Verifying and Isolating Fault

Updated on 10 Jul 2024
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This article describes the initiation of loop back and link trace messages to verify and isolate a fault.

CLI Configurations

At Switch1

Initiate Traceroute to isolate any link failure (error/fault/defect).

your product# traceroute ethernet mac 00:05:02:03:04:02 domain OP7 vlan 2
Traceroute to Macaddress 00:05:02:03:04:02    in domain  OP7 at level 7
with vlanId 2
------------------------------------------------------
Hops  Host  Ingress MAC   Ingress Action  Relay Action
Next Host   Egress MAC    Egress Action    Fwd Status
------------------------------------------------------
1   00:02:02:03:04:01:00:02  00:02:02:03:04:02   IngOK  RlyFDB
    00:06:02:03:04:01:00:02          -           EgrOK  Forwarded
2   00:06:02:03:04:01:00:02  00:00:00:00:00:00          RlyFDB
    -                                            EgrOK  Forwarded

Shows there is a link failure between Switch1 and Switch5, as no reply is received with Relay Action as RlyHit.

Initiate the LoopBack Transaction to verify any link failure (error/fault/defect)

your product# ping  ethernet mac 00:06:02:03:04:02 domain OP7 vlan 2
Sending 1 Ethernet CFM loopback messages, timeout is 5 seconds
Success rate is 100.0 percent 1/1

Shows there is no link failure between Switch1 and Switch6.

Initiate the LoopBack Transaction to verify any link failure (error/fault/defect)

your product# ping ethernet mac 00:05:02:03:04:02 domain OP7 vlan 2
Sending 1 Ethernet CFM loopback messages, timeout is 5 seconds
Success rate is 0.000 percent 0/1

Shows there is a link failure between Switch6 and Switch5.

SNMP Configurations

At Switch1

Initiate traceroute to isolate any link failure (error/fault/defect). [Index: ContextID = 0, MD-Index = 1, MA-Index = 1, MEP-ID = 1]

% snmp0 set {{fsMIEcfmMepTransmitLtmTargetIsMepId.0.1.1.1 false}}
% snmp0 set {{fsMIEcfmMepTransmitLtmTargetMacAddress.0.1.1.1 00:05:02:03:04:02}}
% snmp0 set {{fsMIEcfmMepTransmitLtmStatus.0.1.1.1 transmit}}

Walk the Ltrcache Table.

% snmp0 walk x fsMIY1731LtrTable { puts $x }
{1.3.6.1.4.1.29601.2.7.1.2.6.1.3.0.1.1.1.1.1 INTEGER 41}
{1.3.6.1.4.1.29601.2.7.1.2.6.1.3.0.1.1.1.1.2 INTEGER 52}

Shows there is a link failure between Switch1 and Switch5, as data of only the first two hops is present in the Ltrcache.

Initiate the loopback transaction to MEP on Switch6 for verifying any link failure (error/fault/defect)
[Index: ContextID = 0, MD-Index = 1, MA-Index = 1, MEP-ID = 1]

% snmp0 set {{fsMIEcfmMepTransmitLbmMessages.0.1.1.1 1}}
% snmp0 set {{fsMIEcfmMepTransmitLbmDestMacAddress.0.1.1.1  00:06:02:03:04:02}}
% snmp0 set {{fsMIEcfmMepTransmitLbmDestIsMepId.0.1.1.1 false}}
% snmp0 set {{fsMIEcfmMepTransmitLbmStatus.0.1.1.1 transmit}}

Verify transmission of loopback messages between Switch1 and Switch6.[Index: ContextID = 0, MD-Index = 1, MA-Index = 1, MEP-ID = 1]

% snmp0 get {fsMIEcfmMepLbrIn.0.1.1.1}
{1.3.6.1.4.1.2076.160.1.0.7.1.20.0.1.1.1 Unsigned32 1}
% snmp0 get {fsMIEcfmMepTransmitLbmMessages.0.1.1.1}
{1.3.6.1.4.1.2076.160.1.0.7.1.30.0.1.1.1 INTEGER 0}

Shows there is no link failure between Switch1 and Switch6.

Initiate the loopback transaction to MEP on Switch5 for verifying any link failure (error/fault/defect). [Index: ContextID = 0, MD-Index = 1, MA-Index = 1, MEP-ID = 1]

% snmp0 set {{fsMIEcfmMepTransmitLbmMessages.0.1.1.1 1}}
% snmp0 set {{fsMIEcfmMepTransmitLbmDestMacAddress.0.1.1.1 00:05:02:03:04:02}}
% snmp0 set {{fsMIEcfmMepTransmitLbmDestIsMepId.0.1.1.1 false}}
% snmp0 set {{fsMIEcfmMepTransmitLbmStatus.0.1.1.1 transmit}}

Verify transmission of loopback messages between Switch1 and Switch5.[Index: ContextID = 0, MD-Index = 1, MA-Index = 1, MEP-ID = 1]

% snmp0 get {fsMIEcfmMepLbrIn.0.1.1.1}
{1.3.6.1.4.1.2076.160.1.0.7.1.20.0.1.1.1 Unsigned32 1}
% snmp0 get {fsMIEcfmMepTransmitLbmMessages.0.1.1.1}
{1.3.6.1.4.1.2076.160.1.0.7.1.30.0.1.1.1 INTEGER 0}

Shows there is link failure between Switch 1 and Switch 5.

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