Designing a Network with few equipments without IP address or with fixed IP addr. !!

[thatsparesh]

We have been stuck to design a very network in which we are having 2 equipments/nodes which have no IP address. If at all it is having it is unknown to us. (though they have a MAC address)

The situation is like, we wish to connect 2 computers and these 2 equipments in a single network. these 2 computers act as a redundant of each other (If 1 fails, other takes over !)

Any 1 of these computers need to communication with BOTH the equipments simultaneously (The data or file sent by the computer have to be received by both the equipments at the same time)

Now we understand that a ethernet switch learns the MAC address of the devices connected with it and sends the data or file to the respective nodes. But on the other hand a HUB broadcasts data and sends it to all its nodes. (Please correct us if we are wrong)

What kind of scenario would be preferred to make a successful communication between all these equipments.

I once again emphasis that the equipments dont have any IP addresses or they have the IP address that is not known to us.

[FeuerFrei]

What is this equipement?
Witch OS?
Can you explain this redundancy thing?
What do you mean by no IP?

Only then we will be able to help, because your post is not very clear

[TalRW]

Yes your post is very unclear. Do you want your PC's to have IP addresses?

What I kind of get is that like he might have a file server and backup server and he wants the backup server to automatically backup any files that are put on the main file server. Correct me if this is wrong. If you are using linux you might be able to use rsync I'm not sure exactly what you are trying to do though please clarify.

[TempliNocturnus]

Sounds like he wants to have two computers (perhaps domain controllers?) set up, where data sent to one is copied onto the other. If the two computers are DC's, and you're using a Windows server OS, there's settings in Active Directory that will allow you to designate a secondary DC, and every so often, it will be updated with info from the primary DC.

If it's something else, we'll most likely need to know more details about the applications being used and the type of data you want backed up on the other computer. A diagram of your network topology would also be nice too. As for you question on whether to use a switch or a hub: unless you're really poor and have a very small network, there's no reason why you should use a hub over a switch. And yes, you are correct on how switchs and hubs work. A switch creates a broadcast domain, a hub creates a collision domain. Switches do memorize MAC addresses, and are basically smart hubs.

[El<(')>Maxi]

Strange scenario you have, designing a network without knowing the addressing scheme. Yes a Hub is stupid, it does no packet inspection therefore there is no addressing control and the endpoints are responsible for collsion detection. But that does not mean that you may have redundancy, whatever is sending the data is responsible for that and addresses it accordingly regardless of the type of network its travelling.

Redundancy is usually achieved via clustering although some server apps will do this without a cluster.

[thatsparesh]

Our one of the concern was that we are not going to get the equipment signal in one of the equipment (Ethernet Bridge, Ethernet to V.35/RS422 converter). But as ultimately we will be needing output of only one bridge. Hence we will be using a switching unit that will detect the presence of data in both the bridges and gives the output of that bridge which is working fine.

Our major problem is, for this switching unit to work, the data from the PC must be given to both the Ethernet bridges at the same time (without any offset in delay). For this we were proposing a hub rather than the ethernet switch. Because as far as we understand ethernet swicth will learn the MAC address of the other devices and give the data to the specified device in the network. Due to this the data given from the PC can be destined to any one of the Ethernet Bridges, not both. While a hub will broadcast the data in the network and the data can be given to both the Ethernet Bridges. Here we are attaching the schematic of the system we require. One more thing was there that Ethernet bridge onward the flow of the data is unidirectional ie. no acknowledgement will be given from the modem. The modem will only give the clock to the Bridge.

This is what we think. But we need some confirmation that whether we can get the data on both the Ethernet Bridges simultaneously.

[ErikD]

What is the goal, to have either one of the PCs working at a time but have both up to date? So basically PC1 is primary use (but for what?) and if it fails PC2 automatically takes over? You will still need IP addressing, and using a hub makes no sense. If your goal is to have everything hit at the exact same moment on a hub you get a collision. Then it will wait a random amount of time and retransmit, so it will NEVER reach at the exact moment.

[El<(')>Maxi]

You cannot transmit anything over an ethernet network without acknowledgements using TCP/IP. Also what happens when someone begins working on PC1? If the data flow is only in one direction how will you synchronize the data between PC1 & PC2 or vice versa? What if someone is working on both of them at the same time?

Once again a hub will not create redundancy. TCP/IP has info built into the packet headers which addresses clients in a network, using a hub will not change that.

[TempliNocturnus]

Maybe use a switch and spoof one of the PC's MAC to be the same as the other?? I don't know. What applications are you guys using this for.

[thatsparesh]

What is the goal, to have either one of the PCs working at a time but have both up to date? So basically PC1 is primary use (but for what?) and if it fails PC2 automatically takes over? You will still need IP addressing, and using a hub makes no sense. If your goal is to have everything hit at the exact same moment on a hub you get a collision. Then it will wait a random amount of time and retransmit, so it will NEVER reach at the exact moment.


My ultimate requirement is to get the data from any one PC (say PC1) to the both ethernet Bridges at the same time. I dont bother about the redudancy of the PCs. My only concern is the redundacy of the two Ethernet bridges.

As far as we understand ethernet switch will not give the same data to two devices at the same time, it will only give the data to any one device at a time. But as hub broadcasts the data, Can I get the data from PC1 to the two bridges at the same time?????

[thatsparesh]

You cannot transmit anything over an ethernet network without acknowledgements using TCP/IP. Also what happens when someone begins working on PC1? If the data flow is only in one direction how will you synchronize the data between PC1 & PC2 or vice versa? What if someone is working on both of them at the same time?

Once again a hub will not create redundancy. TCP/IP has info built into the packet headers which addresses clients in a network, using a hub will not change that.


My concern is not at all for the PC1 and PC2 or TCP/IP. My only concern is get the data from any one the PCs to both the Ethernet Bridges at tha same time. That is why I was confused whether I shoud use a ethernet switch or a Hub as ethernet switch gives the data to any one device to which it destined for while hub will broadcast the data to all the devices connected to it (please correct if I m wrong) and hece I think I will be able to get the data from any one PC to the both Bridges at the sam e time.

[darthdana]

You could just use port mirroring on a switch.

[ErikD]

Port mirroring, port spanning will work for what you want. Multicasting should also work for just delivereing data to a group of addresses. Also if a multi-layer switch is an option you can go with HSRP to provide redundancy.

Your idea of getting everything to the switch at the same time is not going to work.