Trigger a Layer 2 Traceroute

Use this procedure to trigger a Layer 2 traceroute, which acts like native traceroute. This feature enables CFM to debug Layer 2 in an SPBM cloud or network. It can determine the path used by IS—IS to get from one MEP to another, by showing all the hops between. Therefore, it can show where connectivity is lost. It can also work for IP shortcuts.

Important

To trace a route to a MAC address, the MAC address must be in the VLAN FDB table.

For B-VLANs, you do not have to trigger an l2ping to learn the MAC address because IS-IS populates the MAC addresses in the FDB table.

linktrace traces the path up to the closest device to that MAC address that supports CFM.

Before you begin

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

Procedure

Trigger a Layer 2 traceroute:

l2 traceroute {ip-address WORD<0–255>} [ttl <1–255>] [vrf WORD<1–16]

l2 traceroute {<vlan <1-4059> routernodename WORD<0–255> | <vlan <1-4059> mac <0x00:0x00:0x00:0x00:0x00:0x00>} [priority <0–7>] [source-mode <nodal|smltVirtual>] [ttl <1–255>]

Examples

Switch:1#l2 traceroute vlan 2 routernodename Switch-MONTIO
Please wait for l2traceroute to complete or press any key to abort

l2traceroute to Switch-MONTI0  (00:14:0d:a2:b3:df),  vlan 2 
0    Switch-PETER4         (00:15:9b:11:33:df) 
1    Switch-MONTI0          (00:14:0d:a2:b3:df)

Switch:1#l2 traceroute ip-address 192.0.2.10
Please wait for l2trace to complete or press any key to abort  

L2 Trace  Statistics : IP 192.0.2.10, paths found 1 
==================================================================
Switch-SHAMIM  (00:1a:8f:08:53:df),  vlan 2  
0    Switch-PETER4          (00:15:9b:11:33:df) 
1    Switch-MONTI0          (00:14:0d:a2:b3:df)

Variable Definitions

The following table defines parameters for the l2 traceroute command.


Variable	Value
{vlan `<1-4059>` routernodename `WORD<0–255>` } (vlan `<1-4059>` mac `<0x00:0x00:0x00:0x00:0x00:0x00>` } {ip-address `WORD<0–255>` }	Specifies the destination for the Layer 2 traceroute: `<1-4059>` — Specifies the VLAN ID WORD<0–255> — Specifies the Router Node Name <XX:XX:XX:XX:XX:XX> — Specifies the MAC address WORD<0–255> — Specifies the IP address
ttl-value `<1–255>`	Specifies the TTL value. The default is 64.
priority `<0–7>`	Specifies the priority. The default is 7.
source-mode`{nodal \| smltVirtual}]\|`	Specifies the source mode: nodal smltVirtual—Use this value with B-VLANs only. The default is nodal.
vrf `WORD<1–16`	Specifies the VRF name.