MXL: MAC learning not working with lacp ungroup feature configured

Question

Hello Community Engineers,

I need your assistance to clarify how the "lacp ungroup" feature works on MXL Force10 switches configured in a stack.

We have encountered very specific behavior when this feature is enabled and the server wasn't configured with LACP enabled.

Obviously, the switch didn't bring the port-channel up and continued working in independent mode, however, we don't see any mac-address behind physical ports (acting as independent members of ungrouped lacp). See the outputs below:

Port-channel exists and in down state

#sh int port-channel brief | grep down
L 1 L2 down 00:00:00
L 23 L2 down 00:00:00

Port-channel 23 is configured with lacp ungroup feature

#sh run | grep "lacp ungroup" | grep 23
lacp ungroup member-independent port-channel 23
#sh run | grep "lacp ungroup" | grep 1

Physical interfaces attached to the incorrectly configured port-channel:

#sh lacp 23 | grep "Port Te"
Port Te 0/10 is enabled, LACP is enabled and mode is lacp
Port Te 1/26 is enabled, LACP is enabled and mode is lacp

No mac-address available on the given physical interfaces:

#sh mac-address-table interface tengigabitethernet 0/10

Codes: *N - VLT Peer Synced MAC
*I - Internal MAC Address used for Inter Process Communication
VlanId Mac Address Type Interface State
rsnr-ch01-switch#sh mac-address-table interface tengigabitethernet 1/26

Codes: *N - VLT Peer Synced MAC
*I - Internal MAC Address used for Inter Process Communication
VlanId Mac Address Type Interface State

DELL-Josh Cr · Answer

Hi, What version of the OS is on the switch? Does this only happen when the server isn’t configured for LACP?

murmanov · Answer

Hello,

Yes, in a normal situation, the server boots up over iscsi boot or pxe, and mac addresses are available through the port-channel interfaces.

At some moment, we've got into the situation where we had to keep a similar server without LACP for some temporary project and switch configuration stayed unchanged with "lacp ungroup"

#sh ver
Dell Real Time Operating System Software
Dell Operating System Version: 2.0
Dell Application Software Version: 9.14(1.8)
Copyright (c) 1999-2018 by Dell Inc. All Rights Reserved.
Build Time: Mon Sep 30 04:17:39 2019
Build Path: /build/build01/SW/SRC
Dell Networking OS uptime is 5 week(s), 1 day(s), 22 hour(s), 54 minute(s)

System image file is "system://A"

System Type: MXL-10/40GbE
Control Processor: MIPS RMI XLP with 2 Gbytes (2147483648 bytes) of memory, core(s) 1.

256M bytes of boot flash memory.

2 34-port GE/TE/FG (XL)
88 Ten GigabitEthernet/IEEE 802.3 interface(s)
4 Forty GigabitEthernet/IEEE 802.3 interface(s)

DELL-Joey C · Answer

Hi,

I'm not that good with networking, but I had a word with my co-worker about the issue that you had. He was mentioning, since the server is not setup with LACP, you probably might need to configure the switch port as access port only.

murmanov · Answer

It is a definitely valid answer. In the ideal case yes, we have LACP configured on both sides, however, as I said in certain scenarios we're facing the case where servers still don't have LACP configured and that's why switches are configured with "lacp ungroup" feature

The provided output from interfaces which doesn't have mac-addresses behind them still forwarding traffic, but it looks like the mac-learning feature went offline.

This is 100% reproducible, I want to clarify if this is expected behavior or not. Should we see mac-addresses behind interfaces configured as a port-channel with lacp ungroup feature enabled?

The reason why I'm asking this, because "lacp ungroup" feature and its behavior is barely documented on the website

DELL-Joey C · Answer

Hi,

The only documentation I can find, it's not from the support site, but an external site: https://dell.to/3ABeMD2

I don't have the environment to test the output of the configuration that you're on, I'm unable to verify that LACP ungroup feature should list the mac-addresses, probably you can try to check by running the command:

#show mac-address-table interface port-channel 23

murmanov · Answer

Hello Joey,

mac addresses are not available on port-channel since it is in down state, when LACP is not configured on the server side.

Anyway thanks for your help, unfortunately, we don't have a support contract to get more detailed information from the Dell TAC service.

Have a great weekend ahead!

Networking General

MXL: MAC learning not working with lacp ungroup feature configured

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