Re: ACS 5250 VPN Issues

> There's no such thing as packet size negotiation with the switch.
> The switch reserves buffer space according to maximum packet size
> (1500 Bytes or larger when enabling jumbo frames), and that's
> about it.

I slightly over simplified that. It isn't a negotiation with the switch it's discovery between, in this case, VIOS and the next hop, typically a router or firewall. Packets are sent to determine what size can be sent to that next without fragmentation. Generally that is 1,500 bytes without jumbo frames in play. Beyond the next hop all bets are off as to whether the packets get fragmented or not. For example recently we have been fighting with Comcast and have had to reduce the packet size that IBM is sending down to about 1,350 bytes just to get the retransmissions down from 'ridiculous' to 'very bad'.

Note that on IBM i to limite the maximum packet size below 1,500 bytes the TCP interface is where that change is made, not the line description.

- Larry "DrFranken" Bolhuis

www.Frankeni.com
www.iDevCloud.com - Personal Development IBM i timeshare service.
www.iInTheCloud.com - Commercial IBM i Cloud Hosting.

On 5/30/2020 6:40 AM, Patrik Schindler wrote:

Hello Larry,

Am 30.05.2020 um 04:13 schrieb DrFranken <midrange@xxxxxxxxxxxx>:

and delivers it to the switch at whatever size is negotiated with the switch.

There's no such thing as packet size negotiation with the switch. The switch reserves buffer space according to maximum packet size (1500 Bytes or larger when enabling jumbo frames), and that's about it.

It's Not a switch thing at all.

Correct.

:wq! PoC

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