PLE Service Configuration

This chapter describes the Private Line Emulation (PLE) service and the configuration procedures.

Private Line Emulation

Private Line Emulation (PLE) is a pillar of the Routed Optical Networking solution. PLE allows non-Ethernet type services such as SONET/SDH, OTN, and Fiber Channel to be carried over the same MPLS or Segment Routing network. PLE also supports bit-transparent Ethernet services where required.

High-revenue and legacy private line services, carried over a dedicated inefficient TDM OTN layer, exist in the network infrastructure of most service providers. PLE enables service providers to carry SONET/SDH, OTN, Ethernet, and Fiber Channel over a circuit-style segment routed packet network while maintaining existing service SLAs. PLE utilizes Circuit Emulation (CEM) to transfer PLE client frames over MPLS or SR networks transparently, without changing the characteristics of the original signal.

Benefits of PLE

PLE enables service providers and enterprises to

  • collapse network layers

  • decrease network complexity, and

  • increase network efficiency

Supported payloads

PLE supports these payloads.

Table 1. Supported payloads

PLE transport type

Supported payloads

Ethernet

1GE and 10GE

OTN

OTU2 and OTU2e

SONET

OC-48 and OC-192

SDH

STM-16 and STM-64

Fiber Channel

FC1, FC2, FC4, FC8, FC16, and FC32

The combination of payloads is also supported.

Supported hardware

PLE supports these hardware:

How PLE works

Summary

This process ensures the transparent transmission of client Layer 1 frames over a Packet Switched Network, maintaining the integrity and format of the original traffic.

Workflow

These stages describe how the PLE works.

  1. Ethernet, OTN, Fiber Channel, or SONET/SDH PLE client traffic is carried on an EVPN-VPWS single-homed service that is created between PLE endpoints.

  2. EVPN-VPWS signalling information is carried using BGP between the PLE circuit endpoints either through direct BGP sessions or through a BGP services route-reflector.

  3. EVPN-VPWS pseudowire channel is set up between the endpoints when the CEM (Circuit Emulation) client interfaces are configured on each endpoint router and end-to-end transport connectivity using MPLS or Segment Routing transport is enabled.

  4. CEM over a packet-switched network (PSN) places the client bit streams into packet payloads with appropriate pseudowire emulation headers.

    CEM is a method through which client data can be transmitted over MPLS or Segment Routing networks in a bit-transparent manner, retaining the client Layer 1 frame between sender and receiver.

  5. The PLE initiator encapsulates the PLE client traffic and carries it using the EVPN-VPWS service, which runs on MPLS or Segment Routing transport.

  6. The PLE terminator node extracts the bit streams from the EVPN-VPWS packets and places them onto the PLE client interfaces as defined by the client attribute and CEM profile.

Circuit-Style Segment Routing

Segment Routing provides an architecture that caters to both IP-centric transport and connection-oriented transport. IP-centric transport uses the benefits of ECMP and automated protection from TI-LFA. Connection-oriented transport, which was historically delivered over circuit-switched SONET/SDH networks, requires the following:

  • End-to-end bidirectional transport that provides congruent forward and reverse paths, predictable latency, and disjointness.

  • Bandwidth commitment to ensure that there is no impact on the SLA due to network load from other services.

  • Monitoring and maintenance of path integrity with end-to-end 50-msec path protection.

  • Persistent end-to-end paths regardless of the state of the control plane.

Introduction to Circuit-Style SR Policies

Circuit-Style SR policies have the following properties:

  • Guaranteed Latency over Non-ECMP Paths

  • Control-Plane Independent Persistency

  • Co-Routed Bidirectional Path

  • Liveness Monitoring with Path Protection Switching

Guaranteed Latency over Non-ECMP Paths

Consider the following network with three possible paths from node 1 to node 7. Of the three paths, the best end-to-end delay is provided by the blue path (1 -> 2 -> 3 -> 7). The chosen path is then encoded with adjacency SIDs corresponding to the traversed interfaces to avoid any ECMP, and therefore guarantee the latency over the path.

Control-Plane Independent Persistency

Adjacency SIDs can provide a persistent path independent from control-plane changes (such as IGP neighbor flaps), and network events (such as interface additions or interface flaps) and even the presence of IP on an interface. To achieve this, adjacency SIDs can be manually allocated to ensure persistent values, for example, after a node reload event. In addition, adjacency SIDs can be programmed as non-protected to avoid any local TI-LFA protection.

With the adjacency SIDs depicted in the following figure, the path from node 1 to node 7 is encoded with the segment list of {24000, 24001, 24000}. By manually allocating the same adjacency SID values for other direction, the path from node 7 to node 1 is encoded with the same segment list of {24000, 24001, 24000}.

Co-Routed Bidirectional Path

Forward and return SR policies with congruent paths are routed along the same nodes.

Liveness Monitoring with Path Protection Switching

Bidirectional liveness monitoring on the working and protect paths ensures fast and consistent switchover, while a protect path is pre-programmed over disjoint facilities.

Usage Guidelines and Limitations

  • Candidate path (CP) behavior:

    • The working path has the highest CP preference value.

    • The protect path has the second highest CP preference value.

    • The restore path has the lowest CP preference value and is configured as "backup ineligible."

    • Paths with the same role in both directions (working, protect, and restore) must have the same CP preference value.

  • Bidirectional path behavior:

    • All paths must be configured as corouted.

    • All paths with the same role in both directions (working, protect, and restore) must have the same bidirectional association ID value.

    • The bidirectional association ID value must be globally unique.

Guaranteed Bandwidth

Most services carried over the CS-SR policy are constant-rate traffic streams. Any packet loss due to temporary congestion leads to bit errors at the service layer. Therefore, bandwidth must be managed very tightly and guaranteed to the services mapped to CS-SR policies.

A centralized controller manages the bandwidth reservation. The controller maintains the reserved bandwidth on each link based on the requested bandwidth:

  • Monitors amount of traffic

  • Uses knowledge of the active path used by the policy

  • Computes the per-link reservable bandwidth accordingly

Bandwidth is reserved on both the working and protect paths.

Configure PLE over EVPN-VPWS

Configuring PLE over the EVPN-VPWS service procedure involves the following tasks:

  1. Enable frequency synchronization

  2. Configure optics controller with payloads

  3. Configure QoS Policy

  4. Configure CEM Interface for L2VPN Service

  5. Configure Performance Measurement

  6. Configure Segment Routing Adjacency SIDs

  7. Define Paths Between PLE Endpoints

  8. Configure Static Circuit-Style SR-TE Policies

  9. Configure PLE over EVPN-VPWS

See the Private Line Emulation over EVPN-VPWS Single Homed section for pre-requisites and other details.

Enable frequency synchronization

Use this task to synchronize clocks between Provider Edge 1 (PE1) and Provider Edge 2 (PE2) routers.

Procedure

Step 1

Enter these commands to enable frequency synchronization on PLE-PE1.

Example:


Router(config)# frequency synchronization 
Router(config-freqsync)# quality itu-t option 1
Router(config-freqsync)# exit
Router(config)# interface TwentyFiveGigE0/0/0/24
Router(config-if)# frequency synchronization
Router(config-if-freqsync)# quality transmit exact itu-t option 1 PRC

Step 2

Enter the show frequency synchronization interfaces command to verify that the clock signal is being transmitted.

Step 3

Enter these commands to enable frequency synchronization on PLE-PE2.

Example:


Router(config)# frequency synchronization
Router(config-freqsync)# quality itu-t option 1
Router(config-freqsync)# exit
Router(config)# interface TwentyFiveGigE0/0/0/32
Router(config-if)# frequency synchronization
Router(config-if-freqsync)# selection input
Router(config-if-freqsync)# priority 1
Router(config-if-freqsync)# wait-to-restore 0

Step 4

Enter the show frequency synchronization selection command to verify that PLE-PE2 is locked to the clock of PLE-PE1.

You have synchronized the clocks between PE1 and PE2 routers.

Configure optics controller with payloads

Use this task to configure the optics controller with different payloads.

Each port on the NC55-OIP-2 (PID of PLE Modular Port Adapter) can be configured independently for a specific PLE transport type. Use the port-mode command under the optics controller to perform this configuration.

For more information about all the supported payloads, refer to the Supported Payloads section.

Procedure

Step 1

Enter these commands to configure the optics controller with Ethernet payload.

Example:


Router(config)# controller Optics0/0/3/1 
Router(config-Optics)# port-mode Ethernet framing cem-packetize rate 10GE

The port-mode command has several parameters:

  • PLE transport type: Choose Ethernet, OTN, SONET, SDH, or Fibre Channel.

  • Framing: Set to cem-packetize to specify a PLE CEM configuration. This parameter is required.

  • Rate: Configure the specific payload.

Step 2

Enter these commands to configure the optics controller with OTN payload.

Example:


Router(config)# controller Optics0/0/3/2 
Router(config-Optics)# port-mode otn framing cem-packetize rate otu2

Step 3

Enter these commands to configure the optics controller with SONET payload.

Example:


Router(config)# controller Optics0/0/3/3 
Router(config-Optics)# port-mode sonet framing cem-packetize rate OC48

Step 4

Enter these commands to configure the optics controller with SDH payload.

Example:


Router(config)# controller Optics0/0/3/4 
Router(config-Optics)# port-mode sdh framing cem-packetize rate STM16

Step 5

Enter these commands to configure the optics controller with Fiber Channel payload.

Example:


Router(config)# controller Optics0/0/3/5 
Router(config-Optics)# port-mode FC framing cem-packetize rate FC1

The optics controller is configured with different payloads.

Configure QoS Policy

Use this task to configure QoS policy to prioritize PLE traffic. This configuration is optional but is recommended so that higher priority PLE traffic is not dropped during network congestion.

Procedure

Step 1

Router(config)# policy-map ple-policy

Defines the parent QoS policy to be applied to the CEM interface to prioritize the PLE traffic.

Step 2

Router(config-pmap)# class class-default

There is only one traffic flow type in a PLE service. Hence, the default class is used to match all the ingress packets on the PLE CEM interface.

Step 3

Router(config-pmap-c)# set traffic-class 6

Cisco NCS 5500 and NCS 5700 platforms use traffic class within the router to identify specific traffic flows and differentiate how they are treated on egress. In this example, traffic class 6 is set on ingress. The egress QoS policy matches traffic class 6 and sets appropriate queuing behavior. This value is used as an example; it must be set to the high priority EXP value used across the network. The egress QoS policy is outside the scope of this guide. For egress QoS policy, see Modular QoS Configuration Guide for Cisco NCS 5500 Series Routers.

Step 4

Router(config-pmap-c)# set mpls experimental topmost 6

Sets the topmost MPLS EXP (TC) value to 6. The value can be used at subsequent nodes in the path to classify PLE traffic and set appropriate queuing behavior. This value is used as an example; it must be set to the high priority EXP value used across the network.

Step 5

Router(config-pmap-c)# end-policy-map

Configure CEM Interface for L2VPN Service

Use this task to configure the CEM interface for the L2VPN EVPN-VPWS service.

Procedure

Step 1

Router(config)# interface CEM0/0/3/1

Configures the appropriate CEM interface.

Step 2

Router(config-if)# l2transport

Enables the CEM interface to be used in a L2VPN EVPN-VPWS service.

Configure Performance Measurement

Use this task to configure the performance measurement to enable the liveness monitoring of the Segment Routing policy.

Procedure

Step 1

Router(config)# performance-measurement

Enters the performance measurement configuration.

Step 2

Router(config-perf-meas)# liveness-profile name liveness-check

Creates a SR Policy liveness profile.

Step 3

Router(config-perf-meas)# liveness-detection multiplier 3

Configures liveness detection parameters and configures the number of missed liveness probes to determine whether the SR Policy is down.

Step 4

Router(config-pm-ld-srpolicy)# probe

Enters the probe parameter configuration mode.

Note

 

By default, probe measurment mode is set to loopback. In this mode, probe packets from the sender node are looped back to the sender node from the receiver node to test end-to-end liveness.

Step 5

Router(config-pm-ld-srpolicy-probe)# tx-interval 30000

Sets the interval of probe packets that are sent by the sender. The interval value is set in microseconds, and set to 30 seconds in this example.

Note

 

Using a tx-interval value lower than 30 seconds requires hw-offload support. NCS-55A2-MOD supports this in R7.9.1.

Step 6

Router(config-pm-ld-srpolicy-probe)# tos dscp 48

The tos parameter sets the Differentiated Services Code Point (DSCP) value on the probe packets to the specified DSCP. In this example it is 48, but must be set to the appropriate QoS value on the provider network to treat the liveness probe packets at high priority.

Configure Segment Routing Adjacency SIDs

Use this task to configure SR Adjacency SIDs between routers. Adjacency SIDs are unidirectional and are used to define the explicit path between endpoints. Adjacency SIDs must set on each interface participating in the SR policy path.

The following figure illustrates the SR adjacency SIDs configured between routers.

Figure 1. Segment Routing Adjacency SIDs
Segment Routing Adjacency SIDs

Procedure

Step 1

Router(config)# router isis core

Enters IS-IS configuration mode for the appropriate instance. In this example, the instance is core.

Step 2

Router(config-isis)# interface HundredGigE0/0/2/0

Configures specific IS-IS interface.

Step 3

Router(config-isis-if)# address-family ipv4 unicast

Enters the IPv4 address family configuration if MPLS segment routing is used.

Step 4

Router(config-isis-if-af)# adjacency-sid absolute 15001

Configures a persistent SR adjacency SID on the interface. This value must be assigned from the Segment Routing Local Block (SRLB) of the router. The default SRLB range in IOS-XR is 15000–15999.

Configure other SR adjacency SIDs as appropriate.

Define Paths Between PLE Endpoints

Use this task to define end-to-end paths between PLE endpoints.


Note

This task applies only for static circuit-style SR-TE policies.
Figure 2. Working and Reverse Path Definitions
Working and Reverse Path Definitions

Perform the following configurations on the NCS57C3-1 router to define the working forward path. In the illustration, the working forward path is a single hop between directly connected routers.

Procedure

Step 1

Router(config)# segment-routing

Enters segment routing configuration.

Step 2

Router(config-sr)# traffic-engineering

Enters segment routing TE configuration.

Step 3

Router(config-sr-te)# segment-list working-forward-path

Creates segment list with name working-forward-path.

Step 4

Router(config-sr-te-sl)# index 1 mpls label 15191

Sets index 1 to the first hop interface adjacency SID.

Perform the following configurations on the NCS57C3-1 router to define the working reverse path. In the illustration, the working reverse path is a single hop between directly connected routers. 


Router(config-sr-te)# segment-list working-reverse-path
Router(config-sr-te-sl)# index 1 mpls label 15119

Perform the following configurations on the NCS57C3-1 router to define the protect forward path. In the illustration, the protect forward path has four interface hops between the near-end and far-end router. 


Router(config-sr-te)# segment-list protect-forward-path
Router(config-sr-te-sl)# index 1 mpls label 15001
Router(config-sr-te-sl)# index 2 mpls label 15002
Router(config-sr-te-sl)# index 3 mpls label 15003
Router(config-sr-te-sl)# index 4 mpls label 15004

Perform the following configurations on the NCS57C3-1 router to define the protect reverse path. In the illustration, the protect reverse path has four interface hops between the near-end and far-end router. 


Router(config-sr-te)# segment-list protect-reversepath
Router(config-sr-te-sl)# index 1 mpls label 15101
Router(config-sr-te-sl)# index 2 mpls label 15102
Router(config-sr-te-sl)# index 3 mpls label 15103
Router(config-sr-te-sl)# index 4 mpls label 15104

Perform the following configurations on the NCS55A2-1 router to define all the paths according to the illustration.


Router(config)# segment-routing
Router(config-sr)# traffic-eng
Router(config-sr-te)# segment-list working-forward-path
Router(config-sr-te-sl)# index 1 mpls label 15119
!
Router(config-sr-te)# segment-list working-reverse-path
Router(config-sr-te-sl)# index 1 mpls label 15191
!
Router(config-sr-te)# segment-list protect-forward-path
Router(config-sr-te-sl)# index 1 mpls label 15101
Router(config-sr-te-sl)# index 2 mpls label 15102
Router(config-sr-te-sl)# index 3 mpls label 15103
Router(config-sr-te-sl)# index 4 mpls label 15104
!
Router(config-sr-te)# segment-list protect-reversepath
Router(config-sr-te-sl)# index 1 mpls label 15001
Router(config-sr-te-sl)# index 2 mpls label 15002
Router(config-sr-te-sl)# index 3 mpls label 15003
Router(config-sr-te-sl)# index 4 mpls label 15004

Configure Static Circuit-Style SR-TE Policies

Use this task to configure static circuit-style SR-TE policies.

Figure 3. Segment Routing Traffic Engineering Policy
Segment Routing Traffic Engineering Policy

Perform the following configurations on the NCS57C3-1 router.

Before you begin

Static Circuit-Style SR-TE policies requires IOS XR 7.7.1 or later software.

Procedure

Step 1

Router(config)# segment-routing

Enters segment routing configuration.

Step 2

Router(config-sr)# traffic-engineering

Enters segment routing TE configuration.

Step 3

Router(config-sr-te)# policy to-55a2-1

Creates a SR-TE policy with the name to-55a2-1.

Step 4

Router(config-sr-te-policy)# color 1001 end-point ipv4 10.0.0.44

Configures the SR-TE policy with the user-defined color and loopback address of the remote PLE far-end router.

Step 5

Router(config-sr-te-policy)# path-protection

Enables path protection on the SR-TE policy. When configured, the near-end router keeps the protect path in warm-standby state to quickly transition to it if the working path is down.

Step 6

Router(config-sr-te-policy)# candidate-paths

Configures the SR working and protect candidate paths.

Step 7

Router(config-sr-te-policy-path)# preference 50

Sets the user-defined preference on the protect path. Higher preference candidate paths are preferred over lower preference paths.

Note

 

The protect path must always be set with lower preference value.

Step 8

Router(config-sr-te-policy-path-pref)# explicit segment-list protect-forward-path

Configures the candidate path to use an explicit segment list. The previously defined protect-forward-path explicit segment list is used.

Step 9

Router(config-sr-te-policy-path-pref)# reverse-path segment-list protect-reverse-path

Configures the reverse path to ensure that the SR-TE Policy uses a corouted bidirectional path. The previously defined protect-reverse-path explicit segment list is used.

Configure the higher priority working path similar to the protect path using the following commands:


Router(config-sr-te-policy-path)# preference 100
Router(config-sr-te-policy-path-pref)# explicit segment-list working-forward-path
Router(config-sr-te-policy-path-pref)# reverse-path segment-list working-reverse-path

Step 10

Router(config)# performance-measurement

Configures performance-measurement for the SR-TE policy.

Step 11

Router(config-perf-meas)# liveness-detection

Configures liveness detection parameters.

Step 12

Router(config-perf-meas)# liveness-profile name liveness-check

Configures a user-defined liveness policy to be used. In this case, the previously defined liveness profile liveness-check is used.

Perform the following configurations on the NCS55A2-1 router:


Router(config)# segment-routing
Router(config-sr)# traffic-eng
Router(config-sr-te)# policy to-57c3-1
Router(config-sr-te-policy)# color 1001 end-point ipv4 10.0.0.42
Router(config-sr-te-policy)# path-protection
Router(config-sr-te-policy)# candidate-paths
Router(config-sr-te-policy-path)# preference 50
Router(config-sr-te-policy-path-pref)# explicit segment-list protect-forward-path
Router(config-sr-te-policy-path-pref)# reverse-path segment-list protect-reverse-path
Router(config-sr-te-policy-path)# preference 100
Router(config-sr-te-policy-path-pref)# explicit segment-list working-forward-path
Router(config-sr-te-policy-path-pref)# reverse-path segment-list working-reverse-path
Router(config)# performance-measurement
Router(config-perf-meas)# liveness-detection
Router(config-perf-meas)# liveness-profile name liveness-check

Configure Dynamic Circuit-Style SR-TE Policies Without Bandwidth CAC

Use this task to configure dynamic circuit-style SR-TE policies without bandwidth Call Admission Control (CAC).

Before you begin

Dynamic Circuit-Style SR-TE policies without bandwidth CAC requires the following software:

  • IOS XR R7.8.1 or later

  • SR-PCE 7.8.1 or later

Procedure

Step 1

Router(config)# segment-routing

Enters segment routing configuration.

Step 2

Router(config-sr)# traffic-engineering

Enters segment routing traffic engineering configuration.

Step 3

Router(config-sr-te)# policy policy-name

Creates a SR-TE policy with the specified name.

Step 4

Router(config-sr-te-policy)# color 119 end-point ipv4 10.0.0.44

Configures the SR-TE policy with the user-defined color and loopback address of the remote PLE far-end router.

Step 5

Router(config-sr-te-policy)# path-protection

Enables path protection on the SR-TE policy. When configured, the near-end router keeps the protect path in standby state to quickly transition to it if the working path is down.

Step 6

Router(config-sr-te-policy)# candidate-paths dynamic pcep

Configures the SR working, protect, and restoration candidate paths.

The candidate-paths parameter is set to dynamic->pcep to enable SR-PCE delegation. The dynamic computation can be based on standard metrics such as traffic engineering, IGP, or latency.

Step 7

Router(config-sr-te-policy-path)# preference 50

Sets the user-defined preference on the protect path. Higher preference candidate paths are preferred over lower preference paths.

Note

 

The protect path must always be set with lower preference value.

The third candidate path with a preference lower than 100 can be defined as a restoration path. The restoration path is not presignaled and must be configured with backup-ineligible. The restoration path does not have a defined disjoint-path ID, but has a bidirectional association-id matching the reverse policy.

The lock-duration parameter determines the reversion behavior. If a higher preference path is available, the policy switches to it after the expiry of lock duration. The default value is 300 seconds; the value 0 disables dynamic reversion.

Step 8

Router(config-sr-te-policy-path)# constraints segments protection {unprotected-only | adjacency-sid-only}

Configures the protection behavior constraints of adjacency-SID.

Circuit-Style uses segments constraints of unprotected-only and adjacency-sid-only. Manual adjacency-SIDs are used if they are defined; otherwise, will use dynamic adjacency-SIDs. Manual adjacency-SIDs are recommended.

Step 9

Router(config-sr-te-path-pref-const)# disjoint-path group-id 10 type {link | node | srlg | srlg-node}

Configures the disjoint-path constraints.

The group-id parameter of the disjoint-path must be the same for both active and backup paths. It must be unique for nodes using the same SR-PCE.

The co-routed association ID must be the same for both bidirectional active and backup paths.

Step 10

Router(config)# performance-measurement

Configures performance-measurement for the SR-TE policy.

Step 11

Router(config-perf-meas)# liveness-detection

Configures liveness detection parameters. The liveness detection is enabled on CS-SR policy to trigger path switchover.

Step 12

Router(config-perf-meas)# liveness-profile name liveness-check

Configures a user-defined liveness policy to be used.

Step 13

Router(config-perf-meas)# invalidation-action down

Brings down the candidate path when it becomes invalid.

The following is an example of dynamic circuit-style SR-TE policy configuration without bandwidth Call Admission Control (CAC).


policy dynamic-cs-srte-to-55a2-p2
   color 119 end-point ipv4 10.0.0.44
   path-protection
   !
   candidate-paths
    preference 100
     dynamic
      pcep
      !
      metric
       type igp
      !
     !
     constraints
      segments
       protection unprotected-only
       adjacency-sid-only
      !
      disjoint-path group-id 10 type link
     !
     bidirectional
      co-routed
      association-id 101
     !
    !
    preference 200
     dynamic
      pcep
      !
      metric
       type igp
      !
     !
     lock 
       duration 30
     !
     constraints
      segments
       protection unprotected-only
       adjacency-sid-only
      !
      disjoint-path group-id 10 type link
     !
     bidirectional
      co-routed
      association-id 201
     !
    !
    preference 50
     dynamic
      pcep
      !
      metric
       type igp
      !
     !
     backup-ineligible
     lock 
       duration 60
     !
     constraints
      segments
       protection unprotected-only
       adjacency-sid-only
      !
     !
     bidirectional
      co-routed
      association-id 301
     !
    !
   !
   performance-measurement
    liveness-detection
     liveness-profile backup name CS-PROTECT
     liveness-profile name CS-WORKING
     invalidation-action down

Configure Dynamic Circuit-Style SR-TE Policies With Bandwidth CAC

Dynamic PLE with bandwidth Call Admission Control (CAC) is supported through Crosswork Network Controller. Bandwidth constraint is specified for the circuit-style policy. Cisco Crosswork Optimization Engine application is part of Circuit Style Manager.

The Circuit Style Segment Routing Traffic Engineering (CS-SR TE) feature pack provides a bandwidth-aware Path Computation Element (PCE) to compute CS-SR policy paths that you can visualize in your network. CS-SR policies guarantee allocated bandwidth services with predictable latency and persistent bidirectional path protection of critical traffic. CS-SR TE reserves a percentage of bandwidth in the network and computes CS-SR policy bidirectional failover paths with the requested bandwidth.

Circuit Style Manager requires policies be configured on each head-end node with matching association IDs, bandwidth values, constraints, computation type, and source/endpoint IP addresses.

Figure 4. Crosswork Optimization Engine - SR—PCE Communication Flow Diagram
COE SR—PCE Communication Flow Diagram
Figure 5. Crosswork Optimization Engine - SR—PCE Call Flow Diagram
COE SR—PCE Call Flow Diagram

Before you begin

Dynamic Circuit-Style SR-TE policies with bandwidth CAC requires the following software:

  • IOS XR R7.9.1 or later

  • SR-PCE 7.9.1 or later

  • Crosswork Optimization Engine 5.0 or later

Procedure

Step 1

Enable the Circuit Style Segment Routing Traffic Engineering (CS-SR TE) feature pack.

Step 2

Configure CS-SR policies on the devices.

Step 3

Verify that the CS-SR policies appear in the SR Policy table.

Enable Circuit Style Segment Routing Traffic Engineering Using Crosswork Network Controller

In order to manage and visualize CS-SR policies on the topology map, you must first enable CS-SR TE and set bandwidth reservation settings.

When CS-SR TE is enabled, it computes the best failover bidirectional paths with the requested bandwidth and other constraints defined in the CS-SR policy configuration between two nodes.

Procedure

Step 1

From the main menu, choose Services & Traffic Engineering > Circuit Style SR-TE > Configuration .

Circuit Style Segment Routing Traffic Engineering Using CNC

Step 2

Toggle the Enable switch to True.

Step 3

Enter the required bandwidth pool size and threshold information.

Enable Circuit Style Segment Routing Traffic Engineering Using CNC
Option Description

Basic Pane

Link CS BW Pool Size

The percentage of bandwidth that each link reserves for CS-SR policies.

Link CS BW Min Threshold

An alert is generated when the bandwidth utilization percentage on a link used for a CS-SR policy exceeds this value.

Advanced Pane

Validation Interval

The interval that CS-SR policy will wait before the bandwidth that is reserved for an undelegated policy is returned to the CS-SR policy bandwidth pool.

Timeout

The duration until which CS-SR policy will wait for the delegation request, to generate a notification.

Restore Delegation Delay

The duration until which CS-SR policy will pause before processing a restore path delegation.

Step 4

Click Commit Changes to save the configuration.

View CS-SR Policy Details Using Crosswork Network Controller

Procedure

Step 1

From the main menu, choose Services & Traffic Engineering > SR-MPLS and click Circuit Style.

The SR Policy table lists all the CS-SR policies.

Step 2

From the Actions column, click View Details for one of the CS-SR policies.

The Circuit Style Policy Details window is displayed in the side panel. By default, the active path is displayed and shows the bidirectional paths (Bi-Dir Path checkbox is checked) on the topology map.

View CS-SR Policy Details Using CNC

If bandwidth of a new policy exceeds bandwidth pool size, the policy will be down. The requested bandwidth is set to the configured bandwidth, but the reserved bandwidth will be 0.

If an existing policy is configured to a new bandwidth exceeding the bandwidth pool size, the policy will stay up but the reserved bandwidth stays at the previous value.

The following sample output shows a policy with requested bandwidth and current bandwidth.

RP/0/RP0/CPU0:ron-ncs57c3-1#show segment-routing traffic-eng policy color 119
Thu May 4 09:01:57.797 PDT

SR-TE policy database
---------------------

Color: 119, End-point: 10.0.0.44
Name: srte_c_119_ep_10.0.0.44
Status:
Admin: up Operational: up for 11:46:42 (since May 3 21:15:14.898)
Candidate-paths:
Preference: 200 (configuration) (active)
Name: dynamic-cs-srte-to-55a2-p2
Requested BSID: dynamic
PCC info:
Symbolic name: cfg_dynamic-cs-srte-to-55a2-p2_discr_200
PLSP-ID: 7
Constraints:
Protection Type: unprotected-only
Maximum SID Depth: 12
Adjacency SIDs Only: True
Dynamic (pce 201.0.0.106) (valid)
Metric Type: IGP, Path Accumulated Metric: 20
SID[0]: 15739 [Adjacency-SID, 10.139.1.1 - 10.139.1.2]
SID[1]: 15720 [Adjacency-SID, 10.1.26.0 - 10.1.26.1]
Reverse path:
SID[0]: 15227 [Adjacency-SID, 10.1.26.1 - 10.1.26.0]
SID[1]: 15727 [Adjacency-SID, 10.139.1.2 - 10.139.1.1]
Protection Information:
Role: WORKING
Path Lock: Timed
Lock Duration: 300(s)
State: ACTIVE
Preference: 100 (configuration) (protect)
Name: dynamic-cs-srte-to-55a2-p2
Requested BSID: dynamic
PCC info:
Symbolic name: cfg_dynamic-cs-srte-to-55a2-p2_discr_100
PLSP-ID: 6
Constraints:
Protection Type: unprotected-only
Maximum SID Depth: 12
Adjacency SIDs Only: True
Dynamic (pce 201.0.0.106) (valid)
Metric Type: IGP, Path Accumulated Metric: 30
SID[0]: 15734 [Adjacency-SID, 10.1.42.0 - 10.1.42.1]
Reverse path:
SID[0]: 15523 [Adjacency-SID, 10.1.42.1 - 10.1.42.0]
Protection Information:
Role: PROTECT
Path Lock: Timed
Lock Duration: 300(s)
State: STANDBY
Attributes:
Binding SID: 24047
Forward Class: Not Configured
Steering labeled-services disabled: no
Steering BGP disabled: no
IPv6 caps enable: yes
Bandwidth Requested: 35.000 Gbps
Bandwidth Current: 35.000 Gbps
Invalidation drop enabled: no
Max Install Standby Candidate Paths: 0

Configure PLE over EVPN-VPWS

Use this task to configure PLE over EVPN-VPWS. The two core components are the Pseudowire class specifying the transport type and xconnect service to configure the EVPN-VPWS service parameters.

Figure 6. PLE EVPN-VPWS Service
EVPN-VPWS Service

Perform the following configurations on the NCS57C3-1 router.

Procedure

Step 1

Router(config)# l2vpn

Enters l2vpn configuration.

Step 2

Router(config-l2vpn)# pw-class circuit-style-srte

Defines the Pseudowire class to be used with the PLE service. The same Pseudowire class can be used for multiple PLE services between the same far-end routers, or a unique class can be used for each service. The Pseudowire class defines the underlying transport for the service, in this case MPLS using a specific SR-TE policy. The pw-class command is followed by a user-defined name, in this example, circuit-style-srte.

Step 3

Router(config-l2vpn-pwc)# encapsulation mpls

Configures transport encapsulation.

Step 4

Router(config-l2vpn-pwc-mpls)# preferred-path sr-te policy srte_c_1001_ep_10.0.0.42

The preferred-path is the circuit-style policy. The preferred-path is used to configure an explicit MPLS path to be used for the l2vpn service. In this case, the preferred-path is set to the SR-TE policy created from the source node to the 10.0.0.42 endpoint node. The path is not the configured name of the policy; it is the computed name.

Step 5

Router(config-l2vpn)# xconnect group ple

Enters xconnect configuration mode. The xconnect group command is used to administratively group similar L2VPN services and can be set to any user-defined value.

Step 6

Router(config-l2vpn-xc)# p2p ple-cs-1

Creates point-to-point L2VPN service with user-defined name ple-cs-1.

Step 7

Router(config-l2vpn-xc-p2p)# interface cem 0/0/2/1

Specifes the client interface. This interface is the CEM interface type for PLE.

Step 8

Router(config-l2vpn-xc-p2p)# neighbor evpn evi 100 target 4201 source 4401

Configures EVPN-VPWS parameters. The user-defined evi value must be the same on each far-end router. The target must be the “source” value that is configured on the remote endpoint.

Step 9

Router(config-l2vpn-xc-p2p-pw)# pw-class circuit-style-srte

Attaches the previously defined Pseudowire class circuit-style-te to the L2VPN service.

Perform the following configurations on the NCS55a2-1 router.


Router(config)# l2vpn 
Router(config-l2vpn)# pw-class circuit-style-srte 
Router(config-l2vpn-pwc)# encapsulation mpls 
Router(config-l2vpn-pwc-mpls)# preferred-path sr-te policy srte_c_1001_ep_10.0.0.44 
Router(config-l2vpn)# xconnect group ple 
Router(config-l2vpn-xc)# p2p ple-cs-1 
Router(config-l2vpn-xc-p2p)# interface cem0/0/2/1 
Router(config-l2vpn-xc-p2p)# neighbor evpn evi 100 target 4201 source 4401 
Router(config-l2vpn-xc-p2p-pw)# pw-class circuit-style-srte

Verify PLE configurations

Verify PLE configurations using these commands.

Procedure

Step 1

Use this command to show the general CEM statistics.

Example:

RP/0/RP0/CPU0:ron-ncs57c3-1#show controllers CEM 0/0/3/1

Sat Sep 24 11:34:22.533 PDT
Interface : CEM0/0/3/1
Admin state : Up
Oper state : Up
Port bandwidth : 10312500 kbps
Dejitter buffer (cfg/oper/in-use) : 0/813/3432 usec
Payload size (cfg/oper) : 1280/1024 bytes
PDV (min/max/avg) : 980/2710/1845 usec
Dummy mode : last-frame
Dummy pattern : 0xaa
Idle pattern : 0xff
Signalling : No CAS
RTP : Enabled
Clock type : Differential
Detected Alarms : None
Statistics Info
---------------
Ingress packets : 517617426962, Ingress packets drop : 0
Egress packets : 517277124278, Egress packets drop : 0
Total error : 0
Missing packets : 0, Malformed packets : 0
Jitter buffer underrun : 0, Jitter buffer overrun : 0
Misorder drops : 0
Reordered packets : 0, Frames fragmented : 0
Error seconds : 0, Severely error seconds : 0
Unavailable seconds : 0, Failure counts : 0
Generated L bits : 0, Received L bits : 0
Generated R bits : 339885178, Received R bits : 17
Endpoint Info
-------------
Passthrough : No

Step 2

Use this command to show the PM statistics for 30 seconds.

Example:

RP/0/RP0/CPU0:ron-ncs57c3-1#show controllers CEM 0/0/3/1 pm current 30-sec cem

Sat Sep 24 11:37:02.374 PDT
CEM in the current interval [11:37:00 - 11:37:02 Sat Sep 24 2022]
CEM current bucket type : Valid
INGRESS-PKTS : 2521591 Threshold : 0 TCA(enable) : NO
EGRESS-PKTS : 2521595 Threshold : 0 TCA(enable) : NO
INGRESS-PKTS-DROPPED : 0 Threshold : 0 TCA(enable) : NO
EGRESS-PKTS-DROPPED : 0 Threshold : 0 TCA(enable) : NO
INPUT-ERRORS : 0 Threshold : 0 TCA(enable) : NO
OUTPUT-ERRORS : 0 Threshold : 0 TCA(enable) : NO
MISSING-PKTS : 0 Threshold : 0 TCA(enable) : NO
PKTS-REORDER : 0 Threshold : 0 TCA(enable) : NO
JTR-BFR-UNDERRUNS : 0 Threshold : 0 TCA(enable) : NO
JTR-BFR-OVERRUNS : 0 Threshold : 0 TCA(enable) : NO
MIS-ORDER-DROPPED : 0 Threshold : 0 TCA(enable) : NO
MALFORMED-PKT : 0 Threshold : 0 TCA(enable) : NO
ES : 0 Threshold : 0 TCA(enable) : NO
SES : 0 Threshold : 0 TCA(enable) : NO
UAS : 0 Threshold : 0 TCA(enable) : NO
FC : 0 Threshold : 0 TCA(enable) : NO
TX-LBITS : 0 Threshold : 0 TCA(enable) : NO
TX-RBITS : 0 Threshold : 0 TCA(enable) : NO
RX-LBITS : 0 Threshold : 0 TCA(enable) : NO
RX-RBITS : 0 Threshold : 0 TCA(enable) : NO

Step 3

Use this command to show the controller information for Ethernet 10GE.

Example:

RP/0/RP0/CPU0:ron-ncs57c3-1#show controllers TenGigECtrlr0/0/3/2

Sat Sep 24 11:43:23.164 PDT
Operational data for interface TenGigECtrlr0/0/3/2:
State:
Administrative state: enabled
Operational state: Up
LED state: Green On
PRBS:
Status: Locked
Mode: Source-sink
Pattern: User-defined
Direction: System
Error-inject: None
Framing: Unframed
User-pattern: 0xabcdef0123456789
Phy:
Media type: Not known
Autonegotiation disabled.
Operational values:
Speed: 10Gbps
Duplex: Full Duplex
Flowcontrol: None
Loopback: None (or external)
Inter-packet gap: standard (12)
BER monitoring:
Not supported

Step 4

Use this command to show the PM statistics for the Ethernet controller.

Example:

RP/0/RP0/CPU0:ron-ncs57c3-1#show controllers TenGigECtrlr0/0/3/2 pm current 30-sec ether

Sat Sep 24 11:45:39.919 PDT
ETHER in the current interval [11:45:30 - 11:45:39 Sat Sep 24 2022]
ETHER current bucket type : Valid
RX-PKT : 4528985 Threshold : 0 TCA(enable) : NO
STAT-PKT : 9057971 Threshold : 0 TCA(enable) : NO
OCTET-STAT : 2318840576 Threshold : 0 TCA(enable) : NO
OVERSIZE-PKT : 0 Threshold : 0 TCA(enable) : NO
FCS-ERR : 0 Threshold : 0 TCA(enable) : NO
LONG-FRAME : 0 Threshold : 0 TCA(enable) : NO
JABBER-STATS : 0 Threshold : 0 TCA(enable) : NO
64-OCTET : 0 Threshold : 0 TCA(enable) : NO
65-127-OCTET : 0 Threshold : 0 TCA(enable) : N
128-255-OCTET : 0 Threshold : 0 TCA(enable) : NO
256-511-OCTET : 9057971 Threshold : 0 TCA(enable) : NO
512-1023-OCTET : 0 Threshold : 0 TCA(enable) : NO
1024-1518-OCTET : 0 Threshold : 0 TCA(enable) : NO
IN-UCAST : 0 Threshold : 0 TCA(enable) : NO
IN-MCAST : 0 Threshold : 0 TCA(enable) : NO
IN-BCAST : 0 Threshold : 0 TCA(enable) : NO
OUT-UCAST : 0 Threshold : 0 TCA(enable) : NO
OUT-BCAST : 0 Threshold : 0 TCA(enable) : NO
OUT-MCAST : 0 Threshold : 0 TCA(enable) : NO
TX-PKT : 4528986 Threshold : 0 TCA(enable) : NO
OUT-OCTET : 1159420416 Threshold : 0 TCA(enable) : NO
IFIN-ERRORS : 0 Threshold : 0 TCA(enable) : NO
IFIN-OCTETS : 0 Threshold : 0 TCA(enable) : NO
STAT-MULTICAST-PKT : 0 Threshold : 0 TCA(enable) : NO
STAT-BROADCAST-PKT : 0 Threshold : 0 TCA(enable) : NO
STAT-UNDERSIZED-PKT : 0 Threshold : 0 TCA(enable) : NO
IN_GOOD_BYTES : 1159420160 Threshold : 0 TCA(enable) : NO
IN_802_1Q_FRAMES : 0 Threshold : 0 TCA(enable) : NO
IN_GOOD_PKTS : 4528985 Threshold : 0 TCA(enable) : NO
IN_DROP_OTHER : 0 Threshold : 0 TCA(enable) : NO
OUT_GOOD_BYTES : 1159420416 Threshold : 0 TCA(enable) : No
OUT_802_1Q_FRAMES : 0 Threshold : 0 TCA(enable) : NO
OUT_GOOD_PKTS : 4528986 Threshold : 0 TCA(enable) : NO
IN_ERROR_FRAGMENTS : 0 Threshold : 0 TCA(enable) : NO
IN_PKT_64_OCTET : 0 Threshold : 0 TCA(enable) : NO
IN_PKTS_65_127_OCTETS : 0 Threshold : 0 TCA(enable) : NO
IN_PKTS_128_255_OCTETS : 0 Threshold : 0 TCA(enable) : NO
IN_PKTS_256_511_OCTETS : 4528985 Threshold : 0 TCA(enable) : NO
IN_PKTS_512_1023_OCTETS : 0 Threshold : 0 TCA(enable) : NO
IN_PKTS_1024_1518_OCTETS : 0 Threshold : 0 TCA(enable) : NO
OUT_PKT_64_OCTET : 0 Threshold : 0 TCA(enable) : NO
OUT_PKTS_65_127_OCTETS : 0 Threshold : 0 TCA(enable) : NO
OUT_PKTS_128_255_OCTETS : 0 Threshold : 0 TCA(enable) : NO
OUT_PKTS_256_511_OCTETS : 4528986 Threshold : 0 TCA(enable) : NO
OUT_PKTS_512_1023_OCTETS : 0 Threshold : 0 TCA(enable) : NO
OUT_PKTS_1024_1518_OCTETS : 0 Threshold : 0 TCA(enable) : NO
TX_UNDERSIZED_PKT : 0 Threshold : 0 TCA(enable) : NO
TX_OVERSIZED_PKT : 0 Threshold : 0 TCA(enable) : NO
TX_FRAGMENTS : 0 Threshold : 0 TCA(enable) : NO
TX_JABBER : 0 Threshold : 0 TCA(enable) : NO
TX_BAD_FCS : 0 Threshold : 0 TCA(enable) : NO

Last clearing of "show controllers ETHERNET" counters never

Step 5

Use this command to show the controller information for Fiber Channel 8G.

Example:

RP/0/RP0/CPU0:ron-ncs57c3-1#show controllers EightGigFibreChanCtrlr0/0/3/4

Sat Sep 24 11:53:09.820 PDT
Operational data for Fibre Channel controller EightGigFibreChanCtrlr0/0/3/4
State:
Admin State : Up
Operational state : Up
LED state : Green On
Secondary admin state : Normal
Laser Squelch : Disabled
Performance Monitoring is enabled
Operational values:
Speed : 8 Gbps
Loopback : None
BER monitoring:
Signal Degrade : 1e-0
Signal Fail : 1e-0
Hold-off Time : 0 ms
Forward Error Correction : Not Configured

Step 6

Use this command to show the PM statistics for Fiber Channel.

Example:

RP/0/RP0/CPU0:ron-ncs57c3-1#show controllers EightGigFibreChanCtrlr0/0/3/4 pm current 30-sec fc
Sat Sep 24 11:51:55.168 PDT
FC in the current interval [11:51:30 - 11:51:55 Sat Sep 24 2022]
FC current bucket type : Valid
IFIN-OCTETS : 16527749196 Threshold : 0 TCA(enable) : NO
RX-PKT : 196758919 Threshold : 0 TCA(enable) : NO
IFIN-ERRORS : 0 Threshold : 0 TCA(enable) : NO
RX-BAD-FCS : 0 Threshold : 0 TCA(enable) : NO
IFOUT-OCTETS : 0 Threshold : 0 TCA(enable) : NO
TX-PKT : 0 Threshold : 0 TCA(enable) : NO
TX-BAD-FCS : 0 Threshold : 0 TCA(enable) : NO
RX-FRAMES-TOO-LONG : 0 Threshold : 0 TCA(enable) : NO
RX-FRAMES-TRUNC : 0 Threshold : 0 TCA(enable) : NO
TX-FRAMES-TOO-LONG : 0 Threshold : 0 TCA(enable) : NO
TX-FRAMES-TRUNC : 0 Threshold : 0 TCA(enable) : NO