Skip to main content

OSPF – stub area

This is second post about OSPF and today I will review how stub area behaves comparing to normal area (from previous post).



 

In this scenario R6, R7 and R8 can't reach R10's prefixes because LSA5 is not allowed withing a stub area.


R6#sh ip route

      10.0.0.0/8 is variably subnetted, 6 subnets, 2 masks

C        10.0.0.0/24 is directly connected, FastEthernet0/0

L        10.0.0.6/32 is directly connected, FastEthernet0/0

O IA     10.1.0.0/24 [110/2] via 10.0.0.7, 00:14:18, FastEthernet0/0

O IA     10.2.0.0/24 [110/3] via 10.0.0.7, 00:00:07, FastEthernet0/0

C        10.10.10.0/24 is directly connected, Loopback0

L        10.10.10.6/32 is directly connected, Loopback0

R6#sh ip ospf database database-summary

            OSPF Router with ID (10.10.10.6) (Process ID 10)

Area 0 database summary

  LSA Type      Count    Delete   Maxage

  Router        2        0        0

  Network       1        0        0

  Summary Net   2        0        0

  Summary ASBR  0        0        0

  Type-7 Ext    0        0        0

    Prefixes redistributed in Type-7  0

  Opaque Link   0        0        0

  Opaque Area   0        0        0

  Subtotal      5        0        0

Process 10 database summary

  LSA Type      Count    Delete   Maxage

  Router        2        0        0

  Network       1        0        0

  Summary Net   2        0        0

  Summary ASBR  0        0        0

  Type-7 Ext    0        0        0

  Opaque Link   0        0        0

  Opaque Area   0        0        0

  Type-5 Ext    0        0        0

      Prefixes redistributed in Type-5  0

  Opaque AS     0        0        0

  Non-self      3

  Total         5        0        0

R6#


R7#sh ip route

      10.0.0.0/8 is variably subnetted, 6 subnets, 2 masks

C        10.0.0.0/24 is directly connected, FastEthernet0/0

L        10.0.0.7/32 is directly connected, FastEthernet0/0

C        10.1.0.0/24 is directly connected, FastEthernet1/0

L        10.1.0.7/32 is directly connected, FastEthernet1/0

O        10.2.0.0/24 [110/2] via 10.1.0.8, 00:01:24, FastEthernet1/0

O        10.10.10.6/32 [110/2] via 10.0.0.6, 00:04:48, FastEthernet0/0

R7#sh ip ospf database database-summary

            OSPF Router with ID (10.1.0.7) (Process ID 10)

Area 0 database summary

  LSA Type      Count    Delete   Maxage

  Router        2        0        0

  Network       1        0        0

  Summary Net   2        0        0

  Summary ASBR  0        0        0

  Type-7 Ext    0        0        0

    Prefixes redistributed in Type-7  0

  Opaque Link   0        0        0

  Opaque Area   0        0        0

  Subtotal      5        0        0

Area 1 database summary

  LSA Type      Count    Delete   Maxage

  Router        3        0        0

  Network       2        0        0

  Summary Net   3        0        0

  Summary ASBR  0        0        0

  Type-7 Ext    0        0        0

    Prefixes redistributed in Type-7  0

  Opaque Link   0        0        0

  Opaque Area   0        0        0

  Subtotal      8        0        0

Process 10 database summary

  LSA Type      Count    Delete   Maxage

  Router        5        0        0

  Network       3        0        0

  Summary Net   5        0        0

  Summary ASBR  0        0        0

  Type-7 Ext    0        0        0

  Opaque Link   0        0        0

  Opaque Area   0        0        0

  Type-5 Ext    0        0        0

      Prefixes redistributed in Type-5  0

  Opaque AS     0        0        0

  Non-self      6

  Total         13       0        0

R7#


R8#sh ip route

Gateway of last resort is 10.1.0.7 to network 0.0.0.0

O*IA  0.0.0.0/0 [110/2] via 10.1.0.7, 00:04:20, FastEthernet1/0

      10.0.0.0/8 is variably subnetted, 6 subnets, 2 masks

O IA     10.0.0.0/24 [110/2] via 10.1.0.7, 00:04:20, FastEthernet1/0

C        10.1.0.0/24 is directly connected, FastEthernet1/0

L        10.1.0.8/32 is directly connected, FastEthernet1/0

C        10.2.0.0/24 is directly connected, FastEthernet0/0

L        10.2.0.8/32 is directly connected, FastEthernet0/0

O IA     10.10.10.6/32 [110/3] via 10.1.0.7, 00:04:20, FastEthernet1/0

R8#sh ip ospf database database-summary

            OSPF Router with ID (10.2.0.8) (Process ID 10)

Area 1 database summary

  LSA Type      Count    Delete   Maxage

  Router        3        0        0

  Network       2        0        0

  Summary Net   3        0        0

  Summary ASBR  0        0        0

  Type-7 Ext    0        0        0

    Prefixes redistributed in Type-7  0

  Opaque Link   0        0        0

  Opaque Area   0        0        0

  Subtotal      8        0        0

Process 10 database summary

  LSA Type      Count    Delete   Maxage

  Router        3        0        0

  Network       2        0        0

  Summary Net   3        0        0

  Summary ASBR  0        0        0

  Type-7 Ext    0        0        0

  Opaque Link   0        0        0

  Opaque Area   0        0        0

  Type-5 Ext    0        0        0

      Prefixes redistributed in Type-5  0

  Opaque AS     0        0        0

  Non-self      6

  Total         8        0        0

R8#


R9#sh ip route

Gateway of last resort is 10.2.0.8 to network 0.0.0.0

O*IA  0.0.0.0/0 [110/3] via 10.2.0.8, 00:05:20, FastEthernet0/0

      10.0.0.0/8 is variably subnetted, 5 subnets, 2 masks

O IA     10.0.0.0/24 [110/3] via 10.2.0.8, 00:05:20, FastEthernet0/0

O        10.1.0.0/24 [110/2] via 10.2.0.8, 00:05:30, FastEthernet0/0

C        10.2.0.0/24 is directly connected, FastEthernet0/0

L        10.2.0.9/32 is directly connected, FastEthernet0/0

O IA     10.10.10.6/32 [110/4] via 10.2.0.8, 00:05:20, FastEthernet0/0

      172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks

C        172.16.3.0/24 is directly connected, FastEthernet1/1

L        172.16.3.9/32 is directly connected, FastEthernet1/1

R        172.16.4.0/24 [120/1] via 172.16.3.10, 00:00:07, FastEthernet1/1

R9#sh ip ospf database database-summary

            OSPF Router with ID (172.16.3.9) (Process ID 10)

Area 1 database summary

  LSA Type      Count    Delete   Maxage

  Router        3        0        0

  Network       2        0        0

  Summary Net   3        0        0

  Summary ASBR  0        0        0

  Type-7 Ext    0        0        0

    Prefixes redistributed in Type-7  0

  Opaque Link   0        0        0

  Opaque Area   0        0        0

  Subtotal      8        0        0

Process 10 database summary

  LSA Type      Count    Delete   Maxage

  Router        3        0        0

  Network       2        0        0

  Summary Net   3        0        0

  Summary ASBR  0        0        0

  Type-7 Ext    0        0        0

  Opaque Link   0        0        0

  Opaque Area   0        0        0

  Type-5 Ext    0        0        0

      Prefixes redistributed in Type-5  0

  Opaque AS     0        0        0

  Non-self      6

  Total         8        0        0

R9#

R10#sh 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

       + - replicated route, % - next hop override

Gateway of last resort is not set

S     10.0.0.0/8 [1/0] via 172.16.3.9

      172.16.0.0/16 is variably subnetted, 4 subnets, 2 masks

C        172.16.3.0/24 is directly connected, FastEthernet1/1

L        172.16.3.10/32 is directly connected, FastEthernet1/1

C        172.16.4.0/24 is directly connected, Loopback0

L        172.16.4.10/32 is directly connected, Loopback0

R10# 
 
 
 
All information on one page:
 

Labels:

Comments

Post a Comment

Popular posts from this blog

What should you know about HA 'override enabled' setting on Fortigate?

High availability is mandatory in most of today's network designs. Only very small companies or branches can run their business without redundancy. When you have Fortigate firewall in your network you have many options to increase network availability. You can use Fortigate Clustering Protocol ( FGCP ) or Virtual Router Redundancy Protocol ( VRRP ). FGCP has two modes: 'override' disabled (default) and 'override' enabled . I'm not going to explain how to set up HA as you can find many resources on Fortinet websites: https://cookbook.fortinet.com/high-availability-two-fortigates-56/ https://cookbook.fortinet.com/high-availability-with-fgcp-56/ Let's recap what is the main difference between them. The default HA setting is 'override' disabled and this is an order of selection an active unit: 1) number of monitored interfaces - when both units have the same number of working (up) interfaces check next parameter 2) HA uptime - an ...
8 comments
Read more

FortiGate and GRE tunnel

Recently I worked on one project where a client requested to re-route web traffic to the GRE tunnel to perform traffic inspection. I would like to share with you what is required if you configure it on FortiGate. We need a new GRE interface and policy base routing (PBR) to change the route for specific source IPs. Of course you need firewall policies to permit the traffic. Let's start with GRE interface. Unfortunately you can't configure it using the GUI, only CLI is the option: config system gre-tunnel edit "gre1" set interface "port1" set local-gw 55.55.55.55 set remote-gw 44.44.44.44 next end When the end peer is Cisco router, you need to set the IP for the GRE interface: config system interface edit gre1 set ip 192.168.10.10 255.255.255.255 set remote-ip192.168.10.20 end In next step we need to fix routing. We need the alternate path via GRE but to keep the route in the active routing table you need to set the same AD (adminis...
Post a Comment
Read more

IKEv1 aggresive mode

I know that IKEv2 is getting popular but still IKEv1 has a huge presence in production networks. There are many reasons but I’m not going to focus on them. I would rather focus on one issue I see from time to time: ikev1 and an aggressive mode. Just to remind you, there are two modes of ikev1: aggressive and main. The first one is much faster, only three messages are exchanged, but it isn’t secure as the main mode (with six messages). The main problem with the aggressive mode is the first two messages  contain data which may help to perform attack on your VPN. For this test I set up VPN on ASA with ‘aggressive mode’ enabled: ciscoasa# sh run crypto crypto ipsec ikev1 transform-set TS esp-3des esp-md5-hmac crypto map MAPA 10 match address ACL crypto map MAPA 10 set peer 192.168.111.128 crypto map MAPA 10 set ikev1 transform-set TS crypto map MAPA interface inside crypto ikev1 enable inside crypto ikev1 policy 10  authentication pre-share  encryption 3des  hash md5...
Post a Comment
Read more