H3C S3100 8C SI Operation Manual page 594

Operation Manual – Stack-Cluster
H3C S3100 Series Ethernet Switches
Note:
By default, the management VLAN interface is used as the network management
interface.
There is only one network management interface on a management device; any
newly configured network management interface will overwrite the old one.
VI. Tracing a device in a cluster
In practice, you need to implement the following in a cluster sometimes:
Know whether there is a loop in the cluster
Locate which port on which switch initiates a network attack
Determine the port and switch that a MAC address corresponds to
Locate which switch in the cluster has a fault
Check whether a link in the cluster and the devices on the link comply with the
original plan
In these situations, you can use the tracemac command to trace a device in the cluster
by specifying a destination MAC address or IP address.
The procedures are as follows:
1) Determine whether the destination MAC address or destination IP address is used
to trace a device in the cluster
If you use the tracemac command to trace the device by its MAC address, the
switch will query its MAC address table according to the MAC address and VLAN
ID in the command to find out the port connected with the downstream switch.
If you use the tracemac command to trace the device by its IP address, the switch
will query the corresponding ARP entry of the IP address to find out the
corresponding MAC address and VLAN ID, and thus find out the port connected
with the downstream switch.
2) After finding out the port connected with the downstream switch, the switch will
send a multicast packet with the VLAN ID and specified hops to the port. Upon
receiving the packet, the downstream switch compares its own MAC address with
the destination MAC address carried in the multicast packet:
If the two MAC addresses are the same, the downstream switch sends a response
to the switch sending the tracemac command, indicating the success of the
tracemac command.
If the two MAC addresses are different, the downstream switch will query the port
connected with its downstream switch based on the MAC address and VLAN ID,
and then forward the packet to its downstream switch. If within the specified hops,
a switch with the specified destination MAC address is found, this switch sends a
response to the switch sending the tracemac command, indicating the success of
the tracemac command. If no switch with the specified destination MAC address
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Chapter 2 Cluster