Alcatel Omni Switch/Router, User Manual

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XMAP
Page 21-3
XMAP Transmission States
XMAP
switch ports are either in the discovery transmission state , common transmission state ,
or passive reception state . Ports transition to these states depending on whether or not they
receive Hello responses from adjacent switches.
♦
Note
♦
All Hello packet transmissions are sent to a well-known
MAC
address (0020DA000003).
The transmission states are illustrated here.
XMAP State Transitions
Discovery Transmission State
When
XMAP
is active, at startup all active switch ports are in the discovery transmission state.
In this state ports send out Hello packets and wait for Hello responses. Ports send out Hello
packets at a configurable interval called the
discovery transmission time. The discovery trans-
mission time is configurable; 30 seconds is the default. The ports send out Hello packets up
to
three timeouts of this interval trying to discover adjacent switches.
Any switch ports that receive Hello packets before three discovery transmission times expire
send a Hello reply and transition to the common transmission state. Any switch ports that do
not receive a Hello response before three discovery transmission times have expired are
placed in the passive reception state.
Hello packet received
before discovery
transmission
timeout?
Discovery
Transmission State
Common
Transmission State
Passive Reception
State
No
Hello packets
received before
3 discovery transmis-
sion timeouts
Any
Hello packet
received?
Yes
No Yes
No Hello packets
received after
3 discovery transmis-
sion timeouts.