Token Ring, the Betamax of Networking

if you're born within the last 20 years you can be easily forgiven for thinking that the only kind of wide connectivity the computer industry used is ethernet or ethernet if you like as it's become dominant basically everywhere local network usually from that long-range stuff that would have been the one technology yeah we now use e for that available in speeds from 10 megabit to 100 gigabits a second but not that many years ago ethernet's Ascension was not guaranteed in fact another technology appeared ready to work around many of the shortcomings of ethernet and maybe even take over the market I mean it didn't but that technology is called token ring but before we get into the history of token ring and the wise and where Force we're gonna have a quick word from our sponsor who helped make these videos possible yes PCV way fine purveyor of pcbs they are still other stuff like 3D printing CNC Machining and make injection molds as well now back to the history of token rank in order for us to understand what was so great about token ring we have to understand the shortcomings of the things token ring was intended to replace ethernet and in fact a bunch of other competing Network Technologies were all based around the concept known as carrier sense multiple access with Collision detection which is quite a mouthful now an older networks based around this technology there's what's known as a shared bus or shared medium between the machines as in the case of ethernet this was typically one thin piece of coax that went from one machine to the next to the next to the next Little T pieces allowing each individual workstation to join on this essentially means that all the machines are transmitting onto the same wire and they're all listening to the same wire so in a typical scenario one machine would transmit onto the wire all the other machines would receive those transmissions and they checked to see if it had the right address for that workstation the MAC address if it did then it would take that packet and it would pass it up to the machine that the card was plugged into nice and simple right although some of you have probably spotted the really obvious floor in this situation which is what happens when two machines transmit at once and if two machines do manage to do that well what you end up on the cable is one intelligible gibberish so this is a situation we need to try and avoid and this is where the first part of that carrier sends multiple access thing comes in yes this is the center part of it so all the time every single network card on the network is listening to see if there's any incoming packets traveling along the network and if it wants to transmit it waits a moment when there's no incoming package this is the sandspit if the network is clear it can then transmit absolutely Flawless scheme right nothing could go wrong I think my tone probably gives away that that's not entirely true that's where the next part of the giant phrase carries into multiple axis with Collision detection comes in yes this is the with Collision detection part two machines transmit at once we call that a collision so hence the phrase Collision detection she's normally needs a center when that happens now you're moving in but how can this happen you've just told me it waits until the network is clear before it sends well this is the small floor a network consists of multiple nodes and a few of those nodes all want to transmit at the same time well they're all listening to the same network and the second not a packet on it yep they all try and transmit at the same time so we need to detect when that's happened now doing that's actually pretty easy whilst the network car is transmitting it's also still listening to the network and if the bits it's transmitting happen to match the bits that it reads from the network then you know you're the only one transmitting if what you get back is different from what you're transmitting well then you know another Network station is trying to transmit at the same time and you've got a collision and you've just successfully detected it now you know there's been a collision you have to decide what you're going to do with it and this is the approach that ethernet adopted in the event of a collision all the machines that we're trying to intermitt back off for an arbitrary period of time a small period of time but a small random one once that period of time has expired the network card again listens to see if the network is clear and if so transmits the idea of this approach being that one workstation will have the shortest timeout and therefore go first stopping the others from then transmitting with this approach eventually every single node on the network gets the transfer its packets the key problem with this is the phrase eventually the problem with eventually is eventually could be a small eternity as far as the network card is concerned as on a busy network with lots and lots of nodes well there are a lot a lot of collisions which means you can be waiting a very long time to get a packet in or out let me give you a practical example of that when I was at University our department had a number of PCS that were remote boot machines you had a little boot disk for them to essentially contained a copy of Das a packet driver and a TCP implementation and an NFS client and your machine will boot up load dose and NFS mounts and remote storage from one of the sun machines if you're just in the lab by yourself once the discs are booted that process could maybe take 30 40 seconds to get to the point where you had a command prompt you'd start doing stuff in a lab session however when there were 30 or 40 of us all trying to boot the machines at the same time well things were very very different it could often take you nearly 20 minutes to get to the point where you were logged in storage is man and you can start typing commands and that's because the whole network essentially generated into mostly collisions very little useful data moved and the Collision count went through the roof now I have glossed over a few of the details of this little problem I mean we've not really talked about things like the channel capture effect and I did miss out little implementation details like the jam signal and preamples as those things aren't really necessary for understanding the core of the problem that token ring was trying to solve yes which that means it's now time to talk about token ring token ring was the land technology created by IBM and was standardized as IEEE 802.5 now token ring avoids the whole Collision problem completely there is no such thing as a collision in a token ring Network and there's a reason for that and it's also where the token part of token ring comes from the system operates much like the Conch from Lord of the Flies see this channel is surprisingly literate sometimes in that if you don't hold the token you can't transmit and the token is passed from node to node around a ring see the other part of the name if you don't have anything to transmit when you get the token then you simply pass it on to the next station if you have something to transmit you hold a token transmit your packets then release the token in this system there is also a maximum token holding time which you know can only hold a token for so long so it doesn't get stuck with one station and it do all the transmitting basically every node gets their fair share now this system of using a token has some great advantages firstly no collisions this meets all the networks bandwidth gets used for something useful we don't have large amounts of times where no one can transmit and nothing useful is happening on the network our next major advantage is the predictability of this network as well if you add more node to the network you can work out how much bandwidths in the worst case those nodes are going to get take the total bandwidth divided by the total number of nodes there you go that's the worst case that each node sees in Ethernet that's not true because most of the bandwidth may end up getting lost on collisions and also that bandwidth is in no way evenly distributed amongst the nodes on the network and that's at this point you may be wondering to yourself so why didn't token ring becomes a dominant land technology it's clearly got a lot of advantages over the likes of ethernet well as I alluded to in the title comparing this thing to beat Max better doesn't always win sometimes technically better still loses and in token Ring's case yeah it didn't win did it the problem for token ring is there's quite a lot of complexity in token ring first of all you have this whole token passing system that adds them out to complexity but also there are a lot of weird Corner cases that bump up the expense and complexity of token ring as well for example you have to deal with what happens if someone turns off the machine that's currently got the token yeah and the way I described how token ring works I didn't mention what we do with that at all you could just assume from my description that the network would just break at that point which obviously is not something they could allow to happen no there is in fact a whole election system to work out which station effectively acts as the token monitor the token Monitor and if it doesn't see the token appear after a certain amount of time generates a new token put that one onto the network and of course you have to do what happened to the Token monitor disappears well you keep having elections until eventually you have a winner all that complexity based around elections and monitoring the token yeah that all adds expense there's a lot more complexity in a token ring network card than there isn't an Ethernet one and as we all know complexity equals expense token ring again was also more expensive just the whole ring nature of things you can just plug a token ring card into a network it didn't just go on a BNC connector like you did in early for now just plug in a quick RJ45 now in token ring at the center of the network is a semi-intelligent box that when you plug your card into it using its drop cable it negotiates joining the ring this range of every token ring Network there's an expensive looking box in the middle admittedly ethernet became more like this as time went on as we moved to First multi-port repeaters and then multi-port Bridges and then eventually switches with an expensive box in the middle of the network but the card still remained very cheap in 1985 IBM launches token ring into the marketplace a channel bandwidth of a whole four megabits a second yes this does negate some of the advantages of token Ring versus Stephen eckers even it's got a 10 megabit bandwidth and even if it's using it very inefficiently and colliding a lot 10 still quite a lot bigger than four but it is still very predictable compared to ethernet when you increase more nodes in the network and with big corporations that sort of thing's quite popular having a predictable Network kind of equates to having a reliable Network in some ways particularly you don't want to get Engineers involved on a regular basis which is kind of what large corporations want they don't mind if the unit cost is a little bit higher as long as the maintenance costs are lower also IBM at this point are huge there are plenty of corporations that are just pure IBM shops they buy all their PCS from IBM their printers from IBM their mainframes from IBM their terminals from IPM everything from IBM so when IBM turns up with a lan technology saying look see you can use this to link your PCS together and also look we've got stuff for our mainframes even a 3270 terminal with the token ring interface on it yeah that's that's going to do pretty well also at this point Lan technology is fairly new there's not an awful lot of land deployments in the world in fact in the UK the biggest technology deployed for land networking is acorns echinap to link BBC micros together at schools yeah unless you watch one of my other videos you didn't see that one coming did you so initially token ring is doing all right it's something in sufficient quantities I mean economic probably still selling more but neither of them is exactly a runaway success now of course IBM and not the only vendor of token ring cards in the world in fact quite a few of the blenders for a relatively short period of time or start making token ring cards but of all the other vendors one particular one Mage networks becomes the big second source of token ring kit and towards the end of the life of token rink it's just IBM and Mage making stuff the 1980s Marches On competition starts together a little bit more heated ethernet continues its drop in price the cars are starting to get cheaper particularly with stuff like the ne2000 from the valve and then the gazillion clones of the ne2000 that appear afterwards the price point of an Ethernet card is starting to drop also the usage of Lan technology is starting to grow again the likes of netware really helps push this forward to give you file and Print Service so you get small smes starting to develop the use of land technology rather than the companies that had mainframes are looking to network a few PCS together this means that the number of ethernet installations are really starting to outnumber the token ring ones so in order to address one of the perceived disadvantages of token ring in speed we get a new speed of token ring we get a 16 megabit token rink in 1989. it's this period after the introduction of 16 megabits the token ring has its most successful values it's during this period that token ring carves itself out a nice little niche for itself it becomes the high-end networking technology of choice for land deployments and it's this Niche that IBM and made seem to feel quite happy with you can charge a relative premium for your network cards and kit and for a number of network attached peripherals that also have token ring interfaces IBM also brings out a bridge box that allows you to connect token ring networks with cheaper ethernet networks now this brings me on to a point that I've previously not mentioned the compatibility of frames between ethernet and token ring at layer 1 electrically these two networking standards are in no way compatible with each other even slightly but the frame you send across the network that source Mac destination Mac what kind of data type it is Packet yeah that is actually compatible between the two in fact it's compatible between all the 802 whatever standards so hence you can pass the frame from ethernet to Wireless's 802.11 the layer 1 format completely different the layer 2 format the same so this meant you could happily interchange packets between a token ring Network and an Ethernet Network assuming you had the right box with a token ring interface in it and an Ethernet interface in it in fact in the very early days of Wireless you did also get Wi-Fi boxes that happen to have a token ring interface as well they weren't very common and they were very expensive it's from this period that all my token ring equipment essentially comes from from my Mage network cards be them either PCI or eisa yeah that's the most type we don't see very often all the portable ones that you'd have for laptops like this pcmca one or if you're feeling really unlucky the parallel version here yes laptops back then tended not to come with their own network interface either be it token ring or E for that and I've got it all connected up to this freecom ring Hub here yes this may look like an ethernet switch but it's not it's a token ring now in fact I've even got this machine here connected up with a token ring in the face and here we go a vulnerable Cisco router yes I'm gonna have a bit of Ip connectivity to the Token ring Network oh look I can ping the router yes it's not actually plugged up to the Internet because that would have been a little bit more complicated than besides pinging one thing on the internet and pinging something on the local network yeah they kind of look very similar don't they yeah I'm running a version of the next from 2013 and a machine from 2006. yeah I did use this laptop for quite a while did have a more period appropriate IBM laptop I could have used but can I find the power adapter for it no no not anywhere oh laptop yeah I can find that it's worth noting this particular token ring card yeah still actually supported another Linux kernel to this day but at the time this driver's CD that you can cut back to yeah that had driver's sort of windows Windows 2000 so on and so forth and of course the network client also during this peak period for token rig cable standards are evolving somewhat now initially IBM starts with this kind of connect FF token ring yeah it's a bit of a monstrosity isn't it it's not not the most attractive connector you've ever seen or or the most compact but this is what IBM go for on these sort of connect to the cow at the center of each token ring or indeed the wall socket in terms of the end that goes into the computer well they go with a DB9 of all things yes the thing that looks a little bit like a joystick or a Serial pop that was the initial connector that you would use of course things change and everything starts moving to RJ45 and CAT5 sockets and this has been driven by the exact same thing that was driving ethernet the same way in that lots of buildings in the US already had this kind of cabling installed for office telephone networks so as they'd already flood cable the building once computers start expanding outside a couple of departments into everywhere in the office well there's a need to want to use the pre-installed cabling so this is one of the these cases of co-evolution where two different Technologies evolve in a similar Direction because they both have the same needs and wants so token Rings little niche being the high performance predictable Network that lasts for a while until we get to 1995 and things start to change a little bit that's why in the world of ethernet things have just continued to get cheaper and cheaper there is something a big leap in its technical capabilities this is when the hundred Meg standard for ethernet first appears now even if you do still have the Collision problem 100 megabits of Channel bandwidth is a heck of a lot more than 16. so let's say you lose 20 of it to collisions you've still got a lot more megabits a second than the 16. this really sort of Damages the sheen on token ring if you like it's not quite seen in the same way anymore it looks like even it's starting to get a leg up on it now of course those involved in producing token Marine cards they don't take this line down they do eventually produce 100 megabit token ring standard in 1998. a full three years after 100 megabit ethernet is introduced and thrust not a heck of a lot of 100 megabit token ring cards are actually produced I've got one here they're not really common it must be said most people should have stayed at 16 and then moved on to ethernet afterwards rather than going up to 100 megabit token rank and another bit of bad timing for token rink 1998 was also the same year that gigabit Ethernet came out so why token Rings just getting its 100 Meg ethernet managed to go 10 times faster now given that token Ring's leash in the market is the high performance high price Dependable Network having ethernet which was seen once as the cheaper option and it still is cheaper go faster than Hugo it is not great and this is the point that really marks the Steep decline of token ring usage although you will still see it in use in some sites lots of large corporations still have it in their warehouses and stuff like that where they have a bunch of IBM kitten still have token ring there still getting on and doing its thing the equipment is just too expensive to be worth replacing really now I know some of you are particularly clued up in the world of token ring but I was thinking wait a minute wasn't there a gig of it standard for token ring and there was in 2001 they released a gigabit standard and then promptly no one built a single piece of equipment that implemented it yeah I'm largely by 2001 very much everyone knew that the game was up for token ring as well even they're kind of taken over everything and also ethernet had solved the one big problem the token ring was also there to solve collisions yeah it's time to talk about the final nail in the coffin of token ring the ethernet switch now as I mentioned earlier cabling solutions for both token ring and ethernet have been changing the idea of a star topology essentially a couple of boxes in the central room somewhere for every other device would individually connect to fire okay well back out to that workstation and in order for ethernet to achieve this to have been a whole new connection standard known as 10 base t 10 for 10 megabit ethernet and then tving the connector type at the end so this is the RJ45 connector you're all very familiar with no doubt and at the center of this network today we're going to need a new glass of device for ethernet to link this all together and this is known as the multi-port repeater or Hub that's very simple commonly refer to it as and this is where you connect each individual ethernet connection and everything linked together on the Hub would be allowed to speak to each other and you could plug one Hub into another Hub and therefore linking even more devices now at this point the whole business said it's a multi-port repeater which is effectively a very dumb analog device there is a small amplifier in there that essentially just amplifies the signal because there's a longer amount of cable involved here and a little bit of noise filtering circuitry just to take any line noise off or reduce it a bit these devices are completely done there is nothing clever or digital going on in these things at all so with these devices you still have all the same Collision problems she did before so we've managed to change essentially the wiring standard free from there but we haven't really improved it but we do now have the idea that there is a core box at the center and this is where things start to change with the Advent of these Central boxes you've now got a point where you can put some more sophistication into ethernet where you couldn't really before when it was just a thin wire now we had gone this way a little bit with the introduction of something known as an Ethernet Bridge early on in the life of ethernet which is essentially a box that had two ethernet ports on it both in coax and essentially this box was an intelligent box it had two ethernet interfaces and would help hold in memory a list of what Mac addresses were on one port and which Mac addresses were on the other Port if it saw a message on one interface that was your Mac address on the other interface face well it read that into memory store it in memory and then we'll transmit that back out the other ethernet interface essentially acting as a bridge between two separate ethernet networks it wouldn't repeat broadcast packets this was a good way of getting around the cable level limits Reef net and still allowing stations to talk to one another it also meant that you could reduce the number of nodes on each Network as well and get the number of collisions down if not eliminate them now in 1993 a company called kalpana came up with a really good idea which used to take this bridge idea and make a multi-port bridge but also add the idea of cut through forwarding to create the world's first ethernet switch one of the disadvantages of bridge is the latency because you have to read the whole packet into RAM and then write the whole packet back out again what cut through forwarding meant that they could do is they could start reading the packet in and when they detected the MAC address they could start writing it out of the writing to face straight away I'm assuming that it was free to transmit this hugely reduced the latency involved now these initial switches were really expensive and didn't at that point in time have a massive impact on the market because very few institutions could afford them and essentially they'd use them to join together a number of existing ethernet networks to make it a bit more efficient when things really kicked up again is when the 100 Meg standard was introduced this is where the switch became an essential part of your network rather than an optional extras it were because the switch essentially having a separate ethernet Network per Port it meant that you could connect one's running on the 10 Meg standard to one running on 100 Meg standard as you could have a number of ports running 10 Meg ethernet and a number of ports running 100 Meg ethernet and they could communicate with each other across the switch because now essentially you don't have one ethernet Network what you have is one ethernet Network per port on the switch and each one can be of an entirely different standard and the switches were sufficiently sophisticated that say if ports one and two took to their full data rate to each other well ports three and four could talk to each other at their full rep data rate too and as each Network basically consists of a node and the switch well there's not much chance of a collision is that and also with 100 made they introduce what's known as full duplex where a port could transmit at full speed and also receive at full speed and that reduces the chance of a collision down even further so essentially the switch is eliminated collisions this means that the final advantage of token ring the lack of collisions basically evaporated so this is why the switch is basically the final nail in the coffin of token ring it's taken away its one final Advantage it lost its advantage over speed and now it lost its advantage over the predictability in the lack of collisions now it's not like token ring vendors don't try and fight back at this point likes of Mage for example soon produces a token ring switch which is basically the same idea as the ethernet switch we've each bought being one token Rings Network the problem is with token ring adapters being so complicated it never really fall in price so it's just a very expensive way of doing more or less the same thing that ethernet does at this point yeah even its great advantage of the cheap network adapter really starts to cut in at this point as well because of its lower implementation cost it starts to appear in machines and that was an optional extra card that you fit but right there on the motherboard same with laptops which up until this point yatter the pcmcia adapter to to do either token ring or ethernet depending on which one you wanted now with everyone seeming to think that the network standards what is over and ethernet has won but she's just start coming bundled with ethernet adapters just built right on in there which really makes life difficult for token ring because you got to persuade someone to buy an additional network card and unless your company already has a big token ring infrastructure that you want to join why would you do that if you made it all the way to this point in the video I'd like to say thank you very much for watching I do apologize for my ever so slightly strained voice but it's still recovering a little bit from the event at Cambridge I went to it the weekend um if you want to see what that event is like uh Kim justice has done a really nice video about it I will link that in the comment section below if you enjoyed this video why not inform YouTube that you did by clicking that little Thumbs Up Button they included to indicate that such a thing has occurred and if you're feeling in a kindly mood why not share this video 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Channel: RetroBytes

Views: 175,217

Keywords: token ring, IBM, Ethernet, 80s LAN, Local Area Network, 90s LAN, Tokenring, Token Ring, TokenRIng, Madge networks, MAU

Id: IjLctlmZSp4

Length: 25min 17sec (1517 seconds)

Published: Sun Dec 11 2022