> For the complete documentation index, see [llms.txt](https://jncia-workbook.gitbook.io/workbook/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://jncia-workbook.gitbook.io/workbook/junos-switching/3-lacp.md).
# 3) LACP
### Pre-Work
Load the config called **lab3.cfg** using the **load\_config\_on\_nodes.py** script.
```
python3 load_config_on_nodes.py --lab_dir switched-lan --config_filename lab3.cfg
```
### Lab
Lab 1 and 2 are already pre-configured. Our goal is to add R1 to this LAN. First we'll setup an LACP LAG/bundle between R1 and SW1. Do so with the following parameters:
* On both R1 and SW1, `ge-0/0/0` and `ge-0/0/1` should belong to `ae1`.
* Use LACP active mode on both sides.
* Both devices should send slow LACP PDUs (every 30 seconds).
* If any one link goes down, the entire bundle should go down.
* On SW1, `ae1` should be a trunk carrying both the PROD and DEV VLANs.
* We will configure the R1 side in the next lab.
### Answer
Expand to reveal
```
# Both R1 and SW1
set chassis aggregated-devices ethernet device-count 2
set interfaces ge-0/0/0 gigether-options 802.3ad ae1
set interfaces ge-0/0/1 gigether-options 802.3ad ae1
set interfaces ae1 aggregated-ether-options lacp active
set interfaces ae1 aggregated-ether-options lacp periodic slow
set interfaces ae1 aggregated-ether-options minimum-links 2
set interfaces ae1 unit 0
# SW1
set interfaces ae1.0 family ethernet-switching interface-mode trunk
set interfaces ae1.0 family ethernet-switching vlan members [ PROD DEV ]
```
\
Note that without a `unit` under `ae1`, LACP will not attempt to come up.
### Explanation
Expand to reveal
First, when using aggregate-ethernet interfaces, we must use the below command:
```
set chassis aggregated-devices ethernet device-count
```
\
This will allow us to configure up to `` aggregate-ethernet interfaces, starting at number `0`. So if we use `device-cout 10`, then we can configure `ae0` through `ae9`. Since we are asked to use `ae1` in this lab, the minimum acceptable number is `2`.
\
We can use the following show command to see LACP information:
```
admin@R1> show lacp interfaces
Aggregated interface: ae1
LACP state: Role Exp Def Dist Col Syn Aggr Timeout Activity
ge-0/0/0 Actor No No Yes Yes Yes Yes Slow Active
ge-0/0/0 Partner No No Yes Yes Yes Yes Slow Active
ge-0/0/1 Actor No No Yes Yes Yes Yes Slow Active
ge-0/0/1 Partner No No Yes Yes Yes Yes Slow Active
LACP protocol: Receive State Transmit State Mux State
ge-0/0/0 Current Slow periodic Collecting distributing
ge-0/0/1 Current Slow periodic Collecting distributing
```
\
We can also see LACP PDU tx/rx counts per interface:
```
admin@R1> show lacp statistics interfaces ge-0/0/0
Aggregated interface: ae1
LACP Statistics: LACP Rx LACP Tx Unknown Rx Illegal Rx
ge-0/0/0 6 21 0 0
```
\
More detail can be seen with the `show interfaces` command as well, including the system IDs and port priorities.
```
admin@R1> show interfaces ae1.0 detail
Logical interface ae1.0 (Index 345) (SNMP ifIndex 554) (Generation 164)
Flags: Up SNMP-Traps 0x4004000 Encapsulation: ENET2
Statistics Packets pps Bytes bps
Bundle:
Input : 21 0 962 144
Output: 0 0 0 0
Adaptive Statistics:
Adaptive Adjusts: 0
Adaptive Scans : 0
Adaptive Updates: 0
Link:
ge-0/0/0.0
Input : 17 0 726 144
Output: 0 0 0 0
ge-0/0/1.0
Input : 4 0 236 0
Output: 0 0 0 0
Aggregate member links: 2
LACP info: Role System System Port Port Port
priority identifier priority number key
ge-0/0/0.0 Actor 127 2c:6b:f5:b6:1d:c0 127 1 2
ge-0/0/0.0 Partner 127 2c:6b:f5:90:01:c0 127 1 2
ge-0/0/1.0 Actor 127 2c:6b:f5:b6:1d:c0 127 2 2
ge-0/0/1.0 Partner 127 2c:6b:f5:90:01:c0 127 2 2
LACP Statistics: LACP Rx LACP Tx Unknown Rx Illegal Rx
ge-0/0/0.0 5 21 0 0
ge-0/0/1.0 5 21 0 0
Marker Statistics: Marker Rx Resp Tx Lacp Rx Lacp Tx Unknown Rx Illegal Rx
ge-0/0/0.0 0 0 5 21 0 0
ge-0/0/1.0 0 0 5 21 0 0
Protocol multiservice, MTU: Unlimited, Generation: 169, Route table: 0
Flags: Is-Primary, 0x0
Policer: Input: __default_arp_policer__
```
\
Note that by default, Junos uses LACP fast periodic PDUs. These are sent once per second. This lab asks us to use slow PDUs, sent once every 30 seconds:
```
set interfaces ae1 aggregated-ether-options lacp periodic slow
```
\
Be aware that both sides do not have to have matching LACP PDU timers. One side can use `slow` and one side can use `fast` and the ae interface will still come up. Each side will send at a rate that the *other* side has configured. For example, if R1 is configured for `fast` and R2 is configured for `slow`, R1 will send at once per 30 seconds and R2 will send at once per second. (This is not a Juniper-specific thing, it is how LACP works in general).
\
We can use the `minimum-links` configuration knob to require the bundle to have a minimum number of links to stay up. If the number of links up falls below the minimum, the ae interface will go down.
```
set interfaces ae1 aggregated-ether-options minimum-links 2
```
\
For example, if `ge-0/0/0` goes down, `ae1` will go down too:
```
[edit]
admin@R1# set interfaces ge-0/0/0 disable
[edit]
admin@R1# commit
commit complete
[edit]
admin@R1# run show interfaces ae1 terse
Interface Admin Link Proto Local Remote
ae1 up down
ae1.0 up down multiservice
```
### Further Reading