Configuring a Network with BWM Resiliency

A customer with a geographically dispersed offices uses a Multiprotocol Label Switching ( MPLS) network to connect them together. To save money on bandwidth charges and to ensure voice quality, the customer would like to use Bandwidth Management.

The headquarters office is located in Chicago and there are eight branch offices that connect to the headquarters and each other via an MPLS network. The eight branch offices are located in:

• Madison

• Highland Park

• Gary

• Elgin

• Schaumburg

• Naperville

• Joliet

• Aurora

During normal operation, all IP phones in the network are registered with the controller located at the headquarters in Chicago. The controller thus functions as the primary ICP, while the branch office ICPs function as gateways to the PSTN. The branch office ICPs also provide resiliency. In the event that the link from the MPLS network to the headquarter fails or the headquarters ICP goes offline, the branch office phones will fail-over to their local ICP gateways.  

Each branch office ICP connects to the MPLS network via a 1Mbit/s link; the headquarters office connects via a 2Mbit/s link.

Requirements

The customer wants to employ bandwidth management on all of the links connecting to the MPLS network. Bandwidth management needs to be operational during both normal network operation and also during resilient operation when the headquarters is unreachable or out of service.

Implementation

The first step is to obtain a diagram of the customer’s network or information about the network so that a drawing can be created. The diagram should indicate:

• Areas where for all practical purposes the amount of available bandwidth is unlimited.

• Where the phones are physically located and where the phones are registered, in a resilient network the location of both the primary and resilient controller needs to be known.

• The communication links between offices and the bandwidth available on the links.

The second step is to draw a network tree that represents the actual network. Creating this drawing helps identify the location of the root. It also serves as a valuable aid when it is time to program the ICPs.

The third step is to create a detailed network drawing. This drawing must identify:

• Areas where the available bandwidth is unlimited; each of these areas will be designated as a Zone.

• Communication links between Zones where bandwidth is limited to a specific capacity.

• The location(s) of the Zone Access Points ( ZAPs). ZAPs are placed on communication links where it is necessary to count bandwidth. The designer needs to consider which ICP will control the ZAPs. This should be documented on the network drawing.

The drawings can be used to determine what may happen if a fault condition occurs such as an ICP or communication link failure. To maintain bandwidth management in the event that the primary ICP fails, it may be necessary to deploy a second set of ZAPs controlled by the resilient ICPs.

Customer’s Network Drawing

Below is a drawing of the customer’s network. All of the IP phones are hosted (registered) with the controller located at the company headquarters in Chicago. This is the primary controller.

Chicago connects to the MPLS network via a 2 Mbit/s link. The branch offices connect to the MPLS network via 1 Mbit/s links.

Resilient controllers are located in each branch office. If the controller in the Chicago office or the link to the Chicago office fails, then the phones in each branch office will fail-over to their local controllers.

Network Tree Drawing

Below is a drawing of the customer’s network tree. Each branch office is shown as a separate Zone and the headquarters is shown as a separate Zone. Zones are used to represent areas of infinite bandwidth capacity or areas where there are effectively no bandwidth limitations. The headquarters office and the MPLS network are also shown as separate Zones.

It can be determined that the MPLS network Zone is the parent of all the other Zones because all packets must pass through the MPLS network to get to any destination. As a result, the MPLS network is shown as the root Zone.

Detailed Network Drawing

Shown below is the detailed network drawing for the customer’s network. The ZAPs are represented by the symbols and each ZAP has a unique name that indicates its associated Zone. The lines that terminate with arrows indicate which ZAPs are controlled by each ICP. Although the branch offices are shown with two links to the MPLS network, this is simply to illustrate the use of two ZAPs; there is only one actual connection between each branch office and the MPLS network.   

Example

The ZAP called "Highland-Park-MPLS" is controlled by the Chicago ICP. This ZAP allows the Chicago ICP to count the bandwidth consumption between Highland Park and the MPLS network. Should the communication link fail or the Chicago ICP go offline, the Highland Park IP phones will fail-over to the ICP located at Highland Park. While the Chicago ICP is out of service, the ICP at Highland Park will start counting bandwidth consumption on the link between Highland Park and the MPLS network. Bandwidth monitoring is achieved via the ZAP called "Highland_Park-Local."

When the Chicago ICP comes back into service, the Highland Park IP phones will fail-back to the Chicago ICP and the Chicago ICP will start using the Highland_Park-MPLS ZAP to monitor bandwidth consumption.

Programming the 3300 ICPs

This section discusses how the designer or administrator might program the 3300 ICP to put bandwidth management in place on the customer’s network. The network tree drawing and the detailed network drawing will be used as guides for programming the ICPs.

Network Element Assignment Form

The Network Element Assignment Form needs to be programmed. In this case the network elements are 3300 ICPs rather than servers. As shown below, each ICP, including the headquarters ICP, is given a name (which may be truncated due to a character limit). Since each element is an ICP, it is assigned a Type of "3300 ICP." The setup for data sharing and Zones depends on the specific network.

Zone Assignment Form

Using the Network Tree diagram as a guide, program the Zone Assignment Form. This form maps the names or labels of each zone to a Zone ID number.

The Zone ID Number in the left-hand column is system generated in a sequential fashion. Decide whether you want intra-zone compression turned on and then program the Label field with the names used to identify the Zones.

Network Topology Assignment Form

There are two forms within the Network Topology assignment Form. As shown below, the upper form is the Zone Tree Assignment Form and the lower form is the Zone Access Point Assignment Form.

When a particular Zone is highlighted in the Zone Tree Assignment Form, the Zone Access Point Assignment Form will allow the user to configure up to six Zone Access Points per Zone. Each Zone Access Point can be programmed with a label or name, the bandwidth limit, and the name of the Network Element that will manage the ZAP.

In our example each branch office has two ZAPs associated with it. The first ZAP is managed by the headquarters ICP. The second ZAP, which will only come into use when resilient operation is in play, is managed by the local ICP at the branch office. In a different network additional ZAPs can be used to provide bandwidth management on redundant links or on links used for load sharing.

In the case of Chicago01 there is no need for a resilient ZAP so only one ZAP will be assigned.

The following forms show how the desired Bandwidth Management configuration can be achieved.

Bandwidth Management Configuration

The Bandwidth Management Configuration form is used to enable the Bandwidth Management feature and to set the Bandwidth Management parameters.

Current Bandwidth Statistics

The Current Bandwidth Statistics form allows the administrator to view current statistics associated with a particular ZAP.

15 Minute Historical Bandwidth Statistics

This form allows the administrator to view bandwidth statistics for a particular ZAP that have been collected over the previous 15 minutes. The information collected and displayed in this form can be used to fine tune the bandwidth management features on a particular communication link.

• Program Bandwidth Management