OSPF IPv6 - Stub

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Stub

In OSPF (Open Shortest Path First) for IPv6, a Stub Area is a designated OSPF area aimed at simplifying routing information within the OSPF Autonomous System (AS). In a Stub Area, routers do not receive detailed external route information; instead, they are provided with a default route by the Area Border Router (ABR). This default route acts as a summary for all routes outside the OSPF domain, streamlining the routing tables and improving network scalability. OSPF Stub Areas are particularly useful in scenarios where routers within the area do not need to be aware of the specific details of external routes. This approach helps reduce OSPF routing overhead and enhances network efficiency. The use of Stub Areas strikes a balance between maintaining a simplified OSPF topology and providing routers within the area the ability to reach destinations outside the OSPF domain through the default route.

Lab:

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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 Stub

Step 1: In the configuration mode of router configure loopbacks with network address in sequence & redistribute these connected network in IPv6 OSPF process

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

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

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

Step 2: Configure IPv6 OSPF Stub

R1:
ipv6 router ospf 1
area 1 stub
exit

R2:
ipv6 router ospf 2
area 1 stub
exit

Task 2: Verification:

Step 1: Verify routes on neighbor router routing table

R1#show ipv6 route
IPv6 Routing Table - default - 23 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
OI  ::/0 [110/65]
     via FE80::A8BB:CCFF:FE00:200, Serial2/0
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
L   FF00::/8 [0/0]
     via Null0, receive

Stub area is area in which external routes LSA 5 does not propagate, instead it automatically creates default route ::/0 towards ABR.

R1#traceroute 100:0:1::2
Type escape sequence to abort.
Tracing the route to 100:0:1::2

1 12::A8BB:CCFF:FE00:200 8 msec 8 msec 9 msec