02-09-2009 12:26 PM - edited 03-04-2019 03:29 AM
Hi guys, I have a cisco 3745 with a wic-adsl card and a IOS 12.3(26) entservices, I was wondering if it is possible to configure a QoS to prioritise the voice traffic.
Some link or example,
Thanks friends.
David
02-09-2009 01:24 PM
Hello David,
you can use CBWFQ with a LLQ queue (priority command) but you need to provide resources to the ATM pvc.
something like
int atmx/0
no ip address
int atmx/0.1 point-to-point
ip address x.x.x.1 255.255.255.252
pvc 8/35
cbr 200
service-policy qos out
see
http://www.cisco.com/en/US/docs/ios/12_2/12_2y/12_2yn8/feature/guide/ft_ipqos.html#wp1027859
Hope to help
Giuseppe
02-09-2009 04:46 PM
I haven't worked with a wic-adsl card, but there's a good chance the interface would support CBWFQ (perhaps as Giuseppe notes).
One important consideration, you might need a parent policy with shaper that corresponds to the ADSL egress bandwidth, unless the card otherwise physically sends at ADSL egress bandwidth.
Something similar to:
class-map match-any VoIP
match . . . (something that matches your VoIP traffic)
policy-map ADSL_Out
class class-default
shape average # (bps available)
policy-map ADSL_Prioritize
class VoIP
priority ### (bandwidth allocated to VoIP)
interface ?
service-policy output ADSL_Out
(If the interface does transmit at egress ADSL bandwidth, you wouldn't need ADSL_Out policy's shaper.)
02-11-2009 03:42 AM
Hi I have the same problem with QOS.
I configure priority to outgoing traffic, and it works fine. But when i start download from ftp or http, my Voice traffic is not prioritized. So I guess i have to prioritize the inbound trafic right ?
And if yes, please help with some suggestions. Thank you!
02-11-2009 04:13 AM
For inbound, what you really want to do is apply QoS on the other side's outbound. If this is not possible, it's very difficult to effectively protect inbound VoIP. Two techniques that can be used, severely rate limit in-bound TCP traffic or shape outbound TCP ACKs. The idea being to keep TCP traffic from using all the link's bandwidth thus preserving bandwidth for VoIP.
02-11-2009 04:39 PM
Hi Joseph % Giuseppe, first thanks for your comments, I tried to apply the QoS on my ATM interface and it seems like it does not work, funny!!!
interface ATM0/0
no ip address
no atm ilmi-keepalive
dsl operating-mode auto
interface ATM0/0.1 point-to-point
description $ES_WAN$
ip address 10.X.X.222 255.255.255.252
pvc 0/35
protocol ip 10.X.X.221 broadcast
encapsulation aal5snap
service-policy output QoS-Voice-Data
But in the show runn, I cannot see this command. Do I'm missing something.
Thanks a lot guys,
David
02-11-2009 07:07 PM
Good chance it's rejecting the policy because it doesn't "know" the bandwidth. If nothing logged on console, there might be something logged within the syslog.
Again, unsure with ADSL. On true ATM interfaces often have something like a vbr-nt under the PVC which defines the PVC's bandwidth. What also might work is a policy with a shaper.
02-11-2009 11:25 PM
Thank you Joseph, that helps me !
03-05-2009 12:33 PM
Here is a functioning QoS policy that I have on a 2600XM running 12.4(13f)
policy-map VoiceLLQ
class VoiceTraffic
priority 256
class class-default
fair-queue 256
random-detect
interface ATM0/0
no ip address
load-interval 30
no atm ilmi-keepalive
dsl operating-mode auto
!
interface ATM0/0.100 point-to-point
no snmp trap link-status
pvc 0/35
ubr 512
tx-ring-limit 1
service-policy output VoiceLLQ
pppoe-client dial-pool-number 1
!
end
This config works on my SBC DSL line, and correctly prioritizes voice during upstream congestion.
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