634 Chapter 8: WAN Protocols and Design
Multipoint subinterfaces will work perfectly well in this topology. Using multipoint also
conserves IP subnets, as seen in the next task in this scenario. When changing strategy to use
only point-to-point subinterfaces, each of the three VCs in the triangle of Routers A, D, and E
will require a different subnet and IPX network number. Table 8-57 shows the choices made
here. Example 8-51 and Example 8-52 show alternate configurations for Router A and Router
E using point-to-point instead of multipoint subinterfaces.
Table 8-57
Scenario 8-4 Layer 3 Address Planning Chart, All Point-to-Point Subinterfaces
Interface
Subinterface
IP Address
IPX Address
A's Ethernet
168.15.101.1
101.0200.AAAA.AAAA
B's Ethernet
168.15.102.1
102.0200.BBBB.BBBB
C's Ethernet
168.15.103.1
103.0200.CCCC.CCCC
D's Ethernet
168.15.104.1
104.0200.DDDD.DDDD
E's Ethernet
168.15.105.1
105.0200.EEEE.EEEE
A's S0
2
168.15.202.1
202.0200.AAAA.AAAA
A's S0
3
168.15.203.1
203.0200.AAAA.AAAA
A's S0
4
168.15.204.1
204.0200.AAAA.AAAA
A's S0
5
168.15.205.1
205.0200.AAAA.AAAA
B's S0
2
168.15.202.2
202.0200.BBBB.BBBB
C's S0
3
168.15.203.3
203.0200.CCCC.CCCC
D's S0
4
168.15.204.4
204.0200.DDDD.DDDD
D's S0
1
168.15.190.4
190.0200.DDDD.DDDD
E's S0
5
168.15.205.5
205.0200.EEEE.EEEE
E's S0
1
168.15.190.5
190.0200.EEEE.EEEE
Example 8-51
Router A Configuration, Scenario 8-4, All Point-to-Point Subinterfaces
ipx routing 0200.aaaa.aaaa
!
interface serial0
encapsulation frame-relay
!
interface serial 0.2 point-to-point
ip address 168.15.202.1 255.255.255.0
ipx network 202
frame-relay interface-dlci 52
!
interface serial 0.3 point-to-point
ip address 168.15.203.1 255.255.255.0
ipx network 203
frame-relay interface-dlci 53
ch08.fm Page 634 Monday, March 20, 2000 5:17 PM