Network Type
|
LSA Flooding
|
DR/BDR Election
|
Timers
|
Neighbor Statement
|
Modify Next-hop
|
Default
|
Broadcast
|
Multicast
|
Yes
|
10/40
|
No
|
No
|
Ethernet
|
NBMA
|
Unicast
|
Yes
|
30/120
|
Yes
|
No
|
Default
on Frame-Relay Physical and Point-to-Multipoint
|
Point-to-Point
|
Multicast
|
No
|
10/40
|
No
|
No
|
Default
on Frame-Relay Point-to-Point sub-interface
|
Point-to-Multipoint
|
Multicast
|
No
|
30/120
|
No
|
Yes
|
Ideal for NBMA
|
Point-to-Multipoint Non-broadcast
|
Unicast
|
No
|
30/120
|
Yes
|
Yes
|
|
Loopback
|
No
|
30/120
|
No
|
No
|
So in this lab I will try to deal with each one of the network
types and for that I will use a hub-and-spoke topology over frame-relay were R1 is the hub
and R2 and R3 are the spokes.
Lab topology:
FRS is configured as frame-relay switch:
interface Serial0/0
no ip address
encapsulation frame-relay
clock rate 128000
frame-relay lmi-type cisco
frame-relay intf-type dce
frame-relay route 102 interface Serial0/1
201
frame-relay route 103 interface Serial0/2
301
!
interface Serial0/1
no ip address
encapsulation frame-relay
clock rate 128000
frame-relay lmi-type cisco
frame-relay intf-type dce
frame-relay route 201 interface Serial0/0
102
!
interface Serial0/2
no ip address
encapsulation frame-relay
clock rate 128000
frame-relay lmi-type cisco
frame-relay intf-type dce
frame-relay route 301 interface Serial0/0
103
<OUTPUT OMMITED>
|
First scenario:
R1 is configured with multi-point network type over
sub-interface (s0/0.123) while R2 and R3 are configured with point-to-point
network type over sub-interface (s0/0.123).
After configuring OSPF on all serial interfaces for all 3
routers nothing happens.
R1 default network type for multipoint is non-broadcast:
R1#sh ip ospf interface
serial 0/0.123
Serial0/0.123 is up, line
protocol is up
Internet Address 10.1.123.1/24, Area 0
Process ID 1, Router ID 192.168.12.1, Network Type NON_BROADCAST,
Cost: 64
Transmit Delay is 1 sec, State WAITING,
Priority 1
No designated router on this network
No backup designated router on this network
Timer intervals configured, Hello 30, Dead 120, Wait 120,
Retransmit 5
oob-resync timeout 120
Hello due in 00:00:23
Wait time before Designated router
selection 00:00:53
Supports Link-local Signaling (LLS)
Index 2/2, flood queue length 0
Next 0x0(0)/0x0(0)
Last flood scan length is 0, maximum is 0
Last flood scan time is 0 msec, maximum is
0 msec
Neighbor Count is 0, Adjacent neighbor
count is 0
Suppress hello for 0 neighbor(s)
|
While R2 and R3 are using point-to-point network type:
R2#sh ip ospf interface
serial 0/0.123
Serial0/0.123 is up, line
protocol is up
Internet Address 10.1.123.2/24, Area 0
Process ID 1, Router ID 192.168.22.1, Network Type POINT_TO_POINT,
Cost: 64
Transmit Delay is 1 sec, State
POINT_TO_POINT,
Timer intervals configured, Hello 10, Dead 40, Wait 40,
Retransmit 5
oob-resync timeout 40
Hello due in 00:00:07
Supports Link-local Signaling (LLS)
Index 2/2, flood queue length 0
Next 0x0(0)/0x0(0)
Last flood scan length is 0, maximum is 0
Last flood scan time is 0 msec, maximum is
0 msec
Neighbor Count is 0, Adjacent neighbor
count is 0
Suppress hello for 0 neighbor(s)
|
Also note that the timers are different, so in order to fix
this I will need to change R1 network type to point-to-multipoint and to adjust
the timers, to be similar to those on R2 and R3, and to configure frame-relay
mapping to each router accordingly with the broadcast statement:
R1#conf t
R1(config)#int s0/0.123
R1(config-subif)#ip ospf
network point-to-multipoint
R1(config-subif)#ip ospf
hello-interval 10
R1(config-subif)#ip ospf dead-interval
40
R1(config-subif)#frame-relay
map ip 10.1.123.2 102 broadcast
R1(config-subif)#frame-relay
map ip 10.1.123.3 103 broadcast
|
And here we go:
R1#sh ip ospf neighbor
Neighbor ID Pri
State Dead Time Address Interface
192.168.32.1 0
FULL/ - 00:00:32 10.1.123.3 Serial0/0.123
192.168.22.1 0
FULL/ - 00:00:31 10.1.123.2 Serial0/0.123
|
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