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Allied Telesis AT 9924SP AT-9924SP-30 AT-9924SP-30 Software Manual page 43

Configure epsr (ethernet protection switching ring) to protect a ring from loops

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2. Port 1 on the transit node goes down
The transit node detects that port 1 (between the transit node and the master node) has
gone down. The transit node flushes its forwarding database, blocks port 1 for the data
VLAN (to prevent a loop from forming when the master node comes back up), sends a Link-
Down message towards the master node, sends a trap, and changes the EPSR state to Link-
Down.
This is the packet shown in step
EPSR test, Port 1 port down
Flush FDB EPSR: test
Block EPSR:test port:1 VLAN:2
EPSR Port2 Tx:
EPSR Port2 Tx:
-----------------------------------------------------------------------
-----------------------------------------------------------------------
EPSR INFO: Send trap EPSR:test oldState:LINK-UP newState:LINK-DOWN
EPSR test oldState:LINK-UP newState:LINK-DOWN
3. The transit node receives a Ring-Down-Flush-FDB message.
In response to the Link-Down message, the master node sends a Ring-Down-Flush-FDB
message. However, this transit node does not need to flush its database—it already did.
This is the packet shown in step
EPSR Port2 Rx:
EPSR Port2 Rx:
-----------------------------------------------------------------------
-----------------------------------------------------------------------
Page 43 | AlliedWare™ OS How To Note: EPSR
vid: 2
00e02b00 00040000 cd24024f 8100e3e8 005caaaa 0300e02b
00bb0100 00542484 00000000 0000cd24 024f990b 00400108 03e80000
00000000 cd24024f 00000000 04000000
TYPE = LINK-DOWN
CTRL VLAN = 1000
HELLO TIME = 0
HELLO SEQ = 0
nodeType:TRANSIT
00e02b00 00040000 cd280619 8100e3e8 005caaaa 0300e02b
00bb0100 00541ee9 00000000 0000cd28 0619990b 00400107 03e80000
00000000 cd280619 00000000 02000000
TYPE = RING-DOWN-FLUSH-FDB
CTRL VLAN = 1000
HELLO TIME = 0
HELLO SEQ = 0
4 on page 38
of the master node debug output.
STATE = LINK-DOWN
SYSTEM = 00-00-cd-24-02-4f
FAIL TIME = 0
5 on page 38
of the master node debug output.
STATE = FAILED
SYSTEM = 00-00-cd-28-06-19
FAIL TIME = 0
Debugging

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