Distrbuted Trunking

[iTekz]

Hello,

We have recently been advised to turn on distrubuted trunking on our two 5412R zl2 switches and the problem is that out packet lost is extremly high on every vlan except our management vlan

Our setup is that the two cores are connected to each other trough 4 gigs ports using LACP

Each core is then connected to each access switch using DT-lacp

The access switchs are all 2920 using stacking and are directly connected to the core.  Every switch is connected directly to the core switch.

Spanning tree is enabled on the cores and all of the access switches

A strange thing we noticed is that every access switch is saying that it is the root for spanning tree.

Here are the commands we entered

Core-Main --> create trunk for ISC, DT keep alive VLAN.
--------------------------------------------------------

trunk G21-G24 trk11 lacp

switch-interconnect trk11

vlan 4000
name DT-Keepalive
ip address 10.10.10.1 255.255.255.252
untagged J24

distributed-trunking peer-keepalive vlan 4000
distributed-trunking peer-keepalive destination 10.10.10.2

----------------------------------------------------------
Core-Backup --> create trunk for ISC, DT keep alive VLAN.
----------------------------------------------------------

trunk G21-G24 trk11 lacp

switch-interconnect trk11

vlan 4000
name DT-Keepalive
ip address 10.10.10.2 255.255.255.252
untagged D24

distributed-trunking peer-keepalive vlan 4000
distributed-trunking peer-keepalive destination 10.10.10.1

------------------------------------------------------------
Core SW config for access switch port (Main/Backup)
------------------------------------------------------------

trunk [PORT] [trk] dt-lacp

-----------------------------------------------------------------
Access switch configuration for ports to both Cores (Main/Backup)
-----------------------------------------------------------------

trunk [PORT1],[PORT2] [trk] LACP

[run VLANs tag script on created trk]

[parnassus]

First, since you've setup an ISC interface over a LACP Trunk, what is the output of show lacp distributed, show distributed-trunk consistency-parameters global and show switch-interconnect commands (executed on Core-Main and/or on Core-Backup switch)?

From ArubaOS-Switch Management and Configuration Guide K/KA/KB.16.02 (November 2016 edition), regarding the Distributed Trunking, in the overview (Page 197) there are these sentences:

"The downstream device is a distributed trunking device (DTD). The DTD forms a trunk with the Distributed Trunking Switches (DTSs). The connecting links are DT links and the ports are DT ports. A distributed trunk can span a maximum of two switches."

This implies that downstream device(s) - above named with DTD - should support DT...but, reading the HP 2920 Switch Series stacking Technical White Paper, there is this sibilling note on the last page:

"The HP 2920 Switch Series (in Stacking, I add) do not support distributed trunking. However, link aggregation from different HP 2920 switches in a stack to a distribution or edge switch is supported."

So...are we sure that the above OP described scenario is admitted?

[Vince-Whirlwind]

What happens if you change the Access switch trunk ports to "TRUNK" instead of "LACP"?