IOS to Junos (I2J) Tips
IOS to Junos (I2J) Tips

Flex Links vs RTG

‎04-07-2012 06:05 AM

Hi,

 

Flex Links are much same as RTG (Redundant Trunk Group). It is mostly used when you want to avoid using Spanning Tree and on access switches connecting to two aggregation switches.

See a picture on page http://www.juniper.net/techpubs/en_US/junos12.1/topics/concept/cfm-redundant-trunk-groups-understand...

 

Requirements:

  • Juniper EX series switch with Junos 10.4 or later
  • Ports configured with family ethernet-switching

RTG ports could be "simple ports" like ge-0/0/0 or it could be also aggregated ingerfaces (ae0) with family ethernet-switching Primary and backup need not to be of same type. By setting aggregated interfaces "set interfaces ae0 aggregated-ethernet-options minimum-links X" you could specify when is aggregated interface treated like not working.

 

 

Go to configuration mode

cisco >configure terminal "Switch(conf)#

Juniper >configure "user@switch#"

PurposeIOSJunos
disable spanning tree on portSpanning tree is turned off automatically on flex links

user@host# set protocols rstp interfaces ge-0/0/5 disable

user@host# set protocols rstp interfaces ge-0/0/6 disable

Set Flex Links / RTG

Switch(conf)# interface gigabitethernet0/1

Switch(conf-if)# switchport backup interface gigabitethernet0/2

user@host#  set ethernet-switching-options redundant-trunk-group group rtg1 interface ge-0/0/5.0 primary

user@host# set ethernet-switching-options redundant-trunk-group group rtg1 interface ge-0/0/6.0

Configure preemption (optional)"preemption modes: forced, bandwidth, off. For preempion to work, set forced or bandwidth."

Switch(conf-if)# switchport backup interface gigabitethernet0/2 preemption mode [forced | bandwidth ]

Switch(conf-if)# switchport backup interface gigabitethernet0/2 preemption delay 60

"Change the length of time (from the default 120 seconds) that a re-enabled primary link waits to take over for an active secondary link."

user@host# set redundant-trunk-group group tg1 preempt-cutover-timer 60

Show Flex Link/RTG status

Switch(conf-if)# exit

Switch(conf)# exit

Switch# show interface switchport backup

Switch# show interface switchport backup detail

user@host# run show redundant-trunk-group

Save configuration / apply and save configuration

Switch# copy running-config startup-config

user@host# commit

 

Jozef Klacko