OSPF IPv6 - Redistribution

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Redistribution

OSPF (Open Shortest Path First) for IPv6 redistribution is a mechanism used to share routing information between OSPF and other routing domains, facilitating the integration of diverse routing protocols within a network. In IPv6 OSPF redistribution, external routes from other OSPF areas or external routing domains, such as RIPng, EIGRPv6, or BGP, are injected into the OSPF routing table. The redistribution process typically occurs at an Autonomous System Border Router (ASBR), where careful configuration is required to maintain route accuracy and consistency across different routing domains. Administrators may manipulate route tags and metrics during the redistribution to influence path selection within OSPF. IPv6 OSPF redistribution is crucial for achieving interoperability between OSPF and other routing protocols, enabling seamless communication and routing in complex, heterogeneous networks. However, proper planning and configuration are essential to avoid potential issues like routing loops and suboptimal path selection that may arise from redistribution.

Lab:

Disclaimer

This Configuration Guide is designed to assist members to enhance their skills in particular technology area. While every effort has been made to ensure that all material is as complete and accurate as possible, the enclosed material is presented on an Dzas isdz basis. Neither the authors nor Forum assume any liability or responsibility to any person or entity with respect to loss or damages incurred from the information contained in this guide. This configuration guide was developed by Forum. Any similarities between material presented in this configuration guide and any other material is completely coincidental.

Cisco IOS Software, Linux Software (I86BI_LINUX-ADVENTERPRISEK9-M), Version 15.2(4)M1, DEVELOPMENT TEST SOFTWARE

Task 1: Configure IPv6 OSPF Redistribution

Step 1: In the configuration mode of router configure 4 loopbacks with network address in sequence

R2:
interface loop101
ipv6 address 100:0:1::2/64
interface loop102
ipv6 address 100:0:2::2/64
interface loop103
ipv6 address 100:0:3::2/64
exit

Step 2: Redistribute these connected network in IPv6 OSPF process (External Type 2)

R2:
ipv6 router ospf 2
redistribute connected
exit

Redistributed connected will redistribute its connected network. Subnet will allow classless IPv6 routes in OSPF process

R1#show ipv6 route
IPv6 Routing Table - default - 26 entries
Codes: C - Connected, L - Local, S - Static, U - Per-user Static route
       B - BGP, HA - Home Agent, MR - Mobile Router, R - RIP
       H - NHRP, I1 - ISIS L1, I2 - ISIS L2, IA - ISIS interarea
       IS - ISIS summary, D - EIGRP, EX - EIGRP external, NM - NEMO
       ND - ND Default, NDp - ND Prefix, DCE - Destination, NDr - Redirect
       O - OSPF Intra, OI - OSPF Inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2
       ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2, l - LISP
C   11::/64 [0/0]
     via Loopback0, directly connected
L   11::1/128 [0/0]
     via Loopback0, receive
C   11:0:1::/64 [0/0]
     via Loopback1, directly connected
L   11:0:1::1/128 [0/0]
     via Loopback1, receive
C   11:0:2::/64 [0/0]
     via Loopback2, directly connected
L   11:0:2::1/128 [0/0]
     via Loopback2, receive
C   11:0:3::/64 [0/0]
     via Loopback3, directly connected
L   11:0:3::1/128 [0/0]
via Loopback3, receive
C   12::/64 [0/0]
     via Serial2/0, directly connected
L   12::A8BB:CCFF:FE00:100/128 [0/0]
     via Serial2/0, receive
OI  22:0:1::2/128 [110/64]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0
OI  22:0:2::2/128 [110/64]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0
OI  22:0:3::2/128 [110/64]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0
OI  23::/64 [110/74]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0
OI  33:0:1::3/128 [110/74]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0
OI  33:0:2::3/128 [110/74]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0
OI  33:0:3::3/128 [110/74]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0
OI  34::/64 [110/138]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0
OI  44:0:1::4/128 [110/138]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0
OI  44:0:2::4/128 [110/138]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0
OI  44:0:3::4/128 [110/138]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0
OE2 100::/64 [110/20]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0
OE2 100:0:1::/64 [110/20]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0
OE2 100:0:2::/64 [110/20]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0
OE2 100:0:3::/64 [110/20]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0
L   FF00::/8 [0/0]
     via Null0, receive

E2 means External type 2, in which will not change cost after every hop throughout the OSPF.

Step 3: Redistribute these connected network in OSPF process (External Type 1)

R2:
ipv6 router ospf 2
redistribute connected metric-type 1
exit

Redistributed connected will redistribute its connected network. Subnet will allow classless IPv6 routes in OSPF process Metric type 1 means will redistribute in the form of E1, in which will change cost after every hop.

R1#show ipv6 route
IPv6 Routing Table - default - 26 entries
Codes: C - Connected, L - Local, S - Static, U - Per-user Static route
       B - BGP, HA - Home Agent, MR - Mobile Router, R - RIP
       H - NHRP, I1 - ISIS L1, I2 - ISIS L2, IA - ISIS interarea
       IS - ISIS summary, D - EIGRP, EX - EIGRP external, NM - NEMO
       ND - ND Default, NDp - ND Prefix, DCE - Destination, NDr - Redirect
       O - OSPF Intra, OI - OSPF Inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2
       ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2, l - LISP
C   11::/64 [0/0]
     via Loopback0, directly connected
L   11::1/128 [0/0]
     via Loopback0, receive
C   11:0:1::/64 [0/0]
     via Loopback1, directly connected
L   11:0:1::1/128 [0/0]
     via Loopback1, receive
C   11:0:2::/64 [0/0]
     via Loopback2, directly connected
L   11:0:2::1/128 [0/0]
     via Loopback2, receive
C   11:0:3::/64 [0/0]
     via Loopback3, directly connected
L   11:0:3::1/128 [0/0]
via Loopback3, receive
C   12::/64 [0/0]
     via Serial2/0, directly connected
L   12::A8BB:CCFF:FE00:100/128 [0/0]
     via Serial2/0, receive
OI  22:0:1::2/128 [110/64]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0
OI  22:0:2::2/128 [110/64]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0
OI  22:0:3::2/128 [110/64]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0
OI  23::/64 [110/74]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0
OI  33:0:1::3/128 [110/74]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0
OI  33:0:2::3/128 [110/74]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0
OI  33:0:3::3/128 [110/74]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0
OI  34::/64 [110/138]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0
OI  44:0:1::4/128 [110/138]
via FE80::A8BB:CCFF:FE00:200, Serial2/0
OI  44:0:2::4/128 [110/138]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0
OI  44:0:3::4/128 [110/138]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0
OE1 100::/64 [110/84]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0
OE1 100:0:1::/64 [110/84]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0
OE1 100:0:2::/64 [110/84]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0
OE1 100:0:3::/64 [110/84]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0
L   FF00::/8 [0/0]
     via Null0, receive

E1 means External type 1, in which will change cost after every hop throughout the OSPF.

Task 2: Verification:

Step 1: Analyze network type as E1 or E2 and its cost of redistribution route in neighbor router

External Type 2:

R1#show ipv6 route
OE2 100::/64 [110/20]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0
OE2 100:0:1::/64 [110/20]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0
OE2 100:0:2::/64 [110/20]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0
OE2 100:0:3::/64 [110/20]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0


R3#show ipv6 route
OE2 100::/64 [110/20]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0
OE2 100:0:1::/64 [110/20]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0
OE2 100:0:2::/64 [110/20]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0
OE2 100:0:3::/64 [110/20]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0

R1 router receives redistributed 100 network with metric (cost) 20 and R3 router also receives redistributed 100 network with metric (cost) 20 Hence External type 2 (E2) cost remains constant after every hop

Step: 2 Analyze network type as E1 or E2 and its cost of redistribution route in neighbor router

External Type 1:

R1#show ipv6 route
OE1 100::/64 [110/84]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0
OE1 100:0:1::/64 [110/84]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0
OE1 100:0:2::/64 [110/84]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0
OE1 100:0:3::/64 [110/84]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0

R3#show ipv6 route
OE1 100::/64 [110/30]
     via FE80::A8BB:CCFF:FE00:200, Ethernet0/0
OE1 100:0:1::/64 [110/30]
     via FE80::A8BB:CCFF:FE00:200, Ethernet0/0
OE1 100:0:2::/64 [110/30]
     via FE80::A8BB:CCFF:FE00:200, Ethernet0/0
OE1 100:0:3::/64 [110/30]
     via FE80::A8BB:CCFF:FE00:200, Ethernet0/0

R1 router receives redistributed 100 network with metric (cost) 84 and R3 router receives redistributed 100 network with metric (cost) 30 Hence External type 1 (E1) allows to change cost after every hop