VSP7400 SMLT to IBM AS400

[TobiasW]

Hi guys,

has anyone tried to connect an IBM AS400 to an VSP7400 cluster using an SMLT?
My customer and I tried this today, and had very strange phenomenons with this setup. Internal, everything was fine, but since the Sophos Firewall couldn’t access the AS400 through the SMLT, every connection using a VPN failed…

Does anyone may have a hint for me?

Thanks and stay safe!

Tobias

[TobiasW]

Thanks for the hint with viewing the statistics, I hadn’t thought of that.

But your assumption confirms mine. If I shut down one SMLT Member, everything is fine.
I’ve already asked the customer about more information, what is configured on the IBM System. let’s see what happens here…

However, thanks for your help and interest!

Best Regards

[Ludovico_Steven]

That looks ok.

It sounds like maybe link aggregation might not be correctly configured on the IBM side ?

Once you have SMLT on the VSP side, the VSP will deliver the traffic to the IBM machine on either SMLT link (whichever is the nearest from the source). But if the IBM is only processing traffic on one interface only  (no LAG or an Active/Backup config) then you will be black-holing half the traffic.

You should be able to get a gist of this by looking at the port stats on the SMLT links; if VSPs deliver traffic on both SMLT links that’s good; if the IBM only send traffic on one link only, that is not good.

[TobiasW]

Hi Ludovico,

I unconfigured the SMLT again, but here are the configs I used:

SWC1206:1(config)#mlt 2

SWC1206:1(config)#mlt 2 name “SMLT2IBM-AS400”

SWC1206:1(config)#mlt 2 member 1/12

SWC1206:1(config)#interface mlt 2

SWC1206:1(config-mlt)#smlt

Then I verified that the Ports were configured correctly regarding VLAN, just like they are configured right now:

SWC1206:1(config)#sho port vlan 1/12
************************************************************************************
                Command Execution Time: Tue May 19 13:24:39 2020 UTC
************************************************************************************

====================================================================================================
                                   Port Vlans
====================================================================================================
PORT             DISCARD DISCARD   DEFAULT VLAN         PORT     UNTAG    DYNAMIC UNTAG
NUM      TAGGING TAGFRAM UNTAGFRAM VLANID  IDS          TYPE     DEFVLAN  VLANS   VLANS
----------------------------------------------------------------------------------------------------
1/12     disable false   false     200     200          normal   disable  P       200   
----------------------------------------------------------------------------------------------------

Like I said, the SMLT is no longer configured, but the “show mlt” looked quite like this:

sho mlt 2
************************************************************************************
                Command Execution Time: Tue May 19 14:28:34 2020 CEST
************************************************************************************

====================================================================================================
                                    Mlt Info
====================================================================================================
                        PORT    MLT   MLT        PORT         VLAN
MLTID IFINDEX NAME      TYPE   ADMIN CURRENT    MEMBERS       IDS
----------------------------------------------------------------------------------------------------
2  6187  SMLT2IBM-AS400 access smlt   smlt     1/12               200

               DESIGNATED   LACP      LACP
MLTID IFINDEX  PORTS        ADMIN     OPER
----------------------------------------------------------------------------------------------------
2     6187    1/12           disable   down

                                                            WHICH PORTS
             WHERE      LOCAL             REMOTE            PROGRAMMED
MLTID NAME   CREATED    PORT MEMBERS      PORT MEMBERS      IN DATA PATH
----------------------------------------------------------------------------------------------------
2   SMLT2IBM-AS400 LOC & REM  1/12               1/12               LOCAL & REMOTE

               ENCAP                          PVLAN        VID
MLTID IFINDEX  DOT1Q     LOSSLESS   PVLAN     TYPE         TYPE         FLEX-UNI
----------------------------------------------------------------------------------------------------
2    6187     disable     disable    disable   -            -            disable  

Regarding LACP, I’d like to use LACP in this case, but the customer said, LACP is not supported on his system…

Best Regards!

[Ludovico_Steven]

Maybe you’d like to share your MLT/SMLT config + show mlt + show lacp interface mlt + show lacp interface gig