Router RIPv2 only verliert Routen, wenn andere OSPF sprechen

[emulbetsup]

Spiele hier gerade mit Routing-Protokollen herum. Habe in dem begefügten Lab mit RIPv2 angefangen und dann noch zusätzlich OSPF konfiguriert, weil ich sehen wollte wie sich die Routing-Tabelle verhält, wenn er das gleiche Ziel über zwei Routing-Protokolle angeboten bekommt. Jetzt habe ich ein Verhalten auf R6, das ich mir nicht erklären kann. Sobald OSPF auf R1 und R3 gesprochen wird, verliert er auch die Routen, die R1 und R2 über RIP propagieren.

Routingtabelle auf R6, wenn R1 und R3 zusätzlich zu RIPv2 OSPF sprechen:

R6#show ip route
Codes: L - local, C - connected, S - static, 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
       i - IS-IS, su - IS-IS summary, 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, H - NHRP, l - LISP
       a - application route
       + - replicated route, % - next hop override, p - overrides from PfR

Gateway of last resort is not set

R     10.0.0.0/8 [120/1] via 172.17.0.3, 00:00:05, GigabitEthernet0/2
      172.17.0.0/16 is variably subnetted, 2 subnets, 2 masks
C        172.17.0.0/16 is directly connected, GigabitEthernet0/2
L        172.17.0.6/32 is directly connected, GigabitEthernet0/2
R     192.168.2.0/24 [120/1] via 172.17.0.3, 00:00:05, GigabitEthernet0/2
R     192.168.6.0/24 [120/1] via 172.17.0.3, 00:00:05, GigabitEthernet0/2

Routingtabelle auf R6, wenn R1 und R3 nur RIPv2 sprechen:

R6#show ip route
Codes: L - local, C - connected, S - static, 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
       i - IS-IS, su - IS-IS summary, 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, H - NHRP, l - LISP
       a - application route
       + - replicated route, % - next hop override, p - overrides from PfR

Gateway of last resort is not set

R     10.0.0.0/8 [120/1] via 172.17.0.3, 00:00:00, GigabitEthernet0/2
R     172.16.0.0/16 [120/3] via 172.17.0.3, 00:00:00, GigabitEthernet0/2
      172.17.0.0/16 is variably subnetted, 2 subnets, 2 masks
C        172.17.0.0/16 is directly connected, GigabitEthernet0/2
L        172.17.0.6/32 is directly connected, GigabitEthernet0/2
R     192.168.1.0/24 [120/2] via 172.17.0.3, 00:00:00, GigabitEthernet0/2
R     192.168.2.0/24 [120/1] via 172.17.0.3, 00:00:00, GigabitEthernet0/2
R     192.168.3.0/24 [120/3] via 172.17.0.3, 00:00:00, GigabitEthernet0/2
R     192.168.4.0/24 [120/2] via 172.17.0.3, 00:00:00, GigabitEthernet0/2
R     192.168.5.0/24 [120/2] via 172.17.0.3, 00:00:00, GigabitEthernet0/2
R     192.168.6.0/24 [120/1] via 172.17.0.3, 00:00:00, GigabitEthernet0/2

Jetzt bin ich etwas ratlos. Wie kommt es zu diesem Verhalten?

 

[emulbetsup]

Ok, hab mit dem Debug-Mode herausgefunden, dass R3 nicht mehr alle von R2 via RIPv2 gemeldeten Netze an R6 weiter gibt. Er spart dabei die Netze aus, für die er selbst über OSPF eine Route mit einer besseren AD gelernt hat.

Arbeitshypothese:
Router geben nur die Routen über ein bestimmtes Protokoll weiter, die sie selbst nicht über ein Protokoll (oder Verfahren) mit einer besseren Administrativen Distanz lernen konnten. Sie streichen also die Einträge aus Protokollen mit einer schlechteren AD vor der Weitergabe raus, zu denen sie selbst einen Weg mit einer besseren AD kennen.

Kann dieses Verhalten jemand bestätigen, bzw. ist das eine bekannte Regel, die nur ich noch nicht kannte?

 

[Arvyr]

Ohne deine Konfiguration hier zu posten kann man natürlich nicht genau sagen, was du da konfiguriert hast.

Aber generell verhält sich das mit Routen wie folgt: In der Routingtabelle landen am Ende immer nur die Routen, die genauer sind und die die beste administrative Distanz haben (bei gleichwertigen Wegen wird Load-Balancing betrieben).

Was bei dir vermutlich aber noch passiert ist, dass du kein Redistributing betreibst. Wenn du OSPF nicht sagst, dass er von durch RIP gelernte Routen weitergeben soll, dann macht er das auch nicht.

 

[emulbetsup]

Danke für deine Antwort. Ja, ein Redistributing der OSPF-Routen über RIP würde die Topologie heilen und dazu führen, dass R3 die Route über R5 an R6 weitergibt.

Hier kann man aber beobachten, dass nur noch die Routen über das unterlegene Routing-Protokoll weitergegeben werden, die R3 auch selbst für seine Routing-Tabelle verwendet. Es gibt ja einen konsistenten Weg für die RIP-Nachrichten von R1 über R2 zu R3. Die RIP-Routen kommen auch bei R3 an und werden dort nur deshalb nicht gelernt, da über OSPF Routen zum gleichen Ziel mit einer überlegenen AD angeboten werden.

Was mich aber verwundert hat: Diese über RIP von R2 an R3 propagierten Routen werden auch nicht an R6 durchgesteckt. Bis dato hatte ich mir die Prozesse der Routing-Protokolle als unabhängig voneinander vorgestellt. Das sind sie wahrscheinlich auch. Es gilt nur zusätzlich die Regel, dass nur Routen propagiert werden, die der Router auch selbst verwenden würde.

Hier mal die Konfigurationen von R1 bis R6.

Spoiler: R1

R1#show run
Building configuration...

Current configuration : 3362 bytes
!
version 15.9
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname R1
!
boot-start-marker
boot-end-marker
!
!
!
no aaa new-model
!
!
!
mmi polling-interval 60
no mmi auto-configure
no mmi pvc
mmi snmp-timeout 180
!
!
!
!
!
no ip icmp rate-limit unreachable
!
!
!
!
!
!
no ip domain lookup
ip cef
no ipv6 cef
!
multilink bundle-name authenticated
!
!
!
!
!
redundancy
!
no cdp log mismatch duplex
!
ip tcp synwait-time 5
!
!
!
!
!
!
!
!
!
!
!
!
!
interface GigabitEthernet0/0
ip address 192.168.1.1 255.255.255.0
duplex auto
speed auto
media-type rj45
!
interface GigabitEthernet0/1
ip address 172.16.0.1 255.255.0.0
duplex auto
speed auto
media-type rj45
!
interface GigabitEthernet0/2
ip address 192.168.3.1 255.255.255.0
duplex auto
speed auto
media-type rj45
!
interface GigabitEthernet0/3
no ip address
shutdown
duplex auto
speed auto
media-type rj45
!
router ospf 128
network 172.16.0.0 0.0.255.255 area 128
network 192.168.1.0 0.0.0.255 area 128
network 192.168.3.0 0.0.0.255 area 128
!
router rip
version 2
network 172.16.0.0
network 192.168.1.0
network 192.168.3.0
no auto-summary
!
ip forward-protocol nd
!
!
no ip http server
no ip http secure-server
!
ipv6 ioam timestamp
!
!
!
control-plane
!
banner exec ^C
**************************************************************************

• IOSv is strictly limited to use for evaluation, demonstration and IOS *
• education. IOSv is provided as-is and is not supported by Cisco's *
• Technical Advisory Center. Any use or disclosure, in whole or in part, *
• of the IOSv Software or Documentation to any third party for any *
• purposes is expressly prohibited except as otherwise authorized by *
• Cisco in writing. *

**************************************************************************^C
banner incoming ^C
**************************************************************************

• IOSv is strictly limited to use for evaluation, demonstration and IOS *
• education. IOSv is provided as-is and is not supported by Cisco's *
• Technical Advisory Center. Any use or disclosure, in whole or in part, *
• of the IOSv Software or Documentation to any third party for any *
• purposes is expressly prohibited except as otherwise authorized by *
• Cisco in writing. *

**************************************************************************^C
banner login ^C
**************************************************************************

• IOSv is strictly limited to use for evaluation, demonstration and IOS *
• education. IOSv is provided as-is and is not supported by Cisco's *
• Technical Advisory Center. Any use or disclosure, in whole or in part, *
• of the IOSv Software or Documentation to any third party for any *
• purposes is expressly prohibited except as otherwise authorized by *
• Cisco in writing. *

**************************************************************************^C
!
line con 0
exec-timeout 0 0
privilege level 15
logging synchronous
line aux 0
exec-timeout 0 0
privilege level 15
logging synchronous
line vty 0 4
login
transport input none
!
no scheduler allocate
!
end

Spoiler: R2

R2#show run
Building configuration...

Current configuration : 3261 bytes
!
version 15.9
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname R2
!
boot-start-marker
boot-end-marker
!
!
!
no aaa new-model
!
!
!
mmi polling-interval 60
no mmi auto-configure
no mmi pvc
mmi snmp-timeout 180
!
!
!
!
!
no ip icmp rate-limit unreachable
!
!
!
!
!
!
no ip domain lookup
ip cef
no ipv6 cef
!
multilink bundle-name authenticated
!
!
!
!
!
redundancy
!
no cdp log mismatch duplex
!
ip tcp synwait-time 5
!
!
!
!
!
!
!
!
!
!
!
!
!
interface GigabitEthernet0/0
ip address 192.168.1.2 255.255.255.0
duplex auto
speed auto
media-type rj45
!
interface GigabitEthernet0/1
ip address 192.168.4.2 255.255.255.0
duplex auto
speed auto
media-type rj45
!
interface GigabitEthernet0/2
ip address 192.168.5.2 255.255.255.0
duplex auto
speed auto
media-type rj45
!
interface GigabitEthernet0/3
ip address 192.168.2.2 255.255.255.0
duplex auto
speed auto
media-type rj45
!
router rip
version 2
network 192.168.1.0
network 192.168.2.0
network 192.168.4.0
network 192.168.5.0
no auto-summary
!
ip forward-protocol nd
!
!
no ip http server
no ip http secure-server
!
ipv6 ioam timestamp
!
!
!
control-plane
!
banner exec ^C
**************************************************************************

• IOSv is strictly limited to use for evaluation, demonstration and IOS *
• education. IOSv is provided as-is and is not supported by Cisco's *
• Technical Advisory Center. Any use or disclosure, in whole or in part, *
• of the IOSv Software or Documentation to any third party for any *
• purposes is expressly prohibited except as otherwise authorized by *
• Cisco in writing. *

**************************************************************************^C
banner incoming ^C
**************************************************************************

• IOSv is strictly limited to use for evaluation, demonstration and IOS *
• education. IOSv is provided as-is and is not supported by Cisco's *
• Technical Advisory Center. Any use or disclosure, in whole or in part, *
• of the IOSv Software or Documentation to any third party for any *
• purposes is expressly prohibited except as otherwise authorized by *
• Cisco in writing. *

**************************************************************************^C
banner login ^C
**************************************************************************

• IOSv is strictly limited to use for evaluation, demonstration and IOS *
• education. IOSv is provided as-is and is not supported by Cisco's *
• Technical Advisory Center. Any use or disclosure, in whole or in part, *
• of the IOSv Software or Documentation to any third party for any *
• purposes is expressly prohibited except as otherwise authorized by *
• Cisco in writing. *

**************************************************************************^C
!
line con 0
exec-timeout 0 0
privilege level 15
logging synchronous
line aux 0
exec-timeout 0 0
privilege level 15
logging synchronous
line vty 0 4
login
transport input none
!
no scheduler allocate
!
end

Spoiler: R3

R3#show run
Building configuration...

Current configuration : 3449 bytes
!
version 15.9
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname R3
!
boot-start-marker
boot-end-marker
!
!
!
no aaa new-model
!
!
!
mmi polling-interval 60
no mmi auto-configure
no mmi pvc
mmi snmp-timeout 180
!
!
!
!
!
no ip icmp rate-limit unreachable
!
!
!
!
!
!
no ip domain lookup
ip cef
no ipv6 cef
!
multilink bundle-name authenticated
!
!
!
!
!
redundancy
!
no cdp log mismatch duplex
!
ip tcp synwait-time 5
!
!
!
!
!
!
!
!
!
!
!
!
!
interface GigabitEthernet0/0
ip address 10.0.0.3 255.0.0.0
duplex auto
speed auto
media-type rj45
!
interface GigabitEthernet0/1
ip address 192.168.6.3 255.255.255.0
duplex auto
speed auto
media-type rj45
!
interface GigabitEthernet0/2
ip address 172.17.0.3 255.255.0.0
duplex auto
speed auto
media-type rj45
!
interface GigabitEthernet0/3
ip address 192.168.2.3 255.255.255.0
duplex auto
speed auto
media-type rj45
!
router ospf 128
network 10.0.0.0 0.255.255.255 area 128
network 172.17.0.0 0.0.255.255 area 128
network 192.168.6.0 0.0.0.255 area 128
network 192.0.0.0 0.255.255.255 area 128
!
router rip
version 2
network 10.0.0.0
network 172.16.0.0
network 172.17.0.0
network 192.168.2.0
network 192.168.6.0
no auto-summary
!
ip forward-protocol nd
!
!
no ip http server
no ip http secure-server
!
ipv6 ioam timestamp
!
!
!
control-plane
!
banner exec ^C
**************************************************************************

• IOSv is strictly limited to use for evaluation, demonstration and IOS *
• education. IOSv is provided as-is and is not supported by Cisco's *
• Technical Advisory Center. Any use or disclosure, in whole or in part, *
• of the IOSv Software or Documentation to any third party for any *
• purposes is expressly prohibited except as otherwise authorized by *
• Cisco in writing. *

**************************************************************************^C
banner incoming ^C
**************************************************************************

• IOSv is strictly limited to use for evaluation, demonstration and IOS *
• education. IOSv is provided as-is and is not supported by Cisco's *
• Technical Advisory Center. Any use or disclosure, in whole or in part, *
• of the IOSv Software or Documentation to any third party for any *
• purposes is expressly prohibited except as otherwise authorized by *
• Cisco in writing. *

**************************************************************************^C
banner login ^C
**************************************************************************

• IOSv is strictly limited to use for evaluation, demonstration and IOS *
• education. IOSv is provided as-is and is not supported by Cisco's *
• Technical Advisory Center. Any use or disclosure, in whole or in part, *
• of the IOSv Software or Documentation to any third party for any *
• purposes is expressly prohibited except as otherwise authorized by *
• Cisco in writing. *

**************************************************************************^C
!
line con 0
exec-timeout 0 0
privilege level 15
logging synchronous
line aux 0
exec-timeout 0 0
privilege level 15
logging synchronous
line vty 0 4
login
transport input none
!
no scheduler allocate
!
end

Spoiler: R4

R4#show run
Building configuration...

Current configuration : 3261 bytes
!
version 15.9
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname R4
!
boot-start-marker
boot-end-marker
!
!
!
no aaa new-model
!
!
!
mmi polling-interval 60
no mmi auto-configure
no mmi pvc
mmi snmp-timeout 180
!
!
!
!
!
no ip icmp rate-limit unreachable
!
!
!
!
!
!
no ip domain lookup
ip cef
no ipv6 cef
!
multilink bundle-name authenticated
!
!
!
!
!
redundancy
!
no cdp log mismatch duplex
!
ip tcp synwait-time 5
!
!
!
!
!
!
!
!
!
!
!
!
!
interface GigabitEthernet0/0
ip address 192.168.7.4 255.255.255.0
duplex auto
speed auto
media-type rj45
!
interface GigabitEthernet0/1
ip address 192.168.4.4 255.255.255.0
duplex auto
speed auto
media-type rj45
!
interface GigabitEthernet0/2
ip address 192.168.3.4 255.255.255.0
duplex auto
speed auto
media-type rj45
!
interface GigabitEthernet0/3
no ip address
shutdown
duplex auto
speed auto
media-type rj45
!
router ospf 128
network 192.168.3.0 0.0.0.255 area 128
network 192.168.4.0 0.0.0.255 area 128
network 192.168.7.0 0.0.0.255 area 128
!
ip forward-protocol nd
!
!
no ip http server
no ip http secure-server
!
ipv6 ioam timestamp
!
!
!
control-plane
!
banner exec ^C
**************************************************************************

• IOSv is strictly limited to use for evaluation, demonstration and IOS *
• education. IOSv is provided as-is and is not supported by Cisco's *
• Technical Advisory Center. Any use or disclosure, in whole or in part, *
• of the IOSv Software or Documentation to any third party for any *
• purposes is expressly prohibited except as otherwise authorized by *
• Cisco in writing. *

**************************************************************************^C
banner incoming ^C
**************************************************************************

• IOSv is strictly limited to use for evaluation, demonstration and IOS *
• education. IOSv is provided as-is and is not supported by Cisco's *
• Technical Advisory Center. Any use or disclosure, in whole or in part, *
• of the IOSv Software or Documentation to any third party for any *
• purposes is expressly prohibited except as otherwise authorized by *
• Cisco in writing. *

**************************************************************************^C
banner login ^C
**************************************************************************

• IOSv is strictly limited to use for evaluation, demonstration and IOS *
• education. IOSv is provided as-is and is not supported by Cisco's *
• Technical Advisory Center. Any use or disclosure, in whole or in part, *
• of the IOSv Software or Documentation to any third party for any *
• purposes is expressly prohibited except as otherwise authorized by *
• Cisco in writing. *

**************************************************************************^C
!
line con 0
exec-timeout 0 0
privilege level 15
logging synchronous
line aux 0
exec-timeout 0 0
privilege level 15
logging synchronous
line vty 0 4
login
transport input none
!
no scheduler allocate
!
end

Spoiler: R5

R5#show run
Building configuration...

Current configuration : 3261 bytes
!
version 15.9
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname R5
!
boot-start-marker
boot-end-marker
!
!
!
no aaa new-model
!
!
!
mmi polling-interval 60
no mmi auto-configure
no mmi pvc
mmi snmp-timeout 180
!
!
!
!
!
no ip icmp rate-limit unreachable
!
!
!
!
!
!
no ip domain lookup
ip cef
no ipv6 cef
!
multilink bundle-name authenticated
!
!
!
!
!
redundancy
!
no cdp log mismatch duplex
!
ip tcp synwait-time 5
!
!
!
!
!
!
!
!
!
!
!
!
!
interface GigabitEthernet0/0
ip address 192.168.7.5 255.255.255.0
duplex auto
speed auto
media-type rj45
!
interface GigabitEthernet0/1
ip address 192.168.6.5 255.255.255.0
duplex auto
speed auto
media-type rj45
!
interface GigabitEthernet0/2
ip address 192.168.5.5 255.255.255.0
duplex auto
speed auto
media-type rj45
!
interface GigabitEthernet0/3
no ip address
shutdown
duplex auto
speed auto
media-type rj45
!
router ospf 128
network 192.168.5.0 0.0.0.255 area 128
network 192.168.6.0 0.0.0.255 area 128
network 192.168.7.0 0.0.0.255 area 128
!
ip forward-protocol nd
!
!
no ip http server
no ip http secure-server
!
ipv6 ioam timestamp
!
!
!
control-plane
!
banner exec ^C
**************************************************************************

• IOSv is strictly limited to use for evaluation, demonstration and IOS *
• education. IOSv is provided as-is and is not supported by Cisco's *
• Technical Advisory Center. Any use or disclosure, in whole or in part, *
• of the IOSv Software or Documentation to any third party for any *
• purposes is expressly prohibited except as otherwise authorized by *
• Cisco in writing. *

**************************************************************************^C
banner incoming ^C
**************************************************************************

• IOSv is strictly limited to use for evaluation, demonstration and IOS *
• education. IOSv is provided as-is and is not supported by Cisco's *
• Technical Advisory Center. Any use or disclosure, in whole or in part, *
• of the IOSv Software or Documentation to any third party for any *
• purposes is expressly prohibited except as otherwise authorized by *
• Cisco in writing. *

**************************************************************************^C
banner login ^C
**************************************************************************

• IOSv is strictly limited to use for evaluation, demonstration and IOS *
• education. IOSv is provided as-is and is not supported by Cisco's *
• Technical Advisory Center. Any use or disclosure, in whole or in part, *
• of the IOSv Software or Documentation to any third party for any *
• purposes is expressly prohibited except as otherwise authorized by *
• Cisco in writing. *

**************************************************************************^C
!
line con 0
exec-timeout 0 0
privilege level 15
logging synchronous
line aux 0
exec-timeout 0 0
privilege level 15
logging synchronous
line vty 0 4
login
transport input none
!
no scheduler allocate
!
end

Spoiler: R6

R6#show run
Building configuration...

Current configuration : 3155 bytes
!
version 15.9
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname R6
!
boot-start-marker
boot-end-marker
!
!
!
no aaa new-model
!
!
!
mmi polling-interval 60
no mmi auto-configure
no mmi pvc
mmi snmp-timeout 180
!
!
!
!
!
no ip icmp rate-limit unreachable
!
!
!
!
!
!
no ip domain lookup
ip cef
no ipv6 cef
!
multilink bundle-name authenticated
!
!
!
!
!
redundancy
!
no cdp log mismatch duplex
!
ip tcp synwait-time 5
!
!
!
!
!
!
!
!
!
!
!
!
!
interface GigabitEthernet0/0
no ip address
shutdown
duplex auto
speed auto
media-type rj45
!
interface GigabitEthernet0/1
no ip address
shutdown
duplex auto
speed auto
media-type rj45
!
interface GigabitEthernet0/2
ip address 172.17.0.6 255.255.0.0
duplex auto
speed auto
media-type rj45
!
interface GigabitEthernet0/3
no ip address
shutdown
duplex auto
speed auto
media-type rj45
!
router rip
version 2
network 172.17.0.0
no auto-summary
!
ip forward-protocol nd
!
!
no ip http server
no ip http secure-server
!
ipv6 ioam timestamp
!
!
!
control-plane
!
banner exec ^C
**************************************************************************

• IOSv is strictly limited to use for evaluation, demonstration and IOS *
• education. IOSv is provided as-is and is not supported by Cisco's *
• Technical Advisory Center. Any use or disclosure, in whole or in part, *
• of the IOSv Software or Documentation to any third party for any *
• purposes is expressly prohibited except as otherwise authorized by *
• Cisco in writing. *

**************************************************************************^C
banner incoming ^C
**************************************************************************

• IOSv is strictly limited to use for evaluation, demonstration and IOS *
• education. IOSv is provided as-is and is not supported by Cisco's *
• Technical Advisory Center. Any use or disclosure, in whole or in part, *
• of the IOSv Software or Documentation to any third party for any *
• purposes is expressly prohibited except as otherwise authorized by *
• Cisco in writing. *

**************************************************************************^C
banner login ^C
**************************************************************************

• IOSv is strictly limited to use for evaluation, demonstration and IOS *
• education. IOSv is provided as-is and is not supported by Cisco's *
• Technical Advisory Center. Any use or disclosure, in whole or in part, *
• of the IOSv Software or Documentation to any third party for any *
• purposes is expressly prohibited except as otherwise authorized by *
• Cisco in writing. *

**************************************************************************^C
!
line con 0
exec-timeout 0 0
privilege level 15
logging synchronous
line aux 0
exec-timeout 0 0
privilege level 15
logging synchronous
line vty 0 4
login
transport input none
!
no scheduler allocate
!
end