Basic QoS over a VPN?

cluovpemb — Tue, 22 Jan 2013 20:53:19 GMT

I have a pair of Cisco 891W routers, deployed one at each site. I have site to site (L2L) IPSec VPN configured and working using crypto maps. All traffic is allowed from one LAN to the other, as far as I know.

Today I dicovered that I need to put in QoS to support an IP Phone. A single IP phone at branch office, to the main phone system at head office.

I do not have experience with QoS at all. Simplicity is key here.

From what i find online, here's what I believe needs to be done:

1. Create an ACL, calling it VOIPACL, specify the IP of the phone going to the network where the phone system is. So:

permit ip host 192.168.4.201 192.168.0.0 0.0.0.255

2. Create a class map to house the ACL

#class-map match-all VoIP

#match access-group name VOIPACL

3. Create policy map to house the clas map

#policy-map VoIP

#class VoIP

Here's where I get lost. There seem to be various opinions of how to do things but as I don't understand the implications of anything, I am not goign to attempt anything without expert or experienced confirmation. For example, I can put bandwidth percent 50, which I guess divides the line into 50% for any traffic coming from 192.168.4.201 IP phone, and since I didn't specify what to do with the other 50%, I assume the router just ttreats that as regular traffic.

Then I saw stuff about IP precedence, and Set priority, and Priority, and fair-queue and so on. At that point I stopped, and now need help

Basic QoS over a VPN?

Marcin Latosiewicz — Wed, 23 Jan 2013 10:02:02 GMT

Voice traffic typically should be guarnateed priority queue to avoid delay/jitter.

You might be also interested in qos pre-classify:

http://www.cisco.com/en/US/docs/solutions/Enterprise/WAN_and_MAN/QoS_SRND/IPSecQoS.html#wp56280

Some config guide material:

http://www.cisco.com/en/US/docs/ios-xml/ios/sec_conn_dplane/configuration/15-mt/sec-llq-ipsec-enrypt.html

What you also need to remember is that voice(RTP) traffic should be marked by default with EF DSCP - this tagging should be copied to the outter header afetr encapsulation, you can also use that when making decision.

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Basic QoS over a VPN?

Basic QoS over a VPN?