Reference Guide

80 | 802.1ag
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Linktrace Message and Response
Linktrace Message and Response (LTM, LTR), also called Layer 2 Traceroute, is an administratively sent
multicast frames transmitted by MEPs to track, hop-by-hop, the path to another MEP or MIP within the
maintenance domain. All MEPs and MIPs in the same domain respond to an LTM with a unicast LTR.
Intermediate MIPs forward the LTM toward the target MEP.
Link trace messages carry a unicast target address (the MAC address of an MIP or MEP) inside a multicast
frame. The destination group address is based on the MD level of the transmitting MEP
(01:80:C2:00:00:3[8 to F]). The MPs on the path to the target MAC address reply to the LTM with an LTR,
and relays the LTM towards the target MAC until the target MAC is reached or TTL equals 0.
Link Trace Cache
After a Link Trace command is executed, the trace information can be cached so that you can view it later
without retracing.
Task Command Syntax Command Mode
Send a Linktrace message. Since the
LTM is a Multicast message sent to the
entire ME, there is no need to specify a
destination.
traceroute ethernet domain
EXEC Privilege
Task Command Syntax Command Mode
Enable Link Trace caching.
traceroute cache
CONFIGURATION
Set the amount of time a trace result is cached. traceroute cache hold-time minutes
Default: 100 minutes
Range: 10-65535 minutes
ETHERNET CFM
MPLS Core
MEP
MIP MIP
MIP
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