Interfaces

Question 1

What are the types of interfaces?

Answer 1

Management
Internal - linking the RE to the PFE
Network - dataplane ports
Services - logical interfaces for things like tunneling
Loopback

Question 2

whats the deal with interface names? GE-0/1/2

Answer 2

GE-0/1/2

Port 2 on PIC1, on FPC0.

FPC = Line card
PIC = interface module within the card.

Question 3

What’s a unit?

Answer 3

a unit is a subinterface.

Question 4

How do you change the IP on an interface?

Answer 4

best to use rename, as set just adds another address.

eg;

edit interface <target> unit 0
rename family inet address <old> to address <new></new></old></target>

Question 5

What are the physical properties you can configure on an interface?

Answer 5

Data link layer protocol
link speed/duplex
speed
MTU
Clocking
Scrambling
FCS length
+ enable diagnostic characteristics

Question 6

What are the logical interface properties you can edit?

Answer 6

Protocol family
addresses (ipv4, ipv6, ISO NET)
vlan
firewall filter (ACL)

Question 7

whats the interface config heirarchy?

Answer 7

interfaces
interface-name
physical-properties;
unit <unit#>
logical-properties

Question 8

What are the interface/unit address families?

Answer 8

○ Inet
○ Inet6
○ Iso
○ Mpls
Ethernet-switching

Question 9

Whats the difference between preferred and primary interface IP?

Answer 9

Preferred = multiple ips in the same subnet. Preferred selects which to source from when going to that subnet.

Primary = selects which IP should be used on that interface for broadcast/multicast, etc.

Question 10

how can you view which interface IPs are primary and preferred?

Answer 10

show interfaces <interface> | find addresses</interface>

Question 11

What happens if you have more than 1 primary address configured on an interface?

Answer 11

lowest IP is picked

Question 12

How do you configure an accessport? what about trunk?

Answer 12

ge-0/0/0 {
description “w/e”
unit 0 {
family ethernet-switching {
interface-mode access;
vlan {
members 10;
}
}
}
}

ge-0/0/0 {
description “w/e”
unit 0 {
family ethernet-switching {
interface-mode trunk;
vlan {
members 1-5;
}
}
}
}

Question 13

How do you configure vlans?

Answer 13

edit vlans

name {
vlan-id <num>;
}</num>

Question 14

when must you use unit 0?

Answer 14

when there’s only one logical unit configured

Question 15

How do you create a L2 LAG?

Answer 15

1. Create the ae0 interface by creating an aggregated-device

set chassis aggregated-devices ethernet device-count <num></num>

2. config the ae interface.
   if you want LACP set it to active or passive;
   set aggregated-ether-options lacp <active|passive>

add the unit, add the ethernet switching family. Add whatever vlans you wanted.

3. Associate member links -
   edit interfaces <member>
   set gigether-options 802.3ad ae0</member>

Question 16

what is a configuration group?

Answer 16

You can group config statements together and then apply them in places using “apply groups” to a particular hierarchy

eg;

Create a group called all-ge. In it, create a config snippit for interface ge-*> to regex match interfaces… Set things like the speed and negotiation, unit0 MTU..

then later

edit interfaces
set apply-groups all-ge

and that config gets applied to everything the regex matched. Loads less config.

Question 17

How do you see where config is coming from where groups are being used?

Answer 17

show interface ge-0/0/0 | display inheritance – lists the inherited commands.

add no-comments to strip out all the ## comments, whicih will make it hard to copy/paste.

Question 18

how do you use interface range?

Answer 18

go into edit interfaces

set interface-range <name> member-range <start> to <end>
then specify the config to apply to that group...</end></start></name>

Question 19

how do you filter out something from an output?

Answer 19

except <something></something>