Transmitting link trace messages, Figure 298 s, Transmitting – Brocade Communications Systems Brocate Ethernet Access Switch 6910 User Manual

Page 1038: Link trace messages

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988

Brocade 6910 Ethernet Access Switch Configuration Guide

53-1002581-01

Connectivity Fault Management

42

4. Select an entry from MD Index and MA Index.

FIGURE 298

Showing Remote Maintenance End Points

Transmitting Link Trace Messages

Use the Administration > CFM (Transmit Link Trace) page to transmit link trace messages (LTMs).
These messages can isolate connectivity faults by tracing the path through a network to the
designated target node (i.e., a remote maintenance end point).

CLI References

“CFM Commands”

on page 523

Command Usage

LTMs can be targeted to MEPs, not MIPs. Before sending a link trace message, be sure you
have configured the target MEP for the specified MA (see

“Configuring Remote Maintenance

End Points”

on page 986).

If MAC address of target MEP has not been learned by any local MEP, then the linktrace may
fail. Use the Show Remote MEP page (see

"Displaying Remote MEPs"

) to verify that a MAC

address has been learned for the target MEP.

LTMs are sent as multicast CFM frames, and forwarded from MIP to MIP, with each MIP
generating a link trace reply, up to the point at which the LTM reaches its destination or can no
longer be forwarded.

LTMs are used to isolate faults. However, this task can be difficult in an Ethernet environment,
since each node is connected through multipoint links. Fault isolation is even more challenging
since the MAC address of the target node can age out in several minutes. This can cause the
traced path to vary over time, or connectivity lost if faults cause the target MEP to be isolated
from other MEPs in an MA.

When using the command line or web interface, the source MEP used by to send a link trace
message is chosen by the CFM protocol. However, when using SNMP, the source MEP can be
specified by the user.

Parameters controlling the link trace cache, including operational state, entry hold time, and
maximum size can be configured on the Configure Global page (see

"Configuring Global

Settings for CFM"

).

Parameters

These parameters are displayed:

MD Index – Domain index. (Range: 1-65535)

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