05-28-2009 02:21 AM - edited 03-15-2019 06:14 PM
Excuse my ignorance on the subject, but we have recently implemented a complete Cisco IP telephony solution, using Call Manager across dozens of sites. At our smaller offices, with maybe a 5-10 people, we have installed VoIP phones, connected via Cisco 877 router, and then over a 2MB ADSL Private Access Broadband service. Data is also going over these lines, and the calls are breaking up. QOS isn't possible over ADSL - but can the router be configured to implement some kind of QOS? Would anyone ever recommend attempting to do this? We feel our supplier has led us up a path to a solution that will never work.
05-28-2009 03:13 AM
Alan,
I have to agree unless the ADSL provder would guarantee you a level of QoS, unlikely, then this should never go over ADSL.
I dont know what your set up is but you could look at GRE tunnels to impliment some form of QoS
http://www.cisco.com/en/US/tech/tk543/tk545/technologies_tech_note09186a008017405e.shtml
or if you can get it you could look at a V3PN connection.
http://www.cisco.com/en/US/docs/solutions/Enterprise/WAN_and_MAN/V3PN_SRND/V3PN_SRND.html
But yes due to the nature of ADSL and the internet latency this should not have been promoted as a solution for an effective voice network. Even if you do add qos to the router then this will not be carried over by the ISP and will in effect be dropped, so the next step would be to look at the GRE tunnel but again this can be affected by the internet latency, though better than nothing. Suggest you speak to your supplier and let me know there solution does not work so how do they propose to sort it
You can get DSL that will have QoS that would help but from what your are saying this is not in your case. Check with whoever is providing your DSL and find out what QoS if any they can provide
Hope this helps
Paul
05-28-2009 05:19 AM
Hi Alan,
Generally the small cable modem /DSL providers do not guarantee any type of QoS, but you can optimize it on your 877.
What you do is shape your traffic to their recommended level, and then do QoS within that.
For brevity, let's say you've already defined your voice traffic and voice signaling in class maps. Your DSL we'll say is 750 kb/sec upload.
policy-map shaper
class class-default
shape average 750000
service-policy shaper-child
policy-map shaper-child
class voice-traffic
priority percent 50
set dscp ef
class voice-signaling
bandwidth 50
set dscp cs3
interface WAN 0/0
service-policy out shaper
hth,
nick
Discover and save your favorite ideas. Come back to expert answers, step-by-step guides, recent topics, and more.
New here? Get started with these tips. How to use Community New member guide