Bandwidth Reservation Using QOS

[fmatrine]

Hi All,

We hv a hub and spoke wan network with one central location and multiple branch location.

At one of our spoke location we want to implement QOS.

Topology is Branch Lan-Router-ISP-Central Router-Central Lan.

Branch router is cisco 1760 with wic-1t card for lease line connectivity.

In branch lan we hv two sets of Users (Multiple IP Subnet)

Primary subnet = 192.168.1.0/24

Secondary Subnet = 192.168.2.0/24

We are not using any layer3 switch for routing between two lan subnets ... instead we hv defined secondary interface on the router ethernet.

Requirement..

Through QOS mechanism We want to allocate certain amount of bandwidth for 192.168.1.0/24 segment and rest bandwidth to 192.168.2.0/24 segment when the traffic passes from branch to central site.

i.e, our lease line capacity is 192KBps from branch to central site.

we want to reserve 64 KBps out of 192KBps for 192.168.1.0/24 segment and rest 128KBPS should be used by 192.168.2.0/24 segment.

Is it possible to acheive this requirement.

Kindly post sample config that depicts above scenario.

Regards

Deepak

[lnguye]

Assuming the 1760 uses the same CLI as other routers (2600/3600/7200...):

config for the branch router:

class-map match-any subnet2

match access-group 102

policy-map limit_bw

class subnet2

bandwidth percent 66 ; or use "bandwidth 128"

interface s0/0

service-policy limit_bw out

access-list 102 permit ip 192.168.2.0 0.0.0.255 any

Keep in mind:

1) This is a flexible allocation: if one subnet does not use its share of allocated bandwidth, the other subnet can use that extra portion.

2) The config above reserves 128kb for subnet 2 and assume the subnet 1 will get the rest. There is no reserve for subnet 1. If want to, you have to expand it to include the class-map for subnet 1 and specifically reserve bandwidth for it. However, the total reserved bandwidth cannot exceed 75% link capacity (Cisco default but can be changed).

3) Uni-direction: the config only set the bandwidth for the direction from the branch toward the hub. You need to develope similar configuration for the hub router. So it will limit the bandwidth for the direction from the hub toward the branch.