compression is the frame-relay payload-compression packet-by-packet interface
subcommand on the subinterface on each end of the VC. Payload compression is enabled on a
per-VC basis, but because the subinterface is a point-to-point subinterface, only one VC is
allowed on the interface--that VC is implied as the one on which to perform compression.
interface subcommand would have been used. Using frf9 stac as two separate keywords might
seem to imply that other options besides stac are available, but there are no other options. In
addition, you might think that the stac keyword can be omitted, but it is required. You can think
of packet-by-packet as referring to the Cisco standard stac algorithm, and frf9 stac as referring
to the FRF.9 standard.
map command, even if Inverse ARP is used to automatically map the DLCIs to the Layer 3
addresses. Examples 8-23 and 8-24 show a similar configuration for the network in Figure
8-20, except that the routers are now using multipoint subinterfaces. (Some unrelated
configuration details are not shown in these examples.)
!
interface Serial0.2 point-to-point
ip address 10.1.5.252 255.255.255.0
frame-relay interface-dlci 903
!
interface Serial1
no ip address
!
interface Ethernet0
ip address 10.1.2.252 255.255.255.0
ipx network 2
!
router igrp 5
network 10.0.0.0