: DSCP or normal marking for VoIP on 2 servers

Tue Apr 25, 2017 9:13 am

It's a changing tide I think. In the most recent access layers from Cisco you'll find they trust markings by default. I tend to take a cautious approach and verify those markings with an ACL this allows me to strip or modify the marking as needed and know that someone hasn't just set their PC to mark everything as voice and enjoy a higher priority queue than everyone else.

If I was you. I'd have the phones mark their traffic but I'd also verify those markings at a congestion point like your point-to-point wireless link. I typically do this by source and destination IPs and ports.

So a little of both. Trust the phones to do the right thing on the LAN but before they can saturate your WAN or Internet check those markings before acting on them with a queue tree. Any shaping you do should also be just below the actual link speed. If your wireless link is fairly consistent at 40 mb then setup your rules for 39 or 38 mb. This will ensure your rules take affect and don't conflict with the links speed, tail drop.

Who is online

Users browsing this forum: No registered users and 87 guests