Bandwidth Throttling - Georgia Libraries Tech Center

Report
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
GPLS Internet
Branch2Switch1
Branch2Switch3
Branch2Switch5
GPLS Network
Branch2Switch2
Internet
GPLS Router
Branch2Switch4
B2 Fiber Connector
B1 Fiber Connector
GPLS Router
Branch1Switch1
HeadquartersSwitch1
Fiber to HQ
RemoteBranch
Switch1
Branch1Switch2
RemoteBranch
Switch2
Remote Firewall
HeadquartersSwitch2
Main Firewall
Branch1Switch3
HeadquartersSwitch3
RemoteBranch
Switch3
Branch1Switch4
RemoteBranch
Switch4
HeadquartersSwitch4
GPLS Network
VPN
Branch1Switch5
Branch1Switch6
VPN between Remote and Main
HeadquartersSwitch5
HeadquartersSwitch1
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 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 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
 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.
Default Settings
Queue ID
Shared
Weights
Shaped
Weights
1
25
25
2
25
0
3
25
0
4
25
0
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.
Default Settings
Adjusted Settings for 300k/s
Queue Shared
ID
Weights
Shaped
Weights
Queue Shared
ID
Weights
Shaped
Weights
1
25
25
1
10
10
2
25
0
2
10
0
3
25
0
3
60
0
4
25
0
4
20
350
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.
Example #1
Queue Shared
ID
Weights
Shaped
Weights
Example #2
Queue Shared
Shaped
ID
Weights
Weights
1
10
10
1
10
10
2
10
0
2
10
0
3
60
0
3
60
0
4
20
355
4
20
345
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 realtime 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]

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