CISCO lab routers not communicating

[elijah.mangwende1]

Hi Guys

I have 3 switches and 3 routers for my lab, see attachment, everytime when i try to use one of the routers to simulate an ISP, it looks like the ISP router doesnt communicate with other routers or switches. Is there anyone with an example of correct connections and configurations so that i try it. 

Thanks in advance, i guess am doing something wrong 

Regards

[Julio E. Moisa]

Hi

What ISP service are you simulating?, how is the logical topology and if you could share the configuration.

Thank you in advance. 

[Jean-Pierre Roux · Accepted solution]

This is an interesting one.

To further troubleshoot this Ill need to see the configs you running. Have you tried to run the basic commands such as "show logs", maybe there is an indication of what is going wrong at the moment?

But I assume you going to need to probably create a loopback address to simulate the public IP address of the site you going to access and bring in a routing protocol such as eigrp to advertise these routes. 

PS just a small train of thought going this side.

If you supply the configs we can then further investigate and come up with a possible solution to make this work. 

Kind Regards
Jean-Pierre Roux

[Muhammad Uzair]

Hi, its interesting of course, do 1 thing first of all draw the topology, make diagram of 3 switches and 3 router and on switches run "show cdp neighbor" then mark the interface on diagrams with respective vlans. Same thing do with router diagram and mark interfaces with IP address and share please, are you running any routing protocol or static routing? Only with picture its hard to find the actual scenario.

HTH

Kindest regards

Uzzi

[elijah.mangwende1]

Thank you for your reply. I am aware of the need for routing protocols , loopback addresses etc, its not one specific scenario but anything i tried seems not to be working, so i just want to see an example from others so that i use it and do the troubleshooting myself, eg the ospf i configured after basic IP addressing etc , i tried the default-information originate always etc but no success

R1(config)# router ospf 101
R1(config-router)# network 192.168.1.0 0.0.0.255 area 0
R1(config-router)# network 10.1.1.0 0.0.0.3 area 0

R2(config)# router ospf 101
R2(config-router)# network 10.1.1.0 0.0.0.3 area 0
R2(config-router)# network 10.2.2.0 0.0.0.3 area 0

R3(config)# router ospf 101
R3(config-router)# network 192.168.3.0 0.0.0.255 area 0
R3(config-router)# network 10.2.2.0 0.0.0.3 area 0

[Muhammad Uzair]

Redistribute ospf in bgp please and then check.

Also do the trace till ISP and see where you stuck then troubleshoot that device, that's what I use to do.

Kindest regards

Uzzi

[elijah.mangwende1]

Ok i will try that and advise accordingly. thanks

[Muhammad Uzair · Accepted solution]

Also one more thing for BGP prospective, as you know BGP runs over IGP. If your IGP is okay and you have network reachable without any issue and BGP neighbor(s) are up (with your ISP peering which you are simulating) please check the BGP routing table (I believe you are familiar that BGP maintain separate routing table) as you have to advertise the networks by "network IP (x.x.x.x) Mask (x.x.x.x) " command on both peers. I believe your problem will be solve. if not then we will discuss it further.

Kindest regards,

Uzzi 

[elijah.mangwende1]

R1(config)# router ospf 101
R1(config-router)# network 192.168.1.0 0.0.0.255 area 0
R1(config-router)# network 10.1.1.0 0.0.0.3 area 0

R2(config)# router ospf 101
R2(config-router)# network 10.1.1.0 0.0.0.3 area 0
R2(config-router)# network 10.2.2.0 0.0.0.3 area 0

R3(config)# router ospf 101
R3(config-router)# network 192.168.3.0 0.0.0.255 area 0
R3(config-router)# network 10.2.2.0 0.0.0.3 area 0