VOIP QOS over T1's

Posted on 2008-06-20
Last Modified: 2008-07-01
Hey Experts, I need a quick tutorial on how to setup QOS for VOIP Packets.  When my router gets busy some of my T1 clients are experiencingbetter than perfect voice quality.  I just need to know how to prioritize the VOIP Packets.  If I need to upgrade my IOS please let me knowwhere to get it.  TIA

7206#sh ver
Cisco Internetwork Operating System Software
IOS (tm) 7200 Software (C7200-IS-M), Version 12.1(9), RELEASE SOFTWARE (fc1)
Copyright (c) 1986-2001 by cisco Systems, Inc.
Compiled Wed 13-Jun-01 16:53 by kellythw
Image text-base: 0x60008950, data-base: 0x61510000

ROM: System Bootstrap, Version 12.0(19990210:195103) [12.0XE 105], DEVELOPMENT SOFTWARE
BOOTLDR: 7200 Software (C7200-BOOT-M), Version 12.0(10)S, EARLY DEPLOYMENT RELEASE SOFTWARE (fc1)

7206 uptime is 2 weeks, 5 days, 33 minutes
System returned to ROM by power-on
System image file is "slot0:c7200-is-mz.121-9.bin"

cisco 7206VXR (NPE300) processor (revision B) with 122880K/40960K bytes of memory.
Processor board ID 23659150
R7000 CPU at 262Mhz, Implementation 39, Rev 1.0, 256KB L2, 2048KB L3 Cache
6 slot VXR midplane, Version 2.1

Last reset from power-on
Bridging software.
X.25 software, Version 3.0.0.
4 Ethernet/IEEE 802.3 interface(s)
3 FastEthernet/IEEE 802.3 interface(s)
22 Serial network interface(s)
1 Channelized T3 port(s)
125K bytes of non-volatile configuration memory.

20480K bytes of Flash PCMCIA card at slot 0 (Sector size 128K).
4096K bytes of Flash internal SIMM (Sector size 256K).
Configuration register is 0x2102
Question by:hgallagher
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LVL 28

Expert Comment

by:Jan Springer
ID: 21841462
Configure class-map[s], policy-map[s] and apply the policy to the interface.

The remote end of the T1 will require a similar configuration.  If is does not prioritize your voice at the remote end, there is no point in you configuring it locally.

Let me know if you need an example.

I would recommend upgrading the IOS before configuring policing.  Are you using CEF?

Author Comment

ID: 21842144
Two things, An example would be tremendous, also how to implement CEF would be also worth the points.  TIA.
LVL 28

Accepted Solution

Jan Springer earned 500 total points
ID: 21842174
2nd part first:

config t
 ip cef

check that the interfaces have cef turned on -> sh ip cef

i'll pull together a QoS example.
LVL 28

Expert Comment

by:Jan Springer
ID: 21842231
Adjust as needed:

ip access-list extended SIP
  permit udp any any eq 5060

class-map match-all VoIP
   match access-group name SIP
class-map match-all RTCP
   match ip rtp 16384 16383
class-map match-any VoIP-DSCP
   match ip dscp ef
   match ip dscp cs3
   match ip dscp af31

policy-map Set-DSCP
 class RTCP
   set ip dscp ef
 class VoIP
   set ip dscp af31
 class VoIP-DSCP
   set ip dscp default

policy-map QoS-Policy
  class RTCP
   bandwidth percent 20
  class VoIP
    bandwidth percent 5
  class class-default
     set ip dscp default

interface Serial<whatever>
  service-policy input Set-DSCP
  service-policy output Qos-Policy

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