Wireless Ethernet

[LeopardSkinQueen]

But it isn't practical, financially. Also, isn't part of the point of the exercise is to make it accessible to as many people as possible? Which wireless networking wouldn't do.

[hr]Slutkiss girls
Won't you promise her smack?
Is she pretty on the inside?
Is she pretty from the back?

[James Baster]

[s]Oli wrote on 17:01, 20th Sep 2002:
Errr.... It's better and easier

How? What are the advantages?

Face it, there is only one. That you don't need a cable. And seeing as the cabling is already in place in the library, why not use it?

I would actually like Wireless networking to be set up; it is the way of the future, its becoming standard, prices have come down, we should embrace it, but not if it means cutting off students with lesser means. Bring back the Corals!

[hr]
[s]One, Nothing wrong with me, Two, Nothing Wrong with me, Three, Nothing Wrong with me, Four, Nothing Wrong with me - Drowning Pool[/s]

[teamonkey]

IBM and ITS are piloting a new scheme for the library. From what I can gather, you'll be able to book out Thinkpads like short loan books. There will be a wireless LAN in the library, so you can take them somewhere and access the internet on them.

[James Baster]

Dude! I dont want this to happen! I might have to start liking ITS if it does!

[hr][s]One, Nothing wrong with me, Two, Nothing Wrong with me, Three, Nothing Wrong with me, Four, Nothing Wrong with me - Drowning Pool[/s]

[Pilmour Boy]

to be an 802.11b network, then whey aren't they going to open it up to others with their own equipment?

[Lika]

Hi,

PROBLEM SETUP:
I have an application on a 10mbps shared Ethernet. The application consists of several client systems that each monitor the state of single door. Every 500 milliseconds the state of the door is checked and a four byte message containg door ID and Door State(open or closed) is send via UDP broadcast. Two servers(a primary and a redundant) are implemented that collect the broadcast messages and display the status of the monitored doors on the screen. It has been noticed that some doors are going unmonitored for several seconds. A preliminary investigation shows that there is a very high number of collisons on the network and that some of the status messages are lost

QUESTION: What modifications to the application(software) might you suggest to solve the problem of collisions and lost messages


I cant come up with an answer...Can someone help me out please

Thanks


Velika Kabakchieva

[TheGamesMaster]

Is it just me or does this sound a like a comp sci practical/tutorial question?

[Prophet Tenebrae]

It sounds like someone wants their homework done for them.

[teamonkey]

[s]Unregisted User Lika wrote on 07:18, 7th Nov 2002:

QUESTION: What modifications to the application(software) might you suggest to solve the problem of collisions and lost messages


I cant come up with an answer...Can someone help me out please


Get the client to send a time index packet, then get the server to send that packet back when it receives it? Then if no reply is received by the client, it would resend the message.

Also if you implement some sort of error checking you only need to send packets when the state of the door changes, and you can forget about sending packets every 500ms.

That's what I would do, considering I know nothing about network programming at all.

--jaa

[Pilmour Boy]

It sounds like over kill in that all of the doors must have a very smart host, when all is needed is some cheap USB Joysticks. But I suppose that reality never was the point of CompSci tutorials was it.

[hr]There is a theory which states that if ever anyone discovers exactly what the universe is for and why it is here, it will instantly disappear and be replaced by something even more bizarrly inexplicable

[James Baster]

[s]Unregisted User Lika wrote on 07:18, 7th Nov 2002:
Hi,

PROBLEM SETUP:
.... is send via UDP broadcast ..... A preliminary investigation shows that there is a very high number of collisons on the network and that some of the status messages are lost

No, I'm not going to do you homework for you but I have another question for all comp sci here (and no its not for my homework ...)

Surely collisions on Ethernet are handled and corrected at the Link Level and since UDP is in the Transport level, there would never be such a thing as a collision of UDP Packets?

UDP Packets may be dropped by routers on the way, but never colide.

[hr]
[s]Its nice to be able to blaspheme. It takes a very special and strong-minded kind of atheist to jump up and down with their hand clasped under their other armpit and shout 'Oh, random-flucuations-in-the-space-time-continuum!' or 'Aaargh, primitive-and-out-moded-concept on a crutch!' - Terry Pratchet, Men at arms[/s]

[Nigel]

Can't you use locks? Then you know for sure that the doors are shut.

Or conversely use door wedges, ensuring the doors stay open.

[teamonkey]

[s]James Baster wrote on 00:10, 19th Nov 2002:
UDP Packets may be dropped by routers on the way, but never colide.

Yeah, I think you're right. TCP packets are guaranteed to arrive at the destination and in the right order with the packets intact. With UDP the packets are guaranteed to be intact, but not to be in order - if they arrive at all.

[James Baster]

[s]teamonkey wrote on 01:01, 20th Nov 2002:
With UDP the packets are guaranteed to be intact, but not to be in order - if they arrive at all.


Oh Yeah, thats another issue: since the udp packets dont include time stamps youve got a danger of a status packet being delayed and thus the moniter reporting what happened 10 seconds ago.

Quite frankly, I would refuse to answer that question on the grounds it stinks.


[hr]
[s]Its nice to be able to blaspheme. It takes a very special and strong-minded kind of atheist to jump up and down with their hand clasped under their other armpit and shout 'Oh, random-flucuations-in-the-space-time-continuum!' or 'Aaargh, primitive-and-out-moded-concept on a crutch!' - Terry Pratchet, Men at arms[/s]