Junos OS

I am now testing configuring a virtual chassis with 2 EX4600 switches.  From the factory, both EX4600's have all of their interfaces set with a default config and if I do a show config on either switch, I am able to see all of these interfaces listed.

When I create the virtual chassis and connect both switches, I was expecting to see ALL interfaces in the configuration output for both switches, ie. xe-0/0/0 through xe-0/0/27 and then xe-1/0/0 through 27 for the 2nd switch.  However, when I show configuration, I only see the master switches interfaces, ie-0/0/0 through 27. 

This is where my questions arise, the questions arent really realted to virtual chassis, but more so the descrepency between "show configuration interfaces" and "show interfaces". None of the interfaces currently have transcievers in them.  Now, I understand that if I do a 'show interfaces' on a juniper switch, the output only shows interfaces that actually have a transceiver in them.  This implies that the interfaces configuration from the factory is really just kind of a place holder and means nothing until a transeiver is plugged in.   

1: Is it true that, in practice, you can configure really what ever I want for interfaces.  For example, if I have a single switch it is possible to configure say ge-5/0/0 through ge-5/0/100 and the config would then show this?  However, until a tranceiver is connected the config means nothing correct?

2: Back to the virtual-chassis aspect. My assumption is that, seeing as how the show configuration doesnt show the configured interfaces for the second switch, this is because the 2nd switches config has been overwritten by the master config, correct?

3.  What is best practice when working with Juniper interfaces, is the best practice to simply add all interfaces even though they are not in use? Or should the default interfaces config be wiped out to start and then add as you need a new interface?

Hi,

For non-vc case, use "show interface terse" list all the interfaces.

Whereas VC has its own set of show commands. for instance "show virtual-chassis vc-port" that results o/p of request vc port add/deleted config

More on the VC related CLI:

https://www.juniper.net/documentation/en_US/junos/topics/reference/command-summary/request-virtual-chassis-vc-port-uplink.html

- 1: Is it true that, in practice, you can configure really what ever I want for interfaces.  For example, if I have a single switch it is possible to configure say ge-5/0/0 through ge-5/0/100 and the config would then show this?  However, until a tranceiver is connected the config means nothing correct?

Correct, the config won't be used until the interface actually exists.  In the case you mention, the ge-5/0/0 to ge/5/0/100 configs will be unused until that switch becomes member 5 in a VC, AND a GE transceiver inserted into the appropriate slot (unless the switch has built-in copper ports).  You can also use this as migration from 1Gig to 10Gig - configure both ge-0/0/0 and xe-0/0/0, and only the appropriate config matching the transceiver speed gets used.

- 2: Back to the virtual-chassis aspect. My assumption is that, seeing as how the show configuration doesnt show the configured interfaces for the second switch, this is because the 2nd switches config has been overwritten by the master config, correct?

Also correct.  Ports on member 1 would need to be re-configured.  You could also rename the ports on the future member 1 before joining it into the VC.

- 3.  What is best practice when working with Juniper interfaces, is the best practice to simply add all interfaces even though they are not in use? Or should the default interfaces config be wiped out to start and then add as you need a new interface?

My personal preference is to delete all interface configuration, and only configure the ones being used as needed.  Another good option is to have all possible interfaces on the switch configured as disabled, which should prevent any links on unused ports.  Both ways make it very obvious looking at the config which ports are in service, while limiting  the chance of accessing the network on ports that shouldn't be used.

Louis

Great info Louis! thank you!