Dynamic PAT

DIAGRAM

      192.168.234.0/24                  10.1.5.0/24
[R2]----------+--------(fa1/0)--[R1]--(fa0/0)--------[R5]
              |              in    out
[R3]----------+
              |
[R4]----------+

CONFIG

hostname R1
!
int fa0/0
 ip nat out
!
int fa1/0
 ip nat in
!
ip access-list stand SOURCE
 permit 192.168.234.0 0.0.0.255
!
ip nat pool POOL 10.1.5.2 10.1.5.3 netmask 255.255.255.0
ip nat inside source list SOURCE pool POOL overload
!
end

VERIFY

R1(config)#do sh ip nat trans
Pro Inside global      Inside local       Outside local      Outside global
icmp 10.1.5.2:4        192.168.234.2:4    10.1.5.5:4         10.1.5.5:4
icmp 10.1.5.2:2        192.168.234.3:2    10.1.5.5:2         10.1.5.5:2
icmp 10.1.5.2:3        192.168.234.4:3    10.1.5.5:3         10.1.5.5:3
R1(config)#

CCOを読む限り、複数IPが使われるのを確認するのは難しそう