The G.8032 and CFM Support for Microwave Adaptive Bandwidth feature extends the functionality of the G.8032 Ethernet Protection Ring (ERP) mechanism and Ethernet Connectivity Fault Management (CFM).

This feature enables the G.8032 ERP mechanism to be used as a trigger in response to bandwidth degradation occurrences (such as a signal degradation [SD] indicator) on microwave links. Ethernet CFM interacts with the microwave transceiver to continuously check the quality and the bandwidth of the microwave link. When microwave link degradation (based on the configured service level agreement [SLA] in use) is detected, CFM notifies the Embedded Event Manager (EEM), which in turn notifies a mechanism such as, G.8032 ERP. G.8032 ERP ensures that the degraded microwave link is bypassed and no longer used. Depending upon the severity of the signal degradation and the configured threshold, G.8032 protection switching occurs on a per-instance basis.

For more information about Ethernet CFM, see the “Configuring IEEE Standard-Compliant Ethernet CFM in a Service Provider Network” module or the “Configuring Ethernet Connectivity Fault Management in a Service Provider Network” module.

For more information about G.8032 ERP, see the “ITU-T G.8032 Ethernet Ring Protection Switching” module.

Traditional microwave radios use fixed modulation schemes whereby any degradation in the wave propagation conditions (for example, due to adverse weather conditions such as heavy fog or rain) led to complete loss of the signal and a disruption of traffic. In a fixed modulation scheme, the microwave radio link had a binary state of either “'available” (on) or “unavailable” (off).

More technologically advanced microwave radios use an adaptive modulation scheme. In an adaptive modulation scheme, when the microwave link degrades due to adverse weather conditions, the radio changes its modulation scheme to a more robust scheme. The radio continues to broadcast but with less capacity. As a result, the radio can be in several capacity or bandwidth states, and not just on or off.

In the case of microwave links with adaptive modulation, the control Operation, Administration, and Maintenance (OAM) protocols are unable to make best use of the available bandwidth due of the following OAM characteristics:

Even though the network topology must be provisioned with enough redundant bandwidth to handle a complete failure, in certain situations where the service committed information rate (CIR) is very low, forwarding as much excess traffic (above the CIR) as possible is important. Therefore, for those situations, treating bandwidth degradation as a complete failure is not desirable.

In a network topology consider a single interface on the head-end router is connected to a topology consisting of multiple microwave links either in series or in a hub-and-spoke arrangement. In such scenarios, the links degrade independently, and send their own VSMs containing current and nominal bandwidth for their links. Identifying the VSMs with the source MAC address does not help identify the degraded link.

To help identify the degraded links in a multi-hop topology, Link IDs can be configured on the VSM. The Link ID is configured in the EEM configuration using the event ethernet microwave sd interface command. The command support registrations on one or more individual links identified by either link ID or source MAC address.

With multi-hop topology, all individual links identified by the interface. If the interface is degraded, the links too get degraded.

The multi-hop topology is supported when multiple microwave links are grouped together into a port-channel.

In this example, two Ethernet microwave events have been created, mw_ring_sdl1 and mw_ring_sd_2:

Device> enable
Device> configure terminal
Device(config)# event manager applet mw_ring_sd1
Device(config-applet)# event ethernet microwave sd interface gigabitethernet0/0/0 threshold 400
Device(config-applet)# action 1 switch ring g8032 ringA instance 1  
Device(config-applet)# exit
Device(config)# event manager applet mw_ring_sd2
Device(config-applet)# event ethernet microwave sd interface gigabitethernet0/0/0 threshold 400
Device(config-applet)# action 1 switch ring g8032 ringA instance 2  
Device(config-applet)# exit

In this example, a microwave event has been configured that clears all the signal degradation (SD) events, as defined by the action switch ring g8032 clear instance all command:

Device> enable
Device> configure terminal
Device(config)# event manager applet mw_ring_clear_sd
Device(config-applet)# event ethernet microwave clear-sd interface gigabitethernet0/0/0 
Device(config-applet)# action 1 switch ring g8032 clear ringA instance all  
Device(config-applet)# exit

The following is sample output from the show ethernet event microwave status command where GigabitEthernet interface 0/0/2 has been specified. Use the command to confirm that the configuration is performing as intended.

Device# show ethernet event microwave status GigabitEthernet 0/0/2

Microwave Bandwidth Status for GigabitEthernet0/0/2
 State : Degraded
 Elapsed time in this state : 1:25:33
 Nominal Bandwidth : 512Mbps
 Current Bandwidth : 256Mbps
 Lowest Bandwidth Since Entering Degraded : 64Mbps
 Last VSM Received : Oct 27 14:06:19.983
 Sender Transmit Period : 1 second
 Sender Address : 01AB.CC00.1881
 Hold Timer : Not Running
 Restore Timer : Not Running
 Periodic Timer : 2333 msec <--Calculated using the configured loss-threshold value.
 Hold Time : 0 seconds      <--This is hold-off timer value.   
 Restore Time : 10 seconds  <--This is the wait-to-restore value.
 Loss-Threshold: 3

Device# show ethernet event microwave status GigabitEthernet 0/0/2

Microwave Bandwidth Status for GigabitEthernet0/0/2
State: SIGNAL_DEGRADED 
Hold Time: 0 seconds
Restore Time: 10 seconds
Loss Threshold: 3
Total VSM Receive Count: 1
Total VSM Drop Count: 0

Sender Address 64f6.9d67.a006
State: SIGNAL_DEGRADED 
Elapsed time in this state: 00:00:43
Nominal Bandwidth: 600 Mbps
Current Bandwidth: 500 Mbps
Lowest Bandwidth: 500 Mbps
Last VSM Received: Thu Apr 30 11:03:45.493
VSM Receive Count: 1
VSM Drop Count: 0
VSM Period: 10 seconds
Hold Timer: Not running
Wait-to-Restore Timer: 1 seconds remaining
Periodic Timer: Not running
Transitions into degraded state: 1

The following is sample output from the show ethernet event microwave status command where Port-channel20 has been specified. Use the command to confirm that the configuration is performing as intended.

Device# show ethernet event microwave status interface Port-channel20/2

Microwave Bandwidth Status for Port-channel20 
State: SIGNAL_DEGRADED
Hold Time: 0 seconds
Restore Time: 10 seconds
Loss Threshold: 3
Total VSM Receive Count: 2
Total VSM Drop Count: 0

Sender Address 64f6.9d67.a053
State: SIGNAL_DEGRADED
Elapsed time in this state: 00:00:26
Nominal Bandwidth: 700 Mbps
Current Bandwidth: 100 Mbps
Lowest Bandwidth: 100 Mbps
Last VSM Received: Fri Apr 24 13:09:13.245
VSM Receive Count: 2
VSM Drop Count: 0
VSM Period: 10 seconds
Hold Timer: Not running
Wait-to-Restore Timer: Not running
Periodic Timer: 29 seconds remaining
Transitions into degraded state: 1 

Device# show ethernet event microwave status GigabitEthernet 0/0/2
Microwave Bandwidth Status for Ethernet0/0
  State:                   SIGNAL_DEGRADED
  Hold Time:               0 seconds
  Restore Time:            10 seconds
  Loss threshold:          3
  Total VSM Receive Count: 6
  Total VSM Drop Count:    0

  Link ID 4 (Sender Address aaa.bbbb.cccc)
    State:                           SIGNAL_OK
    Elapsed time in this state:      01:12:10
    Nominal Bandwidth:               10000 Mbps
    Current Bandwidth:               10000 Mbps
    Lowest Bandwidth:                N/A, not in degraded state
    Last VSM Received:               Fri Jan 24 10:24:43.349
    VSM Receive Count:               3
    VSM Drop Count:                  0
    Hold Timer:                      Not running
    Wait-to-Restore Timer:           Not running
    Periodic Timer:                  Not running
    Transitions into degraded state: 2

The following is sample output from the show ethernet event microwave statistics command where GigabitEthernet interface 0/0/2 has been specified:

Device#show ethernet event microwave statistics GigabitEthernet 0/0/2

Microwave Bandwidth Statistics for GigabitEthernet0/0/2
 Total VSM Receive Count : 145
 Total VSM Drop Count : 0
 Number of transitions into Degraded state : 2

Device#show ethernet event microwave statistics GigabitEthernet 0/0/2

Microwave Bandwidth Status for GigabitEthernet0/0/2
State: SIGNAL_OK
Hold Time: 0 seconds
Restore Time: 10 seconds
Loss Threshold: 3
Total VSM Receive Count: 0
Total VSM Drop Count: 0

Sender Address 64f6.9d67.a00a
State: SIGNAL_OK
Elapsed time in this state: 00:02:58
Nominal Bandwidth: 900 Mbps
Current Bandwidth: 900 Mbps
Lowest Bandwidth: N/A, not in degraded state
Last VSM Received: Fri Apr 24 13:57:42.600
VSM Receive Count: 0
VSM Drop Count: 0
VSM Period: 60 seconds
Hold Timer: Not running
Wait-to-Restore Timer: Not running
Periodic Timer: Not running
Transitions into degraded state: 0

The following example shows the configuration of MEP on a trunk EFP.

interface GigabitEthernet0/3/3
no ip address
negotiation auto
ethernet cfm mep domain md1 mpid 1 service ma1
service instance trunk 1 ethernet
encapsulation dot1q 1-109
rewrite ingress tag pop 1 symmetric
l2protocol peer lacp
bridge-domain from-encapsulation
!
End

The MEP is configured outside EFP. The corresponding domain/service configuration would look like:

ethernet cfm ieee
ethernet cfm global
ethernet cfm domain md1 level 1
service ma1 evc evc1 vlan 100 direction down
continuity-check