OSPF IPv6 - Totally Stubby Area

Totally Stubby Area

In OSPF (Open Shortest Path First) for IPv6, a Totally Stubby Area is a specialized OSPF area designed to minimize routing information and enhance scalability within the OSPF Autonomous System (AS). In a Totally Stubby Area, routers only receive a default route from the Area Border Router (ABR), summarizing all routes external to the OSPF domain. Unlike standard OSPF areas, where Type 3 Summary LSAs may provide some additional information, the Totally Stubby Area further restricts the injected LSAs, resulting in a highly condensed OSPF database. This approach reduces the size of routing tables within the area, improving efficiency. The use of Totally Stubby Areas is particularly advantageous in large networks where the reduction of OSPF overhead and simplified routing tables contribute to optimized network operations.

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 Totally Stubby Area

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:
router ospf 2
redistribute connected subnet 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 OSPF Stub

R1:
ipv6 router ospf 1
area 1 stub no-summary
exit
R2:
ipv6 router ospf 2
area 1 stub no-summary
exit

Task 2: Verification:

Step 1: Verify routes on neighbor router routing table

R1#show ipv6 route
IPv6 Routing Table - default - 12 entries
Codes: C - Connected, L - Local, S - Static, U - Per-user Static route
       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
L   FF00::/8 [0/0]
     via Null0, receive

Total Stubby area is area in which external routes LSA 5 and Inter-area routes LSA3/4 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 9 msec 8 msec 9 msec
R1#traceroute 44:0:1::4
Type escape sequence to abort.
Tracing the route to 44:0:1::4
1 12::A8BB:CCFF:FE00:200 8 msec 9 msec 8 msec
2 23::A8BB:CCFF:FE00:300 30 msec 9 msec 8 msec
3 34::A8BB:CCFF:FE00:400 17 msec 13 msec 17 msec