Dell PowerSwitch S4820T 9.50.1 Configuration Guide for the S4820T System - Page 92

Sending Linktrace Messages and Responses 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. Figure 5. MPLS Core 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. • Send a Linktrace message. Because the LTM is a Multicast message sent to the entire ME, there is no need to specify a destination. EXEC Privilege traceroute ethernet domain Caching Link Trace After you execute a Link Trace command, the trace information can be cached so that you can view it later without retracing. To enable, set, display, and delete link trace caching, use the following commands. • Enable Link Trace caching. CONFIGURATION mode traceroute cache 92 802.1ag