Cisco ASR 900 Series User manual

LAN Switching Configuration Guide Cisco IOS XE Everest 16.5.1 (Cisco
ASR 900 Series)
First Published: 2017-03-30
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CONTENTS
CHAPTER 1 REP Access Gateway 1
Prerequisites for REP Access Gateway 1
Restrictions for REP Access Gateway 2
Information About REP Access Gateway 2
REP Access Gateway Enhancements 2
How to Configure REP Access Gateway 3
Enabling EFD Notifications 3
Configuration Examples 5
Example: Configuring REP AG EFD 5
Verifying REP Access Gateway 6
Example: Verifying REP AG EFD Notifications 6
Additional References 7
CHAPTER 2 Configuring Resilient Ethernet Protocol 9
Restrictions for Resilient Ethernet Protocol 9
Information About REP 10
REP Segments 10
Link Integrity 12
Fast Convergence 12
VLAN Load Balancing 13
Spanning Tree Protocol Interaction 14
REP Ports 14
REP Integrated with VPLS 14
Default REP Configuration 15
REP Segments and REP Administrative VLANs 15
REP Configuration Guidelines 15
REP Support on a Trunk EFP 16
REP Configurable Timers 16
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SSO Support for REP Fast Hello 17
REP Edge No-Neighbor Support 17
How to Configure REP 18
Configuring the REP Administrative VLAN 18
Configuring Trunk EFP on an Interface 20
Configuring REP Support on a Trunk EFP 21
Setting the Preemption for VLAN Load Balancing 24
Restrictions 24
Configuring SNMP Traps for REP 25
Monitoring the REP Configuration 27
Configuring REP Configurable Timers 27
Configuring REP as an Edge No-Neighbor Port 31
Configuration Examples for REP 32
Configuring the REP Administrative VLAN 32
Configuring REP Support on a Trunk EFP 32
Setting the Preemption for VLAN Load Balancing 33
Configuring SNMP Traps for REP 33
Monitoring the REP Configuration 33
Configuring REP Configurable Timers 34
Configuring REP Edge No-Neighbor Support 34
Additional References 34
Feature Information for Resilient Ethernet Protocol 35
CHAPTER 3 UniDirectional Link Detection (UDLD) Protocol 37
Information About the UDLD Protocol 37
UDLD Overview 37
UDLD Normal Mode 38
UDLD Aggressive Mode 38
UDLD Functions 39
Detecting Unidirectional Links 39
How to Configure UDLD Protocol 40
Enabling UDLD Protocol 40
Enabling UDLD Protocol at Interface Level 41
Enabling UDLD Probe Message Interval 42
Recovering the UDLD Protocol 42
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Contents

Resetting Ports 43
Configuration Examples 44
Example: Configuring UDLD Protocol 44
Verifying UDLD Protocol 44
Example: Verifying UDLD Protocol 44
CHAPTER 4 ITU-T G.8032 Ethernet Ring Protection Switching 47
Prerequisites for Configuring ITU-T G.8032 Ethernet Ring Protection Switching 47
About ITU-T G.8032 Ethernet Ring Protection Switching 47
Ring Protection Links 47
ITU-T G.8032 Ethernet Ring Protection Switching Functionality 48
R-APS Control Messages 48
CFM Protocols and Link Failures 49
G.8032 Ring-Supported Commands and Functionality 49
G.8032 ERP Timers 50
Protection Switching Functionality in a Single Link Failure and Recovery 51
Ethernet Flow Points 53
Service Instances and Associated EFPs 54
Restrictions for Configuring ITU-T G.8032 Ethernet Ring Protection Switching 55
How to Configure ITU-T G.8032 Ethernet Ring Protection Switching 55
Configuring the Ethernet Ring Profile 55
Configuring Ethernet CFM MEPs 56
Enabling Ethernet Fault Detection for a Service 57
Configuring the Ethernet Protection Ring 59
Configuring Topology Change Notification Propagation 62
Configuring a Service Instance 63
Verifying the Ethernet Ring Protection (ERP) Switching Configuration 64
Configuration Examples for ITU-T G.8032 Ethernet Ring Protection Switching 67
Example: Configuring Ethernet Ring Protection Switching 67
Example: Enabling Ethernet Fault Detection for a Service 67
Example: Verifying the Ethernet Ring Protection Configuration 68
CHAPTER 5 Multiple Spanning Tree Protocol 69
Restrictions for configuring MSTP 69
How to Configure MST Protocol 69
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Contents

Enabling Multiple Spanning Tree Protocol 70
Configuring Multiple Spanning Tree Protocol 70
Configuring untagged EFP over MST interface 71
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Contents

CHAPTER 1
REP Access Gateway
This chapter is not applicable for Cisco ASR 900 RSP3 Module.Note
Resilient Ethernet Protocol (REP) is a ring protection protocol designed to provide fast failure detection and
recovery. A REP Edge No-Neighbor (RENN) port is a port at the edge of a REP segment, connected to a
peer device that does not support REP. This feature allows CFM to notify REP when an error is detected,
such that CFM can be used to monitor the status of the Edge link, and REP can take actions.
This feature allows communication for REP to enable Ethernet Fault Detection (EFD) notifications between
the Cisco ASR 900 Series Routers and Cisco ASR 9000 Series Aggregation Services Routers configured
with REP Access Gateway (REP-AG).
•Prerequisites for REP Access Gateway, page 1
•Restrictions for REP Access Gateway, page 2
•Information About REP Access Gateway, page 2
•How to Configure REP Access Gateway, page 3
•Configuration Examples, page 5
•Verifying REP Access Gateway, page 6
•Additional References, page 7
Prerequisites for REP Access Gateway
•The interface connected to non-REP device port should be configured as a REP edgeNN port.
•CCM notification is processed only on a REP edgeNN port.
•Port MEP is only supported in REP AG. Port MEPs are configured to protect a single hop and used to
monitor link state through CFM. See Configuring Ethernet Connectivity Fault Management in a Service
Provider Network.
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•EFD is supported on down MEPs. A down MEP sends and receives CFM frames through the wire
connected to the port on which the MEP is configured. See Configuring Ethernet Connectivity Fault
Management in a Service Provider Network.
Restrictions for REP Access Gateway
•REP AG is supported for only for Port MEPs.
•When a link down is observed between the REP and Non-REP device, the convergence time is greater
with a Copper connection.
•EFD is supported on Port MEPs and EFP MEPs.
•CCM interval for MAs on which EFD is supported is limited.
•EFD is not supported on Trunk EFPs.
•EFD notifications are only supported for a single client per MA. EFD notifications are not supported
for both G-8032 and REP simultaneously.
•Only a single MEP can be configured on a the interface or EFP for EFD.
•REP AG is not supported on the ASR 900 RSP3 Module.
Information About REP Access Gateway
In a network when a link failure occurs, a Non-REP device network (access gateway) directly connected to
REP network sends failure notification, so that REP network can reroute the traffic to alternate route. But,
access devices supporting REP Edge No-Neighbor (REP ENN) only support one interface configured as a
REP Edge No-Neighbor port resulting in an unsupported architecture with the REP Access Gateway (REP
AG) device.
Fast failure detection can be established by enabling communication between Connectivity Fault Manager
(CFM) and REP. CFM on the edge ports can notify REP if any failures are detected on the monitored links,
allowing the appropriate re-convergence actions to be taken.
The mechanism for the communication is for REP to register as an Ethernet Fault Detection (EFD) client, so
that any CFM defects above a configurable threshold triggers a notification to REP.
To trigger EFD notifications on the router, CFM must be configured.Note
REP Access Gateway Enhancements
In a network where a REP and non-REP devices are connected and when a link failure occurs, a Non-REP
device network (access gateway) directly connected to REP network sends failure notification, so that REP
network can reroute the traffic to an alternate route. But, access devices supporting REP Edge No-Neighbor
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REP Access Gateway
Restrictions for REP Access Gateway

(REP ENN) only support one interface configured as a REP Edge No-Neighbor port, resulting in an unsupported
architecture with the REP Access Gateway (REP AG) device.
Figure 1: REP Access Gateway
Fast failure detection in a REP-AG configured device can be achieved by enabling communication between
Connectivity Fault Manager (CFM) and REP. CFM on the edge ports can notify REP if any failure is detected
on the monitored links, allowing the appropriate re-convergence actions to be taken.
The mechanism for the communication is for REP to register as an Ethernet Fault Detection (EFD) client, so
that any CFM defects above a configurable threshold triggers a notification to REP.
How to Configure REP Access Gateway
Enabling EFD Notifications
Before You Begin
CFM IEEE must be enabled before enabling EFD notifications. For information, see Configuring Ethernet
Connectivity Fault Management in a Service Provider Network.
For information on CFM configuration, see Carrier Ethernet Configuration Guide, Cisco IOS XE Release
(Cisco ASR 900 Series).
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REP Access Gateway
How to Configure REP Access Gateway

SUMMARY STEPS
1. enable
2. configure terminal
3. ethernet cfm domain domain-name level level-id
4. service {short-ma-name |number MA-number |vlan-id primary-vlan-id |vpn-id vpn-id} {vlan vlan-id
|port |evc evc-name}direction {up |down}
5. continuity-check [interval time |loss-threshold threshold |static rmep]
6. continuity-check [interval cc-interval]
7. efd notify {g8032|rep}
8. end
DETAILED STEPS
PurposeCommand or Action
Enables privileged EXEC mode.enable
Step 1
Example:
Router> enable
Enter your password if prompted.
Enters global configuration mode.configure terminal
Example:
Router# configure terminal
Step 2
Defines a CFM maintenance domain at a specified
maintenance level and places the CLI in Ethernet CFM
configuration mode.
ethernet cfm domain domain-name level level-id
Example:
Router(config)# ethernet cfm domain Customer
level 7
Step 3
Configures a maintenance association within a maintenance
domain and enters Ethernet connectivity fault management
(CFM) service configuration mode.
service {short-ma-name |number MA-number |
vlan-id primary-vlan-id |vpn-id vpn-id} {vlan vlan-id
|port |evc evc-name}direction {up |down}
Example:
Device(config-ecfm)# service s1 port
Step 4
Enables the transmission of CCMs.
continuity-check [interval time |loss-threshold
threshold |static rmep]
Step 5
Example:
Router(config-ecfm-srv)# continuity-check
Configures the per-service parameters and sets the interval at
which CCMs are transmitted.
continuity-check [interval cc-interval]
Example:
Device(config-ecfm-srv)# continuity-check
interval 10s
Step 6
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REP Access Gateway
Enabling EFD Notifications