QoS query

[Kaushik Ray]

I am setting up a QoS where in a subnet 192.168.1.0/24 needs to be prioritzed so created a class map to capture this.

There is a device within the above network with IP address 192.168.1.40 which need to be at a higher priority so setup up like this.

class-map match-any VIDEO
 match access-group 120

class-map match-any class.Corp
 match access-group name acl.Corp
!

policy-map QoS_out
 class VIDEO
    bandwidth 1536
 class class.Corp
    bandwidth 450
     random-detect

ip access-list extended acl.Corp
 permit ip 192.168.1.0 0.0.0.255 any

access-list 120 permit ip host 192.168.1.40 host 1.1.1.1
 

But cannot see any matches when i do a show policy-map int fa 0/1.

is there something wrong I am doing here?

Any advise will be much appreciated.

thanks

[Kaushik Ray]

Anyone sees any potential issues with how this is setup?

[Vasilii Mikhailovskii]

Please provide the configuration the interface and ACLs.

On which interfaces the hosts 192.168.1.40 and 1.1.1.1 are located?

What platform and IOS do you use?

[Kaushik Ray]

Thanks Vasilii

interface FastEthernet0/0.22
 description ### LAN - Corp ###
 encapsulation dot1Q 22
 ip vrf forwarding Corp_Data
 ip address 192.168.1.1 255.255.255.0
 ip accounting output-packets
 ip flow ingress
 ip flow egress
 ip tcp adjust-mss 1400
!

192.168.1.40 is a device (VC unit) in the LAN side of this interface.

1.1.1.1 is located at the Client side where this Corp_Data is backhauled.

Following is the only ACL

ip access-list extended acl.Corp
 permit ip 192.168.1.0 0.0.0.255 any

Platform is PID: CISCO2811

IOS is flash:c2800nm-spservicesk9-mz.150-1.M3.bin

Please let me know your thoughts and if you need any more information on this.

Thanks

[Vasilii Mikhailovskii]

Hello.

Could you please provide configuration of the interface where QoS policy-map is applied (and "show interface ...")?

What is your WAN bandwidth?

[Kaushik Ray]

!
interface FastEthernet0/1
 description ### Trunk  ###
 no ip address
 duplex full
 speed 100
 service-policy output QoS_out
!

The total WAN link is 2Mbps.

Please let me know your thoughts.

[Vasilii Mikhailovskii · Accepted solution]

Hello.

Here you need to use hierarchical QoS, like this:

policy-map QOS
 class VIDEO
  bandwidth 1500
 class OTHER
  bandwidth 400
 

policy-map QOS_OUT
 class class-default
  shapre average 2000000
   service-policy QOS 

[Kaushik Ray]

Thanks very much for your reply;

just to know more what would be the issue if I do it the way; i believe its wrong but just wanted to know whey it does not work this way? if you can share your ideas please?

thanks

[Vasilii Mikhailovskii]

If you do it without "shape", then no QoS would be really working for you.

[Kaushik Ray]

Thanks again Vasilii

Would my config had worked if I put bandwidth command on the interface?

[Vasilii Mikhailovskii]

Hello.

No. The reason for this, is "bandwidth" under class is for scheduling when we have congestion on the interface (policy-map). Bandwidth on the interface won't help you here.

As far as your interface is able to send 100M, it means each of your classes are allowed to burst up to 100M -> it means no QoS.

Shape command is needed to limit the amount of bandwidth you allocate on the wire (when your contracted CIR does not match line-rate).

[Kaushik Ray]

Hello Vasilli

Thanks for this. Apologies but would like to ask one final question; in which situations can I configure like this then? Would be extremely grateful to have your thoughts.

1. Define Class Maps
class-map http
match protocol http
class-map telnet
match protocol telnet
class-map match-any voice
match protocol rtp
match ip dscp ef
class-map voice-signalling
match ip dscp cs3

2. Define Policy Maps
policy-map Example1
class http
bandwidth percent 20

class telnet
bandwidth percent 10

class voice-signalling
bandwidth percent 5

class voice
priority percent 50

class class-default
fair-queue

3. Apply to the Interface:
interface S0/0/0
service-policy output Example1

[Vasilii Mikhailovskii]

Hello.

This would work when your contracted bandwidth matches your line-speed.

Works if:
- serial interface bw 45M and contracted bw is the same;
- ethernet interface running 10/full and contracted bandwidth 10M.

Does not work:
​- serial interface bw 45M and contracted bw is 20M;
- ethernet interface running 100/full and contracted bandwidth is 2M.