Traffic shaping on Cisco ISR 4431 router

[Justin Zhang]

Hi Cisco Gurus,

I have a Cisco ISR router for my WAN connection. Here are the info:

- Router Model: Cisco ISR4331/K9

- Router Firmware: 16.3.8 [Denali] (fc3)

- Lease line bandwidth: 20Mbps

- LAN bandwidth: 1Gbps

My project requirements are:

1. Control the WAN bandwidth and only assign 5Mbps for WSUS application. 

2. WSUS server is located in DC 1, where about 70 PC/Servers are located in DC2. Both DC are connected by this 20Mbps lease line

May i know can ISR 4431 router achieve the above requirement? if yes, how to do it? If no, may i know why?

Many thanks in advance.

Regards,

Justin

[Giuseppe Larosa]

Hello Justin,

the 4331 is able to perform the required task.

To perform these traffic shaping you need hierarchical QoS

policy-map PARENT-SHAPE-20Mb

class class-default

shape average 20000000

service  CHILD

!

! note <WSUS> = IP address of WSUS server

! it is not clear if the server is on local site or remote

! so I have written an ACL that can be used in both cases

access-list 101 remark traffic to/from the server

access-list 101 permit ip any host <WSUS>

access-list 101 permit ip host <WSUS> any

class-map WSUS

match ip address 101

!

policy-map CHILD

class WSUS

priority percent 25

class class-default

fair-queue

!

interface WAN

service-policy ouput PARENT-SHAPE-20Mb

! where WAN is the interface to the leased line

Hope to help

Giuseppe

[Joseph W. Doherty]

What Giuseppe shows is one approach. One consideration using it is 1) whether you want the WSUS to exceed 5 Mbps when the 20 Mbps is not fully used and whether you want the 5 Mbps limited by dropping packets rather than queuing packets.

If not, you might see if that IOS will accept a subordinate shaper like:

policy-map CHILD

class WSUS
shape average 5000000
class class-default
fair-queue

Another issue, you can only shape on egress (you can police ingress or egress), so if you only control one side of the WAN link, you're much more limited how you can regulate your traffic.