Connecting a Cat 4500 core switch to a SX550X (Port Channel) causing hair loss!

[chris.king]

Hi folks,

I'm tearing my hair out here with setting up a connection between a 4500 core switch and a SX550X 52 10GE server switch.

The core switch is already connected to 10 Cat. 2960 access switches with a channel greoup for each switch.

The Core switch is configured like this:

interface TenGigabitEthernet1/1/13
description data1-srv2
switchport mode trunk
channel-protocol lacp
channel-group 22 mode active

interface TenGigabitEthernet2/1/13
description data1-srv2
switchport mode trunk
channel-protocol lacp
channel-group 22 mode active

interface Port-channel22
description data1-srv2
switchport
switchport mode trunk



The Cat. 2960 switches look like this

interface TenGigabitEthernet1/0/1
description datac1-core1 1/1/2
switchport mode trunk
channel-protocol lacp
channel-group 11 mode active
!
interface TenGigabitEthernet1/0/2
description datac2-core1 2/1/2
switchport mode trunk
channel-protocol lacp
channel-group 11 mode active

interface Port-channel11
description MEC datac1-core1
switchport mode trunk

Now this tried and trusted configuration works fine - this is where the fun begins!



The SX550X is configured like this

interface TenGigabitEthernet1/0/49
flowcontrol on
description datac1-core1-2/1/13
channel-group 22 mode auto
switchport mode trunk
!
interface TenGigabitEthernet1/0/52
flowcontrol on
description datac1-core1-1/1/13
channel-group 22 mode auto
switchport mode trunk
!
interface Port-Channel22
description MEC-datac1-core
spanning-tree link-type point-to-point
switchport mode trunk
macro description switch
!next command is internal.
macro auto smartport dynamic_type switch


Now the problem:
If I reload the SX550X  server switch, the portchannel and the interfaces are up but there is no traffic being passed between the switches

Now the interesting bit:
If I unplug one of the Fiberoptic cables and plug it in again (not the SFP+ module but just the cable surprisingly enough ), traffic passes through the interface and everything is working again!!!
I have tried three different SFP+ types, including Cisco original, without success.
Grrr..........

Any ideas, folks. This is really strange and frustrating!!



Cheers

[Richard Burts]

One of the things that I notice is that on your 4500 you configure this

channel-group 22 mode active

but on SX550X is

channel-group 22 mode auto

[chris.king]

Hi Richard,

thanks for your response,

I have just two options on the SX550X,

on Add port without LACP
auto Add port with LACP

So I have to use Auto, which enables LACP.

Cheers,

Chris

[marce1000 · Accepted solution]

 - On the SX remove all (auto)-macro settings, on the involved interfaces and port-channel , also use a central syslog server for the SX and the core, informational messages could pop-up when the channel is tried-formed or breaks afterwards. On the SX use the latest firmware.

 M.

[chris.king]

Well done Mr. marce1000!

The Macro was blocking the VLANs being transported over the port channel.

Even after deleting the macro, the switch kept on rewriting it into the config.

The solution:

Disable the smartport function on the physical ports being used by the port channel. I used the GUI (god forbid) in advanced mode to do this. Then delete the macro on the port channel,using the cosole :
no macro auto smartport

Reassign the mode to the port channel, as this will of been deleted when removing the macro:

switchport mode trunk

Now check the port channel config:

sh inter channel-group 22
description MEC-datac1-core
switchport mode trunk
macro description switch
Wr

Reload the switch and it should forward the VLANs over the port channel without any issues!

Thank you again for the help!

Kind regards

Chris