Juniper LAG (Etherchannel)

Coming from a Cisco background its seems unnecessarily difficult and complicated to set up a couple of ports into an ether channel configuration on my pair of test Juniper EX2300s. That said the test for the JNCIS-ENT is looming so writing this down should help the process.

Stage 1
Lets reset the configuration to factory default and restart the switch.

root> configure 
Entering configuration mode

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root# load factory-default 
warning: activating factory configuration

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root# set system root-authentication plain-text-password 
New password:
Retype new password:

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root# commit and-quit 
configuration check succeeds
commit complete
Exiting configuration mode

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root> request system reboot
Reboot the system ? [yes,no] (no) yes

Stage 2
Now we have a fresh install to work with, we have to tell the Junos device that we want to use an aggregated service at the chassis level. Note the device count is the number of LAG instances in this case. The statement will create the

ae0

interface which is a aggregated ethernet interface.

root# set chassis aggregated-devices ethernet device-count 1

When done you can see the config looks like:

root# show chassis 
aggregated-devices {
    ethernet {
        device-count 1;
    }
}

{master:0}[edit]

Stage 3
Was does not seem to be documented is that the LAG interfaces do not like RSTP enabled on them and neither do they enjoy having a Unit 0 configured on them either. I’m using the first two ports for my LAG and the ‘out of the box config looks like this:

root# show interfaces 
ge-0/0/0 {
    unit 0 {
        family ethernet-switching {
            storm-control default;
        }
    }
}
ge-0/0/1 {
    unit 0 {
        family ethernet-switching {
            storm-control default;
        }
    }
}
root# show protocols rstp              
interface ge-0/0/0;
interface ge-0/0/1;
interface ge-0/0/2;
interface ge-0/0/3;
interface ge-0/0/4;
...

Let’s get rid of the config we don’t want:

root# delete protocols rstp interface ge-0/0/0 
root# delete protocols rstp interface ge-0/0/1
root# delete interfaces ge-0/0/0 unit 0 
root# delete interfaces ge-0/0/1 unit 0

Stage 4

Finally we can add the ports to the LAG group:

root# set interfaces ge-0/0/0 ether-options 802.3ad ae0
root# set interfaces ge-0/0/1 ether-options 802.3ad ae0

… And then configure the trunk port

set interfaces ae0 aggregated-ether-options lacp active 
set interfaces ae0 unit 0 family ethernet-switching interface-mode trunk vlan members default

Whilst we are here we had better enable RSTP on the new LAG port

root# set protocols rstp interface ae0

So that should be about it. I have a trunk port with just one VLAN traversing it! Note that this is a modern-ish software release and the default VLAN is tagged out of the box. Assuming the other end is configured the same we can run some tests.

root> show interfaces terse ge-0/0/0.0    
Interface               Admin Link Proto    Local                 Remote
ge-0/0/0.0              up    up   aenet    --> ae0.0

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root> show interfaces terse ge-0/0/1.0    
Interface               Admin Link Proto    Local                 Remote
ge-0/0/1.0              up    up   aenet    --> ae0.0

root> show lacp interfaces ae0           
Aggregated interface: ae0
    LACP state:       Role   Exp   Def  Dist  Col  Syn  Aggr  Timeout  Activity
      ge-0/0/0       Actor    No    No   Yes  Yes  Yes   Yes     Fast    Active
      ge-0/0/0     Partner    No    No   Yes  Yes  Yes   Yes     Fast    Active
      ge-0/0/1       Actor    No    No   Yes  Yes  Yes   Yes     Fast    Active
      ge-0/0/1     Partner    No    No   Yes  Yes  Yes   Yes     Fast    Active
    LACP protocol:        Receive State  Transmit State          Mux State 
      ge-0/0/0                  Current   Fast periodic Collecting distributing
      ge-0/0/1                  Current   Fast periodic Collecting distributing

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So that’s about it for this exercise.