Ethernet OAM and CFM for Switches
SUMMARY This section describes how ethernet interfaces on Juniper Networks Switches and Juniper Networks Junos operating system (Junos OS) for switches support the IEEE 802.1ag standard for Operation, Administration, and Management (OAM).
Understanding Ethernet OAM Connectivity Fault Management for Switches
The IEEE 802.1ag specification provides for Ethernet connectivity fault management (CFM). CFM monitors Ethernet networks that might comprise one or more service instances for network-compromising connectivity faults.
The major features of CFM are:
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Fault monitoring using the continuity check protocol. This is a neighbor discovery and health check protocol that discovers and maintains adjacencies at the VLAN level.
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Path discovery and fault verification using the linktrace protocol.
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Fault isolation using the loopback protocol.
CFM partitions the service network into various administrative domains. For example, operators, providers, and customers might be part of different administrative domains. Each administrative domain is mapped into one maintenance domain providing enough information to perform its own management, thus avoiding security breaches and making end-to-end monitoring possible.
In a CFM maintenance domain, each service instance is called a maintenance association. A maintenance association can be thought of as a full mesh of maintenance association endpoints (MEPs) having similar characteristics. MEPs are active CFM entities generating and responding to CFM protocol messages. There is also a maintenance intermediate point (MIP), which is a CFM entity similar to the MEP, but more passive (MIPs only respond to CFM messages).
Each maintenance domain is associated with a maintenance domain level from 0 through 7. Level allocation is based on the network hierarchy, where outer domains are assigned a higher level than the inner domains. Configure customer end points to have the highest maintenance domain level. The maintenance domain level is a mandatory parameter that indicates the nesting relationships between various maintenance domains. The level is embedded in each CFM frame. CFM messages within a given level are processed by MEPs at that same level.
To enable CFM on an Ethernet interface, you must configure maintenance domains, maintenance associations, and maintenance association end points (MEPs). Figure 1 shows the relationships among maintenance domains, maintenance association end points (MEPs), and maintenance intermediate points (MIPs) configured on a switch.
CFM Limitations on EX4600 Switches
Starting in Junos OS Release 18.3R1, Junos OS provides CFM support on EX4600. CFM support on EX4600 has the following limitations:
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CFM support is provided via software using filters. This can impact scaling.
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Inline Packet Forwarding Engine (PFE) mode is not supported. In Inline PFE mode, you can delegate periodic packet management (PPM) processing to the Packet Forwarding Engine (PFE) which results in faster packet handling and the CCM interval supported is 10 milliseconds.
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Performance monitoring (ITU-T Y.1731 Ethernet Service OAM) is not supported.
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CCM interval of less than 1 second is not supported.
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CFM is not supported on Routed Interfaces and aggregated Ethernet (lag) interfaces.
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MIP half function, to divide the MIP functionality into two unidirectional segments to improve network coverage, is not supported.
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Up MEP is not supported.
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Total number of CFM sessions supported is 20.
CFM Limitations on QFX5120, QFX5200, and QFX5210 Series Switches
Starting in Junos OS Release 18.4R1, Junos OS provides CFM support on QFX5200 switches and QFX5210 switches. Starting in Junos OS Release 19.4R1, Junos OS provides CFM support on QFX5120 switches. CFM support on QFX5120, QFX5200, and QFX5210 Series switches has the following limitations:
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CFM support is provided via software using filters. This can impact scaling.
-
Inline Packet Forwarding Engine (PFE) mode is not supported. In Inline PFE mode, you can delegate periodic packet management (PPM) processing to the Packet Forwarding Engine (PFE) which results in faster packet handling and the CCM interval supported is 10 milliseconds.
-
Performance monitoring (ITU-T Y.1731 Ethernet Service OAM) is not supported.
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CCM interval of less than 1 second is not supported.
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CFM is not supported on Routed Interfaces and aggregated Ethernet (lag) interfaces.
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MIP half function, to divide the MIP functionality into two unidirectional segments to improve network coverage, is not supported.
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Up MEP is not supported.
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Total number of CFM sessions supported is 20.
See Also
Configuring Ethernet OAM Connectivity Fault Management (CLI Procedure)
Ethernet interfaces on Juniper Networks EX Series Ethernet Switches and Juniper Networks Junos OS for EX Series switches support the IEEE 802.1ag standard for Operation, Administration, and Management (OAM). The IEEE 802.1ag specification provides for Ethernet connectivity fault management (CFM).
This feature is not supported on EX4300 switches on aggregated Ethernet (LAG) interfaces.
This topic describes these tasks:
- Creating the Maintenance Domain
- Configuring the Maintenance Domain MIP Half Function
- Creating a Maintenance Association
- Configuring the Continuity Check Protocol
- Configuring a Maintenance Association End Point
- Configuring a Connectivity Fault Management Action Profile
- Configuring the Linktrace Protocol
Creating the Maintenance Domain
A maintenance domain comprises network entities such as operators, providers, and customers. To enable connectivity fault management (CFM) on an Ethernet interface, you must create a maintenance domains, maintenance associations, and MEPs.
To create a maintenance domain:
Configuring the Maintenance Domain MIP Half Function
MIP Half Function (MHF) is not supported on EX4600, QFX5200, and QFX5210 switches.
MIP Half Function (MHF) divides the maintenance association intermediate point (MIP) functionality into two unidirectional segments, improves visibility with minimal configuration, and improves network coverage by increasing the number of points that can be monitored. MHF extends monitoring capability by responding to loop-back and link-trace messages to help isolate faults. Whenever a MIP is configured, the MIP half function value for all maintenance domains and maintenance associations must be the same.
To configure the MIP half function:
[edit protocols oam ethernet connectivity-fault-management maintenance-domain domain-name] user@switch# set mip-half-function (none | default | explicit)
Creating a Maintenance Association
In a CFM maintenance domain, each service instance is called a maintenance association.
To create a maintenance association:
[edit protocols oam ethernet connectivity-fault-management maintenance-domain domain-name] user@switch# set maintenance-association ma-name
Configuring the Continuity Check Protocol
The continuity check protocol is used for fault detection by a maintenance association end point (MEP) within a maintenance association. The MEP periodically sends continuity check multicast messages. The receiving MEPs use the continuity check messages (CCMs) to build a MEP database of all MEPs in the maintenance association.
To configure the continuity check protocol:
Configuring a Maintenance Association End Point
To configure a maintenance association end point:
Configuring a Connectivity Fault Management Action Profile
You can configure an action profile and specify the action to be taken when any of the configured events occur. Alternatively, you can configure an action profile and specify default actions when connectivity to a remote MEP fails.
To configure an action profile:
Configuring the Linktrace Protocol
The linktrace protocol is used for path discovery between a
pair of maintenance points. Linktrace messages are triggered by an
administrator using the traceroute
command to verify the
path between a pair of MEPs under the same maintenance association.
Linktrace messages can also be used to verify the path between a MEP
and a MIP under the same maintenance domain.
To configure the linktrace protocol:
Example: Configuring Ethernet OAM Connectivity Fault Management on EX Series Switches
Ethernet interfaces on EX Series switches and Junos OS for EX Series switches support the IEEE 802.1ag standard for Operation, Administration, and Management (OAM). The IEEE 802.1ag specification provides for Ethernet connectivity fault management (CFM).
This example describes how to enable and configure OAM CFM on a Gigabit Ethernet interface:
- Requirements
- Overview and Topology
- Configuring Ethernet OAM Connectivity Fault Management on Switch 1
- Configuring Ethernet OAM Connectivity Fault Management on Switch 2
- Verification
Requirements
This example uses the following hardware and software components:
Junos OS Release 10.2 or later for EX Series switches
Two EX Series switches connected by a point-to-point Gigabit Ethernet link
Overview and Topology
CFM can be used to monitor the physical link between two switches. In the following example, two switches are connected by a point-to-point Gigabit Ethernet link. The link between these two switches is monitored using CFM.
Configuring Ethernet OAM Connectivity Fault Management on Switch 1
CLI Quick Configuration
To quickly configure Ethernet OAM CFM, copy the following commands and paste them into the switch terminal window:
[edit protocols oam ethernet connectivity-fault-management maintenance-domain] set name-format character-string set maintenance-domain private level 0 set maintenance-association private-ma set continuity-check hold-interval 1s
Procedure
Step-by-Step Procedure
To enable and configure OAM CFM on switch 1:
Specify the maintenance domain name format:
[edit protocols oam ethernet connectivity-fault-management maintenance-domain] user@switch1# set name-format character-string
Specify the maintenance domain name and the maintenance domain level:
[edit protocols oam ethernet connectivity-fault-management] user@switch1# set maintenance-domain private level 0
Create a maintenance association:
[edit protocols oam ethernet connectivity-fault-management maintenance-domain private] user@switch1# set maintenance-association private-ma
Enable the continuity check protocol and specify the continuity check hold interval:
[edit protocols oam ethernet connectivity-fault-management maintenance-domain private maintenance-association private-ma] user@switch1# set continuity-check hold-interval 1s
Configure the maintenance association end point (MEP):
[edit protocols oam ethernet connectivity-fault-management maintenance-domain private maintenance-association private-ma] user@switch1# set mep 100 interface ge-1/0/1 auto-discovery direction down
Results
Check the results of the configuration.
[edit] user@switch1 > show
protocols { oam { ethernet { connectivity-fault-management { maintenance-domain private { level 0; maintenance-association private-ma { continuity-check { interval 1s; } mep 100 { interface ge-1/0/1; auto-discovery; direction down; } } } } }
Configuring Ethernet OAM Connectivity Fault Management on Switch 2
CLI Quick Configuration
To quickly configure Ethernet OAM CFM, copy the following commands and paste them into the switch terminal window:
[edit protocols oam ethernet connectivity-fault-management maintenance-domain] set name-format character-string set maintenance-domain private level 0 set maintenance-association private-ma set continuity-check hold-interval 1s
Procedure
Step-by-Step Procedure
The configuration on switch 2 mirrors that on switch 2.
Specify the maintenance domain name format:
[edit protocols oam ethernet connectivity-fault-management] user@switch2# set name-format character-string
Specify the maintenance domain name and the maintenance domain level:
[edit protocols oam ethernet connectivity-fault-management] user@switch2# set maintenance-domain private level 0
Create a maintenance association:
[edit protocols oam ethernet connectivity-fault-management maintenance-domain private] user@switch2# set maintenance-association private-ma
Enable the continuity check protocol and specify the continuity check hold interval:
[edit protocols oam ethernet connectivity-fault-management maintenance-domain private maintenance-association private-ma] user@switch2# set continuity-check hold-interval 1s
Configure the maintenance association end point (MEP)
[edit protocols oam ethernet connectivity-fault-management maintenance-domain private maintenance-association private-ma] user@switch2# set mep 200 interface ge-0/2/5 auto-discovery direction down
Results
Check the results of the configuration.
[edit] user@switch2 > show
protocols { oam { ethernet { connectivity-fault-management { maintenance-domain private { level 0; maintenance-association private-ma { continuity-check { interval 1s; } mep 200 { interface ge-0/2/5; auto-discovery; direction down; } } } } }
Verification
To confirm that the configuration is working properly, perform these tasks:
Verifying That OAM CFM Has Been Configured Properly
Purpose
Verify that OAM CFM has been configured properly.
Action
Use the show oam ethernet connectivity-fault-management
interfaces detail
command:
user@switch1# show oam ethernet connectivity-fault-management interfaces
detail
Sample Output
command-name
Interface name: ge-1/0/1.0, Interface status: Active, Link status: Up Maintenance domain name: private, Format: string, Level: 0 Maintenance association name: private-ma, Format: string Continuity-check status: enabled, Interval: 1ms, Loss-threshold: 3 frames MEP identifier: 100, Direction: down, MAC address: 00:90:69:0b:4b:94 MEP status: running Defects: Remote MEP not receiving CCM : no Erroneous CCM received : yes Cross-connect CCM received : no RDI sent by some MEP : yes Statistics: CCMs sent : 76 CCMs received out of sequence : 0 LBMs sent : 0 Valid in-order LBRs received : 0 Valid out-of-order LBRs received : 0 LBRs received with corrupted data : 0 LBRs sent : 0 LTMs sent : 0 LTMs received : 0 LTRs sent : 0 LTRs received : 0 Sequence number of next LTM request : 0 Remote MEP count: 2 Identifier MAC address State Interface 2001 00:90:69:0b:7f:71 ok ge-0/2/5.0
Meaning
When the output displays that continuity-check status
is enabled
and displays details of
the remote MEP, it means that connectivity fault management (CFM)
has been configured properly.