QOS at Branch Router
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10-10-2001 03:43 PM - edited 03-12-2019 12:51 PM
We are deploying our first remote site and are experiencing problems with call quality. In reference to the document 78-11549 "Cisco IP Telephony QOS Design Guide" we implemented several QOS functions on layer 2 and are currently implementing them on layer 3. When we applied the Traffic Shapping (reference page 5-27 in document) we lost the ability to do almost everything including telnet to the router over the Serial Interface. Here is an example config from our router:
Current configuration : 3705 bytes
!
version 12.1
no service single-slot-reload-enable
service timestamps debug uptime
service timestamps log uptime
service password-encryption
!
hostname router-wcm1
!
logging rate-limit console 10 except errors
enable secret 5 password
enable password 7 password
!
!
!
ip subnet-zero
!
!
no ip finger
ip host ccm1 10.x.1.252
ip host ccm2 10.x.1.253
!
!
class-map match-all VoIP-Control
match access-group 101
class-map match-all VoIP-RTP
match access-group 100
!
!
policy-map QoS-Policy-512k
class VoIP-RTP
priority 100
class VoIP-Control
bandwidth 8
class class-default
fair-queue
!
!
!
!
!
!
!
ccm-manager redundant-host ccm1
ccm-manager mgcp
!
!
!
!
interface Ethernet0/0
ip address 172.x.17.1 255.255.255.0
full-duplex
!
interface Serial0/0
no ip address
encapsulation frame-relay
frame-relay traffic-shaping
no ip mroute-cache
load-interval 30
no fair-queue
cdp enable
!
interface Serial0/0.195 point-to-point
ip address 10.x.16.2 255.255.255.252
no ip mroute-cache
frame-relay class VoIP-512kbs
frame-relay interface-dlci 195 CISCO
frame-relay ip rtp header-compression passive
!
router eigrp 15
network 10.x.0.0 0.0.255.255
network 172.x.17.0 0.0.0.255
no auto-summary
no eigrp log-neighbor-changes
!
ip default-gateway 10.x.16.1
ip classless
ip route 0.0.0.0 0.0.0.0 10.x.16.1
no ip http server
!
!
map-class frame-relay VoIP-512kbs
no frame-relay adaptive-shaping
frame-relay cir 512000
frame-relay bc 1000
frame-relay be 0
frame-relay mincir 512000
service-policy output QoS-Policy-512k
frame-relay fragment 128
logging 172.x.1.x
access-list 100 permit ip any any precedence critical
access-list 100 permit ip any any dscp ef
access-list 101 permit ip any any precedence flash
access-list 101 permit ip any any dscp af31
!
!
snmp-server engineID local
snmp-server community
snmp-server community
snmp-server packetsize 4096
call rsvp-sync
!
voice-port 1/0/0
!
voice-port 1/0/1
!
voice-port 1/1/0
!
voice-port 1/1/1
!
mgcp
mgcp call-agent ccm2 service-type mgcp version 0.1
no mgcp timer receive-rtcp
!
mgcp profile default
!
dial-peer cor custom
!
!
!
dial-peer voice 1 pots
application mgcpapp
port 1/0/0
!
dial-peer voice 2 pots
application mgcpapp
port 1/0/1
!
dial-peer voice 3 pots
application mgcpapp
port 1/1/0
!
dial-peer voice 4 pots
application mgcpapp
port 1/1/1
!
dial-peer voice 100 pots
destination-pattern 9.+
port 1/0/0
!
dial-peer voice 200 pots
destination-pattern 9.+
port 1/0/1
!
dial-peer voice 300 pots
destination-pattern 9.+
port 1/1/0
!
dial-peer voice 400 pots
destination-pattern 9.+
port 1/1/1
!
!
call-manager-fallback
ip source-address 172.x.17.1 port 2000
max-ephones 24
max-dn 48
!
banner motd ^C
*****************************************
* *
* All access is logged and monitored. *
* Any unauthorized access will be *
* prosecuted to the fullest extent *
* allowed by the laws of the *
* United States of America. *
* *
*****************************************
^C
!
line con 0
transport input none
line aux 0
line vty 0 4
password 7 password
login
!
no scheduler allocate
end
I assumed that the access lists may have had something to do with it so I attempted adding
access-list 10x permit ip any any
to the end of both access lists. This did not resolve the issue. Any assistance or pointers toward more documentation on QOS for AVVID is appreciated.
Matthew Pickens
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10-11-2001 12:16 PM
I assume that you configured frame-relay traffic-shaping on both ends of the connection, and that both map-classes were using the same fragment size of 128 ?
Also why did you choose a fragment size of 128? For a 512kbps PVC if that is really your true CIR then you should be able to use a fragment size of up to 480 bytes. (80 bytes per 64 kbps)
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10-12-2001 06:56 AM
Two errors I saw in the traffic shaping parameters, are Bc should be 5120 and fragmentation should be 640.
The formula for Bc is Bc=CIR(Tc/1000), where Tc is the desired serialization (shoot for 10ms in voice and 125ms in data).
The formula for fragmentation is 80k for every 64k in clock speed. So 512/64(80)=640k.
That will fix your problem.
Steve
