Hi
This is the number of wings (half-sessions) per NPU. For 40x1GE and 4x10GE
IOCs, you have 4 NPUs on each card, each NPU is capable of handling 2M entries.
For FlexIOCs, you have 2 NPUs on each card, each can handle 4M entries.
So even on one card you have more that one NPU. With several cards, you
get even more. So with proper load-balancing, you can get much more than
2M sessions on SRX. As far as I remember, SRX5800 scales up to about 10M
sessions in total, depending on sw release.
And if you need more then 2M sessions on one interface, there is a feature
called (if I remember correctly) NP bonding which solves this problem too.