VI. Feature Setup

Bandwidth Management - Session & Bandwidth Limitation

Products:
Vigor 2620Ln
Vigor 2760
Vigor 2762
Vigor 2765
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Keywords:
bandwidth
session
session limit
throttling

The Session and Bandwidth limitation features are useful where you are concerned that individual users on your network might make disproportionate use of your Internet connection, causing inconvenience for other users.

These features restrict LAN clients identified by their IP address. For this reason, it is important to either separate groups of IP addresses using the router's multi subnet and VLAN facilities or by ensuring that the PCs always have the same IP address so that the correct limitations are applied. If the router is operating as the DHCP server on the network, it is possible to pre-set the DHCP allocations from the router (the latter being preferred).

This article covers three setup examples:

Bandwidth Limit Limit the maximum download or upload speeds to the Internet for individual users or groups of users
Session Limit Limit the number of TCP/UDP sessions a user or group can establish. Good for controlling things like Peer to Peer traffic or managing session counts for busy networks.
Scheduling Bandwidth or Session Limit Define when bandwidth and session limits are applied to users, with multiple schedules possible

Bandwidth Limitation

The Bandwidth Limit facility in [Bandwidth Management] > [Bandwidth Limit] allows the router to limit the amount of Upstream and Downstream Bandwidth that any device on your network is allowed to use, based on their IP Address. If a devices goes over the throughput value specified, the router will throttle the traffic until it conforms to the bandwidth limit value specified.

When enabled, this applies to all NAT clients. To apply this to routed traffic, select the "IP Routed Subnet" option.

It can apply to the entire network with the Default TX / RX Limit values, allowing each IP on the network to use up to that amount of bandwidth.

The Rate is specified in either Kilobits or Megabits per second. For example, a '10 megabit' ADSL2+ line is 10000 Kilobits so to prevent a user consuming more than half of that, set the RX (receive/download) limit to 5000. TX is for transmission/upload limits.

It can be applied to specific addresses using the Limitation List which allows bandwidth limits to over-ride the default value and can be specified either as a pool (Shared) to share amongst the range of IP addresses or as a per IP address (Each) bandwidth limit.

Enter the range of IP Addresses you wish to limit in the Specific Limitation settings and click Add to add it to the Limitation List table. To configure a bandwidth limit for a single PC or device's IP address, set the start and end IP the same. Selecting an entry in that table allows the values to be edited, click Edit when done to save the altered values.

Vigor Bandwidth Limitation

The "Allow Auto Adjustment to make the best utilisation of available bandwidth" option allows the router to use bandwidth values specified under [WAN] > [General Setup] for each of the WAN interfaces as a pool of available bandwidth. If there is spare bandwidth available, clients on the network will be able to use more than their allocated bandwidth amount (not the full amount), temporarily ignoring the bandwidth limit. When the full amount of bandwidth is in use, the router would apply the bandwidth limit specified either using the Default TX / RX Limit values or the values specified in the Limitation List.

The "Smart Bandwidth Limit" option is designed to automatically limit the speeds for clients that are using too many sessions on the network using the session value specified.

High session counts could be caused by Peer To Peer (P2P) traffic or other malicious network activity and this facility allows the router to significantly limit the impact of either type of traffic on the rest of the network.

Devices on the network that could trigger this from normal use can be exempted from the Smart Bandwidth Limit by adding their IP addresses in the Limitation List and setting a suitable TX and RX limit value.


To view the Bandwidth Limit in use, go to [Diagnostics] > [Data Flow Monitor], tick Enable Data Flow Monitor for it to operate and it will be possible to view the amount of bandwidth (in kbps) that each client is using for internet access. Under the TX / RX rate values, the value on the left is the current bandwidth usage and the value on the right is the value that it is limited to.

Session Limitation

A 'Session' is a single connection from one device to another across a network. For example; when you visit a website on the Internet your PC creates a single session between itself and the Web Server. When using NAT, your PC, the router and your onward ISP connectivity has to keep track of all of these sessions. A Vigor router, for example, might have room for up to 50000 simultaneous sessions - that's a lot, equivalent to connecting to 50000 web servers, however if you or your users make use of Peer-to-Peer (P2P) which may use many more sessions, you may wish to enforce user policy by restricting sessions.

Go to [Bandwidth Management] > [Session Limit] and enable it. The Default Max Sessions value applies to any clients not in the limitation list and is per IP address.

To enable this feature for a particular client (identified by its IP address), enter the Start IP and End IP of the computers you wish to limit in the Specific Limitation settings, along with the maximum number of Sessions allowed. If the setup is just for one single IP Address set the Start IP and End IP the same. Click OK to apply any setting changes on this page.

Session Limitation
Figure 2 - Session Limitation Setup


When the session limit is reached, the router will display a message to end users affected by this when accessing any website in a web browser. This message can be customised in the Administration Message setting box, which can contain HTML:

With that set, the router would display this message:

The session limit can also be configured in the firewall, under [Firewall] > [General Setup], it can be configured in the Default Rule settings or in any filter rules. Applying a session limit through the filter rules makes it possible to apply different schedules to different IP addresses instead of scheduling all session limitation.


To check the sessions in use, go to [Diagnostics] > [Data Flow Monitor], tick Enable Data Flow Monitor to enable it and the data flow monitor will then show traffic and session use per IP address:

The Sessions column shows the current session usage on the left and the session limit specified on the right.

Scheduling Bandwidth or Session Limits

The Bandwidth Limit and Session Limit settings each have options for Time Schedule, this links to the schedule that is configured under [Applications] > [Schedule], setting a number will link to the schedule index configured in that section.

This example will demonstrate how to activate a session or bandwidth limit between 08:00 until 18:00 by using a schedule entry.

In the Bandwidth or Session Limit settings, enter the number 1 in the Time Schedule settings and click OK to save that change.


To configure the schedule, go to [Applications] > [Schedule], click the Index 1. link to go into the settings for the first index profile, which will be used by the Time Schedule settings in the Bandwidth / Session limit settings.


In the schedule settings, configure these settings:

a. Enable the schedule entry

b. The Start Date can be left on its default settings. Configure the Start Time to 8 : 00 to start at 8am, set the Duration Time to 10 : 00 so that the schedule will take effect from 08:00 until 18:00.

Please note that schedule entries used for Bandwidth or Session Limit schedules will ignore the Action setting and it can be left on its default of Force On.

c. Set the How Often setting to Weekdays and select the days of the week that the schedule should be active.

Click OK to save and apply the changes.

The schedule will take effect from the next point that the Start Time of the schedule occurs.


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