QoS Configuration Help

ricardo.viteri · ‎09-19-2010

Hello and thanks for taking a look,

I am trying to achieve the following behavior through Cisco QoS.

The goal is that when rtp audio packets are flowing then VoIP Queue reserves 464kbps and the other queues have 64 kbps available to share.

Therefore, if I have an uplink of 512kbps and If there are rtp packets going through the interface, I want the Policy class to reserve 464kbps (regardless of how many actual kbps of rtp audio packets are flowing through). If there are no rtp audio packets going through the interface then share the the 512kbps according to the other classes.

Another way to look at what I am trying to achieve is the following (maybe it will help to clarify):

If RTP Packets in class CCP-Voice-1 are present then shape all other traffic to 64kbps

This is my current config:

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class-map match-any CCP-Transactional-1
 match protocol citrix
 match protocol finger
 match protocol notes
 match protocol novadigm
 match protocol pcanywhere
 match protocol sap
 match protocol secure-telnet
 match protocol sqlnet
 match protocol sqlserver
 match protocol ssh
 match protocol telnet
 match protocol xwindows
class-map match-any CCP-Voice-1
 match protocol rtp audio 
class-map match-any CCP-Routing-1
 match protocol bgp
 match protocol eigrp
 match protocol ospf
 match protocol rip
 match protocol rsvp
class-map match-any CCP-Signaling-1
 match protocol h323
 match protocol rtcp
 match protocol sip
class-map match-any CCP-Management-1
 match protocol dhcp
 match protocol dns
 match protocol imap
 match protocol kerberos
 match protocol ldap
 match protocol secure-imap
 match protocol secure-ldap
 match protocol snmp
 match protocol socks
 match protocol syslog
class-map match-any HTTP/S
 match protocol http
 match protocol secure-http
!
!
policy-map CCP-QoS-Policy-1
 class CCP-Voice-1
  set dscp ef
    priority 464
 class CCP-Signaling-1
  set dscp cs3
    bandwidth percent 1
 class CCP-Routing-1
  set dscp cs6
    bandwidth percent 1
 class CCP-Management-1
  set dscp cs2
    bandwidth percent 1
 class CCP-Transactional-1
  set dscp af21
    bandwidth percent 1
 class HTTP/S
    bandwidth percent 4
 class class-default
    fair-queue
     random-detect
policy-map CCP-QoS-Policy-2
 class class-default
    shape average 512000
  service-policy CCP-QoS-Policy-1

interface FastEthernet4
 description $FW_OUTSIDE$$ES_WAN$
 bandwidth 512
 bandwidth receive 4096
 ip address dhcp client-id FastEthernet4
 no ip redirects
 no ip unreachables
 no ip proxy-arp
 ip mtu 576
 ip nbar protocol-discovery
 ip flow ingress
 ip nat outside
 ip virtual-reassembly
 ip tcp adjust-mss 512
 duplex auto
 speed auto
 !        
 max-reserved-bandwidth 1
 service-policy output CCP-QoS-Policy-2
!         
interface Vlan1
 description $ETH-SW-LAUNCH$$INTF-INFO-HWIC 4ESW$$ES_LAN$$FW_INSIDE$
 ip address 10.0.11.254 255.255.252.0
 no ip redirects
 no ip unreachables
 no ip proxy-arp
 ip flow ingress
 ip nat inside
 ip virtual-reassembly
 ip tcp adjust-mss 1452
 !        
!         
ip forward-protocol nd
ip http server
ip http authentication local
ip http secure-server
ip http timeout-policy idle 60 life 86400 requests 10000
!         
!         
ip nat inside source list 1 interface FastEthernet4 overload
!         
logging trap debugging
access-list 1 remark CCP_ACL Category=2
access-list 1 permit 10.0.8.0 0.0.3.255
no cdp run





Cisco IOS Software, C880 Software (C880DATA-UNIVERSALK9-M), Version 15.0(1)M3, RELEASE SOFTWARE (fc2)


Cisco 881 (MPC8300) processor (revision 1.0) with 236544K/25600K bytes of memory.
Processor board ID FTX143200J6

5 FastEthernet interfaces
1 Virtual Private Network (VPN) Module
256K bytes of non-volatile configuration memory.
125440K bytes of ATA CompactFlash (Read/Write)


License Info:

License UDI:

-------------------------------------------------
Device#&#9;  PID&#9;&#9;&#9;SN
-------------------------------------------------
*0  &#9;  CISCO881-SEC-K9           



License Information for 'c880-data'
    License Level: advipservices   Type: Permanent
    Next reboot license Level: advipservices

Giuseppe Larosa · ‎09-19-2010

Hello Ricardo,

two notes:

1)

>> Therefore, if I have an uplink of 512kbps and If there are rtp packets going through the interface, I want the Policy class to reserve 464kbps (regardless of how many actual kbps of rtp audio packets are flowing through). If there are no rtp audio packets going through the interface then share the the 512kbps according to the other classes.

Class Based Weighted Fair Queueing has built in elasticity and resources unused by VOIP packets are available for other resources.

This is usually enough.

2) about your configuration

there are some strange commands on WAN interface Fas4:

if you set bandwidth to 512 kbps the max-reserved-bandwidth should be set to 100 (100%) and not to 1.

The bandwidth command sets a new reference value for QoS.

ip mtu 576: this MTU is too small and it causes a lot of fragmentation of data traffic IP packets

I usually mark on LAN interfaces and then match on DSCP or IP precedence settings on exit interface this helps in troubleshooting as the command show policy-map interface provides counters for each traffic class and so you can compare traffic entering the router with traffic that is sent out the WAN interface.

Hope to help

Giuseppe

ricardo.viteri · ‎09-20-2010

Hi Giuseppe,

You are correct I did notice I had 1% and not 100%, I fixed this soon after my post. Still it did not fix my issue.

I have set MTU to 576 bytes and MSS to 536 bytes for the following reason:

Serialization Delay. ( http://www.cisco.com/en/US/tech/tk652/tk698/technologies_white_paper09186a00800a8993.shtml#serializationdelay )

I was hoping I could implement Link Fragmentation and Interleaving; unfortunately soon I discovered this only works for PPP connections so my FastEthernet connected to my Cable Modem would not support it.

Is it possible to allow the elasticity of bandwidth only when there are no VoIP packets present?

My goal is to achieve this behavior using just the router (perhaps with EEM TCLs - if someone out there could code it):

http://www.xmission.com/~hidden/aatqos/

Regards,

Ricardo