Cisco Routing/Switching – RIPV2 Routing, Corporate to Branch Office.

Configuring a corporate office to a branch via RIPV2 without advertising into the branches local LAN.

Assuming you have a base configuration set already and the equipment in place, we are going to configure in the test lab some basic RIPV2 routing to connect our Corporate office into our branch office, see topology below: NOTE: ensure you have the SVI’s configured on the switches so they can communicate through, those are on the default vlan -> ip int vlan 1 ip address 10.1.0.11 /24

Configure CO-R1 (Corporate Router 1) with RIP and only allow advertisements within the network (Not over ISP)

CO-R1#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
CO-R1(config)#router rip
CO-R1(config-router)#version 2
CO-R1(config-router)#no auto-summary
CO-R1(config-router)#network 10.0.0.0
CO-R1(config-router)#

This allows Router 1 to advertise out on all ports programmed within the 10 network.

Now we need to configure CO-R2 (Corporate Router 2) with the same configuration:

CO-R2#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
CO-R2(config)#router rip
CO-R2(config-router)#version 2 
CO-R2(config-router)#no auto-summary
CO-R2(config-router)#network 10.0.0.0
CO-R2(config-router)#end
CO-R2#
%SYS-5-CONFIG_I: Configured from console by console

Now we are going to configure the branch router, however we do not want RIP Advertisements to be sent to any device within the Branch Office LAN.

B1-R1#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
B1-R1(config)#router rip 
B1-R1(config-router)#version 2
B1-R1(config-router)#no auto-summary
B1-R1(config-router)#network 10.0.0.0
B1-R1(config-router)#do sh ip int brief
Interface              IP-Address      OK? Method Status                Protocol 
GigabitEthernet0/0     10.23.2.1       YES manual up                    up 
GigabitEthernet0/1     unassigned      YES unset  administratively down down 
GigabitEthernet0/2     unassigned      YES unset  administratively down down 
Serial0/0/0            10.16.1.14      YES manual up                    up 
Serial0/0/1            unassigned      YES unset  administratively down down 
Vlan1                  unassigned      YES unset  administratively down down
B1-R1(config-router)#passive-interface g0/0
B1-R1(config-router)#

Notice in the code above I do a do sh ip int brief this is because I needed to identify which port was the port communicating with the branch in which case was 10.23.2.1 on GigabitEthernet0/0, we have assigned the passive-interface g0/0 command to ensure no RIP Advertisements are to be sent via that port down into the Branch Office LAN. If you wanted to do this the opposite way by not allowing it on all ports you could run, passive-interface default and then select the interface you would like to send advertisements on using command no passive-interface serial0/0 as an example.

We now need to enable our switches to use CO-R1 as their default gateway – ensure this is done on all three switches

S3(config)#ip default-gateway 10.1.0.1
S3(config)#end
S3#

Now in theory everything should be able to ping and communicate just fine, so we need to confirm this.

I’ll do a ping from Switch 1 all the way down to the branch LAN

S1#ping 10.23.2.1

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.23.2.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/5 ms

Assuming your default gateway is configured correctly and routing is correct you should see all devices in the routing table and be able to ping all the way down.

 

also running a sh ip route from the Corporate Router 1 we can see all the routes configured via RIPv2

CO-R1#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, 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

     10.0.0.0/8 is variably subnetted, 6 subnets, 4 masks
C       10.1.0.0/24 is directly connected, GigabitEthernet0/0
L       10.1.0.1/32 is directly connected, GigabitEthernet0/0
R       10.16.1.12/30 [120/1] via 10.1.0.2, 00:00:16, GigabitEthernet0/0
R       10.23.2.0/24 [120/2] via 10.1.0.2, 00:00:16, GigabitEthernet0/0
C       10.29.163.168/29 is directly connected, Serial0/0/0
L       10.29.163.173/32 is directly connected, Serial0/0/0

CO-R1#

 

 

 

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