(XXX-R2) (Config)#monitor session 1 source interface 1/0/19
(XXX-R2) (Config)#monitor session 1 destination interface 1/0/20
(XXX-R2) (Config)#monitor session 2 destination interface 1/0/22
(XXX-R2) (Config)#monitor session 2 source interface 1/0/21

(Config)#show running-config | include monitor

monitor session 1 destination interface 1/0/20
monitor session 1 source interface 1/0/19
monitor session 2 destination interface 1/0/22
monitor session 2 source interface 1/0/21

(Config)#monitor session ?

<1-4>                    Session number.