Legacy Network and Newer Network Integration

Why did that happen?

There are a couple of reasons that you have to consider when upgrading your network card or NIC (Network Interface Card) .

The problem lies with the newer NIC's software, in particular the "Auto negotiating" feature that sets the speed and duplex of the connection.

There is "supposed" to be backward compatibility built into the software and hardware for the 1 GBPS (Giga Bit Per Second) NIC but occasionally (more often than not) the compatibility fails.

Consider this: Having a mixed speed network will cause the network to be slow...

Why?

Because all the faster NIC's have to negotiate the speed and duplex to the slower NIC's on your network.

Fact of life in the network world: Your network will be as fast as the slowest network device.

To make your network respond the way it is intended you should (take this advice with a grain of salt) separate the older slower NIC's from the newer faster NIC's.

OR

Set all your newer NIC's (where possible) to the speed of the slowest NIC until you can upgrade all your devices to the newer 1 GBPS NIC's.

OR

You can separate the slower legacy network devices from the faster devices by using two smart switches (not a hub) one for the older legacy NIC's and one for the newer 1 GBPS NIC's.

This will allow the older legacy network to operate at optimum speed and the 1 GBPS network will also operate at the optimum speed.

1) This is the typical home network, normally the ISP (Internet Service Provider) will supply the cabling and the modem to connect to their network. Once the cable is installed and the modem is setup most computer owners only have one maybe two computers connected by cable to the modem.  In addition most also have hand held devices to connect wirelessly to the modem.

Note: Some computer owners do not have a desktop computer, disregard the desktop if you are using the modem for your wireless access

2) This is a typical business network where the company had older legacy network and decided to add a server and more computers. However the design has a very large vulnerability, can you spot it?

Even if the 1 GBPS section of the network was a Domain it is wide open to hackers, the firewall will not stop someone from getting into the server. Nor will it stop a virus from "harvesting [as the hackers call it] all the company / personal data and sending home to the originator of the virus...

This is an actual layout for a local company, I advised them to put a router between the cable / DSL modem as soon as possible, however I do not know if they actually did the work.

3) This scenario is where a computer owner has a small network and would like to add more computers, but the existing network is fairly old or a legacy network. The newer computers have 1 GBPS NIC's.

The older 100 MBPS (Mega Bit Per Second) NIC's should be separated from the 1 GBPS NIC's or the network will be slower than if the 1 GBPS NIC's were not there. One way to do this would be to set all the NIC's to 100 MBPS / Full Duplex. However you want the speed of the 1 GBPS NIC or you wouldn't have upgraded.

What you need to do is invest in two devices called "switches" (not expensive) and isolate the two different speeds, that is one switch will have only 1oo MBPS NIC's connected and the other switch will have only the 1 GBPS NIC's connected.

Then using a cable that is designed to "cross over" you would connect the two switches together. This way all the computers on the network will be able to communicate with each other.

Your last step would be to connect the 100 MBPS switch to your cable / DSL modem, then all computers will have access to the internet.

Note: The next three images do not have the wireless added, it would look like the image above.

4) The only difference between this network and the one above is that the cable / DSL modem is a 1 GBPS connect speed, therefore it would be better to connect the 100 MBPS switch to the 1 GBPS switch and then 1 GBPS switch to the cable / DSL modem.

Note: The above network designs with the legacy network will work but it will not stop a hacker nor will it stop a virus from harvesting your data and sending it to a thief.

5) This legacy network scenario has a Firewall and Proxy server between the LAN to WAN router, the reason for the server is to keep unauthorized connections to the internet (primarily viruses) and to stop a hacker from invading your network either to use the computers for other (nefarious) reasons or to steal and destroy your data. You will see three firewalls.

The Server has the Proxy service installed, part of the proxy service is also a firewall service. When you setup your server you need two network interface cards (NIC) that are dissimilar, that is that are made by two deferent companies, most desktop motherboards now come with two to five NIC's embedded, normally these NIC's will be chip sets from different manufactures, most will  also have a wireless NIC.

You would use one NIC for the LAN (your network) connection and the other for the WAN (the router between your Server and the cable / DSL modem. You would also enable the firewall (if it is configurable) and turn on the "Block WAN requests".

For the cable / DSL modem you would do the same, turn on the firewall and the block WAN requests.

This gives you three layers of protection from hackers / viruses inbound from the internet.

Note: This does not mean you can skip the AV (Anti Virus) software on your computers because people download programs and some newer programs download updates automatically, you still need the AV protection!

Last word:  All 100/1000 MBPS cable / DSL modems are full duplex, if you are having connection problems set your computer NIC's to 100 or 1000 / Full for the connect speed and duplex from Auto negotiate.