2. List 103 is used for packets entering subinterface 3, and list 104 is used for packets entering
subinterface 4. Lists 102 and 103 check for packets between sites 2 and 3, and they also check
for packets to PC11 and PC12. The mask used to check all hosts in subnets 170.1.4.0 and
170.1.6.0 is rather tricky. The mask represents 23 binary 0s and 9 binary 1s, meaning that the
first 23 bits of the number in the access list must match the first 23 bits in the source or
destination address in the packet. This matches all hosts in each subnet because there are 23
combined network and subnet bits.
!
interface serial0
encapsulation frame-relay
interface serial 0.1 point-to-point
ip address 170.1.12.3 255.255.254.0
ipx network 12
frame-relay interface-dlci 301
!
interface ethernet 0
ip address 170.1.7.3 255.255.254.0
ipx network 6 encapsulation sap
ipx network 7 encapsulation snap secondary
!
router igrp 1
network 170.1.0.0
!
interface serial0
encapsulation frame-relay ietf
interface serial 0.1 point-to-point
ip address 170.1.14.4 255.255.254.0
ipx network 14
frame-relay interface-dlci 301
!
interface ethernet 0
ip address 170.1.9.4 255.255.254.0
ipx network 8 encapsulation sap
ipx network 9 encapsulation snap secondary
!
router igrp 1
network 170.1.0.0