Observe advertisement of Default Route by automatic routing protocol, still using RIPv1 (CNA-02-004)

CCNA Exploration 4.0, Semester 2, "Observe advertisement of Default Route by automatic routing protocol, still using RIPv1" Packet Tracer 5.0 practice file (CNA-02-004).

• CNA-02-004.pkt, (Backup Link)

In this example we do observation only. You will see how I use RIPv1 to advertise "Default Route".

Making that happen depends on 2 keys:

1. The "Default Route" should be already in R2's routing table.
2. R2 is configured with "default-information originate" statement.
   

So the key configurations on R2 are:

ip route 0.0.0.0 0.0.0.0 172.30.2.1 
router rip
 network 172.30.0.0
 network 192.168.4.0
 default-information originate

Then we can see the "Default Route" on R3:

R3>show ip route
Codes: C - connected, S - static, I - IGRP, 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, E - EGP
       i - IS-IS, 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

Gateway of last resort is 192.168.4.2 to network 0.0.0.0

R    172.30.0.0/16 [120/1] via 192.168.4.2, 00:00:19, Serial0/0/0
C    192.168.4.0/24 is directly connected, Serial0/0/0
C    192.168.5.0/24 is directly connected, FastEthernet0/0
R*   0.0.0.0/0 [120/1] via 192.168.4.2, 00:00:19, Serial0/0/0
R3>

Automatic routing table maintenance by routing protocol configuration, still using RIPv1 (CNA-02-003)

CCNA Exploration 4.0, Semester 2, "Automatic routing table maintenance by routing protocol configuration, still using RIPv1" Packet Tracer 5.0 practice file (CNA-02-003).

• CNA-02-003.pkt, (Backup Link)
• CNA-02-003-sol.pkt (solution for reference), (Backup Link)

I believe many people were not quite satisfied by previous practice: the IP addresses were not the same. Now in this practice I changed all the IP addresses to the same as the first practice. We still use RIPv1 this time.

It would be much more persuasive that "automatic" ways are better than "manual" ways.

In addition to this, I also want to illustrate one "Classful" behavior in this practice. Classful world's router always summarize all subnet routes to only one route: the class network address it belongs to, when telling to other routers not in the same class network address.

We have 3 subnet routes of 172.30.1.0/24, 172.30.2.0/24, 172.30.3.0/24 in this practice. But R3 will only see 172.30.0.0/16, the one B class network address they belong to.

R3#show ip route
Codes: C - connected, S - static, I - IGRP, 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, E - EGP
       i - IS-IS, 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

Gateway of last resort is not set

R    172.30.0.0/16 [120/1] via 192.168.4.2, 00:00:25, Serial0/0/0
C    192.168.4.0/24 is directly connected, Serial0/0/0
C    192.168.5.0/24 is directly connected, FastEthernet0/0
R3#

Automatic routing table maintenance by routing protocol configuration, using RIPv1 (CNA-02-002)

CCNA Exploration 4.0, Semester 2, "Automatic routing table maintenance by routing protocol configuration, using RIPv1" Packet Tracer 5.0 practice file (CNA-02-002).

• CNA-02-002.pkt, (Backup Link)
• CNA-02-002-sol.pkt (solution for references), (Backup Link)

In this example, we are experiencing "automatic" way of routing table maintenance. We use RIPv1 (RIP version 1) .

Note, the IP addresses are not the same as the previous practice.

I believe after this practice, everyone would appreciate the beauty of such "automatic" way!

IOS OSPF Multi-VRF support: remember to add "capability vrf-lite" statement

IOS "Multi-VRF" to me is a solution to one of my headache. Since I failed to persuade my colleagues buying new switches, I have to make one hardware acting as two.

(The following story is really demonstrating a bad habit. You should avoid the same mistakes by prepare well before you do anything!)

Without study further at the beginning, I jumped right into configuring and enabling the Multi-VRF feature. I decided to use OSPF, so my first configuration looked like this:

router ospf 1 vrf XXXXX
 router-id 1.2.3.4
 area 1.2.3.0 authentication message-digest
 network 1.2.3.0 0.0.0.255 area 1.2.3.0

Looks not too wrong, isn't it?

In fact, I immediately saw a lot of routing entries coming in. That's why I thought I was right at the first moment.

Then something strange came out. I checked more carefully about the routing table entries and found some routes are just missing. All OSPF externals and "intra-area"s are there, but not those "inter-area"s.

I googled a while and found this page on Cisco.com. The missing statement is "capability vrf-lite". So the correct configuration should be like this:

router ospf 1 vrf XXXXX
 router-id 1.2.3.4
 capability vrf-lite
 area 1.2.3.0 authentication message-digest
 network 1.2.3.0 0.0.0.255 area 1.2.3.0

A good lessen for myself!

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