06-13-2005 01:15 AM - edited 03-03-2019 09:48 AM
Hi All
We have two sites - each with its own PABX, and a 320KB direct line between them. This line is being used for data, but we want to route PABX voice traffic over it as well.
This is where the problem comes in. I went to http://www.cisco.com/en/US/customer/tech/tk652/tk698/technologies_white_paper09186a00800d6b73.shtml#xtocid11 to have a look at what Cisco recommends. I configured both the 2620 routers linking the sites as described in the chapter http://www.cisco.com/en/US/customer/tech/tk652/tk698/technologies_white_paper09186a00800d6b73.shtml#69895.
This, however, did not work too well. :-(
The two PABXs have fixed IP addresses, so identifying and tagging the traffic that needs to be shaped is quite easy (using an ACL). After this solution had been implemented, general performance over this link became so bad, that we had to revert back to the original config to restore normal service.
The problem with our voice, is that it starts breaking up quote badly as soon as we reach 80K on our 320K link. Hence the QoS attempt.
Does anybody have any thoughts? I upgraded both routers IOS's to 12.2(29).
06-13-2005 03:41 AM
Hi,
Cud you attached the config's you tried. and the original config of the router before the change.
Regards,
Vincent
06-13-2005 05:37 AM
Hi Vincent
The config on both routers look like this (except for the IP addresses being different, of course). I have removed some of the more sensitive information, but take my word for it that connectivity is not an issue. ;-)
We are using interface s0/1 on both routers for this 320K link. The PABX IP address on site A is 10.30.200.1, and on site B is is 10.34.200.1.
Config before:
---------------------------
version 12.2
service timestamps debug uptime
service timestamps log datetime
service password-encryption
!
hostname
!
boot system flash:c2600-js-mz.122-29.bin
logging buffered 20000 debugging
aaa new-model
aaa authentication login vtymethod group radius enable
enable secret 5
!
ip subnet-zero
no ip rcmd domain-lookup
ip rcmd rsh-enable
!
!
interface FastEthernet0/0
ip address 10.32.5.253 255.255.255.0
speed 100
full-duplex
!
interface Serial0/0
bandwidth 192
ip address
no ip mroute-cache
!
interface Serial0/1
bandwidth 320
ip address
no ip mroute-cache
!
router eigrp 2050
variance 2
redistribute static
no auto-summary
no eigrp log-neighbor-changes
!
ip classless
ip route 0.0.0.0 0.0.0.0 10.1.1.254
no ip http server
!
!
snmp-server engineID local xxx
snmp-server community
snmp-server community
snmp-server enable traps tty
radius-server host 10.1.1.201 auth-port 1645 acct-port 1646
radius-server key 7
!
line con 0
exec-timeout 0 0
line aux 0
line vty 0 4
exec-timeout 10 10
password 7
logging synchronous
login authentication vtymethod
length 14
width 162
!
end
Config After:
---------------------------
version 12.2
service timestamps debug uptime
service timestamps log datetime
service password-encryption
!
hostname Hurteria2620
!
boot system flash:c2600-js-mz.122-29.bin
logging buffered 20000 debugging
aaa new-model
aaa authentication login vtymethod group radius enable
enable secret 5
!
ip subnet-zero
no ip rcmd domain-lookup
ip rcmd rsh-enable
!
!
class-map match-all C_VoIP
match access-group name A_VoIP
match ip precedence 5
!
!
policy-map P_VoIP
class C_VoIP
priority 64
class class-default
fair-queue
!
!
!
interface Multilink1
bandwidth 320
ip address
service-policy output P_VoIP
no ip mroute-cache
no cdp enable
ip rtp header-compression iphc-format
ip tcp header-compression iphc-format
ppp multilink
ppp multilink fragment-delay 10
ppp multilink interleave
multilink-group 1
!
interface FastEthernet0/0
ip address 10.32.5.253 255.255.255.0
speed 100
full-duplex
!
interface Serial0/0
bandwidth 192
ip address
no ip mroute-cache
no fair-queue
!
interface Serial0/1
bandwidth 320
encapsulation ppp
ppp multilink
multilink-group 1
no ip mroute-cache
!
router eigrp 2050
variance 2
redistribute static
no auto-summary
no eigrp log-neighbor-changes
!
ip classless
ip route 0.0.0.0 0.0.0.0 10.1.1.254
no ip http server
!
!
ip access-list extended A_VoIP
permit ip host 10.30.200.1 host 10.34.200.1
permit ip host 10.34.200.1 host 10.30.200.1
snmp-server engineID local xxx
snmp-server community
snmp-server community
snmp-server enable traps tty
radius-server host 10.1.1.201 auth-port 1645 acct-port 1646
radius-server key 7
!
!
!
line con 0
exec-timeout 0 0
line aux 0
line vty 0 4
exec-timeout 10 10
password 7
logging synchronous
login authentication vtymethod
length 14
width 162
!
end
06-13-2005 07:49 AM
How much voice traffic are you sending accross, the policy-map P_VoIP
class C_VoIP
priority 64
policy map strickly prioritizes 64kbps of traffic defined by your ACL, if you are using g711 codec over mp with comression that's 67.6 kbps for RTP stream plus additional signaling overhead (couple kbps). With g729 that's 11.6kbps. With LLQ (priority) if excess bandwidth is available, the priority class will be allowed to utilize the bandwidth. If no excess bandwidth is available, the priority traffic will be constrained to the configured rate via packet drops. Make sure 64k is enough bandwidth for that traffic.
Chris
06-13-2005 09:47 AM
Thanks for the reply Chris.
We have four voice channels available between the two PABX's (Siemens HiPath 300). Each of these channels is configured to use 17K of bandwidth. We had the channels down to 3 at one stage, and we even had the priority bandwidth up to 128K. It made no difference.
After about 1 hour of configuring the routers, we started having problem with both voice and data transmission. On our bandwidth graphs, the link never exceeded 54K!
The routers on site A and B both use interface s0/0 to connect back to our head office. Both sites had trouble connecting back to our head office after about an hour of changing the config.
Initially, the config worked fine. We managed to make voice call while the link was running at 317K. Then quality started degrading until such a stage that neither voice nor data was at acceptable levels. Like I said, 54K was the maximum throughput we got...
IOS bug?
06-13-2005 05:40 PM
It sounds like your voice is not hitting the priority queue. show policy-map interface mu1 will tell you.
If you are not seeing the voice in your priority queue, I would suggest applying an inbound service policy on your ethernet to set the IP Precedence, then matching IP Precedence on the outbound service policy. The following changes to your config should get this working:
class-map match-all voice
match ip precedence 5
class-map match-all pabx
match access-group name A_VoIP
policy-map Set_IP_Prec
class pabx
set ip precedence 5
policy-map P_VoIP
class voice
priority 64
class class-default
fair-queue
interface fast0/0
service-policy input Set_IP_Prec
interface multilink1
service-policy output P_VoIP
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