Configuring Basic CFM Functions
This section describes how to configure basic connectivity fault management (CFM) functions.
Usage Scenario
IP-layer mechanisms, such as IP ping and traceroute, are used to manage network-wide services, detect faults, and monitor performance on traditional Ethernet networks. These mechanisms are not effective for Ethernet operation and management.
Both interfaces of the direct link between the CE and PE1 are Layer 2 interfaces.
A Layer 2 network is deployed between the CE and PE2.
A Layer 2 network is connected to a Layer 3 network through PE3.
Pre-configuration Tasks
Group the devices of each Internet service provider (ISP) into a maintenance domain (MD).
Specify the name and level of the MD and configure the same MD name and level on the devices in the MD.
Specify maintenance associations (MAs) for the MD based on service types, such as VLAN, VPLS and VLL.
Specify each MA's name and configure the same MA name on the devices in the MD.
Specify maintenance association end points (MEPs) and maintenance association intermediate points (MIPs) for each MA in the MD.
Enabling CFM Globally
(Optional) Switching CFM Versions
This section describes how to switch between connectivity fault management (CFM) versions.
Context
CFM has two versions: IEEE 802.1ag Draft 7 and IEEE Standard 802.1ag-2007. The default CFM version is IEEE Standard 802.1ag-2007.
Perform the following steps on each device on which CFM versions need to be switched:
Procedure
- Run system-view
The system view is displayed.
- Run cfm version { draft7 | standard }
CFM versions are switched.
Devices running different CFM versions cannot send CFM packets to each other. Therefore, the devices in a maintenance domain (MD) must run the same CFM version.
- Run commit
The configuration is committed.
Creating an MD
This section describes how to create a maintenance domain (MD).
Context
no-md-name: The MAID field in a sent continuity check message (CCM) does not carry an MD name.
dns-md-format-name: The MD information in the MAID field in a sent CCM is a character string obtained from a domain name service (DNS) text.
mac-md-format-name: The MD information in the MAID field in a sent CCM consists of a 6-byte Media Access Control (MAC) address and a 2-byte integer ranging from 0 to 65535.
string: The MD information in the MAID field in a sent CCM is a character string.
Perform the following steps on each NE20E on which CFM needs to be deployed:
Procedure
- Run system-view
The system view is displayed.
- Run cfm md md-name [ format { no-md-name | dns dns-md-format-name | mac-address mac-md-format-name | string string-md-format-name } ] [ level level ]
An MD is created, and the MD view is displayed.
To create multiple MDs, repeat this step. Each device supports a maximum of 64 MDs.
CFM packets in low-level MDs cannot pass through identical- or high-level MDs, whereas CFM packets in high-level MDs can pass through low-level MDs.
- (Optional) Run senderid-tlv-type { { chassis | chassis-manage } [ chassis-subtype { mac-address | locally-assigned } ] | defer | manage | none }
configures the type of the sender ID TLV in a CFM packet.
- Run commit
The configuration is committed.
(Optional) Creating a Default MD
This section describes how to create a default maintenance domain (MD).
Procedure
- Run system-view
The system view is displayed.
- Run cfm default md [ level level ]
A default MD is created, and the default MD view is displayed.
You can create only one default MD on each device.
The default MD must have a higher level than all MDs to which maintenance association end points (MEPs) configured on the local device belong. In addition, the default MD must have the same level as a high-level MD. The default MD is used to transmit high-level continuity check messages (CCMs) and create maintenance association intermediate points (MIPs) to send linktrace reply (LTR) messages.
- Run commit
The configuration is committed.
Creating an MA
This section describes how to create a maintenance association (MA).
Context
Connectivity fault management (CFM) can detect direct or end-to-end link faults. As shown in Figure 6-7, CFM is deployed to monitor the link between the CE and PE3. PE3 is a Layer 2 device or a device that connects a Layer 2 network to a Layer 3 network.
To deploy CFM to detect link faults, create an MD to determine a detected range, create MAs for the MD, and map the MAs to service instances. You can deploy multiple MAs in a single MD. For example, you can deploy MD1 between the CE and PE3 and create MA1, MA2, and MA3 in MD1 based on service types. Generally, each MA is mapped to a service instance and serves the service instance. The type of a service instance can be virtual local area network (VLAN), virtual private LAN service (VPLS), or virtual leased line (VLL).
Table 6-4 describes the rules for the association between MAs and service instances in different networking scenarios.
Networking Scenario |
Rule |
|---|---|
Direct link |
When an MA (for example, MA1 in the figure above) is deployed on directly connected devices and both interfaces of the direct link are Layer 2 interfaces, the MA does not need to be mapped to a service instance. |
End-to-end link |
When an MA (for example, MA2 in the figure above) is deployed on an end-to-end network, the MA needs to be mapped to a service instance. An MA can be mapped to a service instance directly or indirectly. As shown in Figure 6-7:
After an MA is mapped to a service instance, a maintenance point (MP) in the MA sends packets carrying the service instance's tag and receives packets from other MPs in the MA. This section describes how to directly map an MA to a service instance. For details about how to indirectly map an MA to a service instance, see Creating MEPs. |
Procedure
- Run system-view
The system view is displayed.
- Run cfm md md-name
The MD view is displayed.
- Run ma ma-name [ format { icc-based iccbased-ma-format-name | string ma-format-name } ]
An MA is created, and the MA view is displayed.
ITU-T Y.1731 defines ITU carrier code (ICC)-based continuity check messages (CCMs), which have similar formats to CCMs defined by IEEE 802.1ag. The meanings of some fields in an ICC-based CCM are different from those in a CCM defined by IEEE 802.1ag. To implement compatibility with ICC-based CCMs, specify the iccbased-ma-format-name parameter in this command.
- Configure the MA according to Table 6-5.Table 6-5 MA configurations in different networking environments
Networking Environment
Configuration Description
Direct link with Layer 2 interfaces configured at both ends
The MA does not need to be mapped to a service instance.
End-to-end link in VLAN scenarios
The MA is created on a Layer 2 device.
Run the map vlan vlan-id command to map the MA to a specified VLAN.
The MA is created on a device that connects a Layer 2 network to a Layer 3 network.
Specify a VLAN during MEP creation to map the MA to the VLAN. For details, see Creating MEPs.
End-to-end link in Martini VLL scenarios
Run the map mpls l2vc l2vc-id { tagged | raw } command on each Layer 2 device to associate the MA with a specified VLL.
End-to-end link in Kompella VLL scenarios
Run the map l2vpn l2vpn-name ce ce-id ce-offset ce-offset-id command on each Layer 2 device to associate the MA with a specified VLL.
End-to-end link in VPLS scenarios
Run the map vsi vsi-name command on each Layer 2 device to map the MA to a specified virtual switching instance (VSI).
End-to-end link in CCC scenarios
Run the map ccc ccc-connection-name command on each Layer 2 device to associate the MA with a specified CCC.
End-to-end link in EVPN scenarios
Run the map evpn vpn-instance evpn-instance-name command on each Layer 2 device to associate the MA with a specified EVPN instance.
End-to-end link in BD scenarios
Run the map bridge-domain bd-id command on each Layer 2 device to associate the MA with a specified bridge domain.
- Run commit
The configuration is committed.
Creating MEPs
This section describes how to create maintenance association end points (MEPs).
Context
Create MEPs to implement continuity check (CC).
MEPs can be either local MEP or remote maintenance association end points (RMEPs).
MEPs are also classified by direction: inward and outward. Table 6-6 describes MEP type configurations in different networking scenarios.
Networking Environment |
Description |
||||
|---|---|---|---|---|---|
Direct link |
Both interfaces of a direct link must be physical interfaces, Eth-Trunk interfaces, or Trunk member interfaces. These interfaces support outward MEPs. |
||||
End-to-end link |
Device that connects a Layer 2 network to a Layer 3 network |
This device supports only common sub-interfaces, L3VE interfaces, and outward MEPs. |
|||
Layer 2 device |
MEPs have different types in different networking scenarios:
|
||||
Perform the following steps on each device on which MEPs need to be configured:
(Optional) Creating a MIP
This section describes how to create a maintenance association intermediate point (MIP).
Context
MIPs can be automatically generated based on rules or manually configured on interfaces. Table 6-8 describes MIP creation modes.
Creation Mode |
Description |
|---|---|
Automatic generation |
A device automatically generates MIPs based on a configured creation rule in the maintenance domain (MD) or the default MD view. Configuring a creation rule is complex, but a configured creation rule can ensure correct MIP settings. |
Manual configuration |
You must specify a MIP level. Manually configured MIPs are preferable to automatically generated MIPs. Although configuring MIPs manually is easy, managing many manually configured MIPs is difficult and errors may be inadvertently introduced into the configurations. |
MIP creation rules are classified into three types: explicit, default, and none. Table 6-9 describes these MIP creation rules.
Manually Configured MIPs Exist on an Interface |
Creation Rule Type |
MEPs Are Configured for Low-Level MDs |
MIPs Are Created |
|---|---|---|---|
Yes |
– |
– |
No |
No |
default |
No |
Yes |
explicit |
Yes |
Yes |
|
none |
– |
– |
If the defer MIP generation rule is configured in the MA view, MIPs are created in an MA using rules configured in the MD to which MIPs belong.
Connectivity fault management (CFM) is enabled or disabled.
The configured MIP creation rule changes.
Perform either of the following operations on each device on which a MIP needs to be created:
(Optional) Switching MAC Address Models for MPs
This section describes how to switch Media Access Control (MAC) address models for maintenance points (MPs).
Context
Individual MAC address model: MPs are mapped to interface MAC addresses. If the individual MAC address model is configured, each MP on a device uses an interface MAC address as its MAC address. If the interfaces are Layer 2 interfaces switched from Layer 3 interfaces using the portswitch command, the MAC addresses of Layer 3 interfaces are used. This model facilitates fault locating.
Shared MAC address model: MPs share a bridge MAC address. If the shared MAC address model is configured, all MPs on a device use the same bridge MAC address as their MAC addresses. This model reduces the amount of space reserved for storing MAC entries.
Perform the following steps on each device on which MAC address models need to be switched for MPs:
Procedure
- Run system-view
The system view is displayed.
- Run cfm mp-address-model { bridge | individual }
MAC address models are switched for MPs.
If connectivity fault management (CFM) has been enabled, run the undo cfm enable command to disable it before switching MAC address models for MPs.
- Run commit
The configuration is committed.
Configuring CC
This section describes how to configure continuity check (CC) in an L2TPv3 scenario.
Context
CC enables a local maintenance association end point (MEP) and a remote maintenance association end point (RMEP) to periodically send continuity check messages (CCMs) to check the continuity of the link between them. When CC is enabled for connectivity fault management (CFM), CFM provides different CCM intervals to meet carriers' requirements for different quality of service (QoS) levels. Table 6-10 lists the CCM intervals and the RMEP timeout time that each one corresponds to.
If CC detection is configured on a Layer 3 physical main interface, CC detection fails once each time this interface is added to or removed from an Eth-Trunk interface.
Procedure
- Run system-view
The system view is displayed.
- Run cfm md md-name
The maintenance domain (MD) view is displayed.
- Run ma ma-name
The maintenance association (MA) view is displayed.
In L2TPv3 scenario, MA name of CCM packet is in ICC-based mode.
- Run ccm-interval interval
An interval at which a MEP in the MA sends or monitors CCMs is configured.
The same interval must be configured on the MEPs in the same MD and MA.
- (Optional) Run ccm tlv interface-status
CCMs are configured to carry Interface Status TLV.
- (Optional) Run ccm tlv port-status
CCMs to be sent are enabled to carry the Port Status TLV field.
- (Optional) Run ccm tlv sender-id
CCMs to be sent are enabled to carry the Sender ID TLV field.
- Run mep ccm-send [ mep-id mep-id ] enable
The specified local MEP is enabled to send CCMs.
If you do not specify the mep-id mep-id parameter, all local MEPs in the MA are enabled to send CCMs.
- Run remote-mep ccm-receive [ mep-id mep-id ] enable
The specified local MEP in the MA is enabled to receive CCMs from an RMEP in the MA.
If a local MEP has been enabled to receive CCMs from an RMEP and the link between the local MEP and RMEP fails, an RMEP continuity alarm is generated on the local MEP.
If you do not specify the mep-id mep-id parameter, all local MEPs in the MA are enabled to receive CCMs from RMEPs in the MA.
- Run commit
The configuration is committed.
Verifying the Basic CFM Function Configuration
After configuring basic connectivity fault management (CFM) functions, verify the configurations.
Procedure
- Run the display cfm md [ md-name ] command to check the information about a maintenance domain (MD).
- Run the display cfm ma [ md md-name [ ma ma-name ] ] command to check the information about a maintenance association (MA).
- Run the display cfm mep [ md md-name [ ma ma-name [ mep-id mep-id ] ] ] command to check the information about a local maintenance association end point (MEP).
- Run the display cfm remote-mep [ [ md md-name [ ma ma-name [ mep-id mep-id ] ] ] | [ md md-name [ ma ma-name ] ] cfm-state { disable | down | up } ] command to check the information about a remote maintenance association end point (RMEP).
- Run the display cfm mip [ interface interface-type interface-number | level level ] command to check the information about a maintenance association intermediate point (MIP).
- Run the display cfm default md command to check information about the default MD.
- Run the display cfm mp-info [ interface interface-type interface-number ] [ level md-level ] [ inward | outward ] [ vlan vlanid | vsi vsi-name | no-associated-vlan | mpls l2vc ] command to check information about the CFM objects on a specified interface or virtual local area network (VLAN) or in a specified virtual switching instance (VSI).
- Run the display oam global configuration command to check the MAC address model for maintenance points (MPs).
