sundance-communications.com/forum Forums VOIP Phones & IP PBX VoIP & Cloud Phones, Hosted PBX, General IP Phones VOIP priority with routers

I just bought a new router and I must say that my VOIP phones are working 100% more reliably than before with the old router. I replaced the router only because I needed wireless capabilities.

While looking at the new router's logs, I noticed that the IP phones had a much lower priority number (meaning higher priority) than other devices on my network. This would likely explain why I don't have voice quality issues when Outlook sends/receives messages anymore.

My question is, how does the router know that a packet is voice vs: data? I thought a packet was a packet. Is there something included in a header that instructs the router to handle them with a higher priority? I did nothing in the router's setup except to plug it in, so I am really curious.

i belive most voice ip equipment has a priority number in the header that the routers see

That's what QOS is for...it tags the packet.

QoS marking are done at either layer 2 or layer 3. A layer 2 marking is know as a COS marking and a L3 marking is know as a TOS marking. Typically an IP phone (like a Cisco 7960) marks the packet with a COS value of 5 and the L2 switch is aware of this. However, by default COS4-5 are in que 3 in a Catalyst 3550 and 2950 switch, therefore you must change the COS5 to but into que 4 (strict priority que). This is done at the interface level. This is all at L2, if you want to continue to do QoS across the WAN circuit, you should enable NBAR (Network Based Application Recognition) and do LLQ through a policy map on the low speed WAN links. NBAR is kind of like a sniffer built right into the router. It classifies the traffic and you can build policies based on this classification.

What kind of router did you get, Ed?

Yes, tell us now before it gets nasty!!!
:toothy: :toothy: :banana: :banana:

Larry, it's a D-Link DIR625. I am really happy with it.

Ed, here is your OFFICIAL CG Pocket Protector !!!



This is awarded for service above and beyond your taped, horn-rimmed glasses and Dr. Pepper-stained white short-sleeved shirt with skinny tie for not wearing your feathered hat, gold tooth, and gold medallion to the last CG Meeting, which was held via IP Conference from the local Circuit City.



3Com wants only Level 3 or better for their IP systems. They almost give the systems away to get the schools to up-buy on the switches. As long as there is not too much traffic the school boards love the IT guy who bought them.

:toothy:

$2.98

QOS may also be done strictly on a port basis when packets do not have a COS or TOS marking. This method however would not apply to SIP as that protocol inherently negotiates the port.

I've noticed most of the newer Linksys/D-Link/Netgear routers can select QoS based on physical jack number or MAC address, eliminating the need to set up COS, TOS, or 802.11p on the phones.

Also, from D-Link's site, "Award-Winning QoS Engine for Superior VoIP and Online Gaming", so QoS is probably enabled as default.

one other common way that many routers prioritize VoIP is by port number. Most VoIP uses SIP, which uses port 5060 for control. If the router has some simple intelligence it can then watch the SIP packets and figure out what ports the RTP is going on, and prioritize those also.

Also as was mentioned, most dedicated IP phones flag their packets as high priority, which also helps.

Cyberguard make an "slightly higher then entry level" router that has some nice features such QoS (based on TCP or UDP port) Also has VPN (both client and server).

I use the SG300 at my office and my home for my VoIP extension. I think I paid around $300 for it a year or so ago.