How do you simulate 'the internet' in Packet Tracer 5?

nelsonnr · 06-29-2009, 07:33 PM

I've searched the forums, help files and Google but cant find an answer to this one. I see that you can add a 'cloud' device, but since I've just starting to learn about DLCIs and Frame Relay I'm not sure how to set this virtual device up in PT to simulate the internet, if indeed you can simulate it at all?

Is this one of PT's many weaknesses? Is it possible?

Thanks chaps!

knwminus · 06-29-2009, 07:56 PM

Quote:

Originally Posted by nelsonnr

I've searched the forums, help files and Google but cant find an answer to this one. I see that you can add a 'cloud' device, but since I've just starting to learn about DLCIs and Frame Relay I'm not sure how to set this virtual device up in PT to simulate the internet, if indeed you can simulate it at all?

Is this one of PT's many weaknesses? Is it possible?

Thanks chaps!

IF you are inside of PT look towards the bottom where you can add things from. Look for WAN emulation and click on it. You will see a cloud.

nelsonnr · 07:59 PM

Thanks knwminus, I managed to get that far. I'm not sure how to setup the cloud device though to emulate the internet.

Do you simply add a 'public' IP address to a serial interface and then send packets to that interface? I suppose that would work hey? Guess I just want to emulate a network outside my private address range to force the packets out the default gateway.

knwminus · 06-30-2009, 12:33 AM

Quote:

Originally Posted by nelsonnr

Thanks knwminus, I managed to get that far. I'm not sure how to setup the cloud device though to emulate the internet.

Do you simply add a 'public' IP address to a serial interface and then send packets to that interface? I suppose that would work hey? Guess I just want to emulate a network outside my private address range to force the packets out the default gateway.

Not sure about that one. I will take a look later tonight.

ccnacertified2000 · 06-30-2009, 01:23 AM

There is no such thing as a simulation of the Internet. The Internet consist of a bunch of servers, routers, switches, transport platforms, and many other various devices all connected to one another and shares routes using various routing protocols. Different companies have their own network that they manage called an "autonomous system" from here on referred to as AS. Within this AS, a series of routers, switches, servers, etc are connected together, including but not limited to your own PC. Also within this AS, the network is configured with some form of routing protocol so that every device (hopefully) within the network is able to reach any other computer in the AS.

You are within such an AS, although specifically, your PC are within you ISP's customer network AS. The Internet therefore consists of your PC, your AS, and by applying this rule to others, also consists of other people's PCs like yours, the AS they're in, and such.

So we've established that every computer on the internet is in some AS. We've also established that every computer in every AS is connected to every computer within their AS by way of a routing protocol within their AS.

To connect every computer on the internet to another computer on the internet, we need to route between different AS. So each AS is connected to another Peering site where various AS's have a connection to and share routing information. This routing protocol is called BGP (border gateway protocol). It is the protocol that shares routes between ASes on the internet so that different ASes can reach other ASes. This routing protocol helps establish a route between your computer to any other computer in the internet.

Thats the Internet.

SO PT is a simulation. Looking at the above of what is the Internet, you can see that there are no such thing as simulating the Internet, rather you simulate pieces of the internet. And looking at the list of things needed to simulate all of the pieces, you will see that some pieces are not available in PT.

The Cloud in PT is a simulation of your ISP's layer 1 and layer 2 device. So it simulates the fact that you may use cable or DSL to connect to the internet, and simulates companys' use of frame relay etc. It does not simulate the other end of the connection being the internet. Your cable or dsl modem connects to a router of some sorts at the ISP's end, to simulate this in PT, you would need to have a router connected to the cloud along with the dsl modem and such.
If you want to model the entire internet, that means you would need to create a bunch of routers and connect them to simulate different ASes. If you want, you could cluster these routers so that it looks like a cloud. The idea of the cloud is that it is a bunch of devices.

I'm too tired to type more....so i'll leave it at that.

sandman748 · 03:01 PM

Here's how we did it in class.

Add another router named ISP (or whatever) and connect it to the router in your local network you want the traffic to pass through.

Put the passive interface command on the interface connected to the ISP router in order to suppress your routing updates.

Put a static route 0.0.0.0 0.0.0.0 to the ISP router and redistribute that route to the other routers in your LAN.

From here, all of your routers will forward the data out to the "internet." In order for that data to return you'll need to have NAT set up. If you want your local hosts to ping "websites" you can either use loopbacks on the ISP router or servers attached to it. You'll also need to set up a local DNS server to convert the url's to the ip address of the loopbacks/servers. The cool thing about using servers instead of the loopback is that you can actually go into the browser of your local hosts and browse to those websites. This comes in handy if you want to set up ACL's where you can test connectivity by pinging but still block web traffic.

This may not simulate the actual routing outside of your network but it does simulate what you need to do to get your local network communicating with the WAN. Add in your own DHCP server and you've got a fairly decent lab setup that covers most of the communicating with WAN topics.

nelsonnr · 07-01-2009, 08:56 AM

Very very very helpful analysis ccnacertified2000 and thanks so much for typing such a great reply when you were tired. Really appreciate that. It has really helped on re-briefing me about AS's and what the internet is in a physical sense as a cloud. I reckon someone should pay you for that paragraph as an entry into a training book!

sandman - thanks to you too. Thats how I'm beginning to set it up on PT5. I'm needing this for CBT Nuggets video 3 where Jeremy is beginning to implement the static route out to the 'internet'. In his video he does actually have the internet in his lab (he pings 4.2.2.2) and I was wanting to work out how I could replicate it to a certain degree. Your solution sounds ace so will set it up.

mrengineer · 11-15-2009, 04:51 PM

Quote:

Originally Posted by sandman748

Here's how we did it in class.

Add another router named ISP (or whatever) and connect it to the router in your local network you want the traffic to pass through.

Put the passive interface command on the interface connected to the ISP router in order to suppress your routing updates.

Put a static route 0.0.0.0 0.0.0.0 to the ISP router and redistribute that route to the other routers in your LAN.

From here, all of your routers will forward the data out to the "internet." In order for that data to return you'll need to have NAT set up. If you want your local hosts to ping "websites" you can either use loopbacks on the ISP router or servers attached to it. You'll also need to set up a local DNS server to convert the url's to the ip address of the loopbacks/servers. The cool thing about using servers instead of the loopback is that you can actually go into the browser of your local hosts and browse to those websites. This comes in handy if you want to set up ACL's where you can test connectivity by pinging but still block web traffic.

This may not simulate the actual routing outside of your network but it does simulate what you need to do to get your local network communicating with the WAN. Add in your own DHCP server and you've got a fairly decent lab setup that covers most of the communicating with WAN topics.

sandman, are you talking about realtime simulation with physical equipments, or using the packet tracer emulator??

billscott92787 · 11-15-2009, 05:26 PM

Some people even set up a loopback interface on the particular "Gateway" route and then set up a static route to 0.0.0.0 0.0.0.0 ip address of next hop here.

really the WAN cloud is more of like a Frame relay. You could set it up with a router then the cloud then another Route, and set up frame relay between the two. It really depends on how you want to do it.