10-09-2007 05:03 PM - edited 03-03-2019 07:06 PM
We are setting up our first site to do VOIP over our MPLS network. We have a CME in our remote site and CCM in our head site. Our service provider has us set up with EF Que for the voice priority EF QUE. On the remote side we have a 2811 which I have setup the following and applied to the serial interface:
class-map match-all L3-to-L2_VoIP-Cntrl
match ip dscp af31
match ip dscp cs3
class-map match-all L3-to-L2_VoIP-RTP
match ip dscp ef
policy-map Voice_wan
class L3-to-L2_VoIP-RTP
bandwidth percent 5
class L3-to-L2_VoIP-Cntrl
priority percent 25
On the head end side we have a Cisco 3845 which I have setup and applied on the serial interface:
class-map match-all L3-to-L2_VoIP-RTP
match ip dscp ef
class-map match-all L3-to-L2_VOIP-Cntrl
match ip dscp af31
match ip dscp cs3
policy-map Voice_wan
class L3-to-L2_VOIP-Cntrl
priority percent 2
class L3-to-L2_VoIP-RTP
bandwidth percent 5
class class-default
fair-queue
We also have a Catalyst 4500 which has the following setup:
qos dbl
qos map dscp 24 25 26 27 28 29 30 31 to tx-queue 4
qos map dscp 32 33 34 35 36 37 38 39 to tx-queue 4
qos map cos 3 to dscp 26
qos map cos 5 to dscp 46
qos
interface GigabitEthernet
description link to Router
no switchport
ip address x.x.x.x x.x.x.x.
speed 1000
duplex full
qos trust dscp
auto qos voip trust
tx-queue 3
bandwidth percent 33
priority high
shape percent 33
service-policy output autoqos-voip-policy
The interface on the 4500 above connects to the 3845. I have a few questions, first on the 3845 on the Ethernet interface do I need to set a trust from the 4500? If so can anyone explain how to do this? Third is the QOS I setup so far correct? Thanks all.
10-10-2007 01:11 AM
Hi
The 3800 will accept the the markings from the 4500 with your configuration.
Looks like you got your LLQ swapped around (Priority/Bandwidth statements in policy-maps), remember the voice (RTP) is more important than the signalling (Cntrl).
If you are not trusting the CoS markings from your IP phones you should remark the traffic on your Switch or router on udp ports 16384 to 32767.
Other than that your QoS will work.
Regards
Phillip
10-10-2007 04:35 AM
You may have to use "mls qos trust" on interfaces to which IP phones are connected.
Also change the bandwidth to Priority for RTP traffic in the policy-maps. RTP is the actual voice traffic & needs priority queuing.
Another method of QoS if 1 is not sure of the markings, turn-on "ip nbar protocol-discovery" on the router & then match clas-maps with protocols rather than dscp markings.
10-10-2007 05:14 AM
Hi,
You dont need trust between (2) laye-3 interfaces, since your SW-interface is connected to a layer-3 router interface with policer applied.
The Only point is to make sure ur IP-Phones are trusted in the Sw ports, and you override ur PC's Data traffic associated with the IP-Phones to have diffrent marking in order to avoid it to be priotrized , here is example:
int e0/1
mls qos trust cos
switchport mode access
switchport voice vlan x
switchport access vlan y
switchport priority extend cos 2
this will override all PC's traffic with a COS of 2 and leaves Voice with its default CoS 5.
Another Method if u have Switches between the L3 routers, and you have the Same DSCP values and needs to be configured for future, you can configure the SW to forward any DSCP value it receives rather than doing L3-to-L2 mapping and Vice vers.
HTH
Mohamed Sobair
10-10-2007 05:18 AM
This is what I have on my phone ports on the switch.
switchport access vlan xx
switchport mode access
switchport voice vlan xx
qos trust device cisco-phone
qos trust cos
auto qos voip cisco-phone
tx-queue 3
bandwidth percent 33
priority high
shape percent 33
spanning-tree portfast
spanning-tree bpduguard enable
service-policy output autoqos-voip-policy
10-10-2007 06:10 AM
Hi,
Looks OK,
HTH
Mohamed Sobair
10-10-2007 06:31 AM
I have make all the changes and I am still getting choppy calls across the wan. Is there a way I can debug that packets and ensure they are being marked correctly?
10-11-2007 04:17 AM
I would use Wireshark.
Also make sure you have enough bandwith, correct codecs for the WAN (G729) and CAC configured on the CMs.
10-11-2007 12:27 PM
What is your round-trip delay time when you ping from one voice source to destination? Choppiness may be due to latency in the circuit as well.
10-12-2007 10:32 AM
Hi,
You might use the EXEC mode command bellow to check QoS values at specific interface:
# show mls qos int x
HTH
Mohamed Sobair
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