Laboratorio de Frame-Relay ( topologia Multipunto en
casa Central )
Escenario realizado el 6 de Junio del 2009 en CCNA 4, Acadenia Cisco, Rosario
Instructor: Ernesto Vilarrasa
La topología apunta a un PVC por sucursal y 4 PVC en casa Central, con topología Punto-Multipunto
logrando que todos los PVC esten en la misma subred IP ( 10.0.0.0 /29 ) y OSPF area 0, por lo cual
se elejirá un DR y BDR para el vecindario.
Configuración de Central:
¡
hostname Central
!
interface
FastEthernet0/0
ip address 172.16.0.1 255.255.255.0
!
interface Serial0/0
no ip address
encapsulation frame-relay
ip ospf network broadcast
!
interface
Serial0/0.100 multipoint
ip address 10.0.0.1 255.255.255.248
frame-relay map ip 10.0.0.2 666 broadcast
frame-relay map ip 10.0.0.3 777 broadcast
frame-relay map ip 10.0.0.4 888 broadcast
frame-relay map ip 10.0.0.5 999 broadcast
ip ospf network broadcast
ip
ospf priority 2 este comando
es para elejir siempre como DR a Central ya que
! no hay interfaces Loopback
configuradas
!
router ospf 1
log-adjacency-changes
network 10.0.0.0 0.0.0.7 area 0
network 172.16.0.0 0.0.0.255 area 0
!
end
Central#sh ip ospf
nei
Neighbor ID Pri
State Dead Time Address Interface
172.16.4.1 1
FULL/BDR
00:00:39 10.0.0.5 Serial0/0.100
172.16.3.1 1
FULL/DROTHER 00:00:36 10.0.0.4 Serial0/0.100
172.16.1.1 1
FULL/DROTHER 00:00:36 10.0.0.2 Serial0/0.100
172.16.2.1 1
FULL/DROTHER 00:00:36 10.0.0.3 Serial0/0.100
Central#sh ip ro
....
10.0.0.0/29 is subnetted, 1 subnets
C 10.0.0.0 is directly connected,
Serial0/0.100
172.16.0.0/24 is subnetted, 5 subnets
C 172.16.0.0 is directly connected,
FastEthernet0/0
O 172.16.1.0 [110/65] via 10.0.0.2,
00:22:16, Serial0/0.100
O 172.16.2.0 [110/65] via 10.0.0.3,
00:22:16, Serial0/0.100
O 172.16.3.0 [110/65] via 10.0.0.4,
00:22:16, Serial0/0.100
O 172.16.4.0 [110/65] via 10.0.0.5,
00:19:27, Serial0/0.100
Central#
Central#sh
frame-relay map
Serial0/0.100 (up):
ip 10.0.0.2 dlci 666, static, broadcast, CISCO, status defined, active
Serial0/0.100 (up):
ip 10.0.0.3 dlci 777, static, broadcast, CISCO, status defined, active
Serial0/0.100 (up):
ip 10.0.0.4 dlci 888, static, broadcast, CISCO, status defined, active
Serial0/0.100 (up):
ip 10.0.0.5 dlci 999, static, broadcast, CISCO, status defined, active
Central#
Sucursal 1:
!
hostname suc1
!
interface
FastEthernet0/0
ip address 172.16.1.1 255.255.255.0
!
interface Serial0/0
ip address 10.0.0.2 255.255.255.248
encapsulation frame-relay
frame-relay map ip 10.0.0.1 100 broadcast
frame-relay map ip 10.0.0.3 100 broadcast
frame-relay map ip 10.0.0.4 100 broadcast
frame-relay map ip 10.0.0.5 100 broadcast
frame-relay interface-dlci 100
ip ospf network broadcast
!
router ospf 1
log-adjacency-changes
network 10.0.0.0 0.0.0.7 area 0
network 172.16.1.0 0.0.0.255 area 0
!
end
suc1#sh ip ro
....
10.0.0.0/29 is subnetted, 1 subnets
C 10.0.0.0 is directly connected,
Serial0/0
172.16.0.0/24 is subnetted, 5 subnets
O 172.16.0.0 [110/65] via 10.0.0.1,
00:27:22, Serial0/0
C 172.16.1.0 is directly connected,
FastEthernet0/0
O 172.16.2.0 [110/65] via 10.0.0.3,
00:27:22, Serial0/0
O 172.16.3.0 [110/65] via 10.0.0.4,
00:27:22, Serial0/0
O 172.16.4.0 [110/65] via 10.0.0.5,
00:24:44, Serial0/0
suc1#
Sucursal 2:
!
hostname suc2
!
interface
FastEthernet0/0
ip address 172.16.2.1 255.255.255.0
!
interface Serial0/0
ip address 10.0.0.3 255.255.255.248
encapsulation frame-relay
frame-relay map ip 10.0.0.1 200 broadcast
frame-relay map ip 10.0.0.2 200 broadcast
frame-relay map ip 10.0.0.4 200 broadcast
frame-relay map ip 10.0.0.5 200 broadcast
frame-relay interface-dlci 200
ip ospf network broadcast
!
router ospf 1
log-adjacency-changes
network 10.0.0.0 0.0.0.7 area 0
network 172.16.2.0 0.0.0.255 area 0
!
end
Sucursal 3 y 4 comparten la misma configuración que Suc 1 y 2, cambiando únicamente
lo que respecta a las subredes conectadas y no realizando el mapeo Frame Relay en su propia
IP de la interfaz WAN.
Verificación:
Desde la PC de Suc4 a la PC de Suc 2:
PC>ping 172.16.1.2
Pinging 172.16.1.2
with 32 bytes of data:
Reply from
172.16.1.2: bytes=32 time=187ms TTL=125
Reply from
172.16.1.2: bytes=32 time=172ms TTL=125
Reply from
172.16.1.2: bytes=32 time=140ms TTL=125
Reply from
172.16.1.2: bytes=32 time=172ms TTL=125
Observación: de no encontrarse el mapeo Frame Relay a una IP que es gateway a una red o subred,
el router no podrá encapsular el paquete con el DLCI destino, ya que esta topología es multiacceso, por
lo cual se “asemeja” al funcionamiento de ethernet.
OSPF realiza la convergencia, muestra el destino en la tabla de enrutamiento, pero esta información no
asegura que el paquete llegue a destino, ya que en este caso se encapsula en una trama de Layer 2 y no
posee el DLCI destino.
¿Por qué OSPF converge ? porque en esta topología en particular -multiacceso- la base de datos OSPF llega
desde el DR ( Central ) y no de cada router ( repasar temas de CCNA 3 )
suc4#sh ip ospf
neibor
Neighbor ID Pri
State Dead Time Address Interface
172.16.0.1 2
FULL/DR
00:00:34 10.0.0.1 Serial0/0
suc4#sh ip
protocol
Routing Protocol is
"ospf 1"
....
Router ID 172.16.4.1
Routing for Networks:
10.0.0.0 0.0.0.7 area 0
172.16.4.0 0.0.0.255 area 0
Routing Information Sources:
Gateway Distance Last
Update
10.0.0.1
110 00:10:26
Por lo que nos generaría el siguiente error:
PC>ping 172.16.1.2
Pinging 172.16.1.2
with 32 bytes of data:
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Y en el router Suc4, en el
cual ahora NO tiene mapeo Frame Relay (DLCI -> IP 10.0.0.2 ) a Suc2:
IP: s=172.16.4.2
(FastEthernet0/0), d=172.16.1.2 (Serial0/0), g=10.0.0.2, len 0, forward
IP: s=172.16.4.2
(FastEthernet0/0), d=172.16.1.2 (Serial0/0), len 0, encapsulation failed
IP: s=172.16.4.2
(FastEthernet0/0), d=172.16.1.2 (Serial0/0), g=10.0.0.2, len 0, forward
IP: s=172.16.4.2
(FastEthernet0/0), d=172.16.1.2 (Serial0/0), len 0, encapsulation failed
IP: s=172.16.4.2
(FastEthernet0/0), d=172.16.1.2 (Serial0/0), g=10.0.0.2, len 0, forward
IP: s=172.16.4.2
(FastEthernet0/0), d=172.16.1.2 (Serial0/0), len 0, encapsulation failed
Router# labs end
Router# Connection
lost !