3Com Switch 7700 Configuration Manual page 62

54 C 3: VLAN C
HAPTER ONFIGURATION
messages cooperate to ensure the logout and the re-registration of a message. By
exchanging messages, all the attribute information to be registered can be
propagated to all the switches in the same switching network.
The destination MAC addresses of the packets of the GARP participants are
specific multicast MAC addresses. A switch that supports GARP classifies the
packets that it receives from GARP participants and processes them with the
corresponding GARP applications (GVRP or GMRP).
GARP and GMRP are described in details in the IEEE 802.1p standard. The Switch
7700 fully supports GARP compliant with the IEEE standards.
The value of the GARP timer is used in all GARP applications, including GVRP
■
and GMRP, that are running in a switching network.
In one switching network, GARP timers on all the switching devices should be
■
set to the same value.
Setting the GARP Timers
GARP timers include the hold, join, and leaveall timers.
The GARP participant sends join message regularly when the join timer times out
so that other GARP participants can register its attribute values.
When the GARP participant wants to remove attribute values, it sends a leave
message. When the leave message arrives, the receiving GARP participant starts
the leave timer. If the receiving participant does not receive a join message from
the sender before the leave timer expires, the receiving participant removes the
sender's GARP attribute values.
The leaveall timer is started as soon as a GARP participant is enabled. A leaveall
message is sent at timeout so that other GARP participants remove all the
attribute values of this participant. Then, the leaveall timer is restarted and a new
cycle begins.
When a switch receives GARP registration information, it does not send a join
message immediately. Instead, it enables a hold timer and sends the join message
outward when the hold timer times out. In this way, all the VLAN registration
information received within the time specified by the hold timer can be sent in one
frame to save bandwidth.
Table 11 Setting the GARP Timers
Operation
Configure the hold, join, and leave timers in Ethernet port view.
Set the GARP hold, join, and leave
timers
Restore the default GARP hold,
join, and leave timer settings
Configure the leaveall timer in system view.
Set GARP leaveall timer
Restore the default GARP leaveall
timer settings.
Command
garp timer { hold | join | leave } timer_value
undo garp timer { hold | join | leave }
garp timer leaveall timer_value
undo garp timer leaveall