Automatically—Tunnel Builder Pro calculates the backup tunnel and guarantees bandwidth for more than one element at a time. See "Create Backup Tunnels Automatically".
Manually—You calculate the backup tunnels. See the "Create Backup Tunnels Manually".

Information About Protecting Your Network

To protect your network, you must understand the following concepts:

P rimary Tunnel Usage of Backup Tunnels for Bandwidth Protection

To ensure that the primary tunnel will use bandwidth protection, the tunnel must be fast-reroutable, and the following elements on the primary tunnel path must be bandwidth-protected:

Tail-end link
Intermediate nodes

Figure 5-1 illustrates bandwidth protection for a 4-hop primary tunnel.

Figure 5-1: Bandwidth Protection

Table 5-1 explains how NHOP and NNHOP tunnels provide bandwidth protection.

Table 5-1: Bandwidth Protection Provided by Tunnels

If this element fails...	This backup tunnel provides bandwidth protection for primary tunnel R1—R2—R3—R4—R5
Head-end link R1—R2	T2
Node R2	T2
Link R2—R3	T3
Node R3	T3
Link R3—R4	T4
Node R4	T4
Tail-end link R4—R5	T5

Note When a link fails, all protected primary tunnels that terminate at the endpoint of an NNHOP tunnel are rerouted by the NNHOP tunnel and not by any NHOP tunnel. This ensures that all traffic gets rerouted as quickly as possible, even before node and link failures are distinguished by a neighbor node.

L oad Balancing

Load balancing increases the amount of traffic that can be routed across a network by protecting a single traffic flow (a single NHOP or NNHOP) with more than one backup tunnel. Consequently, primary tunnels that use the same primary bandwidth on a link can be carried over different backup tunnels if an element fails.

For each single flow, the following requirements exist:

There can be no more than a specified number of backup tunnels created to protect a single flow. This number is called the Max Tunnel Number and is configurable from the Options window of the Backup tunnels tab.
Each backup tunnel must have a minimum amount of bandwidth. This value is the Min Tunnel Bandwidth Quota, and is configurable from the Options window of the Backup tunnels tab.

The default value of Max Tunnel Number is 1; that is, by default, load balancing does not occur. If you want load balancing to occur, the recommended value for the Max Tunnel Number parameter is 4.

If the Max Tunnel Number is greater than 1, Tunnel Builder Pro still performs load balancing only if it cannot protect the element fully by generating one backup tunnel for each flow to be protected.

Example: To protect a link that has a primary bandwidth of 100 Kbps, and where Max Tunnel Number has been set to 4, Tunnel Builder Pro will create up to 4 backup tunnels per link direction. In the case where 4 backup tunnels are required to protect the link, each will have a bandwidth of 25 Kbps.

T imeout

For most elements, Tunnel Builder Pro finds backup tunnels that provide a backup protection solution very quickly, or it determines that full protection is not possible.

For a few elements, Tunnel Builder Pro will spend a long time improving the solution. To limit the time spent per calculation, you can specify a timeout value. For example, if you set the timeout to 1000 seconds, the algorithm spends a maximum of 16 minutes 40 seconds.

Response times vary. For example, if you set a timeout of 1000 seconds for all nodes in a large network (for example, a network comprising over 200 nodes), the typical response time is approximately 2 to 3 hours. However, the response time can be shorter or longer.

If a timeout occurs while computing backup tunnels, BRG will return the best solution it has found in the time available.

A symmetric Links

Asymmetric links are links for which the properties of the interfaces (for example, Max Global Reservable, Max SubPool Reservable) at each end of the link are different. When the Max Global Reservable value for a link is different in each of the link's two interfaces, Tunnel Builder Pro "pads" the lower value to make the link symmetric, so that the Max Global Reservable is assumed to be the higher value in both directions.

How to Protect Your Network

This section contains the following procedures:

Create and Maintain SRLGs (optional)
Set Up Backup Tunnel Calculations (optional)
Set Up BRG Options (optional)
Create Backup Tunnels Automatically (optional)
Create Backup Tunnels Manually (optional)

To interpret the results, go to the following:

B ackup Tunnel Computation Results and Color Display

Results of backup tunnel computations (Check Protection and Compute Backups) are displayed in the following areas of the Backup Tunnels window:

Backup Tunnels list box. Existing backup tunnels are highlighted.

Green—Backup tunnel backs up the currently selected elements.
Pink—Backup tunnel interferes with bandwidth protection for the selected element at the tunnel and should be deleted.

Elements list box. Elements (nodes, non-SRLG links, and links) that cannot be fully protected by backup tunnels are highlighted in pink.
Violations and Warnings list box. Describes the violations and warnings.

T unnels list box. When you create backup tunnels (Compute Backups), the resulting suggested backup tunnels are displayed in the Tunnels list box.

The following warning conditions are highlighted in the Backup Tunnels list box:

Existing tunnels are highlighted in yellow to indicate that the current backup pool option does not match the pool being protected by the highlighted tunnel. Tunnels highlighted in yellow are not considered when computing backup routes. To guarantee that backup tunnels will provide adequate bandwidth protection, we recommend that you delete tunnels highlighted in yellow.
No Fast Reroute-enabled primary tunnels are associated with items highlighted in yellow in the Nodes, NonSRLG Links, and SRLGs list boxes. Until a Fast Reroute-enabled primary tunnel is created with an LSP that uses the node or link, a backup tunnel protecting that node or link is not used.

B ackup Tunnel Status

You can display information about requests to run Tunnel Builder Pro's Backup Route Generator (BRG) algorithm for checking or suggesting backup tunnel placement. Click the BRG Status tab in the bottom right corner of the Backup Tunnels window. The following information appears:

Client—Host name of the system running the Tunnel Builder Pro client.
State—Status of BRG operations. Valid values are Working or Pending.
Request type—User-requested operation. Valid values are Compute Backups, Check Protection, Installing Backup Tunnels, and Deleting Backup Tunnels.
Node count—Number of nodes in elements being computed or checked.
Link count—Number of links in elements being computed or checked.
SRLG count—Number of SRLGs in elements being computed or checked.
Timestamp—Time that the compute or check operation was requested.

C reate and Maintain SRLGs

This section contains the following procedures:

Identify and Delete SRLGs (optional)
Create SRLGs (optional)
Modify SRLGs (optional)

I dentify and Delete SRLGs

To identify which links are part of which SRLGs, perform the following steps:

Step 1 Click the Backup tunnels tab. The Backup Tunnels window shown in Figure 5-2 appears.

Figure 5-2: Backup Tunnels Window

Step 2 Click SRLGs. The SRLG Management window shown in Figure 5-3 appears with the names of the SRLGs listed in the scroll box.

Figure 5-3: SRLG Management Window

Step 3 Select an SRLG in the list. The links that belong to the SRLG are highlighted in the map, and the link names appear in the Links list as shown in Figure 5-3.

Step 4 Click Cancel to close the window.

Note To delete an SRLG, select the SRLG in the SRLG table and press the Delete key. Click OK.

C reate SRLGs

To create SRLGs, perform the following steps:

Step 1 Click the Backup tunnels tab. The Backup Tunnels window shown in Figure 5-4 appears.

Figure 5-4: Backup Tunnels Window

Step 2 Click SRLGs. The SRLG Management window shown in Figure 5-5 appears.

Figure 5-5: SRLG Management Window

Step 3 In the Name field, enter the name of the SRLG.

Step 4 Shift-click each link in the network map that you want to include in the SRLG. The selected links appear in the Links field, as shown in Figure 5-6.

Figure 5-6: SRLG Management Window with Links Selected

Step 5 Click Apply if you want to continue adding links, or click OK to complete SRLG configuration.

M odify SRLGs

To add or delete a link from an SRLG, access the SRLG Management window shown in Figure 5-5 and select the SRLG of interest.

To add a link, Shift-click the link in the network map and click Apply.

To delete a link, select the link in the SRLG Management window and press the Delete key on your keyboard.

S et Up Backup Tunnel Calculations

To set up backup tunnel calculations, perform the following steps:

Step 1 Click the Backup Tunnels tab. The Backup Tunnels window shown in Figure 5-7 appears.

Figure 5-7: Backup Tunnels Window

Step 2 Click one of the following:

Backup Any pool
Backup sub pool only

If you click Compute Backups, only tunnels created with the specified parameter are sent to the BRG for consideration in backing up an element.

Step 3 At Linkspeed Factor, enter the number by which the link speed for every link in the TE network will be multiplied before the backup route calculations begin. A value greater than 1 allows overbooking. A value less than 1 ensures bandwidth guarantees. For more information, see the "Protecting Bandwidth" section in "Determining if Your Network is Protected."

S et Up BRG Options

You can configure the Backup Route Generator (BRG) options that are used in performing compute backup and check protection operations.

This section describes how to do the following:

Designate the timeout; that is, how long the algorithm should search for a backup tunnel.
Set load balancing; that is, the maximum number of backup tunnels that can be created for load balancing per element.
Specify the minimum backup tunnel bandwidth parameters that will be used for backup tunnels.

To set up BRG options, perform the following steps:

Step 1 Click the Backup tunnels tab. The Backup Tunnels window shown in Figure 5-8 appears.

Figure 5-8: Backup Tunnels Window

Step 2 Click Options. The Set BRG Options popup window shown in Figure 5-9 appears.

Figure 5-9: Set BRG Options Window

Step 3 At Timeout (secs), enter a timeout value (in seconds). This is the maximum amount of time Tunnel Builder Pro will search for a set of backup tunnels that fully protect an individual element. The default is 500 seconds.

Step 4 At Max Tunnel Number, specify the maximum number of backup tunnels that can be created for a single next hop (NHOP) or next-next hop (NNHOP). The default is 1.

Step 5 At Min Bandwidth Quota (Kbps), enter the minimum amount of bandwidth that a backup tunnel can have. The default is 10 Kbps.

Step 6 Click OK.

C reate Backup Tunnels Automatically

To have Tunnel Builder Pro create backup tunnels automatically, perform the following steps:

Step 1 Click the Backup tunnels tab. The Backup Tunnels window shown in Figure 5-10 appears.

Figure 5-10: Backup Tunnels Window

Step 2 Specify the nodes, non-SRLG links, and SRLGs that you want to protect by selecting them in the Nodes, NonSRLG Links, and SRLGs list boxes, respectively.

Note You can select elements individually, or you can select all the elements within a list box by selecting an element in the box and then pressing Ctrl-A.

Step 3 Click Compute Backups.

Note This may take some time. To stop the compute backup function, click Cancel Calculation.

After the calculation is complete, the selected elements are listed in the Elements list box. Figure 5-11 shows an example in which a node, a non-SRLG link, and an SRLG were selected, and the elements are in the Elements list box.

Figure 5-11: Creating a Backup Tunnel Automatically

If Tunnel Builder Pro cannot fully protect the element, the element is highlighted in pink in the Elements list box and there is an explanation in the Violations and Warnings list box after you select the element.

Figure 5-12 illustrates elements that cannot be fully protected. We recommend that you delete backup tunnels if they are highlighted in pink in the Backup Tunnels list box. To delete tunnels, select them and then click Delete or press the Delete key.

Figure 5-12: Elements That Cannot Be Fully Protected

Step 4 To view recommended backup tunnels, select a node, non-SRLG link, or SRLG in the Elements list box. The backup tunnels that you should install are listed in the Suggested Tunnels list box. The following information is displayed for each tunnel, as shown in Figure 5-12:

Head—Router that is at the head of the tunnel.
BW Limit (Kbps)—Maximum backup bandwidth of the tunnel.
Protects—The nodes, non-SRLG links, and SRLGs that the backup tunnel protects.
Links—Links that the tunnel will cross.

Existing backup tunnels that protect the selected element are highlighted in green in the Backup Tunnels list box.

Note To view the suggested backup tunnels for more than one element at the same time, select more than one element in the Elements list box. To view the suggested backup tunnels for all elements, press Ctrl-A.

Step 5 Install backup tunnels.

a. In the Suggested Tunnels table, select the backup tunnels that you want to install. To install all suggested backup tunnels, highlight all the backup tunnels by pressing Ctrl-A. Backup tunnels that already protect the node, non-SRLG link, or SRLG are highlighted in green in the Suggested Tunnels list box.

b. Click Install Selected Tunnels. In the bottom right of the window there is text showing the status of the backup tunnel creation process.

Note If backup tunnels are highlighted in pink in the Backup Tunnels list box, the computation process recommends that you delete them before installing the suggested tunnels. To delete the backup tunnels, select them and press the Delete key.

Troubleshooting

Table 5-2 describes how to respond to status messages that Compute Backups may return. Table 5-3 describes warnings and violations that Compute Backups may return, and how to respond to them.

Table 5-2: Status Messages

Message	Meaning	Solution
NoSolutionExists	The algorithm proved that it is not possible to find backup tunnels that fully protect the element with the current topology, algorithm parameters, and load balancing rules. The algorithm will return the best set of backup tunnels it found during the search. Violations and warnings will be provided for this set of tunnels.	Examine the violations and warnings for a more detailed understanding of which flows could not be protected. From these messages, determine topology and/or parameter changes necessary to achieve full protection.
TimeOut	The algorithm could not find backup tunnels that fully protect the element in the time specified by the timeout parameter. The algorithm will return the best set of backup tunnels it found. Violations and warnings will be provided for this set of tunnels.	It is possible, but not guaranteed, that you can solve the problem by increasing the timeout. Change the load balancing parameters. Otherwise, examine the violations and warnings for a more detailed understanding of which flows could not be protected within the timeout period.
Invalid Tunnels	The algorithm could not find backup tunnels that fully protect the element, but could not prove that it would be impossible to do so. The algorithm will return the best set of backup tunnels it found. Violations and warnings will be provided for this set of tunnels.	Examine the violations and warnings for a more detailed understanding of which flows could not be protected.

Message

Meaning

Solution

NoSolutionExists

The algorithm proved that it is not possible to find backup tunnels that fully protect the element with the current topology, algorithm parameters, and load balancing rules. The algorithm will return the best set of backup tunnels it found during the search. Violations and warnings will be provided for this set of tunnels.

Examine the violations and warnings for a more detailed understanding of which flows could not be protected. From these messages, determine topology and/or parameter changes necessary to achieve full protection.

TimeOut

The algorithm could not find backup tunnels that fully protect the element in the time specified by the timeout parameter. The algorithm will return the best set of backup tunnels it found. Violations and warnings will be provided for this set of tunnels.

It is possible, but not guaranteed, that you can solve the problem by increasing the timeout.

Change the load balancing parameters.

Otherwise, examine the violations and warnings for a more detailed understanding of which flows could not be protected within the timeout period.

Invalid Tunnels

The algorithm could not find backup tunnels that fully protect the element, but could not prove that it would be impossible to do so. The algorithm will return the best set of backup tunnels it found. Violations and warnings will be provided for this set of tunnels.

Examine the violations and warnings for a more detailed understanding of which flows could not be protected.

Table 5-3: Warnings and Violations

Message	Meaning	Solution
No backup tunnels for flow	No backup tunnels exist for the flow. This message may appear twice for a link, once in each direction.	If there is a problem with connectivity for the element in question, change the topology to allow connectivity. The identification of the flow may help identify where to make the changes.
WarningFixVetoed	When computing backup tunnels for a router, a solution was generated that would protect the router. However, installing the generated backup tunnels would cause previously protected links attached to the router to become unprotected.	The solution for the router is vetoed in order to maintain protection on the links.
Insufficient backup tunnel capacity for NHOP (1000 < 2000)	No backup tunnels could be computed for the specified primary flow across the element that satisfied all the constraints (bandwidth and algorithmic parameters).	Do one of the following: Change the primary bandwidth settings to reduce the amount of the primary flow that needs to be protected. Increase the amount of backup bandwidth available. Increase the overbooking level to allow more backup bandwidth. Increase the allowable amount of load balancing. The identification of the flow may help identify the links on which you should make necessary bandwidth changes, or determine how much global parameters must be changed.

Message

Meaning

Solution

No backup tunnels for flow

No backup tunnels exist for the flow. This message may appear twice for a link, once in each direction.

If there is a problem with connectivity for the element in question, change the topology to allow connectivity. The identification of the flow may help identify where to make the changes.

WarningFixVetoed

When computing backup tunnels for a router, a solution was generated that would protect the router. However, installing the generated backup tunnels would cause previously protected links attached to the router to become unprotected.

The solution for the router is vetoed in order to maintain protection on the links.

Insufficient backup tunnel capacity for NHOP (1000 < 2000)

No backup tunnels could be computed for the specified primary flow across the element that satisfied all the constraints (bandwidth and algorithmic parameters).

Do one of the following:

Change the primary bandwidth settings to reduce the amount of the primary flow that needs to be protected.
Increase the amount of backup bandwidth available.
Increase the overbooking level to allow more backup bandwidth.
Increase the allowable amount of load balancing.

The identification of the flow may help identify the links on which you should make necessary bandwidth changes, or determine how much global parameters must be changed.

C reate Backup Tunnels Manually

To create backup tunnels manually, perform the following steps:

Step 1 Click the Tunnels tab. The Tunnels window shown in Figure 5-13 appears.

Figure 5-13: Tunnels Window

Step 2 Do one of the following:

In the network map, select the head node and click Create Tunnel.
In the topology map, right-click the node for which you want to create a backup tunnel and choose Create Backup Tunnel.

The Create Backup Tunnel window shown in Figure 5-14 appears.

Figure 5-14: Create Backup Tunnel Window

Step 3 In the Protect list box, select the links or nodes you want to protect. The paths that are valid for protecting the selected links or nodes are displayed in the Explicit Paths list box.

Step 4 Select a path in the Explicit Paths list box or click New Path to create a new explicit path.

Step 5 Click Use Path. The path is listed in the Path Options list box.

Step 6 Enter values into the following fields:

Tunnel Name—Name of the tunnel. The default is router_t#, where router is the node's host name and # is the tunnel number.
Bandwidth limit—Bandwidth value for the tunnel.
Global pool/Sub-pool/Any pool—Bandwidth pool that the backup tunnel will protect.
Setup-Priority—When Tunnel Builder Pro signals an LSP for this tunnel, Tunnel Builder Pro uses the setup priority to determine what existing tunnels can be preempted. Valid values are 0 to 7, where a lower number indicates a higher priority. An LSP with a setup priority of 0 can preempt any LSP with a non-0 priority. The setup priority and hold priorities are typically configured to be equal. The setup priority cannot be better (numerically smaller) than the hold priority.
Hold-Priority—Determines if the tunnel should be preempted by other LSPs that are being signaled. Valid values are 0 to 7, where a lower number indicates a higher priority. The hold priority and the setup priority are typically configured to be equal.
Affinity—A 32-bit hexadecimal number representing attribute values required for links carrying this tunnel. Valid values are 0x0 to 0xFFFFFFFF. The value of an attribute is 0 or 1. The default is 0x00000000/0x0000FFFF.
Mask—Determines which link attribute the node should check. If a bit in the mask is 0, a link's attribute value for that bit is irrelevant. If a bit in the mask is 1, the link's attribute value and the tunnel's required affinity for that bit must match. A tunnel can use a link if the tunnel affinity equals the link attributes and the tunnel affinity mask. Any properties set to 1 in the affinity should also be 1 in the mask.

Step 7 Click Apply or OK.

What to Do Next

To make your changes permanent, see "Using Tunnel Builder Pro for the First Time."

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