How many logical systems are required to connect between one XI and R3 sytm

Hi Experts,

I need to know how many Logical systems we need to create when connecting an SAP XI and SAP R3 system.

details wht I configured is as follows :

For XI : LOGSYSXI assigned to 100 client

For R3: LOGSYSR3 assigned to 800 client.

Do I need to create two log'cal systems on one side?

How many logical systems can a Client can support simultaneously? is it only one or more that one?

THANKS IN ADVANCE.

Sunil K Shetty