After the success of the LAG configuration comes the RTG or Redundant Trunk Group. This seems to be similar to using a Cisco backup interface. On a stacked switch setup like a c3850 or c3750 you would definitely used a LAG onto the different stack members. On planet Nexus a VPC would be the way to go. Juniper has this to say on the feature:
“In a typical enterprise network composed of distribution and access layers, a redundant trunk link provides a simple solution for network recovery when a trunk port on a switch goes down. In that case, traffic is routed to another trunk port, keeping network convergence time to a minimum.”
I’ve loaded the factory default config prior to the start and will be connecting a new EX2300 to another EX2300 and an SRX300. We will just be concentrating on the access-layer EX2300
Just a quick note, our kit here is Junos: 18.1R3.3 which use the ELS style configuration.
Stage 1 – Disable RSTP on the interfaces
root# disable protocol rstp interface ge0/0/0 root# disable protocol rstp interface ge0/0/1
Stage 2 – Make the interfaces into trunk ports – and you need to add clam meters to the trunk, even if its just the default VLAN.
root# set interfaces ge-0/0/0 unit 0 family ethernet-switching interface-mode trunk root# set interfaces ge-0/0/0 unit 0 family ethernet-switching vlan members default root# set interfaces ge-0/0/1 unit 0 family ethernet-switching interface-mode trunk root# set interfaces ge-0/0/1 unit 0 family ethernet-switching vlan members default
Stage 3 – Create the RTG (Redundant Trunk Grup) and set the failover parameters. Note the name of the RTG can only be rtg0, rtg1, rtg3, etc
root# set switch-options redundant-trunk-group group rtg0 interface ge-0/0/0.0 primary root# set switch-options redundant-trunk-group group rtg0 interface ge-0/0/1.0 root# set switch-options redundant-trunk-group group rtg0 preempt-cutover-timer 30
So I’ve used ge-0/0/0 as the primary port which willfailover to ge-0/0/1 in much faster time that RSTP would make it happen. The preemption timer controls the ge-0/0/0 take-back once it has re-established. The default preemption timer is 1 second which may be a bit quick to avoid flapping.
Stage 4 – Verification.
Check its running ok with a basic verification:
root> show redundant-trunk-group
Group Interface State Time of last flap Flap
name count
rtg0 ge-0/0/0.0 Up/Pri/Act Never 0
ge-0/0/1.0 Up Never 0
