Catalyst 4500 Series Switch Software Configuration Guide, 12.2(46)SG

Configuring Y.1731 (AIS and RDI)

The Catalyst 4500 series switch supports Y.1731 Ethernet Alarm Indication Signal function (ETH-AIS) and Ethernet Remote Defect Indication function (ETH-RDI) to provide fault and performance management for service providers in large networks. This chapter describes how to configure Y.1731 ETH-AIS and ETH-RDI.

Note For complete command and configuration information for Y.1731, see the Cisco IOS feature module at this URL:

http://www.cisco.com/en/US/docs/ios-xml/ios/cether/configuration/12-2sr/ce-cfm-y1731.html

This chapter contains these sections:

•Definition List

•Y.1731 Overview

•Configuring Y.1731

•Displaying Y.1731 Information

Definition List

Y.1731 Overview

These sections contain conceptual information about Y.1731:

•Background

•Alarm Indication Signal

•Ethernet Remote Defect Indication

Background

The advent of Ethernet as a metropolitan and WAN technology imposes a new set of Operations, Administration and Maintenance (OAM) requirements on Ethernet's traditionally Enterprise-oriented functions. The expansion of this technology into the larger and more complex wider user base makes operational management of link uptime crucial. Isolating and responding to failures quickly directly affects the competitiveness of the Service Provider.

Server MEP

A Server MEP represents the compound function of the Server layer termination and Server/ETH adaptation function that is used to notify the ETH layer MEPs upon failure detection by the Server layer termination function or Server/ETH adaptation function, where the Server layer termination function is expected to run OAM mechanisms specific to the Server layer. A Server MEP needs to support ETH-AIS function and the Server/ETH adaptation function is required to issue frames with ETH-AIS information upon detection of a defect at the Server layer by the Server layer termination and/or adaptation function.

A virtual MEP represents the logical termination point of CFM MAs defined at the link or transport layer. You might imagine a server MEP as one running or defined at Maintenance Level -1. For example, you could associate an outward facing Server MEP with each termination point of IEEE 802.3ah OAM, or with each termination point of MPLS PW OAM.

Alarm Indication Signal

ETH-AIS enables you to suppress alarms following detection of defect conditions at the server (sub) layer. Due to independent restoration capabilities provided within the Spanning Tree Protocol (STP) environments, you would not expect to apply ETH-AIS in the STP environments. For the Catalyst 4500 Metro switch, AIS is configurable; the administrator can enable and disable AIS in the STP environment.

Transmission of frames with ETH-AIS information can be enabled or disabled on a MEP (or on a Server MEP).

Frames with ETH-AIS information can be issued at the client Maintenance Level by a MEP, including a Server MEP upon detecting defect conditions. For example, the defect conditions may include:

•Signal fail conditions in the case that ETH-CC is enabled

•AIS condition in the case that ETH-CC is disabled

For multipoint ETH connectivity, a MEP cannot determine the specific server (sub) layer entity that has encountered defect conditions upon receiving a frame with ETH-AIS information. More importantly, it cannot determine the associated subset of its peer MEPs for which it should suppress alarms since the received ETH-AIS information does not contain that information. Therefore, upon reception of a frame with ETH-AIS information, the MEP suppresses alarms for all peer MEPs whether there is still connectivity or not.

For a point-to-point ETH connection, however, a MEP has only a single peer MEP. Therefore, there is no ambiguity regarding the peer MEP for which it should suppress alarms when it receives the ETH-AIS information.

Only a MEP, including a Server MEP, is configured to issue frames with ETH-AIS information. Upon detecting a defect condition the MEP can immediately start transmitting periodic frames with ETH-AIS information at a configured client Maintenance Level. In Cisco IOS we send at MIP level configured at the interface. A MEP continues to transmit periodic frames with ETH-AIS information until the defect condition is removed. Upon receiving a frame with ETH-AIS information a MEP detects AIS condition and suppresses loss of continuity alarms associated with all its peer MEPs. A MEP resumes loss of continuity alarm generation upon detecting loss of continuity defect conditions in the absence of AIS condition.

Ethernet Remote Defect Indication

A MEP can use ETH-RDI to communicate to its peer MEPs that a defect condition has been encountered. ETH-RDI is used only when ETH-CC transmission is enabled.

ETH-RDI has the following two applications:

•Single-ended fault management: The receiving MEP detects an RDI defect condition, which gets correlated with other defect conditions in this MEP and may become a fault cause. The absence of received ETH-RDI information in a single MEP indicates the absence of defects in the entire Maintenance.

•Contribution to far-end performance monitoring: It reflects that there was a defect condition in the far-end which is used as an input to the performance monitoring process.

A MEP that is in a defect condition transmits frames with ETH-RDI information. A MEP, upon receiving frames with ETH-RDI information, determines that its peer MEP has encountered a defect condition. For multipoint ETH connectivity, however, a MEP, upon receiving frames with ETH-RDI information, cannot determine the associated subset of its peer MEPs with which the MEP transmitting RDI information encounters defect conditions. This is because the transmitting MEP itself does not always have that information.

Figure 57-1 Generation and Propagation of AIS Messages and the CC with RDI upon a Defect (link fail)I

Configuring Y.1731

Note Y.1731 is enabled by default.

These sections are included

•Y.1731 Configuration Guideline

•Configuring AIS Parameters

•Clearing MEP from the AIS defect condition

•Clearing SMEP from the AIS defect condition

Y.1731 Configuration Guideline

Configuration guidelines and restrictions for Y.1731 include the following:

•ETH-AIS is not expected to be applied in the STP environments, because of independent restoration capabilities provided within the STP.

•AIS is enabled by default on an CFM maintenance domain. The following section illustrates the commands you can use to disable AIS on a maintenance domain. Like-wise, RDI is a flag bit in the CC message. Provided CC transmission is enabled, the present RDI flag of the CC message is set to true or false.

Configuring AIS Parameters

To set the parameters for AIS, do the following:

Use the no versions of the commands to remove the configuration or return to the default configurations.

Clearing MEP from the AIS defect condition

To do this, use one of the following commands:

Switch# clear ethernet cfm ais domain domain name mpid local mpid vlan vlan#

Switch# clear ethernet cfm ais domain domain name mpid local mpid evc evc_name

Clearing SMEP from the AIS defect condition

To do this, use one of the following commands:

Switch# clear ethernet cfm ais link-status interface interface_name

Switch# clear ethernet cfm error

Note This also clears all error conditions including AIS.

Displaying Y.1731 Information

This example show how to track the RDI defect and to verify the configuration parameters:

Switch# show ethernet cfm main local detail

MEP Settings:

-------------

MPID: 1109

DomainName: PROVIDER_DOMAIN

Level: 4

Direction: I

EVC: evc_1

Interface: Gi3/1

CC-Status: Enabled

MAC: 001b.d550.91fd

Defect Condition: No Defect

presentRDI: FALSE (RDI defect is NOT present)

AIS-Status: Enabled

AIS Period: 60000(ms)

AIS Expiry Threshold: 3.5

Level to transmit AIS: Default

Suppress Alarm configuration: Enabled

Suppressing Alarms: No

MIP Settings:

-------------

Level Type  Port                      MAC

7     MIP   Gi3/1                     001b.d550.91fd

4     MIP   Te1/2                     001b.d550.91fd

Switch#

*Feb 18 05:40:35.659: %ETHER_CFM-6-ENTER_AIS: local mep with mpid 1109 level 4 id 100 dir 
I Interface GigabitEthernet3/1 enters AIS defect condition  
(gi3/2 enters AIS state)

Switch# show ethernet cfm main local detail

MEP Settings:

-------------

MPID: 1109

DomainName: PROVIDER_DOMAIN

Level: 4

Direction: I

EVC: evc_1

Interface: Gi3/1

CC-Status: Enabled

MAC: 001b.d550.91fd

Defect Condition: AIS

presentRDI: TRUE (RDI defect IS present)

AIS-Status: Enabled

AIS Period: 60000(ms)

AIS Expiry Threshold: 3.5

Level to transmit AIS: Default

Suppress Alarm configuration: Enabled

Suppressing Alarms: Yes

MIP Settings:

-------------

Level Type  Port                      MAC

7     MIP   Gi3/1                     001b.d550.91fd

4     MIP   Te1/2                     001b.d550.91fd

Switch# show ethernet cfm error

Level Vlan MPID Remote MAC     Reason               Service ID

4     100  2101 001d.4566.aa3d 0 lifetime TLV       customerX

4     100    -  001b.d550.91fd Receive AIS          customerX

Switch#

*Feb 18 05:51:08.567: %ETHER_CFM-6-EXIT_AIS: local mep with mpid 1109 level 4 id 100 dir I 
Interface GigabitEthernet3/1 exited AIS defect condition

(gi3/1 exits AIS state)

Switch# show ethernet cfm main local detail

MEP Settings:

-------------

MPID: 1109

DomainName: PROVIDER_DOMAIN

Level: 4

Direction: I

EVC: evc_1

Interface: Gi3/1

CC-Status: Enabled

MAC: 001b.d550.91fd

Defect Condition: No Defect

presentRDI: FALSE (RDI defect is not present anymore)

AIS-Status: Enabled

AIS Period: 60000(ms)

AIS Expiry Threshold: 3.5

Level to transmit AIS: Default

Suppress Alarm configuration: Enabled

Suppressing Alarms: No

MIP Settings:

-------------

Level Type  Port                      MAC

7     MIP   Gi3/1                     001b.d550.91fd

4     MIP   Te1/2                     001b.d550.91fd

Switch#

To display Y.1731 information, you can use the following commands (Table 57-1).

show ethernet cfm maintenance-point local 
detail

show ethernet cfm smep [interface <name>]

show ethernet cfm error

show ethernet cfm maintenance-points 
remote [detail