CFM Link Monitoring

To enable CFM to report link events, the link must first be registered with CFM. ERPS (Ethernet Ring Protection Switching) acts as a client of CFM and creates the required Management Entity Points (MEPs). For G.8032 v1/v2 implementation:

It is generally recommended to have the CCM interval as short as possible to detect link failures faster, which improves convergence time.

Creating a DOWN-MEP is by creating the DOWN-MEP with the CFM commands, and then assigning a group name to it. This group can then be associated to the ERPS ring.

Here is an example:

switch # sh  cfm   
Domain: "erps_6",  MD Level: 6     
   Association: "erps_MA_100", Destination MAC Type:  Multicast, VLAN "v2" with 2 cfm ports     
   Transmit Interval: 1000 ms       
     port 27; Down End Point, mepid: 11, transmit-interval: 10000 ms (configured),             
        MEP State: Enabled, CCM Message: Enabled,  Send SenderId TLV: Disabled       
     port 37; Down End Point, mepid: 21,
        transmit-interval: 10000 ms (configured), 
        MEP State: Enabled, CCM Message: Enabled, Send SenderId TLV: Disabled     
   Association: "erps_MA_100", Destination MAC Type: Multicast, VLAN "v2" with 2 cfm ports     
   Transmit Interval: 1000 ms       
Total Number of Domain             : 1   
Total Number of Association        : 2   
Total Number of Up MEP             : 0   
Total Number of Down MEP           : 2   
Total Number of MIP                : 0   
Total Number of Number of CFM port : 4   
Total Number of VPLS MIP(Static/Up): 0 / 0

switch # show cfm detail       
Domain/       Port     MP  Remote End-Point  Remote End-Point   MEP   Life       Flags    
Association                  MAC Address       IP Address       ID    time   Age   
======================================================================================   
erps_6           
  erps_MA_100  27      DE     00:04:96:34:e3:43  0.0.0.0        10    35000  4430   DM                   
               37      DE     00:04:96:27:fb:7b 0.0.0.0         20    35000  2790   DM    
======================================================================================   
Maintenance Point: (UE) Up End-Point, (DE) Down End-Point   
Flags: S - Static  Entry D - Dynamic Entry          
           CCM Destination MAC: (U) Unicast (M)  Multicast   
NOTE: The Domain and Association names are truncated to 13 characters, Lifetime and Age are in milliseconds.   
======================================================================================       
Total Number of Dynamic Up RMEP      : 0   
Total Number of Dynamic Down RMEP    : 2   
Total Number of Active Static RMEP   : 0   
Total Number of Inactive Static RMEP : 0

Note

You must configure a remote MEP-ID for the local MEPs so that a specific association can be maintained between the two ends.

Limitations

CFM PDU transmit intervals are limited by the supported limits of CFM module. Platforms that do not support CFM in hardware are limited to a minimum interval of 100 ms. The maximum number of down MEPs is limited by the CFM module. This is as low as 32 MEPs in some platforms.

Published March 2020prev | next

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