Pruebas de sumarización de OSPF en un escenario multiárea

Fecha: 14 de julio del 2014 Clase: particular para rendir el exámen R&S

 

Escenario

 

En este escenario se intenta verificar la sumarización de rutas en OSPF en un ambiente multiárea, donde con otros

protocolos esto se realizaría de forma automática (aunque también forzada con un prefijo óptimo en caso de EIGRP).

Recordemos que por defecto, OSPF no sumariza rutas, y también es confuso el termino summary LSA ya que no se

sumarizan rutas sino que es sólo el nombre del paquete OSPF tipo 3.

 

El router CasaCentral se comporta como ABR (Area Border Router), este escenario se realizó con equipos reales,

Packet Tracert no soporta el comando de sumarizar las rutas en OSPF.

 

Verficación en Casa Central:

 

CasaCentral#sh ip route

Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP

       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

       E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP

       i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area

       * - candidate default, U - per-user static route, o - ODR

       P - periodic downloaded static route

 

Gateway of last resort is not set

 

     10.0.0.0/30 is subnetted, 1 subnets

C       10.0.0.0 is directly connected, FastEthernet0/1

C    192.168.1.0/24 is directly connected, FastEthernet0/0.1

C    192.168.2.0/24 is directly connected, FastEthernet0/0.2

C    192.168.3.0/24 is directly connected, FastEthernet0/0.3

C    192.168.4.0/24 is directly connected, FastEthernet0/0.4

C    192.168.5.0/24 is directly connected, FastEthernet0/0.5

C    192.168.6.0/24 is directly connected, FastEthernet0/0.6

C    192.168.7.0/24 is directly connected, FastEthernet0/0.7

CasaCentral#

 

Verificación en Sucursal:

 

Sucursal#sh ip route

Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP

       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

       E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP

       i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area

       * - candidate default, U - per-user static route, o - ODR

       P - periodic downloaded static route

 

Gateway of last resort is not set

 

O IA 192.168.4.0/24 [110/11] via 10.0.0.1, 00:08:55, Ethernet0/0

O IA 192.168.5.0/24 [110/11] via 10.0.0.1, 00:08:55, Ethernet0/0

     10.0.0.0/30 is subnetted, 1 subnets

C       10.0.0.0 is directly connected, Ethernet0/0

O IA 192.168.6.0/24 [110/11] via 10.0.0.1, 00:08:55, Ethernet0/0

O IA 192.168.7.0/24 [110/11] via 10.0.0.1, 00:08:55, Ethernet0/0

O IA 192.168.1.0/24 [110/11] via 10.0.0.1, 00:08:55, Ethernet0/0

O IA 192.168.2.0/24 [110/11] via 10.0.0.1, 00:08:55, Ethernet0/0

O IA 192.168.3.0/24 [110/11] via 10.0.0.1, 00:08:56, Ethernet0/0

Sucursal#

 

CasaCentral (config)#router ospf 1 (sumariza manualmente las rutas, este comando difiere a EIGRP, que lo

CasaCentral(config-router)#area 1 range 192.168.0.0 255.255.248.0                      realiza dentro de la interface)

CasaCentral(config-router)#^Z

CasaCentral#

 

Sucursal#sh ip route (verificación)

Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP

       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

       E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP

       i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area

       * - candidate default, U - per-user static route, o - ODR

       P - periodic downloaded static route

 

Gateway of last resort is not set

 

     10.0.0.0/30 is subnetted, 1 subnets

C       10.0.0.0 is directly connected, Ethernet0/0

O IA 192.168.0.0/21 [110/11] via 10.0.0.1, 00:00:37, Ethernet0/0

Sucursal#

 

Lectura recomendada:

 

http://www.cisco.com/c/en/us/support/docs/ip/open-shortest-path-first-ospf/7039-1.html#t29

 

Rollback de la sumarización:

 

CasaCentral(config)#router ospf 1

CasaCentral(config-router)#no area 1 range 192.168.0.0 255.255.248.0

CasaCentral(config-router)#^Z

CasaCentral#

 

Sucursal#sh ip route (verificación)

Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP

       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

       E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP

       i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area

       * - candidate default, U - per-user static route, o - ODR

       P - periodic downloaded static route

 

Gateway of last resort is not set

 

O IA 192.168.4.0/24 [110/11] via 10.0.0.1, 00:00:02, Ethernet0/0

O IA 192.168.5.0/24 [110/11] via 10.0.0.1, 00:00:02, Ethernet0/0

     10.0.0.0/30 is subnetted, 1 subnets

C       10.0.0.0 is directly connected, Ethernet0/0

O IA 192.168.6.0/24 [110/11] via 10.0.0.1, 00:00:02, Ethernet0/0

O IA 192.168.7.0/24 [110/11] via 10.0.0.1, 00:00:02, Ethernet0/0

O IA 192.168.1.0/24 [110/11] via 10.0.0.1, 00:00:02, Ethernet0/0

O IA 192.168.2.0/24 [110/11] via 10.0.0.1, 00:00:02, Ethernet0/0

O IA 192.168.3.0/24 [110/11] via 10.0.0.1, 00:00:03, Ethernet0/0

Sucursal#

 

Captura de los paquetes sin sumarizar (pero son LSA summary type 3):

 

 

Frame 30: 258 bytes on wire (2064 bits), 258 bytes captured (2064 bits) on interface 0

Ethernet II, Src: 00:18:ba:d1:1f:91, Dst: 01:00:5e:00:00:05

Internet Protocol Version 4, Src: 10.0.0.1 (10.0.0.1), Dst: 224.0.0.5 (224.0.0.5)

Open Shortest Path First

    OSPF Header

    LS Update Packet

        Number of LSAs: 7

        LS Type: Summary-LSA (IP network)

            LS Age: 3600 seconds

            Do Not Age: False

            Options: 0x22 (DC, E)

            Link-State Advertisement Type: Summary-LSA (IP network) (3)

            Link State ID: 192.168.7.0

            Advertising Router: 192.168.254.254 (192.168.254.254)

            LS Sequence Number: 0x80000002

            LS Checksum: 0x89da

            Length: 28

            Netmask: 255.255.255.0

            Metric: 16777215

        LS Type: Summary-LSA (IP network)

            LS Age: 3600 seconds

            Do Not Age: False

            Options: 0x22 (DC, E)

            Link-State Advertisement Type: Summary-LSA (IP network) (3)

            Link State ID: 192.168.6.0

            Advertising Router: 192.168.254.254 (192.168.254.254)

            LS Sequence Number: 0x80000002

            LS Checksum: 0x94d0

            Length: 28

            Netmask: 255.255.255.0

            Metric: 16777215

        LS Type: Summary-LSA (IP network)

            LS Age: 3600 seconds

            Do Not Age: False

            Options: 0x22 (DC, E)

            Link-State Advertisement Type: Summary-LSA (IP network) (3)

            Link State ID: 192.168.5.0

            Advertising Router: 192.168.254.254 (192.168.254.254)

            LS Sequence Number: 0x80000002

            LS Checksum: 0x9fc6

            Length: 28

            Netmask: 255.255.255.0

            Metric: 16777215

        LS Type: Summary-LSA (IP network)

            LS Age: 3600 seconds

            Do Not Age: False

            Options: 0x22 (DC, E)

            Link-State Advertisement Type: Summary-LSA (IP network) (3)

            Link State ID: 192.168.4.0

            Advertising Router: 192.168.254.254 (192.168.254.254)

            LS Sequence Number: 0x80000002

            LS Checksum: 0xaabc

            Length: 28

            Netmask: 255.255.255.0

            Metric: 16777215

        LS Type: Summary-LSA (IP network)

            LS Age: 3600 seconds

            Do Not Age: False

            Options: 0x22 (DC, E)

            Link-State Advertisement Type: Summary-LSA (IP network) (3)

            Link State ID: 192.168.3.0

            Advertising Router: 192.168.254.254 (192.168.254.254)

            LS Sequence Number: 0x80000002

            LS Checksum: 0xb5b2

            Length: 28

            Netmask: 255.255.255.0

            Metric: 16777215

        LS Type: Summary-LSA (IP network)

            LS Age: 3600 seconds

            Do Not Age: False

            Options: 0x22 (DC, E)

            Link-State Advertisement Type: Summary-LSA (IP network) (3)

            Link State ID: 192.168.2.0

            Advertising Router: 192.168.254.254 (192.168.254.254)

            LS Sequence Number: 0x80000002

            LS Checksum: 0xc0a8

            Length: 28

            Netmask: 255.255.255.0

            Metric: 16777215

        LS Type: Summary-LSA (IP network)

            LS Age: 3600 seconds

            Do Not Age: False

            Options: 0x22 (DC, E)

            Link-State Advertisement Type: Summary-LSA (IP network) (3)

            Link State ID: 192.168.1.0

            Advertising Router: 192.168.254.254 (192.168.254.254)

            LS Sequence Number: 0x80000002

            LS Checksum: 0xcb9e

            Length: 28

            Netmask: 255.255.255.0

            Metric: 16777215

 

Captura de la trama sumarizada:

 

 

Frame 29: 90 bytes on wire (720 bits), 90 bytes

Ethernet II, Src: 00:18:ba:d1:1f:91 ,Dst: 01:00:5e:00:00:05

Internet Protocol Version 4, Src: 10.0.0.1 (10.0.0.1), Dst: 224.0.0.5 (224.0.0.5)

Open Shortest Path First

    OSPF Header

    LS Update Packet

        Number of LSAs: 1

        LS Type: Summary-LSA (IP network)

            LS Age: 1 seconds

            Do Not Age: False

            Options: 0x22 (DC, E)

                0... .... = DN: DN-bit is NOT set

                .0.. .... = O: O-bit is NOT set

                ..1. .... = DC: Demand Circuits are supported

                ...0 .... = L: The packet does NOT contain LLS data block

                .... 0... = NP: NSSA is NOT supported

                .... .0.. = MC: NOT Multicast Capable

                .... ..1. = E: External Routing Capability

                .... ...0 = MT: NO Multi-Topology Routing

            Link-State Advertisement Type: Summary-LSA (IP network) (3)

            Link State ID: 192.168.0.0

            Advertising Router: 192.168.254.254 (192.168.254.254)

            LS Sequence Number: 0x80000001

            LS Checksum: 0xbfb2

            Length: 28

            Netmask: 255.255.248.0

            Metric: 1

 

(2014) Networking may cause synesthesia

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