Bandwidth Throttling

Reason for Implementing Bandwidth Throttling

Limited Available BandwidthIf left unattended, patron internet traffic can place a

strain on the available bandwidth. Limiting can stabilize and increase the productivity of

both staff and other library services.

Prioritize Important Programs and ServicesAt peak usage, patron internet traffic can essentially

absorb all the available bandwidth. Limiting allows other important programs and services

access to the required bandwidth when they need it no matter the time or day.

FCPL Data Network Overview

GPLS Network

VPN

GPLS Network

Internet

GPLS Router GPLS Router

Remote Firewall Main Firewall

VPN between Remote and Main

GPLS Internet

RemoteBranchSwitch1

RemoteBranchSwitch2

RemoteBranch Switch4

RemoteBranch Switch3

Branch1Switch1

Branch1Switch2

Branch1Switch3

Branch1Switch4

B1 Fiber Connector

B2 Fiber Connector

Branch2Switch1

Branch2Switch2

Branch2Switch3

Branch2Switch4

HeadquartersSwitch1Fiber to HQ

HeadquartersSwitch2

HeadquartersSwitch3

HeadquartersSwitch4

Branch1Switch5 HeadquartersSwitch5

HeadquartersSwitch1Branch1Switch6

Branch2Switch5

Our Switching Environment

Switches– Cisco 2960 Series Switches

– WS-C2960-48TC-L– WS-C2960-48TT-L– WS-C2960-24TC-L

– IOS– 12.2(44) SE2 LAN BASE CRYPTO– 12.2 (50) SE1 LAN BASE CRYPTO

Where to BeginOrganize your Network

Organizing your switching network allows for a more seamless implementation of changes. We have separate switches for, server, staff, and patron

computers. If having multiple switches isn't an option, organize group together the interfaces on the switches. This will make adjusting these interfaces in the future easier.

Document your InterfacesKnow which interfaces have servers, workstations

and patron computers. Know your switch usernames and passwords.

Backup your Switches

Bandwidth Throttling

Several Different MethodsMost throttling options center around Quality of

Service settings. Quality of service is the ability to provide different

priority to different applications, users, or data flows, or to guarantee a certain level of performance to a data flow.

We Throttle Using Egress QueuesAdjust Shared and Shaped Egress Queue Settings.

Shaped and Shared Mode Our Cisco switches employ Shaped Round Robin (SRR). SRR is a

scheduling service for specifying the rate at which packets are de-queued. With SRR there are two modes, shaped and shared.

Shaped Shaped mode is only available on the egress queues. Shaped egress

queues reserve a set of port bandwidth and then send evenly spaced packets as per the reservation. Shaped SRR is used to shape a queue or set a hard limit on how much bandwidth a queue can use. When you use shaped SRR, you can shape queues within a port's overall shaped rate.

Shared Shared egress queues are also guaranteed a configured share of

bandwidth, but do not reserve the bandwidth. That is, in shared mode, if a higher priority queue is empty, instead of the servicer waiting for that reserved bandwidth to expire, the lower priority queue can take the unused bandwidth. Shared SRR is used to get the maximum efficiency out of a queuing system, because unused time slots can be reused by queues with excess traffic.

Shaping and sharing is configured per interface. Each interface can be uniquely configured.

Different ways to Adjust the Egress Queues

Cisco Network AssistantGraphic User Interface created by Cisco for

managing network devices

CommandsAccessing the switches through network using

telnet or serial port using hyper terminal

Cisco Network AssistantUsing Cisco Network Assistant

Version DownloadInstallSetupConnecting

• Adjust Egress Queues using Cisco Network Assistant• Where to adjust• How to adjust• What to adjust• Base Settings• Increase • Decrease

Using Cisco Network AssistantVersion

The latest version is 5.6.1 Any version of Cisco Network Assistant (CNA) will allow you to

connect to network devices, but recommend latest version.

Download Cisco Network Assistant can be downloaded directly from the

Cisco website. Log in using your Cisco credentials, search for Cisco Network

Assistant within product support, then follow the prompts to download the software.

Install Initiate the install and follow all default prompts. The only adjustable option is the installation location. Adjust if

necessary.

Using Cisco Network Assistant Continued

SetupLaunch Cisco Network AssistantUnder Connect select “Create Community”Name the CommunitySelect the best way to discover your devicesSelect the devicesClick “OK” to create the communityEnter in the device username and password

ConnectingSelect “Connect to:” If your community name isn’t already within the field,

click the drop down and select it.Click “OK” to connect to your community.

Adjust Egress Queues using Cisco Network Assistant

Where to AdjustSelect Configure | Quality of Service | Queues.

How to AdjustAdjust Single Interface

Select the single interface and click “Configure”. This displays the “Configure QoS Queues for Interfaces” window. Make adjustments to the egress queues of a single interface

within this window.Adjust Multiple Interfaces

Select multiple ports using control or shift click and then click “Configure”.

This displays the “Configure QoS Queues for Interfaces” window. Make adjustments to the egress queues of multiple interfaces

within this window.

Adjust Egress Queues using Cisco Network Assistant Continued

Base Settings Make sure that you document your base settings so that you

can revert back to them if needed. In addition to base setting documentation, be certain that

you document which interfaces you have adjusted.

Queue ID Shared Weights

Shaped Weights

1 25 25

2 25 0

3 25 0

4 25 0

Default Settings

Adjust Egress Queues using Cisco Network Assistant Continued

What to Adjust Adjust the values within the “Shaped” and “Shared” fields assigned to

Queues 1-4. Be cautious when adjusting these queues. Verify which interfaces you

are adjusting. We worked with Cisco to develop these settings, and they work well for

our environment. These may not be ideal for your infrastructure, but can be adjusted to best fit your needs.

Queue ID

Shared Weights

Shaped Weights

1 25 25

2 25 0

3 25 0

4 25 0

Queue ID

Shared Weights

Shaped Weights

1 10 10

2 10 0

3 60 0

4 20 350

Default Settings Adjusted Settings for 300k/s

Adjust Egress Queues using Cisco Network Assistant Continued

Increasing and Decreasing Bandwidth If you increase the Queue ID 4 under the “Shaped Weight” field, it will

decrease the bandwidth. If you decrease the Queue ID 4 under the “Shaped Weight” field, it will increase the bandwidth.

“5” equals roughly 10k/s. We started with a 350 in Queue ID 4 under the “Shaped Weight” field.

Example #1 shows it increased to 355, which will decrease the bandwidth. Example #2 shows a decrease to 345, which will increase the bandwidth.

Queue ID

Shared Weights

Shaped Weights

1 10 10

2 10 0

3 60 0

4 20 355

Queue ID

Shared Weights

Shaped Weights

1 10 10

2 10 0

3 60 0

4 20 345

Example #1

Example #2

Cisco Network Assistant Video Demonstration

Video DemonstrationSetting up a communityAdding a switch to the communityAdjusting the shared and shaped weights on a

single interfaceSaving the changes to the switch

Suggested Implementation and Limitations

Start Out Slow Start with an unused interface or a backup switch. Adjust the

settings and test them before performing a bulk implementation.

Double -Check Interfaces Before Applying Settings If you have several workstations that use one interface through

a standalone hub or switch, all of those workstations must share the bandwidth that you allocate to that interface.

Know the Limitations These settings will throttle not only outbound internet traffic,

but all network traffic. File transfers , Windows update downloads, and other common LAN tasks will also be affected. Keep that in mind when you are implementing this solution.

Testing and MonitoringTesting

Several free programs are available that can be installed on workstations to test your bandwidth speeds.

Using a web based solution, like speedtest.net or cnet.com, offers a less intrusive way to gauge your throttled settings and provide you with a real-time analysis when increasing or decreasing those settings.

Monitoring A library’s network is constantly changing and evolving.

Settings you implement today may not be ideal for the network weeks, months, or years from now.

Set up basic throttling and adjust the settings for how it works best with your programs and services.

The GPLS InterMapper is a great resource to view your network utilization and make throttling adjustments based upon that data.

Questions? Contact Derek Williams at williamsd@forsythpl.org