Information About LSP Attributes for MPLS TE
You can configure an LSP attribute list and associate it with one or more MPLS TE tunnels. This LSP attribute list supports multiple LSP attributes such as bandwidth and priority. You can also configure a TE tunnel to fall back temporarily to use path options that can reduce bandwidth constraints.
A port-profile can be used to provide a template of configuration for an entire tunnel. The attribute list can be used to apply a template for the configuration for one or more path options.
This section includes the following topics:
LSP Attribute Lists
Cisco NX-OS tunneling interfaces have many parameters that are associated with MPLS TE. Typically, you configure these parameters on an interface. Many of these attributes determine tunnel-specific properties, such as load sharing for the tunnel. These parameters are unrelated to the particular LSP in use by the tunnel. However, some of the tunneling parameters apply to the LSP that the tunnel uses.
You can configure the LSP-specific properties using an LSP attribute list. An LSP attribute list can contain values for each LSP-specific parameter that is configurable for a TE tunnel. You can specify the following LSP attributes in an attribute list:
- Attribute flags for links that make up the LSP
- LSP bandwidth from the global pool
- Disabling reoptimization of the LSP
- LSP priority
- Protection failure
- Recording the route used by the LSP
You can relist all attributes or remove specific attributes from an LSP attribute list.
Based on your requirements, you can configure LSP attribute lists with different sets of attributes for different path options. LSP attribute lists also provide an easy way to configure multiple TE tunnels to use the same LSP attributes. You can reference the same LSP attribute list to configure LSP-specific parameters for one or more TE tunnels.
Path Option Selection for MPLS TE Tunnel LSPs
This section includes the following topics:
Constraint-Based Routing and Path Option Selection
MPLS TE automatically establishes and maintains LSPs across the backbone by using the Resource Reservation Protocol (RSVP). The path that an LSP uses is determined by the LSP resource requirements and network resources, such as bandwidth. TE tunnels are calculated at the LSP head based on a fit between required and available resources (constraint-based routing).
A TE tunnel establishes an LSP based on dynamic or explicit path options in order of preference. However, the bandwidth and other attributes configured on the TE tunnel allow the setup of an LSP only if LSP path options satisfy the constraints. If a path cannot be found that satisfies the configured path options, then the tunnel is not set up.
You can configure the path option for bandwidth override as a fallback path option that allows overriding the bandwidth configured on the TE tunnel interface. For example, you can configure a path option that sets the bandwidth to zero (0), which effectively removes the bandwidth constraint imposed by the constraint-based routing calculation.
If the bandwidth is the only LSP attribute that you need to set on the path option, use the path option for the bandwidth override, which is the simplest way to configure multiple path options with decreasing bandwidth constraints.
Note You cannot configure both the bandwidth in the LSP attribute list and the bandwidth override because they are mutually exclusive.
Tunnel Reoptimization and Path Option Selection
Reoptimization occurs when a device with TE tunnels periodically examines tunnels with established LSPs to learn if better LSPs are available. If a better LSP is available, the device signals the better LSP. If the signaling is successful, the device replaces the older LSP with the new, better LSP.
You can trigger reoptimization using a configurable timer, a reoptimize command, or a configuration change that requires the resignaling of a tunnel. The path option for bandwidth override can switch between the bandwidth that is configured on the TE tunnel interface and the bandwidth that is configured on a specific path option. This override increases the success of signaling an LSP for the TE tunnel.
When you configure the bandwidth override on a path option, TE reoptimizes the bandwidth every 30 seconds to reestablish the bandwidth that is configured on the tunnel (see the “Configuring a Path Option for Bandwidth Override”).
You can disable reoptimization of an LSP in an LSP attribute list and apply this LSP attribute list to a path option.
Path Option Selection with Bandwidth Override
When you enable the bandwidth override path option, you can configure bandwidth parameters on a specific path option. When an LSP is signaled using a path option with a configured bandwidth, the bandwidth that is associated with the path option is signaled instead of the bandwidth that is configured directly on the tunnel.
You can configure multiple path options that reduce the bandwidth constraint each time the headend of a tunnel fails to establish an LSP.
The following example shows three path-option commands:
path-option 1 explicit name path1
path-option 2 explicit name path2 bandwidth 500
path-option 3 dynamic bandwidth 0
The device selects a path option for an LSP in order of preference, as follows:
- The device signals an LSP using path options that start with path option 1.
The device signals an LSP with the 1000-kbps bandwidth configured on the tunnel interface because path option 1 has no bandwidth configured.
- If 1000 kbps is not available, the device tries to establish an LSP using path option 2.
Path option 2 has a 500-kbps bandwidth configured, which reduces the bandwidth constraint from the original 1000-kbps configured on the tunnel interface.
- If 500 kbps is not available, the device tries to establish an LSP using path option 3.
Path option 3 is configured as dynamic and has a bandwidth of 0. The device establishes the LSP if an IP path exists to the destination and all other tunnel constraints are met.
Configuring LSP Attributes for MPLS TE
This section includes the following topics:
Configuring LSP Attributes in an MPLS TE Tunnel
You can configure LSP attributes in an MPLS TE tunnel. These values are overridden by an LSP attribute list that is associated with this MPLS TE tunnel.
Prerequisites
You must have the MPLS TE feature enabled (see the “Configuring MPLS TE”).
Ensure that you are in the correct VDC (or use the switchto vdc command).
SUMMARY STEPS
1. configure terminal
2. interface tunnel-te number
3. destination { ip-address }
4. (Optional) autoroute announce
5. (Optional) bandwidth kbps
6. (Optional) priority setup-priority [ hold-priority ]
7. (Optional) show interface tunnel-te number
8. (Optional) show mpls traffic-eng tunnels tunnel-te number
9. (Optional) show running config interface tunnel-te number
10. (Optional) copy running-config startup-config
DETAILED STEPS
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Step 1 |
configure terminal Example: switch# configure terminal switch(config)# |
Enters global configuration mode. |
Step 2 |
interface tunnel-te number Example: switch(config)# interface tunnel-te 1 |
Enters TE interface configuration mode. The number argument identifies the tunnel number to be configured. |
Step 3 |
destination { ip-address } Example: switch(config-if-te)# destination 10.10.10.12 |
Specifies the destination of the tunnel for this path option. The ip-address argument is the IP address of the host destination expressed in decimal in four-part, dotted notation. |
Step 4 |
autoroute announce Example: switch(config-if-te)# autoroute announce |
(Optional) Specifies that the IGP should use the tunnel (if the tunnel is up) in its enhanced shortest path first (SPF) calculation. |
Step 5 |
bandwidth kbps Example: switch(config-if-te)# bandwidth 1000 |
(Optional) Configures the bandwidth required for an MPLS TE tunnel and assigns it to the global pool. The kbps argument is the bandwidth, in kilobits per second, set aside for the MPLS TE tunnel. The range is from 1 to 4294967295. |
Step 6 |
priority setup-priority [ hold-priority ] Example: switch(config-if-te)# priority 1 1 |
(Optional) Sets the priority to be used when the system determines which existing tunnels are eligible to be preempted. The setup-priority argument is the priority used when signaling an LSP for this tunnel to determine which existing tunnels can be preempted. Valid values are from 0 to 7. A lower number indicates a higher priority. An LSP with a setup priority of 0 can preempt any LSP with a nonzero priority. The hold-priority argument is the priority associated with an LSP for this tunnel to determine if it should be preempted by other LSPs that are being signaled. Valid values are from 0 to 7, where a lower number indicates a higher priority. |
Step 7 |
show interface tunnel-te number Example: switch(config-if-te)# show interface tunnel-te 1 |
(Optional) Displays information about the TE tunnel. |
Step 8 |
show mpls traffic-eng tunnels tunnel-te number |
(Optional) Displays the MPLS TE tunnels for the configured tunnel number. |
Step 9 |
show running config interface tunnel-te number |
(Optional) Displays the running configuration of the interface MPLS TE tunnels for the configured tunnel number. |
Step 10 |
copy running-config startup-config Example: switch(config-if-te)# copy running-config startup-config |
(Optional) Copies the running configuration to the startup configuration. |
Configuring an LSP Attribute List
You can configure an LSP attribute list with the desired attributes to apply on a path option. You can also add or modify an attribute in an existing LSP attribute list, or use the no subcommand to remove an attribute from an existing attribute list.
Note You cannot configure both the bandwidth in the LSP attribute list and the path-option bandwidth override because they are mutually exclusive.
Prerequisites
You must have the MPLS TE feature enabled (see the “Configuring MPLS TE”).
Ensure that you are in the correct VDC (or use the switchto vdc command).
SUMMARY STEPS
1. configure terminal
2. mpls traffic-eng configuration
3. lsp attributes name
4. (Optional) affinity value [ mask value ]
5. (Optional) bandwidth kbps
6. (Optional) list
7. (Optional) lockdown
8. (Optional) priority setup-priority [ hold-priority ]
9. (Optional) protection fast-reroute
10. (Optional) record-route
11. (Optional) no sub-command
12. (Optional) show mpls traffic-eng lsp attributes [ name ]
13. (Optional) show running mpls traffic-eng
14. (Optional) show mpls traffic-eng tunnels tunnel-te number
15. (Optional) show running config interface tunnel-te number
16. (Optional) copy running-config startup-config
DETAILED STEPS
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Step 1 |
configure terminal Example: switch# configure terminal switch(config)# |
Enters global configuration mode. |
Step 2 |
mpls traffic-eng configuration Example: switch(config)# mpls traffic-eng configuration switch(config-te)# |
Enters MPLS TE configuration mode. |
Step 3 |
lsp attributes string Example: switch(config-te)# lsp attributes 1 switch(config-lsp-attr)# |
Configures an LSP attribute list and enters LSP attributes configuration mode. The name argument identifies a specific LSP attribute list and can be any case-sensitive, alphanumeric string up to 63 characters. |
Step 4 |
affinity value [ mask value ] Example: switch(config-lsp-attr)# affinity 0 mask 0 |
(Optional) Specifies attribute flags for links that comprise an LSP. The value argument is a value required for links that make up an LSP. Values of the bits are either 0 or 1. The mask value keyword argument combination indicates which attribute values should be checked. If a bit in the mask is 0, an attribute value of the link or that bit is irrelevant. If a bit in the mask is 1, the attribute value of that link and the required affinity of the LSP for that bit must match. |
Step 5 |
bandwidth kbps Example: switch(config-lsp-attr)# bandwidth 5000 |
(Optional) Specifies the LSP bandwidth. The kbps argument is the number of kilobits per second set aside for the path option. The range is from 1 to 4294967295. |
Step 6 |
list Example: switch(config-lsp-attr)# list |
(Optional) Displays the contents of the LSP attribute list. |
Step 7 |
lockdown Example: switch(config-lsp-attr)# lockdown |
(Optional) Disables reoptimization of the LSP. |
Step 8 |
priority setup-priority [ hold-priority ] Example: switch(config-lsp-attr)# priority 1 1 |
(Optional) Specifies the LSP priority. The setup-priority argument is used when signaling an LSP to determine which existing LSPs can be preempted. The range is from 0 to 7, where a lower number indicates a higher priority. Therefore, an LSP with a setup priority of 0 can preempt any LSP with a nonzero priority. The hold-priority argument is associated with an LSP to determine if it should be preempted by other LSPs that are being signaled. The range is from 0 to 7, where a lower number indicates a higher priority. |
Step 9 |
protection fast-reroute Example: switch(config-lsp-attr)# protection fast-reroute |
(Optional) Enables failure protection on the LSP. |
Step 10 |
record-route Example: switch(config-lsp-attr)# record-route |
(Optional) Records the route used by the LSP. |
Step 11 |
no sub-command Example: switch(config-lsp-attr)# no record-route |
(Optional) Removes a specific attribute from the LSP attributes list. The sub-command argument names the LSP attribute to remove from the attributes list. |
Step 12 |
show mpls traffic-eng lsp attributes [ name ] Example: switch(config)# show mpls traffic-eng lsp attributes |
(Optional) Displays information about configured LSP attribute lists. Use the show mpls traffic-eng lsp attributes command to verify that the LSP attribute list was deleted from the switch. |
Step 13 |
show running mpls traffic-eng Example: switch(config)# show running mpls traffic-eng |
(Optional) Displays information about the running configuration of the MPLS TE feature. |
Step 14 |
show mpls traffic-eng tunnels tunnel-te number Example: switch(config)# show mpls traffic-eng tunnels tunnel-te 12 |
(Optional) Displays the MPLS TE tunnels for the configured tunnel number. |
Step 15 |
show running config interface tunnel-te number Example: switch(config)# show running config interface tunnel-te 12 |
(Optional) Displays the running configuration of the interface MPLS TE tunnels for the configured tunnel number. |
Step 16 |
copy running-config startup-config Example: switch(config-lsp-attr)# copy running-config startup-config |
(Optional) Copies the running configuration to the startup configuration. |
Associating an LSP Attribute List with an MPLS TE Tunnel
You can associate an LSP attribute list with a path option for one or more MPLS TE tunnels.
Path option attributes for a TE tunnel are determined as follows:
- Attributes configured in an LSP attribute list on a path-option take precedence over the same attributes if they are configured directly in the tunnel interface configuration mode.
- If an attribute is not specified in the LSP attribute list, the device uses the attribute in the tunnel configuration. An LSP attribute list has no default values.
- If the attribute is not configured on the tunnel and not in the attribute list, the device uses the tunnel default attribute value. See the “Default Settings for LSP Attributes for MPLS TE”.
Prerequisites
You must have the MPLS TE feature enabled (see the “Configuring MPLS TE”).
Ensure that you are in the correct VDC (or use the switchto vdc command).
SUMMARY STEPS
1. configure terminal
2. interface tunnel-te number
3. path-option number { dynamic | explicit { name path-name | path-number } [ verbatim ] } [ attributes string ] [ bandwidth kbps ] [ lockdown ]
4. (Optional) show interface tunnel-te number
5. (Optional) show mpls traffic-eng tunnels tunnel-te number
6. (Optional) show running config interface tunnel-te number
7. (Optional) copy running-config startup-config
DETAILED STEPS
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Step 1 |
configure terminal Example: switch# configure terminal switch(config)# |
Enters global configuration mode. |
Step 2 |
interface tunnel-te number Example: switch(config)# interface tunnel-te 1 |
Enters TE interface configuration mode. The number argument identifies the tunnel number to be configured. |
Step 3 |
path-option number { dynamic | explicit { name path-name | path-number } [ verbatim ]} [ attributes string ] [ bandwidth kbps ] [ lockdown ] Example: switch(config-if-te)# path-option 1 dynamic attributes 1 |
Adds an LSP attribute list to specify LSP-related parameters for path options for an MPLS TE tunnel. The arguments are as follows:
- The number argument identifies the path option.
- The dynamic keyword indicates that the path option is dynamically calculated (the switch figures out the best path).
- The explicit keyword indicates that the path option is specified. You specify the IP addresses of the path.
- The name path-name keyword argument combination identifies the name of the explicit path option.
- The path-number argument identifies the number of the explicit path option.
- The verbatim keyword bypasses the topology database verification.
Note You can use the verbatim keyword only with the explicit path option.
- The attributes string keyword argument combination names an attribute list to specify path options for the LSP.
- The bandwidth keyword specifies LSP bandwidth.
- The kbps argument is the number of kilobits per second set aside for the tunnel when signaled with this path option. The range is from 1 to 4294967295.
- The lockdown keyword disables reoptimization of the LSP when the tunnel is signaled with this path option.
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Step 4 |
show interface tunnel-te number Example: switch(config-if-te)# show interface tunnel-te 1 |
(Optional) Displays information about the TE tunnel. |
Step 5 |
show mpls traffic-eng tunnels tunnel-te number Example: switch(config-if-te)# show mpls traffic-eng tunnels tunnel-te 12 |
(Optional) Displays the MPLS TE tunnels for TE for the configured tunnel number. |
Step 6 |
show running config interface tunnel-te number Example: switch(config-if-te)# show running config interface tunnel-te 12 |
(Optional) Displays the running configuration of the interface MPLS TE tunnels for the configured tunnel number. |
Step 7 |
copy running-config startup-config Example: switch(config-if-te)# copy running-config startup-config |
(Optional) Copies the running configuration to the startup configuration. |
Configuring a Path Option for Bandwidth Override
You can configure fallback bandwidth path options for a TE tunnel using the bandwidth parameter in the path option. You can configure path options that reduce the bandwidth constraint each time the headend of a tunnel fails to establish an LSP.
The bandwidth path option override is a temporary reduction in the bandwidth constraint. You can also use this feature to increase the bandwidth requirement. To force immediate reoptimization of all TE tunnels, use the global reoptimize command. You can also configure the lockdown command with the bandwidth override to prevent automatic reoptimization.
Note Once you configure the bandwidth as a path-option parameter, you can no longer configure an LSP attribute list as a path-option parameter.
SUMMARY STEPS
1. configure terminal
2. interface tunnel-te number
3. path-option number { dynamic | explicit { name path--name | path-number } [ verbatim ] } [ attributes string ] [ bandwidth kbps ] [ lockdown ]
4. (Optional) show interface tunnel-te number
5. (Optional) show mpls traffic-eng tunnels tunnel-te number
6. (Optional) show running config interface tunnel-te number
7. (Optional) copy running-config startup-config
DETAILED STEPS
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Step 1 |
configure terminal Example: switch# configure terminal switch(config)# |
Enters global configuration mode. |
Step 2 |
interface tunnel-te number Example: switch(config)# interface tunnel-te 1 |
Enters TE interface configuration mode. The number argument identifies the tunnel number to be configured. |
Step 3 |
path-option number { dynamic | explicit { name path-name | path-number } [ verbatim ]} [ attributes string ] [ bandwidth kbps ] [ lockdown ] Example: switch(config-if-te)# path-option 1 dynamic attributes 1 |
Adds an LSP attribute list to specify LSP-related parameters for path options for an MPLS TE tunnel. The arguments are as follows:
- The number argument identifies the path option.
- The dynamic keyword indicates that the path option is dynamically calculated (the switch figures out the best path).
- The explicit keyword indicates that the path option is specified. You specify the IP addresses of the path.
- The name path-name keyword argument combination identifies the name of the explicit path option.
- The path-number argument identifies the number of the explicit path option.
- The verbatim keyword bypasses the topology database verification.
Note You can use the verbatim keyword only with the explicit path option.
- The attributes string keyword argument combination names an attribute list to specify path options for the LSP.
- The bandwidth keyword specifies the LSP bandwidth.
- The kbps argument is the number of kilobits per second set aside for the path option. The range is from 1 to 4294967295.
- The lockdown keyword disables reoptimization of the LSP.
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Step 4 |
show interface tunnel-te number Example: switch(config-if-te)# show interface tunnel-te 1 |
(Optional) Displays information about the TE tunnel. |
Step 5 |
show mpls traffic-eng tunnels tunnel-te number Example: switch(config-if-te)# show mpls traffic-eng tunnels tunnel-te 1 |
(Optional) Displays the MPLS TE tunnels for the configured tunnel number. |
Step 6 |
show running config interface tunnel-te number Example: switch(config-if-te)# show running config interface tunnel-te 1 |
(Optional) Displays the running configuration of the interface MPLS TE tunnels for the configured tunnel number. |
Step 7 |
copy running-config startup-config Example: switch(config-if-te)# copy running-config startup-config |
(Optional) Copies the running configuration to the startup configuration. |
Configuration Examples for LSP Attributes for MPLS TE
This section includes the following topics:
Example: LSP Attribute List on a TE Tunnel
The following example shows how to configure an LSP attribute list and associate it with an MPLS TE tunnel:
feature mpls traffic-engineering
mpls traffic-eng configuration
ip unnumbered Ethernet2/1
path-option 1 dynamic attributes 3
Example: Path Option for Bandwidth Override
The following example shows how to configure a path option to override the bandwidth:
Note Once you configure the bandwidth as a path-option parameter, you can no longer configure an LSP attribute list as a path-option parameter.
feature mpls traffic-engineering
path-option 1 explicit name path1
path-option 2 explicit name path2 bandwidth 500
path-option 3 dynamic bandwidth 0
The device selects a path option for an LSP in order of preference, as follows:
- The device tries to signal an LSP using path options starting with path option 1.
The device tries to signal an LSP with the 1000-kbps bandwidth configured on the tunnel interface because path option 1 has no bandwidth configured.
- If 1000 kbps is not available, the device tries to establish an LSP using path option 2.
Path option 2 has 500 kbps configured, which reduces the bandwidth constraint from the original 1000-kbps configured on the tunnel interface.
- If 500 kbps is not available, the device tries to establish an LSP using path option 3.
Path option 3 is configured as dynamic and has a bandwidth of 0. The device establishes the LSP if an MPLS TE path exists to the destination and all other tunnel constraints are met.
If explicit path option 1 and explicit path option 2 both fail, dynamic path option 3 is attempted with 0 bandwidth, so it should succeed if any path exists. This option is a fallback to best effort.