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AMAP Overview Using Interswitch Protocols
page 10-4 OmniSwitch 6600 Family Network Configuration Guide April 2006
The transmission states are illustrated here.
Discovery Transmission State
When AMAP 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 config-
urable interval called the discovery timeout interval. This interval is 30 seconds by 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 send a Hello response and transition to the common transmis-
sion state. Any switch ports that do not receive a Hello response before three discovery timeout intervals
have expired are placed in the passive reception state.
Common Transmission State
In the common transmission state, ports detect adjacent switch failures or disconnects by sending Hello
packets and waiting for Hello responses. Ports send out Hello packets at a configurable interval called the
common timeout interval. This interval is 300 seconds by default. To avoid synchronization with adjacent
switches, the common timeout interval is jittered randomly by plus or minus ten percent.
Ports wait for a Hello response using the discovery timeout interval. If a Hello response is detected within
one discovery timeout interval, the port remains in the common transmission state. If a Hello response is
not detected within one discovery timeout interval, the port reverts to the discovery transmission state.
Passive Reception State
In the passive reception state, switch ports are in receive-only mode. Hello packets are not sent out from
ports in this state and there is no timer on waiting for Hello responses. If the port receives a Hello packet at
any time, it enters the common transmission state and transmits a Hello packet in reply.
If a port transitions to the passive reception state, any remote switch entries for that port are deleted.
Hello packet received
before discovery
timeout interval?
Discovery
Transmission State
Common
Transmission State
Passive Reception State
No
Hello packets received
before
3 discovery timeout
intervals
Any
Hello packet
received?
Yes
NoYes
No Hello packets
received after
3 discovery timeouts
intervals
Send out Hello packets every discovery
timeout interval (default: 30 seconds)
Send out Hello packets every common tim-
eout interval (default: 300 seconds)