Trigger a Loopback Test (LBM)

Use this procedure to trigger a loopback test.

The LBM packet is often compared to ping. An MEP transmits the loopback message to an intermediate or endpoint within a domain for the purpose of fault verification. This can be used to check the ability of the network to forward different sized frames.

Before you begin

You must have a MEP that is associated with a B-VLAN.

Procedure

Trigger the loopback test:

loopback WORD<0–22> WORD<0–22> <1–8191> <0x00:0x00:0x00:0x00:0x00:0x00> [burst-count <1–200>] [data-tlv-size <0–400>] [frame-size <64–1500>] [interframe-interval <msecs>] [priority <0–7>] [source-mode {nodal| smltVirtual}][testfill-pattern <all-zero|all-zero-crc|pseudo-random-bit-sequence|pseudo-random-bit-sequence-crc>] [time-out <1–10>]

Example

Switch:1# loopback md1 4001 13 00:14:0D:A2:B3:DF burst-count 10 priority 3 time-out 5

Result of LBM from mep: spbm.bvlan1000.8 to MAC address: 00:66:00:66:00:66 :
  Sequence number of the first LBM is 150404162
  The total number of LBMs sent out is 1
  The number of LBRs received is 1
  The number of LBRs lost is 0
  The percentage of LBMs lost is 0.00%
  The RTT Min is 15071 microsecs, Max is 15071 microsecs, Average is 15071.00 microsecs
  The Standard Deviation of RTT is 0.00 microsecs

Variable Definitions

The following table defines parameters for the loopback command.


Variable	Value
`WORD<0–22>`	The first parameter, specifies the MD name.
`WORD<0–22>`	The second parameter, specifies the MA name.
`<1–8191>`	Specifies the MEP ID.
`<0x00:0x00:0x00:0x00:0x00:0x00>`	Specifies the remote MAC address to reach the MEP/MIP.
burst-count `<1–200>`	Specifies the burst-count.
data-tlv-size `<0–400>`	Specifies the data TLV size.
frame-size `<64–1500>`	Specifies the frame-size. The default is 0.
priority `<0–7>`	Specifies the priority. The default is 7.
source-mode`{nodal \| smltVirtual}]\|` Note: Exception: smltVirtual is not supported on 5320 Series.	Specifies the source mode: nodal smltVirtual—Use this value with B-VLANs only. The default is nodal.
testfill-pattern `{all-zero\|all-zero-crc\|pseudo-random-bit-sequence\|pseudo-random-bit-sequence-crc}`	Specifies the testfill pattern: all-zero — null signal without cyclic redundancy check all-zero-crc — null signal with cyclic redundancy check with 32-bit polynomial pseudo-random-bit-sequence — pseudo-random-bit-sequence without cyclic redundancy check pseudo-random-bit-sequence-crc — pseudo-random-bit-sequence with cyclic redundancy check with 32-bit polynomial. A cyclic redundancy check is a code that detects errors. The default is 1: all-zero.
time-out `<1–10>`	Specifies the time-out interval in seconds. The default is 3.