Re: DDM over VPN

Hi Bob,

You've mentioned that you've tested this between two on-prem machines and ask about MPLS vs VPN. This makes it hard to draw a comparison because local network performance is always going to be different than tunneled networks.

Are you able to test an MPLS circuit and compare the performance of MPLS vs VPN In your case?

Also - make sure to check MTU settings on all interfaces. If your VPN connection's MTU doesn't allow your DDM packets to encapsulated in a single VPN packet, you'll end up building a cascading system where each packet send or received will translate to multiple being sent or received by your router.

If you have experienced network people around, try to get them to do a packet capture on a SPAN port of the switch to see what's going on there on the wire. Issues such as a MTU mismatch or retransmits should be very visible.

Bear in mind - DDM is also very latency-sensitive; local network access is always "near-instant", while remote traffic will have to pass through multiple hops. If requesting a record requires multiple messages on the lower level to be sent back and forth, it also quickly snowballs into delays.

Another thing - some of the older protocols in use (eg the remote debugging aids) do not deal well with NAT. NAT-related issues should also be very visible once you do a packet capture.

I hope this helps with starting your investigation.

/y

On 21/12/2023, 15:04, "MIDRANGE-L on behalf of Bob Snuggs" <midrange-l-bounces@xxxxxxxxxxxxxxxxxx <mailto:midrange-l-bounces@xxxxxxxxxxxxxxxxxx> on behalf of bsnuggs@xxxxxxxxxxxx <mailto:bsnuggs@xxxxxxxxxxxx>> wrote:


Has anyone ever done heavy DDM I/Os between 2 AS/400s connected by a VPN over the general internet instead of using an MPLS connection? We're trying to set this up and it takes 400 seconds to read 10,000 records via DDM as opposed to 4 seconds between 2 on-prem AS/400s. I'm just trying to figure out if this is normal or not. I don't see how it could be. All other traffic doesn't appear to be an issue.






Any feedback would be greatly appreciated.