How to enable largesend on AIX partition ?

In Short

Before configuring the IP address on the interface perform below commands

ifconfig en1 largesend
chdev -l en1 -a mtu_bypass=on
chdev -l ent1 -a chksum_offload=yes
chdev -l en1 -a mtu=9000 -P

Then configure the IP address on interface en1 and start ping test of 64 payload data.

Detailed explanation

Normal internet works with the payload size / mtu size of 1500. But in some high bandwidth requirements it requires to enable Jumbo Frames where payload size can be increased to more then 1500. In case of Large Send the packets send to TCP segment are segmented and reassembled it is performed by the Network Interface Card (NIC) to fit into the systems mtu size.
Enable Disable Largesend AIX
Large send enables the packets looks to be of size max 64000 data bytes but it has been segmented and reassembled by sender and receiver o improve the throughput.

Enable large send on AIX partition using ifconfig interface en1
ifconfig en1 largesend

Set the mtu_bypass flag to on to enable segmentation
chdev -l en1 -a mtu_bypass=on
en1 changed

Enable checksum offload to transmit and receive checksum
chdev -l ent1 -a chksum_offload=yes
ent1 changed

Set the mtu size to 9000 Jumbo Frame settings
chdev -l en1 -a mtu=9000 -P
en1 changed

Set the IP address on en1 interface
mktcpip -h partition1 -a 9.x.x.x -i en1 -m subnet_mask -g gateway_address -d domain

Check the mtu size of interface using netstat
netstat -in
Name   Mtu 
en1    9000
en1    9000

Troubleshoot the large send packets are getting transferred
ping -s 64000 9.x.x.x1

Remove Large Send

With the above steps we enable the Large Send and Jumbo Frame. To remove the jumbo Frame and large send settings follow below commands

Remove interface
rmdev -dl en1; rmdev -dl et1; rmdev -dl ent1

The perform cfgmgr or cfgdev
cfgdev; cfgmgr

Configure the IP address on interface en1
mktcpip -h partition1 -a 9.x.x.x -i en1 -m subnet_mask -g gateway_address -d domain

With removal of interface and configuring new IP address it will work as standard TCP network of less than 1500 mtu size network. the large send offloading the throughput will be increased it will be efficient when transferring large file transfer using ftp / scp.