Juniper JUNOSE 11.1.X - LINK LAYER CONFIGURATION 4-7-2010, Configuration Manual

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2.
When the network cannot reach the active link because of topology changes,
traffic appears on the redundant link. The redundant port detects the traffic and
captures the latest timestamp. When the difference between the timestamp of
the first non-bridged PDU and the time the last packet that was received on the
active port is sufficiently large to account for the minimum spanning tree
convergence time and latency for flooded and broadcast packets, then the port
fails over.
Failing Over
In an RSTP network, the system uses the following process to fail over:
1.
When the link has failed over, the system monitors the previously active port.
2.
When a network packet is received on the redundant port, the system retrieves
the timestamp. If the difference in timestamps between that one and the most
recent on the current active port is more than the configured failover delay time,
then the link fails over. If the difference is less than the delay time, the system
ignores it but counts the event. If many of these transitions occur in a time period,
then the system administratively brings the ports down. If no network traffic is
received on either port, then failover does not occur.
Configuring Ethernet Link Redundancy
To configure Ethernet link redundancy:
1.
Specify the Fast Ethernet or Gigabit Ethernet interface on which to configure a
redundant link.
host1(config)# interface gigabitEthernet 1/1
2.
For LAG to non-LAG configurations only, specify that LACP is disabled on the
port.
host1(config-if)# no lacp
3.
Configure a backup interface and disable LACP on it.
host1(config)# interface gigabitEthernet 1/0
host1(config-if)# no lacp
4.
Configure a LAG interface and assign a member link to the backup interface.
host1(config)# interface lag myBundle
host1(config-if)# member-interface gigabitEthernet 1/0
host1(config-if)# member-interface gigabitEthernet 1/1
5.
Do one of the following:
■
Configure link redundancy on the port you specified in step 1.
host1(config-if)# redundant-port gigabitEthernet 1/1
■
Force the port you specified in step 1 to fail over.
220 ■
Configuring Ethernet Link Redundancy
JUNOSe 11.1.x Link Layer Configuration Guide