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 [email protected]
Top Related