MPLS Traffic Engineering—Configurable Path Calculation Metric for Tunnels
ErrorMessage : Error while constructing the Hinav

null
Downloads: This chapterpdf (PDF - 166.0KB) | Feedback

MPLS Traffic Engineering—Configurable Path Calculation Metric for Tunnels

Table Of Contents

MPLS Traffic Engineering—Configurable Path Calculation Metric for Tunnels

Finding Feature Information

Contents

Feature Overview

Benefits

Restrictions

Related Features and Technologies

Prerequisites

Configuration Tasks

Configuring a Platform to Support Traffic Engineering Tunnels

Configuring IS-IS for MPLS Traffic Engineering

Configuring OSPF for MPLS Traffic Engineering

Configuring Traffic Engineering Link Metrics

Configuring an MPLS Traffic Engineering Tunnel

Configuring the Metric Type for Tunnel Path Calculation

Verifying the Configuration

Configuration Examples

Additional References

Related Document

Standards

MIBs

RFCs

Technical Assistance

Feature Information for MPLS Traffic Engineering—Configurable Path Calculation Metric for Tunnels


MPLS Traffic Engineering—Configurable Path Calculation Metric for Tunnels


First Published: March 18, 2002
Last Updated: February 27, 2009

The MPLS Traffic Engineering—Configurable Path Calculation Metric for Tunnels feature enables the user to control the metric used in path calculation for traffic engineering (TE) tunnels on a per-tunnel basis. Certain tunnels are used to carry voice traffic, which requires low delay, and other tunnels are used to carry data. A TE link metric can be used to represent link delay and configure tunnels that carry voice traffic for path calculation and configure tunnels that carry data to use the Interior Gateway Protocol (IGP) metric for path calculation.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the "Feature Information for MPLS Traffic Engineering—Configurable Path Calculation Metric for Tunnels" section.

Use Cisco Feature Navigator to find information about platform support and Cisco IOS and Catalyst OS software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.

Contents

Feature Overview

Prerequisites

Configuration Tasks

Configuration Examples

Additional References

Feature Information for MPLS Traffic Engineering—Configurable Path Calculation Metric for Tunnels

Feature Overview

When Multiprotocol Label Switching (MPLS) TE is configured in a network, the Interior Gateway Protocol (IGP) floods two metrics for every link: the normal IGP (Open Shortest Path First (OSPF) or (Intermediate System-to-Intermediate System (IS-IS)) link metric and a TE link metric. The IGP uses the IGP link metric in the normal way to compute routes for destination networks. In releases previous to Cisco IOS Release 12.2(18)ST, MPLS TE used the TE link metric to calculate and verify paths for TE tunnels. When the traffic engineering metric was not explicitly configured, the traffic engineering metric was the IGP metric.

The enhancement as of release Cisco IOS Release 12.2(18)ST allows you to specify that the path calculation for a given tunnel be based on either of the following:

IGP link metrics.

TE link metrics, which you can configure so that they represent the needs of a particular application. For example, the TE link metrics can be configured to represent link transmission delay.

Benefits

When TE tunnels are used to carry two types of traffic, the Configurable Path Calculation Metric for Tunnels enhancement allows you to tailor tunnel path selection to the requirements of each type of traffic.

For example, suppose certain tunnels are to carry voice traffic (which requires low delay) and other tunnels are to carry data. In this situation, you can use the TE link metric to represent link delay and do the following:

Configure tunnels that carry voice to use the TE link metric set to represent link delay for path calculation.

Configure tunnels that carry data to use the IGP metric for path calculation.

Restrictions

Unless explicitly configured, the TE link metric for a given link is the IGP link metric. When the TE link metric is used to represent a link property that is different from cost/distance, you must configure every network link that can be used for TE tunnels with a TE link metric that represents that property by using the mpls traffic-eng administrative-weight command. Failure to do so might cause tunnels to use unexpected paths.

You cannot configure MPLS Traffic Engineering over the logical GRE tunnel interface.

MPLS traffic engineering supports only a single IGP process/instance. Multiple IGP processes/instances are not supported and MPLS traffic engineering should not be configured in more than one IGP process/instance.

Related Features and Technologies

The configurable path calculation metric feature is related to MPLS TE.

Prerequisites

Before you configure tunnel path calculation metrics, your network must support the following Cisco IOS features:

MPLS traffic engineering tunnels

IP Cisco Express Forwarding

OSPF or IS-IS

Configuration Tasks

See the following sections for configuration tasks for the configurable path calculation metric feature. Each task in the list indicates if it is optional or required.

Configuring a Platform to Support Traffic Engineering Tunnels (required)

Configuring IS-IS for MPLS Traffic Engineering

Configuring OSPF for MPLS Traffic Engineering

Configuring Traffic Engineering Link Metrics (required)

Configuring an MPLS Traffic Engineering Tunnel (required)

Configuring the Metric Type for Tunnel Path Calculation (required)

Configuring a Platform to Support Traffic Engineering Tunnels

To configure a platform to support traffic engineering tunnels, perform the following steps in global configuration mode:

 
Command
Purpose

Step 1 

Router(config)# ip cef

Enables standard Cisco Express Forwarding operation.

Step 2 

Router(config)# mpls traffic-eng tunnels

Enables the MPLS traffic engineering tunnel feature on a device.

Configuring IS-IS for MPLS Traffic Engineering

To configure IS-IS for MPLS traffic engineering, perform the following steps.


Note MPLS traffic engineering supports only a single IGP process/instance. Multiple IGP processes/instances are not supported and MPLS traffic engineering should not be configured in more than one IGP process/instance.


 
Command
Purpose

Step 1 

Router(config)# router isis

Enables IS-IS routing and specifies an IS-IS process for IP. The router is placed in configuration mode.

Step 2 

Router(config-router)# mpls traffic-eng level-1

Turns on MPLS traffic engineering for IS-IS level 1.

Step 3 

Router(config-router)# mpls traffic-eng level-2

Turns on MPLS traffic engineering for IS-IS level 2.

Step 4 

Router(config-router)# mpls traffic-eng router-id loopback0

Specifies that the traffic engineering router identifier for the node is the IP address associated with interface loopback0.

Step 5 

Router(config-router)# metric-style wide

Configures a router to generate and accept only new-style type, length, value objects (TLVs).

Configuring OSPF for MPLS Traffic Engineering


Note MPLS traffic engineering supports only a single IGP process/instance. Multiple IGP processes/instances are not supported and MPLS traffic engineering should not be configured in more than one IGP process/instance.


 
Command
Purpose

Step 1 

Router(config)# router ospf process-id

Configures an OSPF routing process for IP. The router is placed in router configuration mode.

The process-id argument is an internally used identification parameter for an OSPF routing process. It is locally assigned and can be any positive integer. Assign a unique value for each OSPF routing process.

Step 2 

Router(config-router)# mpls traffic-eng area x

Turns on MPLS traffic engineering for OSPF area x.

Step 3 

Router(config-router)# mpls traffic-eng router-id loopback0

Specifies that the traffic engineering router identifier for the node is the IP address associated with interface loopback0.

Configuring Traffic Engineering Link Metrics

Unless explicitly configured, the TE link metric is the IGP link metric. To configure the TE link metric, perform these steps:

 
Command
Purpose

Step 1 

Router(config)# interface interface

Configures properties of the specified interface.

Step 2 

Router(config-router)# mpls traffic-eng administrative-weight weight

Specifies the traffic engineering metric for the link.

Configuring an MPLS Traffic Engineering Tunnel

To configure an MPLS traffic engineering tunnel, perform the following steps in interface configuration mode. This tunnel has two path setup options: a preferred explicit path and a backup dynamic path.

 
Command
Purpose

Step 1 

Router(config)# interface tunnel-interface

Configures a tunnel interface and enters interface configuration mode.

Step 2 

Router(config-if)# ip unnumbered loopback0

Gives the tunnel interface an IP address.

An MPLS traffic engineering tunnel interface should be unnumbered because it represents a unidirectional link.

Step 3 

Router(config-if)# tunnel destination ip-address

Specifies the destination for a tunnel. The destination must be the MPLS traffic engineering router ID of the destination device.

Step 4 

Router(config-if)# tunnel mode mpls traffic-eng

Sets the tunnel encapsulation mode to MPLS traffic engineering.

Step 5 

Router(config-if)# tunnel mpls traffic-eng bandwidth bandwidth

Configures the bandwidth for the MPLS traffic engineering tunnel. If automatic bandwidth is configured for the tunnel, use the tunnel mpls traffic-eng bandwidth command to configure the initial tunnel bandwidth, which is adjusted by the autobandwidth mechanism.

Step 6 

Router(config-if)# tunnel mpls traffic-eng path-option number {dynamic | explicit {name path-name | id path-number}} [lockdown]

Configures the tunnel to use a named IP explicit path or a path dynamically calculated from the traffic engineering topology database. A dynamic path is used if an explicit path is currently unavailable.

Configuring the Metric Type for Tunnel Path Calculation

Unless explicitly configured, the TE link metric type is used for tunnel path calculation. Two commands are provided for controlling the metric type to be used: an interface configuration command that specifies the metric type to be used for a particular TE tunnel and a global configuration command that specifies the metric type to be used for TE tunnels for which a metric type has not been specified by the interface configuration command.

To configure the metric type for tunnel path calculation, perform one or both of the following steps:

Command
Purpose

Router(config-if)# tunnel mpls traffic-eng path-selection metric {igp | te}

Specifies the metric type to use for path calculation when you are determining a tunnel's path.

Router(config)# mpls traffic-eng path-selection metric {igp | te}

Specifies the metric type to use if a metric type was not explicitly configured for a given tunnel.



Note If you do not enter either of the commands, the traffic engineering (te) metric is used.


Verifying the Configuration

Use the show mpls traffic-eng topology command, which displays TE and IGP metrics for each link, to verify that link metrics have been correctly configured for a network.

Router# show mpls traffic-eng topology
 
   
My_System_id: 1440.0000.0044.00 (isis  level-1)
IGP Id: 0090.0000.0009.00, MPLS TE Id:192.168.9.9 Router Node  (isis  level-1)
      link[0 ]:Nbr IGP Id: 0090.0000.0009.03, gen:7
          frag_id 0, Intf Address:10.0.0.99
          TE metric:100, IGP metric:48, attribute_flags:0x0     !!Note TE and IGP metrics
          physical_bw: 10000 (kbps), max_reservable_bw_global: 0 (kbps)
          max_reservable_bw_sub: 0 (kbps)
  .
.
.
      link[1 ]:Nbr IGP Id: 0055.0000.0055.00, gen:7
          frag_id 0, Intf Address:10.205.0.9, Nbr Intf Address:10.205.0.55
          TE metric:120, IGP metric:10, attribute_flags:0x0     !!Note TE and IGP metrics
          physical_bw: 155000 (kbps), max_reservable_bw_global: 500000 (kbps)
          max_reservable_bw_sub: 0 (kbps)
.
.
.

Use the show mpls traffic-eng tunnels command, which displays the link metric used for tunnel path calculation, to verify that the desired link metrics are being used for each tunnel.

Router# show mpls traffic-eng tunnels
 
   
Name: te3640-17-c_t221              (Tunnel22) Destination: 192.168.100.22
  Status:
    Admin: up         Oper: up     Path: valid       Signalling: connected
    path option 1, type dynamic (Basis for Setup, path weight 10)
 
   
  Config Parameters:
    Bandwidth: 400 kps (Global)    Priority: 1  1   Affinity: 0x0/0xFFFF
    Metric Type: IGP                                            !!Note metric type
    AutoRoute:  enabled   LockDown: disabled  Loadshare: 0   bw-based
    auto-bw: disabled(0/115) 0  Bandwidth Requested: 0
.
.
.
Name: te3640-17-c_t222              (Tunnel33) Destination: 192.168.100.22
  Status:
    Admin: up         Oper: up     Path: valid       Signalling: connected
    path option 1, type dynamic (Basis for Setup, path weight 10)
 
   
  Config Parameters:
    Bandwidth: 200 kbps (Global)   Priority: 1  1   Affinity: 0x0/0xFFFF
    Metric Type: TE                                              !!Note metric type
    AutoRoute:  enabled   LockDown: disabled  Loadshare: 0   bw-based
    auto-bw: disabled(0/115) 0  Bandwidth Requested: 0
.
.
.

Configuration Examples

The section illustrates how to configure the link metric type to be used for tunnel path selection, and how to configure the link metrics themselves. The configuration commands included focus on specifying the metric type for path calculation and assigning metrics to links. Additional commands are required to fully configure the example scenario: for example, the IGP commands for traffic engineering and the link interface commands for enabling traffic engineering and specifying available bandwidth.

The examples in this section support the simple network topology shown in Figure 1.

Figure 1 Network Topology

In Figure 1:

Tunnel1 and Tunnel2 run from R1 (headend) to R4 (tailend).

Tunnel3 runs from R1 to R5.

Path calculation for Tunnel1 and Tunnel3 should use a metric that represents link delay because these tunnels carry voice traffic.

Path calculation for Tunnel2 should use IGP metrics because MPLS TE carries data traffic with no delay requirement.

Configuration fragments follow for each of the routers that illustrate the configuration relating to link metrics and their use in tunnel path calculation. TE metrics that represent link delay must be configured for the network links on each of the routers, and the three tunnels must be configured on R1.

These configuration fragments force Tunnel1 to take path R1-R3-R4, Tunnel2 to take path R1-R2-R4, and Tunnel3 to take path R1-R3-R4-R5 (assuming the links have sufficient bandwidth to accommodate the tunnels).

R1 Configuration

interface pos0/1
mpls traffic-eng administrative-weight 15       !TE metric different from IGP metric
interface pos0/2
mpls traffic-eng administrative-weight 15       !TE metric different from IGP metric
 
   
interface Tunnel1                               !Tunnel1 uses TE metric (default)
                                                !for path selection
ip unnumbered loopback0
tunnel destination 192.168.4.4 255.255.255.0
tunnel mode mpls traffic-eng
tunnel mpls traffic-eng bandwidth 1000
tunnel mpls traffic-eng path-option 1 dynamic
 
   
interface Tunnel2                                !Tunnel2 uses IGP metric
                                                 !for path selection
ip unnumbered loopback0
tunnel destination 192.168.4.4 255.255.255.0
tunnel mode mpls traffic-eng
tunnel mpls traffic-eng bandwidth 1000
tunnel mpls traffic-eng path-option 1 dynamic
tunnel mpls traffic-eng path-selection-metric igp !Use IGP cost for path selection.
 
   
interface Tunnel3                                 !Tunnel3 uses TE metric (default)
                                                  !for path selection
ip unnumbered loopback0
tunnel destination 192.168.5.5 255.255.255.0
tunnel mode mpls traffic-eng
tunnel mpls traffic-eng bandwidth 1000
tunnel mpls traffic-eng path-option 1 dynamic
 
   

R2 Configuration

interface pos3/0
mpls traffic-eng administrative-weight 15       !TE metric different from IGP metric
interface pos4/1
mpls traffic-eng administrative-weight 40       !TE metric different from IGP metric
 
   

R3 Configuration

interface pos2/0/0
mpls traffic-eng administrative-weight 15       !TE metric different from IGP metric
interface pos3/0/0
mpls traffic-eng administrative-weight 15       !TE metric different from IGP metric
interface pos6/0/0
mpls traffic-eng administrative-weight 5        !TE metric different from IGP metric
 
   

R4 Configuration

interface pos2/0
mpls traffic-eng administrative-weight 15       !TE metric different from IGP metric
interface pos2/1
mpls traffic-eng administrative-weight 15       !TE metric different from IGP metric
interface pos2/2
mpls traffic-eng administrative-weight 5        !TE metric different from IGP metric
 
   

R5 Configuration

interface pos1/0
mpls traffic-eng administrative-weight 15       !TE metric different from IGP metric
interface pos1/1
mpls traffic-eng administrative-weight 5        !TE metric different from IGP metric

Additional References

Related Document

Related Topic
Document Title

MPLS Traffic Engineering Path Protection

MPLS Traffic Engineering Path Protection

MPLS Traffic Engineering—Fast Reroute Link and Node Protection

MPLS Traffic Engineering—Fast Reroute Link and Node Protection


Standards

Standard
Title

No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.

-


MIBs

MIB
MIBs Link

No new or modified MIBs are supported by this feature, and support for existing MIBs has not been modified by this feature.

To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:

http://www.cisco.com/go/mibs


RFCs

RFC
Title

No new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified.

-


Technical Assistance

Description
Link

The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies.

To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds.

Access to most tools on the Cisco Support website requires a Cisco.com user ID and password.

http://www.cisco.com/techsupport


Feature Information for MPLS Traffic Engineering—Configurable Path Calculation Metric for Tunnels

Table 1 lists the release history for this feature.

Not all commands may be available in your Cisco IOS software release. For release information about a specific command, see the command reference documentation.

Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which Cisco IOS and Catalyst OS software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.


Note Table 1 lists only the Cisco IOS software release that introduced support for a given feature in a given Cisco IOS software release train. Unless noted otherwise, subsequent releases of that Cisco IOS software release train also support that feature.


Table 1 Feature Information for MPLS Traffic Engineering—Configurable Path Calculation Metric for Tunnels

Feature Name
Releases
Feature Information

MPLS Traffic Engineering—Configurable Path Calculation Metric for Tunnels

12.0(18)ST
12.2(11)S
12.2(14)S
12.2(28)SB
12.4(20)T

This feature was introduced.

This feature was integrated into Cisco IOS Release 12.2(11)S.

This feature was integrated into Cisco IOS Release 12.2(14)S.

This feature was integrated into Cisco IOS Release 12.2(28)SB.

This feature was integrated into Cisco IOS Release 12.4(20)T.