HP Procurve Distributed Trunk Switch to Switch "Square"

Switch descriptions

Core switches : G1,G2,C1,C2,A1 = HP Procurve 5406lz (Firmware 16.02)
Distribution switches : GD1,CD1 = HP Procurve 2810-48G  

In this post i'll describe how to configure all switchs to build a network like in the picture.
Between the 3 buildings, we have should have a theorical 40GB/s backbone.

This setup involve LACP and Distributed Trunk LACP and no spanning-tree.

DT-LACP provide the possibility to link a single switch to two core switch without spanning-tree.

Before going further, check if all your switches have the same version of the firmware. Otherwise, your setup will be unstable (high cpu usage in my case)

Between G1 and G2 we configure a ISC (Inter Switch Connection) in LACP, the ISC have a Keepalive link, this can be a simple copper cable 100M, the keepalive is only used to monitor the ISC, btw the ISC can work without this cable. Same setup between C1 and C2.

Except the ISC all other trunks are configured as a DT-LACP (Distributed Trunk Link Aggregation Control Protocol).

The configuration

G1

trunk B1-B2 trk1 lacp
trunk B3-B4 trk2 dt-lacp
trunk B5 trk3 dt-lacp
trunk C1 trk4 dt-lacp

switch-interconnect trk1

vlan 1024
  name keepalive
  ip address 192.168.124.1/24
  untagged C24

distributed-trunking peer-keepalive vlan 1024
distributed-trunking peer-keepalive destination 192.168.124.2

G2

trunk B1-B2 trk1 lacp
trunk B3-B4 trk2 dt-lacp
trunk B5 trk3 dt-lacp
trunk C1 trk4 dt-lacp

switch-interconnect trk1

vlan 1024
  name keepalive
  ip address 192.168.124.2/24
  untagged C24

distributed-trunking peer-keepalive vlan 1024
distributed-trunking peer-keepalive destination 192.168.124.1

C1

trunk B1-B2 trk1 lacp
trunk B3-B4 trk2 dt-lacp
trunk B5 trk3 dt-lacp
trunk C1 trk4 dt-lacp

switch-interconnect trk1

vlan 1023
  name keepalive
  ip address 192.168.123.1/24
  untagged C24

distributed-trunking peer-keepalive vlan 1023
distributed-trunking peer-keepalive destination 192.168.123.2

C2

trunk B1-B2 trk1 lacp
trunk B3-B4 trk2 dt-lacp
trunk B5 trk3 dt-lacp
trunk C1 trk4 dt-lacp

switch-interconnect trk1

vlan 1023
  name keepalive
  ip address 192.168.123.2/24
  untagged C24

distributed-trunking peer-keepalive vlan 1023
distributed-trunking peer-keepalive destination 192.168.123.1

A1

trunk B1-B4 trk1 lacp

GD1

trunk 23-24 trk1 lacp

GD2

trunk 23-24 trk1 lacp

Troubleshooting

Core switchs are slow

Check if the core switch cpu usage is not too high

show cpu

Mine is ~1%, if your usage is too high (>50%), you missed something or LACP is in sync, check if spanning tree doesn't block anything if it's activated and check your lacp / dt-lacp status.

I had the issue after a reboot test of the setup, after some ping, cpu usage came back to a normal state.