Bandwidth Throttling

Reason for Implementing Bandwidth Throttling Limited Available Bandwidth If 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 Services At 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

Our Switching Environment Switches – Cisco 2960 Series Switches – WS-C TC-L – WS-C TT-L – WS-C TC-L – IOS – 12.2(44) SE2 LAN BASE CRYPTO – 12.2 (50) SE1 LAN BASE CRYPTO

Where to Begin Organize 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 Interfaces Know which interfaces have servers, workstations and patron computers. Know your switch usernames and passwords. Backup your Switches

Bandwidth Throttling Several Different Methods Most 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 Queues Adjust 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 Assistant Graphic User Interface created by Cisco for managing network devices Commands Accessing the switches through network using telnet or serial port using hyper terminal

Cisco Network Assistant Using Cisco Network Assistant Version Download Install Setup Connecting Adjust Egress Queues using Cisco Network Assistant Where to adjust How to adjust What to adjust Base Settings Increase Decrease

Using Cisco Network Assistant Version The latest version is 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 Setup Launch Cisco Network Assistant Under Connect select “Create Community” Name the Community Select the best way to discover your devices Select the devices Click “OK” to create the community Enter in the device username and password Connecting Select “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 Adjust Select Configure | Quality of Service | Queues. How to Adjust Adjust 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 IDShared Weights Shaped Weights 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 Queue ID Shared Weights Shaped Weights Default SettingsAdjusted 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 Queue ID Shared Weights Shaped Weights Example #1Example #2

Cisco Network Assistant Video Demonstration Video Demonstration Setting up a community Adding a switch to the community Adjusting the shared and shaped weights on a single interface Saving 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 Monitoring Testing 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