Automotive Ethernet in One Hour! by Colt Correa Author - Automotive Ethernet - The Definitive Guide

hi my name is Colt Correa I am the vice president and chief operating officer of intrepid control systems and also an author of the automobile net book that we published as you can see from this book it's more than 1,100 pages of automotive networking technology specific specifically focused on automotive Ethernet that it's going to be difficult to cover all of the topics in one hour but we're going to touch on the main points and we'll help you find the presentation useful intrepid control syst

ems as a company has been around for more than 25 years and during that time we have been focused on automotive Ethernet automotive networking testing technologies this goes back to the old days when we had o om specific technologies like JT 50k line van VA n and so forth and we adopted to the standardize networks specifically the dominant one today controller area network er can and our tools have supported that for a long time and of course when automotive Ethernet became a new and exciting te

chnology in the automotive industry we adopted our tools and technologies and products for that and we're excited to say that automotive Ethernet is still developing still exciting and still relatively new in the automotive world what we sell is tools around vehicle networking that includes remote wireless data logging capabilities with OTA functionality built in we sell vehicle network interfaces media converters so you can connect on controller area network flex rail in and of course automotiv

e Ethernet and we hope you'll visit our website and check out our tools and consider using them in your development process so as I mentioned controller area network is has been for the past thirty years and could arguably be called still today the dominant networking technology for the automotive industry this is developed by Bosch back in the late 80s and has been very successful and back at that that time the dominant need for vehicle networking was really sharing sensor and what we call sign

al data throughout the vehicle so that means engine speed temperatures the different types of sensors and parameters that needed to be shared among a relatively small number of controllers but in today's world we have the need for a lot more DCU's electronic control units as well as the data itself that needs to be transmitted between those ECU's has changed significantly as well so for example an autonomous driving or advanced driver assistance systems there's a need to transmit uncompressed vi

deo data or audio data for infotainment systems and this need for more bandwidth and more sophisticated communication methods has driven the need for something different than kin controller area network is limited on its method of transmission how it transmits data as well as its bandwidth and therefore it's been a long time more than 1020 years that automotive industry has needed more bandwidth so without going into the long history of Ethernet and ye thir net has been adopted for the automotiv

e industry we can see the need for things that II through net can provide so for example bandwidth if we look back at Ethernet history more than 45 years now we can see one thing that it's been able to do really well and that is a depth for more bandwidth over time so in an Ethernet in its original form was relatively slow speed by today's standards I think it was 1.6 megabits per second on bus topology and today we see many multiple gigabits supported on top of Ethernet so one thing that Ethern

et is proven is its ability to adapt to more and more bandwidth so this would be attractive for the automotive industry as well also has a long history of adapting to evolving applications and requirements so you can imagine that back in the 70s I doubt anybody imagined that we would have such full proliferation of world wide web streaming video YouTube Spotify these types of things and Ethernet has been adopted over time not only at the base bandwidth speeds with better physical layer communica

tion but also with a wide variety of communication protocols and technologies that enable Ethernet to be used in a wide variety of different ways so this makes it very attractive for the automotive industry as well so we can see that all of these technologies its ability to increase in bandwidth has been would be very beneficial for the automotive industry as well so this is some of the reasons why automotive Ethernet or Ethernet in general would be beneficial to bring into the automotive indust

ry and they're hence we have the term automotive Ethernet even when I was myself an automotive electronics engineer in the automotive industry back in the 1990's I would get sometimes ask the question why doesn't the automotive industry use Ethernet and back at that time the dominant form of Ethernet was a hundred base TX that's four wire Ethernet and that was in every laptop and every computer and the reason why at that time Ethernet was not fit for the vehicle is that for wires for example is

more expensive than the dominant to wire technology we look at most of the dominant dominant automotive networking technologies that have been used in the last 30 years it's two wires and that not only reduces costs but also weight which is very important for the automotive industry and also just as detrimental to the to Ethernet being used in the automotive world is its electromagnetic compatibility requirements so in the automotive world the MC requirements is much more stringent compared to t

he consumer electronics world and it didn't just Ethernet didn't fit additionally things like power modes so in the vehicle it's important to have it use very low power when you're not in the vehicle so for example if you go to to the airport you leave on vacation you don't want your battery debt when you return additionally networking technologies in the automotive world must be able to be woken up and be useful in active in a very short period of time the general requirement for that is haven'

t have an electronic control unit be from completely asleep to fully awake and functional in less than 100 milliseconds and standard Ethernet that we use in consumer electronics simply doesn't have the ability to start from zero to fully active in that amount of time so there's as those are some of the reasons why standard Ethernet has not been able to be used in the automotive industry but we're going to talk about automotive Ethernet and how Eterna has been adapted to take care of these shortc

omings with the standard Ethernet and that's the main difference between standard Ethernet and automotive Ethernet is taking care of these these issues so let's compare Ethernet to dominate technologies that we're familiar with in the automotive industry specifically the two big ones and flex rate controller area network first should be understood as a bus technology or multi-drop technology what does that mean that means that every node or every Cu on the network is electrically physically conn

ected to the same wires as every other node that's a bus technology it's a single twisted pair so it's two wires twisted pair which makes it lightweight and low-cost and like most networking technology is a message or packet based communication one unique thing about can't controller area network is it's non destructive arbitration method for handling message or packet collisions so with any type of networking technology there needs to be a way for multiple nodes or ECU's that want to transmit t

o have some method of avoiding collisions on the network and controller area network has what's called a non-destructive arbitration and that is handled in the arbitration section or arbitration ID of the can network so it is very elegant and how it works in that when two or more nodes want to transmit at the same time each one each message on the network or each node is allowed to only transmit unique ids and those ids essentially just a number and the lower number is a higher priority and what

happens is is that through a mechanism of the dominant recessive bits on the network that the message with the lower number will automatically go out and any message with a higher number will have to wait so the transmitting nodes of the higher number will detect on the network that it has lost arbitration and then have to hold back or not transmit further and it's non-destructive in its nature which makes it nice and that the higher priority message makes it out without any need for retransmit

whatsoever so the arbitration works in a non-destructive way that means when the nodes try to transmit multiple messages at one time the node with the lowest number highest priority message makes it out without any loss in time or any need for retransmit and that makes a controller area network very nice in some ways but it also makes it not so nice in other ways so for example the nodes that have lost arbitration that are lower priority have to wait to transmit the message at a future time and

this makes controller area network not as time critical not a not as accurate in time so when you go to transmit a message you are not guaranteed an exact time slot or rigour of when that message will go out so if you need to transmit your data in a very repetitive way and that repetition needs to be very accurate controller area network is limited in its ability to do that that's one of the main reasons why flex rate was developed so if we move on to the next technology flex rate it's very sim

ilar we can in some ways in that it has a very similar wiring it's two layers it's twisted pair just like kin and flex rate also is a bus technology every other node is connected electrically to every other node it is different than can in the way that collisions are handled in Flex rate every node on the network is aware of a time base and this time base is used to to for each know to understand and know when it's allowed to transmit so that essentially we have a cycle time and that cycle time

is divided up and there's a time slot in each for each node to be able to transmit so each node is aware of time and each node is aware of when its time slot to transmit is available and therefore collisions don't happen on the Flex rain network because it they're collisions are avoided by dividing the cycle time to each node so each notice is is aware of time and knows when it can and when it cannot transmit and by doing this flex array provides the benefit of over can in that the timing of whe

n messages can go out can be very accurately repetitive and this was developed so that flex rate can be used for safety critical applications where timing and guaranteed delivery of data is very very important now Ethernet in its modern form whether we're talking about automotive Ethernet or normal Ethernet is not a bus technology it's fundamentally different than a bus technology Ethernet in all its modern forms currently available is essentially just a point-to-point network point-to-point mea

ning that one node or one electronic unit can be connected to only one other node electronically and if you want multiple nodes more than two to communicate to each other we have to introduce what's called a switch into the equation and the switch enables multiple ECU's to communicate to each other and a switch we're going to cover in great detail in later part of this presentation so switch essentially routes traffic to different nodes within a network based on their physical address that's the

primary primary use of a switch but in the current forms of automotive Ethernet commercially available today we call them one hundred base t1 and a thousand base T one hundred base meaning hunter megabits per second thousand base meaning a thousand megabits per second or Gigabit Ethernet we're going to cover the details of this as we move through the presentation so as an overview automotive Ethernet can be thought of as a very cost-effective network if you need higher bandwidth some data more

than 10 megabit so you can see that can and even newer forms of can can FD can flexible data rate have a maximum practical throughput of around 10 megabits per second which is still not enough for things like audio video streaming we do have flex ray that goes up to 10 megabit as well and again not really adapted for some of the streaming technologies that are used in the vehicle an automotive Ethernet with its base bandwidth of 100 megabits per second at the slowest rate can support many applic

ations that these other networks cannot at a relatively effective cost and we'll see as we move through that when we say automotive Ethernet that base transmission rate let's say 100 megabits per second or or a gigabit per second does not mean that the aggregate amount of data on the network is limited to 100 Meg or a gigabit and that's another benefit of automotive Ethernet when we talk about can flex ray or any other bus technology when you're transmitting data on the bus you're consuming the

entire bandwidth of the bus it's at a hundred percent bus load in Ethernet it doesn't work that way and therefore when we say 100 megabit Ethernet and from an aggregate standpoint that we can transmit more than a hundred megabits of data on a network we're going to talk about how that works as we move through this so we talked about different networking technologies and in automotive Ethernet several different topologies are used in vehicle networking so point-to-point is one for example that is

very useful Ethernet as the base technology at the physical layer is is in its current forms only point-to-point as we see here we've talked about bust apologies with flex rating and and Kant and Ethernet in most of its forms comes in a star topology that is where you have a switch at the center of the network of a local area network and this is how we see Ethernet configured for most of the commercial space and consumer electronics space and also very dominant in the automotive world in this f

orm for example most important systems that are built off of automotive Ethernet have this type of topology and we see newer forms of topology used for Ethernet that is automotive Ethernet ring topology used for safety critical applications at the very end of this presentation will cover some of these things another fundamental feature of Ethernet when we talk about switches is that it's sort of a tree topology or star of stars meaning you can add and remove switches add and remove nodes and the

way Ethernet addressing works and because of the smart intelligent nature of switches we can do this reconfiguration with no changes to the firmware or any other changes to the network so for example if you wanted to add more nodes we could add another switch here add more nodes and the rest of the network remains unaffected or you could remove this node here and move it over here and the network would automatically recognize the address change or the change in the network and be able to commun

icate with again no changes to the firmware or the electronic so it makes it very flexible and configurable we can add and remove switches add and remove nodes and everything just automatically works and how that works will be covered shortly so as we mentioned automotive Ethernet and its modern forms or most of its modern forms I should say is a switch has a switch at its core if you have more than two nodes and the switch has high intelligence to be able to route messaging to and forth and sho

uld be understood that at a physical layer what we have here is only a point-to-point network so for example a switch if it has three ports a B and C physically a is connected only to this node the display physically port B is connected only to the amp and physically port C is only connected to the Ox display here and this has very fundamental implications of how the networks used how you use tools in the network compared to kin and flex ring one thing that we're going to see as a result of this

is that because each node is physically connected to only one other device either a switch or another node that there's no possibility for collision because the data can be transmitted at full speed in one direction and then we'll see can also be transmitted in the other direction at full speed at the same time with no collisions so often especially when we're talking about Ethernet we use the OSI model which is used in academics and in commercial space to describe different features of a netwo

rk so let's talk about specifically the physical layer and we're going to see that the physical layer is the most important thing we talked about automotive Ethernet compared to normal Ethernet one way in which Ethernet has been able to be adopted over time and increase in speed grades is the fundamental architecture in a way an Ethernet node works so what we have is essentially an ethernet phy this is the ethernet physical layer and this Ethernet physical layer can can change and adopt over tim

e then there's a mi I media independent interface there's several variants of that and then the mi is connected to to what's called an Ethernet Mac media access controller and what is important to understand is that in history this part of it the Mac does not change so that means the fundamental method of addressing on an Ethernet network the frame the frame format of the ethernet messages are all processed in the Mac and by keeping the Mac constant it enables physical layers to be swapped out a

nd essentially adapted whereby the Mac stays the same and therefore all other parts of the Ethernet stack the OSI model stay identical so this gives Ethernet the ability to adopt and change over time for example we see even currently different forms of physical layers of Ethernet and you can even think of automotive Ethernet as an adaptation or a change in only the physical layer so when we talk about automotive ethernet predominantly we're talking about a change only to the physical layer of th

e network so in automotive Ethernet compared to normal Ethernet there's really just a physical layer change and even in normal Ethernet we have different types of Ethernet for example 100 base TX that's 4 wire Ethernet we have Gigabit Ethernet that is the most dominant form of Ethernet and that's eight wires twisted pair and in the automotive world the dominant forms currently a hundred base t1 under base t1 meeting hunter megabit and t1 meaning single twisted pair so that's just 2 wires of Ethe

rnet and then we also have a thousand base T 1 which is Gigabit Ethernet that is also just 2 wires at the physical layer and we're even seeing interest now what with optical fiber Ethernet so plastic optical fiber paths and those forms are also available so this gives the the the media independent interface and the architecture of how a node works where physical layers can change meaning access controller does not change over time gives Ethernet its ability to be flexible and to be adapted so I

mentioned some forms of Ethernet already 100 base TX this is for wired Ethernet this is standard Ethernet and this was the dominant form back in the 90s we don't see this a lot in commercial space today but it is used in the automotive world when we when we talk about do IP or Diagnostics over IP this is a form of Ethernet it's based on 100 based TX that is the standard Ethernet not the new forms of Ethernet designed specifically for the automotive industry that can be put on an OB deport or Dia

gnostics port and when we talk about Diagnostics in a vehicle the requirements for that type of communication is different than in vehicle networking so when we're talking about Diagnostics that's communication that occurs with the vehicle with an external external device or computer that is only used for diagnostic purposes and not part of the normal operation of the safety critical systems of the vehicle therefore the EMC requirements waking sleeping power requirements are not the same they're

much more relaxed compared to the fundamental part of the network that you use while the vehicles riding down the road so we do see this 400 base TX 4 wired Ethernet use 4 do IP but that's not to be confused with the 2 the 2 wire form the single twisted pair and Gigabit Ethernet in its current form the dominant networking technology that's used today for consumer electronics computers and so forth there's a thousand beastie that's 8 wire Ethernet and Ethernet also at the physical layer works di

fferent than controller area network and flex ray in that controller area network flex rail in all have just the binary binary states on the physical layer so you have just two states within each time slot in Ethernet engineers devised a very nice way of provide within the same time slot to be able to provide more information more data and that is providing more logical states than just two and thousand bastey this is again the commercial ethernet there's five different states so if you looked a

t it from an oscilloscope you'd see five different states on that network thereby packing more information inside of what's called a symbol window automotive internet both 100 base t1 and thousand base t1 have pan three that means there's three different levels within one symbol window packing more information it operates at a base frequency of thirty three point three megahertz it's a maximum cable length practically speaking is 15 meters in both the thousand Basin under base 100 basically go u

p to 25 meters but then we have more stringent requirements on the connectors and cabling but most of the specifications and standards that have been developed have been developed around 15 meter maximum cable length Gigabit Ethernet for automotive purposes thousand base t1 operates 125 megahertz base clock and these two technologies are similar whereas of course the thousand base the higher speed grades have higher requirements on cabling and connectors now this slide represents something that'

s fundamentally important to understand about Ethernet in that a couple things first of all Ethernet is also inherently electrically isolated so it's it's either transformer coupled which we represent here or capacitive coupled and in both cases essentially from from a DC standpoint we have a network that's inherently electrically isolated and that's also another reason why Ethernet has become so dominant in the industry outside of automotive and now becoming dominant within automotive is becaus

e you can have very differences in ground planes across the network and Ethernet remains unaffected because its inherent electoral isolation nature second thing and equally is important is that point-to-point networks with Ethernet in all their modern forms are full duplex what that means is is that one node can communicate data in one direction at full speed and at the same time the other node can communicate in the other direction at same speed at full speed so this right here for example Hunt

er megabit base Ethernet means that if both nodes are communicating at full speed in both directions that's 200 megabits of aggregate data so if we're talking about Gigabit Ethernet that's 2 gigabits aggregate data transfer so that provides an additional benefit for Ethernet over bus topologies now as soon as I said that Ethernet in in all of their modern forms are point-to-point network I did lie a little bit to you unfortunately because there is a new Ethernet technology that's just now becomi

ng commercially available called 10 base T 1s 10 base T 1s is in a form of Ethernet that is a bus technology and the reason why this network was developed was essentially as a direct competitor in the future to controller area network now when we talk about point-to-point networks versus bus networks bus networks do have an advantage in that cabling and routing of the cables throughout the vehicle can be more cost-effective sometimes with the bus technology and that is one reason why flex rate a

nd can it's become so dominant and that's what we see it often use in the automotive industry King Ethernet in the past did not have this ability to be a bus technology in modern forms and there or was adopted for this purpose and the new standard is 10 base T 1s where 10 base means it's 10 megabit Ethernet and the T 1s means as a bus topology with with single twisted pair and the way it works on the network is not that different then then flex rate so in this case we have a transmission cycle a

cycle time and during that transmission cycle there's a beacon that goes out from a master controller and each node then will recognize it it's what beacon it's associated with and then have a ability to transmit data after it sees its beacon so essentially what's important to understand is that 10 base T 1 is somewhat similar to flex flex right in that it's a time divided type of network and that's how this network avoids collisions collision avoidance mechanism on the network whereby each nod

e understands when it is allowed to transmit and when it's not allowed to transmit and there's a unique time when each node can and cannot transmit so it'll it'll be interesting to see what happens in the future this is a brand-new technology as this presentation is being made and there's a lot of debate in in the industry whether this technology will dominate or take over can it has not yet but it has a potential for doing that and the kin community they're not sitting by and doing no developme

nts and can not the focus of this presentation but in the Kin world there's something called can excel and essentially can Excel is a direct competitor to 10 base T 1s so we'll see which one becomes dominant or some Williams use one and other OEM to use another that that remains to be seen but important to understand automotive Ethernet and its newest form is actually slower speed 10 base but it's a bus topology and that's available just beginning to be commercially available as this is written

as I'm doing this presentation so it should be understood that different physical mediums are not compatible with each other so for example if you wanted to plug in an automotive Ethernet if you wanted to plug in an ECU with Automotive Ethernet 100 base T one thing into a computer for debugging and development purposes it's not possible to do that so one thing that intrepid for lights is what's called a media converter whereby the device the media converter converts one form of Ethernet to anoth

er form so we have media converters 400 base T 1 200 base TX and 100 base TX is a standard form of Ethernet that every laptop or computer supports if the computer supports I'll give you an Ethernet it can also auto no go she ate to a slower speed about 100 base TX with with 4 wires so that's a product that we we provide we have different forms one 400 base TX one 400 base T and also thousand base T called Redmoon family okay so with those slides what I've presented so far is essentially most dif

ferences between automotive Ethernet and normal Ethernet so as I mentioned because of the way that the media access controller is separated from the physical layer everything above the physical layer starting with the data link layer and above is identical with normally through them that means everything that I'm going to talk about from now on can be used and commercial Ethernet or with automotive Ethernet so this is a Mac frame just like with Canon flex rate we have packetized data and there's

a frame in Ethernet that looks like this starts with the preamble 7 bytes of 1 0 1 0 s this allows the two thighs to synchronize each other in time so that they can receive the rest of the data there's a start of frame delimiter 8 bytes to enable the fight some time to get ready to receive data and the first information that's actually transmitted and used is the media access controller destination address and this is sometimes called the physical address of the network so every node on the net

work within a local area network has to have a unique MAC address if you don't have a unique MAC address then bad things happen so one rule is that every node on the network must have a unique MAC address and the first part of a frame is the destination where is this message going to be delivered to or whom will it be delivered to which address the source MAC address comes next who transmitted this message who is the original source of this message then we have 4 bytes of what's called a 802 dot

1q tag this is a VLAN tag we're going to talk about this in more detail it says the optional here in fact in most commercial spaces especially world-wide-web communication this tag is not used but in automotive Ethernet especially for real-time transmission and protocols that that are developed for real-time control do in fact use this tag for routing and quality of service purposes so in the automotive work sense of Ethernet this becomes very important and most of the time is not optional then

we have fundamentally new number called ether type and this is very important to understand ether type is essentially just a number that either tells the length of data coming next or more importantly the type of data that was going to come next in the payload so for example a very common ether type is hexadecimal 800 hexadecimal 800 if that's here means that what comes next is an IP frame Internet Protocol frame and so that would mean there and another header is coming next so ether types very

important to understand and we'll cover that in a little more detail in a minute then we have a CRC this CRC cyclical redundancy check enables the receiver of this frame to know that it received all of the bits prior in a correct correct way and it's another thing that it's important to understand about Ethernet is that any receiving node or receiving switch of a frame if there's any problems with the frame either CRC error or any other type of error too long or too short partial fragment of a f

rame if it receives any frame that's a problem by definition the rule is that the receiving node that is receiving a media access controller must simply just drop the message drop the message and don't tell anybody that you drop the message so it's important understand and currently at the low level there is no retransmits there is no form of error correction or even to know that an error occurred which sounds really bad and it is really bad if we didn't have another method to take care of that

and the way that we take care of that and Ethernet is with higher-level protocols and we'll touch on some of those things and later part of this presentation so by way of comparison if we want to compare let's say 100 megabit Ethernet to can for example in Hunter megabit Ethernet we can transmit about 12,000 bytes at 123 microseconds and 101 Meg can can transmit 8 bytes of data so much less than 12,000 in about I think the number is 110 microseconds for a can frame so and about the same amount o

f time that can has the ability to transmit eight bytes of data we have the ability to transmit twelve thousand by so you'll see the advantage of Automotive Ethernet in this sense okay so as I mentioned the MAC address is fundamental component of how messages are routed across the network and the MAC address consists of a six byte number the first three bytes is called an O UI number the O you and I number is assigned by I Triple E and it represents the organization that's producing the hardware

so for example Intrepid we have an O you I number big companies like Apple for example might have many o UI numbers and the second three bytes is use at the discretion of the manufacturer sometimes it's a serial number for example there are some special MAC addresses we don't have time to cover all of the details but I uncover the most important ones a special MAC address of all F's is called a broadcast address what this means is this tells any switches involved in the network in the local are

a network to broadcast this message on all ports this is a message designed to be sent from a single sender and intended to be received by all recipients of the local area network okay so as I mentioned the next thing in a Mack frame is the 8o 2.1 or otherwise known as VLAN tag and ether type so we'll cover some of the key points of that right now VLAN tag is essentially a way to virtually separate different traffic on a network and it's also used in several different types of protocols for exam

ple a VB and TSN to provide quality of service and it's used by switches to prioritize traffic for example but fundamentally a virtual LAN means that we want to separate traffic on a network virtually so that we get practically speaking the possibility of having multiple networks that are logically separated on the same physical network so in this case the example shown here is that VLAN one would be these three nodes and VLAN two could be these five nodes whereby VLAN twos data would only be se

nt and received by VLAN two tags and VLAN one data will only be sent and received by the nodes associated with VLAN one ether type comes next it's a 2-byte number and as I mentioned has some very general purpose use to separate different protocols on a network and this is fundamentally how Ethernet separates many different types of protocols so that if you're not interested in a particular protocol or particular type of data you can just ignore anything past this number and consume any data of e

ither types that you are interested in so for example as I mentioned before 800 hexadecimal is associated with ipv4 so if a node or switch is interested in processing ipv4 data it just needs to look at the ether type 800 if it's 800 it means it's ipv4 data if it's not 800 it can be ignored many different protocols within automotive Ethernet as well as normal Ethernet separate data in this way so we'll get into what a VB is in a little bit but a VB has a set of ether types associated with it ther

e are TSM protocols that have special ether types and if your organization wants its own protocol that's unique you can create your own new ether type and be assured that that ether type or that data of your new protocol is not going to conflict with existing data on the network and so again very important concept that this is how fundamentally Ethernet separates and is able to support multiple protocols simultaneously on the same network while keeping data consistent without conflicting with on

e another so for times sake we'll move on we touched on the CRC checks and now we have to get into switches Ethernet switches so Ethan ETSU itches are first they're very important parts of Ethernet networks and they're very intelligent they make decisions they make decisions predominantly on the MAC address but also on VLAN tags and they can even do so on ether types and data within the payload of a mac frame depending upon the type of switch and what type of features are needed for the network

the switch routes traffic in and out of its ports so this provides also a big benefit so as I mentioned before Ethernet is of only a point-to-point network so for example display physically is only connected to port 0 on this network speaker is physically only connected to port 1 and console port 2 and 4 3 is the DVD hug unit for example this also enables Ethernet to be have the ability to have multiple disparate streams of data within one network so for example speaker and display can talk to e

ach other both at a hundred megabits a second in each direction while at the same time the console on the head unit can talk hundred megabits in each direction to each other as well so this network represents 400 megabits of an aggregate bandwidth so you can see that by bringing in the switch and the point-to-point technology with full duplex really provides bandwidth capabilities that we don't find on bus topology type of networks Ethernet switches internally all have address tables this is how

they know what data to send to which ports out of which ports so as soon as any node transmits a message that node is required to put its source MAC address in the frame regardless of what the best the nation is and by doing so what you're doing what that node is doing is advertising to the switch of which MAC address or MAC addresses is on it particular ports and so what we have is internal to the switch is a MAC address table where a set of a single or multiple MAC addresses can be associated

with the port so if the switch sees that it needs to route a message to a specific MAC address and that Mecca dress is already in its table it knows which port it needs to send that message out on and it will not send that message out on any other port leaving the ports bandwidth available for other purposes now MAC address tables can be static or they can be dynamically learned by the switch and it's important to understand that there can be multiple MAC addresses per port as well if you have

multiple switches connected to each other different types of switches that exist there are unmanaged switch switches smart switches and managed switches unmanaged switches are the simplest kind that essentially just have a Mac Oh stable with little to no configuration smart switches generally support VLAN tagging so they support VLANs and thereby enabling different priorities priority classes or priority queues based on VLAN tags smart switches also have much more configuration and more advanced

features like people art marrying that we don't have time to cover today but we do cover in our full day's switch class matted switches are the most sophisticated type of switch they contain all the features of a smart switch but then also have additional capabilities for quality of service dynamic VLAN management ingress and egress of policing deep packet inspection meaning you can make decisions based on an IP address for example or ether type it's important for this one-hour course just to u

nderstand there's different types of switches and generally speaking in the automotive industry we find mostly smart and managed switches because again the ability to prioritize data for real-time control is often very important in the automotive world turbo control systems sells two types of switches for development purposes one is a smart switch based on it off an index PSJA one 105 chipset it's a five ports which you don't have time to go into the details per time and we sell a managed switch

this is our highest and switch a seven port managed to adjust on the marbella chipset eighteen 8q 50/50 you can buy this chip off the shelf but what interprets product provides is a rugged automotive enclosure with the power supply connectors and so forth so you can buy this off the shelf from interpret if that's the benefit to you so that's pretty much all we're going to cover at the data link later or MAC addresses or physical addresses so next we're going to cover some basics of IP addressin

g IP addresses are sometimes called logical addresses different than the physical MAC address and they work as all of Ethernet does on a layered approach so this screen shows you at the physical layer we're talking about electrons bits and bytes at layer two we're talking to predominantly about physical addresses and VLAN tags and then now what we're talking about is IP in an IP essentially what we do is that if the layer two header is ether type for ipv4 or ipv6 then we know that at layer three

starting in the payload we have an IP header an IP header contains information of whatever protocol it is the most popular to our TCP IP and UDP IP what's important to understand is once we have an IP layer three frame that's essentially encapsulated inside of a layer 2 frame and Ethernet sort of like an onion approach to networking where at each layer we peel off a layer pass it up a layer the processing happens peel it off and that continues until you actually start operating on the data that

you're interested in so we don't have time to go through all of the details of this but I'm going to skip through some some things and just talk about a few points let me go to the transport layer because I just want to touch on a couple points we have only about 10 minutes left in tcp/ip and UDP IP which is essentially all the traffic that's rotted across the internet we have a TCP or UDP header and the combination of the IP header with the UDP header or the IP header with the TCP header bring

s in two things an IP address which in ipv4 is a four byte address and in ipv6 it's a 128-bit address which is a much larger address space and the reason why we have ipv6 is that we've already run out of ipv4 addresses so when ipv4 was originally created no one had envisioned that will become so popular and have so many different addresses across the internet in the world that we run out of billions of addresses but yet we have done that and therefore ipv6 was developed and in IP world the IP ad

dress is a logical address and IP address is generally associated with a also a port so when we're using UDP or TCP IP we associate a IP address with the port an IP address associated with the port has a special term it's called a socket and when you open up a socket connection to a device on the internet there's some very specific port numbers that are used for very specific purposes so for example there's a specific port number that's used for HTTP data a different port number that's used for

FTP data and servers on the Internet use these port numbers that are pseudo standardized to do firewall policing so if you opened up a port connection and try to communicate FTP protocol to a non-standard port that's an indication to the server that you are doing bad things and it will block you from doing that typically speaking now TCP and UDP are both ways of transferring large amounts of data across the internet and streams so as we mentioned in the Datagram at the low level at the mat cutte

r you only have up to 1,500 data bytes so with dudp and TCP this enables us to combine those low-level packets of data together in a larger stream so if you wanted to send for example two gigabytes of data to a server you could do that with either TCP or UDP the difference between TCP and UDP fundamentally is that UDP is a connectionless where you connect this connectionless type of sending data where you package up the data and you send it and you have no guarantee that the receiver actually re

ceived the data in TCP we finally have our first way of knowing that the receiver actually received the data correctly as sent by the sender and TCP uses a connection a connection method to have two or more devices communicate to each other so when you want to open up a connection on TCP you have to send connection requests to the to the server and there's a three-way handshake that occurs in the connection then can be established and then when you send data the receiver will respond back that i

t in fact did sent did receive the data correctly or not and if not it will allow you to retransmit and there's a whole bunch of details with timeouts routing information and so forth that we just don't have time to cover now so the last two things we wanted to cover in the final few minutes we have is a set of protocols that are very important in the automotive industry the first set is called ABB audio/video bridging this was originally designed by professional audio companies that supply syst

ems for like stadiums and opera houses things like that so that they could transmit in real time audio and video data and have that data time align and replay in real time and this these protocols it's important to understand that they operate in parallel to everything that we've discussed so far and they're separated again by ethertype so tcp/ip and all of its protocols FTP HTTP and so forth can operate simultaneously in parallel to the ABB stack of protocols and nav B there's lots of different

protocols that are that are that work together to provide real time data transmission so one of the most fundamental is GP GP or 802 that one a s that is time synchronization that enables in that to synchronize clocks across the entire network all nodes on top across the entire network that's fundamental for replaying data everyone needs to know the common time base so in GP TP there's a grandmaster clock that sends out its clock information and all other nodes on the network must synchronize t

o that clock again we don't have time to cover the details of that some of the other fundamental components of ABB are transport layer this 1722 this tells you how to transport the audio and video data itself so within an I Triple E 1722 stream you might have mp4 data or mp3 audio data and there's different compression methods that are supported in the automotive world and autumn what's called automotive profile for these so what the automotive industry has done is is taken these avb protocols a

nd it's adopted it inside for use in prominently in infotainment systems and we see many series vehicles production vehicles supporting this now we also have stream reservation protocol this enables sender to reserve amount of data that it needs to send across a network so that your ensured equality of service and finally in addition to AV be the automotive industry predominantly has taken the ABB protocols and extended them to include things that are needed for safety critical real-time control

so for example in ABB we've had for a long time GP TP that is the ability time super kinase a network in TSN we have what's called a dell 2.1 a s rev and this is a in some ways a simplification of PTP but it also provides the ability to have multiple grandmasters so you could have multiple clocks available that in case the grand master goes away a secondary grandmaster can take over right away and this gives again redundancy so that the network can be improved for the safety critical nature of

the networks that are used for real-time control and automotive sets there's many other features frame replication and reliability this allows senders to send multiple copies of the same data so that the receiver case there's one path that goes down the receiver will still receive the data and it also enables the receiver to ensure that the data received is is correct data because it haven't have a second copy there's frame preemption frame preemption provides the ability for a switch to begin t

ransmitting if it begins if it begins transmitting a lower priority message and a higher priority frame comes in at the neck frame level you can stop transmitting that transmit the higher priority frame and then continue finishing the lower priority frame after the higher priority frame comes out there's also tying a wear shaper where you can transmit data in a way based on a time base and time windows and there's lots of details and there's lots of complicate lots of complicated interactions wi

thin these protocols as well again we're basically out of time now so we don't have time to go into all the details but one thing that I will say is these types of networks for safety critical applications we have nodes this T stands for talker or the center of the data and L stands for listener or the receiver of the data it's important that most of these networks are formed in a ring and the ring gives you the ability to have multiple paths of passive data so that in case one path is broken yo

u have a backup path to receive data on all for all nodes to be able to receive data and as I mentioned enhanced GP TP gives you the ability for multiple grandmasters and important as a summary for this is that there's two main sets of protocols used for real-time transmission of data real-time non safety critical data like audio and video data for infotainment systems is av B and extended set of protocols that's generally referred to as TSN extends ABB to include features and functions that ena

ble the network to be used for safety critical real-time applications so I was able to almost achieve our goal it is one hour in two minutes hopefully you found this presentation useful and really appreciate your time if you have any further questions or comments we welcome them we have an address here you can send it to ICS sales or ICS support and intrepid CS comm we do on-site training we do specialized training for automotive Ethernet on-site as well when when we're allowed to do that for wh

en travel restrictions are lifted and we look forward to hearing from you again we thank you for your time and hope you found this useful