A token ring is a type of local area network (LAN) where computers take turns sending data. A small control message called a token travels around the network, and only the computer holding the token can transmit. IBM introduced Token Ring in 1984, and the IEEE 802.5 standard describes how it works.
Before Ethernet took over, many companies used Token Ring to connect computers, printers, and servers. It gave every device an orderly turn to use the network. Today it is mostly a legacy technology, but it is still a great way to learn how networks share a cable.
What Is a Token Ring Network?
A token ring network is a LAN in which connected devices take turns sending data. The method it uses is called token passing. A free token moves from one device to the next, and a device must have the token before it can send anything.
IBM built Token Ring to link business computers, servers, and printers inside an office or building. The IEEE later standardized it as 802.5, which covers the access method and the physical layer. The main goal was simple: give many devices a fair, organized way to share one network.
Think of it like a talking stick in a meeting. Only the person holding the stick can speak, and then the stick moves on to the next person. Token Ring works the same way, with data instead of words.
What Does Token Ring Mean?
The name has two parts. The token is a small control frame that gives a device permission to send data. The ring is the path the token and data frames follow from one device to the next.
Each device on the network is called a station. A station can be a computer, a server, or any other compatible device. Stations pass the token along until one of them needs it.
Is Token Ring a Topology or a Protocol?
Token Ring is a LAN technology with its own access method. A ring topology is only a way of arranging devices. The two ideas are related, but they are not the same thing.
Token Ring uses a logical ring, which means the data moves from station to station in a fixed order. The cables, however, do not have to form a circle. Most IBM networks wired every station to a central box, which you will see below.
Which OSI Layers Does Token Ring Use?
Token Ring works at the first two layers of the OSI model. The physical layer (Layer 1) covers the cables and the signals. The data link layer (Layer 2) covers frames, station addresses, and the rules for when a device may send.
The media access control (MAC) part of Layer 2 is the key piece. It decides who gets to transmit and when. The IEEE 802.5 standard defines both of these layers for Token Ring.
How Does a Token Ring Network Work?
A token ring network works by passing a token from station to station. A station that captures the token can send one or more frames, up to its allowed token-holding time. It then releases the token so another station can transmit. To see it clearly, picture four computers named A, B, C, and D.
Step 1: A Free Token Circulates
When the network is idle, a free token travels around the ring. Each station gets the token, checks whether it has data to send, and passes it on if it does not. The token is only three bytes long, so it is a control frame and not a carrier of user data.
Step 2: A Computer Captures the Token
Say Computer A wants to send a file to Computer C. It waits until the free token arrives. Then it captures the token, which gives it permission to transmit. No other station can send while A holds the token.
Step 3: The Sender Transmits a Data Frame
Computer A builds a data frame. The frame holds the source address, the destination address, the frame type, the data itself, and a check value that helps catch errors. A then sends the frame onto the ring.
Step 4: The Destination Copies the Data
The frame passes through Computer B first. B sees that the frame is not addressed to it, so it simply forwards the frame. When the frame reaches Computer C, the address matches. C copies the data and marks the frame to show that it recognized the address and copied the frame. Then C sends the frame on.
Step 5: The Frame Returns to the Sender
The frame keeps moving until it gets back to Computer A. A takes the frame off the ring and reads the status bits to see whether C received it. Then A releases a new free token. Now Computer D, or any other station, can take a turn.
What Happens If No One Has Data to Send?
The free token just keeps circulating. Each station sees it, has nothing to send, and passes it along. The token moves around the ring until a station needs it.
What Is Early Token Release?
In the normal process, a station waits for its frame to come back before it releases a new token. Some Token Ring networks support early token release instead. Here, the sender releases a new token right after it finishes sending the frame. This lets the ring carry more traffic, especially on larger rings.
What Is Token Ring Topology?
Token Ring uses a logical ring, but it usually does not look like a ring on the floor. Many people assume the computers are wired in a circle. In most IBM networks, they were not.
Logical Ring Topology
In a logical ring, every station has a set place in the order. The token and the frames move from one station to the next in that order. Each station repeats and forwards frames around the ring, and the destination copies frames addressed to it.
Physical Star Topology
In a typical IBM setup, each computer connects to a central device called a multistation access unit (MAU). The cable from a computer to the MAU is called a lobe cable. Inside the MAU, the connections are linked so that the signal travels through each station in turn. You can also join several MAUs together to add more stations.
Why Use Both a Ring and a Star?
The ring controls how data moves. The star makes the network easier to build and fix. If a computer is turned off or unplugged, the MAU can skip over it so the rest of the ring keeps working. As a result, the network looks like a star on a floor plan but behaves like a ring.
What Are the Main Components of a Token Ring Network?
A token ring network is built from a few basic parts. The table below shows what each one does.
| Component | What it does |
|---|---|
| Token | Gives a station permission to transmit |
| Network station | Sends, receives, and forwards frames |
| MAU (or MSAU) | Connects stations and keeps the ring linked |
| Network interface card (NIC) | Connects a computer to the network |
| Data frame | Carries the actual information |
| Active monitor | Keeps the ring running smoothly |
| Cables | Link stations to the MAU and MAUs to each other |
What Is a Token Ring MAU?
A multistation access unit (MAU) is the central connection box in a typical IBM Token Ring network. Some vendors call it an MSAU. Each station plugs into it with a lobe cable, and MAUs connect to one another with patch cables.
Most MAUs have bypass relays. If a station goes offline, the relay lets the signal skip that port and the ring stays closed. This is one reason star wiring was easier to manage than a true physical ring.
What Is an Active Monitor?
The active monitor is one station that takes on extra duties for the whole ring. The network picks it automatically, and any station can fill the role. If the active monitor fails, another station takes over.
The active monitor helps with timing and watches for problems. It can notice when a frame keeps circling the ring and remove it. It can also help the ring recover if the token gets lost.
What Is a Token Ring Frame Format?
Token Ring uses two kinds of frames. A token is a short control frame. A data frame carries real information. They are not the same thing.
The Three-Byte Token
A token has three fields, and each one is one byte.
| Field | Size | Purpose |
|---|---|---|
| Start Delimiter (SD) | 1 byte | Marks the start of the token |
| Access Control (AC) | 1 byte | Holds priority and token information |
| End Delimiter (ED) | 1 byte | Marks the end of the token |
The Data Frame
A data frame has more fields because it must carry information from one station to another. The size changes depending on how much data it holds.
| Field | Purpose |
|---|---|
| Start Delimiter (SD) | Marks the start of the frame |
| Access Control (AC) | Holds priority and reservation information |
| Frame Control (FC) | Shows the type of frame |
| Destination Address (DA) | Identifies the receiving station |
| Source Address (SA) | Identifies the sending station |
| Routing Information (RI/RIF) | Provides route details when source routing is used; optional |
| Data | Carries the information being sent |
| Frame Check Sequence (FCS) | Helps detect errors |
| End Delimiter (ED) | Marks the end of the frame |
| Frame Status (FS) | Shows whether the frame was recognized and copied |
What Are the A and C Bits?
The frame status field has two indicators that tell the sender what happened. The A bit means the address was recognized. The C bit means the destination copied the frame. Both indicators are repeated in the field, which adds a little protection against errors.
How Does the Priority System Work?
The access control field has priority bits and reservation bits. A station can capture a token if its data priority is equal to or higher than the token’s priority. Stations with higher-priority data can reserve a higher priority for the next token, allowing that traffic to get access sooner.
What Are the Key Features of Token Ring?
Token Ring is built around controlled access. A station must have a free token to send, and the token moves in a set order. Priority levels let some traffic go first. The active monitor and the MAU help the network spot and handle certain problems.
These features made it a good fit for offices that wanted steady, orderly network use. The sections below look at where that design helped and where it fell short.
What Are the Advantages of Token Ring?
Token Ring had real strengths, especially when compared with older shared Ethernet.
No Collisions on the Shared Ring
Only one station sends at a time, so stations do not collide on the ring. This avoids the collisions common on older shared Ethernet. It does not mean the network can never be slow or fail. Congestion and hardware faults can still happen.
Predictable Access
Every station gets a turn as the token goes around. This makes waiting times easier to estimate than on a network where all devices compete. The actual delay still depends on the ring speed, the number of stations, and how long each station holds the token.
Fair Access
Because the token moves from station to station, no single computer can block everyone else for long. Each station gets its chance to send.
Priority Support
The priority and reservation fields let urgent traffic move ahead of less urgent traffic. This was useful on busy business networks.
Built-In Fault Handling
The active monitor and MAU bypass relays help the ring handle some problems. They improve reliability, but they cannot stop every failure.
What Are the Disadvantages of Token Ring?
Token Ring also had drawbacks, and many of them grew more serious as Ethernet improved.
Higher Cost
Token Ring needed its own adapters and MAUs. This equipment often cost more than comparable Ethernet gear.
Lower Common Speeds
Most networks ran at 4 or 16 Mbps. That was fine in the 1980s, but it became a limit once faster Ethernet arrived.
Token Overhead
A station has to wait for the token before it can send. Managing the token adds extra work that switched Ethernet does not need.
Harder Troubleshooting
A problem with a token, a cable, a MAU, or a station setting can affect the whole ring. Finding the cause often meant checking several parts of the network.
Hard-to-Find Hardware
Token Ring gear is now mostly old equipment. Adapters, MAUs, and spare parts can be difficult to find.
Fewer Upgrade Paths
Ethernet grew into a huge family of faster products from many vendors. Token Ring never matched that range of choices.
Token Ring vs Ethernet: What’s the Difference?
Token Ring and Ethernet are both LAN technologies, but they manage network access in different ways. Token Ring uses a token. Early Ethernet let devices share a cable and handle collisions. Modern Ethernet uses switches.
The fairest comparison looks at three things: Token Ring, old shared Ethernet, and today’s switched Ethernet.
| Feature | Token Ring | Ethernet |
|---|---|---|
| Standard | IEEE 802.5 | IEEE 802.3 |
| Access method | Token passing | Older shared Ethernet used CSMA/CD; modern Ethernet uses switches |
| Logical layout | Ring | Usually a switched star |
| Physical layout | Often star-wired through a MAU | Usually star-wired through a switch |
| Common speeds | 4 and 16 Mbps | 10 Mbps and much higher |
| Collisions | Avoided on a shared ring by the token | Possible on old shared Ethernet; not an issue on full-duplex switched links |
| Key equipment | MAUs and Token Ring adapters | Switches and Ethernet adapters |
| Use today | Mostly legacy | Used almost everywhere |
How Does Token Passing Differ From CSMA/CD?
In Token Ring, a station waits for a free token before it sends. In older shared Ethernet, a station listened to the cable first, and then sent if the line was quiet. This method is called Carrier Sense Multiple Access with Collision Detection (CSMA/CD).
If two Ethernet stations sent at the same moment, their signals collided. Both stations stopped, waited a random time, and tried again. Modern switched Ethernet avoids this problem because each device gets its own link, and full-duplex links can send and receive at the same time.
Which Technology Is Faster?
Most Token Ring networks ran at 4 or 16 Mbps. Ethernet moved from 10 Mbps to 100 Mbps, 1 Gbps, 10 Gbps, and beyond. Token Ring did get faster versions later, but they were rare.
Why Did Ethernet Replace Token Ring?
Ethernet won for practical reasons. It reached higher speeds sooner, and many vendors made Ethernet equipment, which pushed prices down. Switches also made networks easier to build and expand. Over time, Ethernet became the safe and affordable choice for most organizations.
Is Token Ring Better Than Ethernet?
Not today. On a shared network, Token Ring’s orderly access was a real advantage. But modern switched Ethernet is faster, cheaper, and more flexible. For nearly every current network, Ethernet is the better pick.
How Fast Was Token Ring?
Most Token Ring networks ran at 4 Mbps or 16 Mbps. Later IEEE standards added faster versions.
| Version | Speed |
|---|---|
| Original | 4 Mbps |
| Faster version | 16 Mbps |
| Dedicated Token Ring | 100 Mbps |
| Gigabit Dedicated Token Ring | 1,000 Mbps |
Dedicated Token Ring (DTR) supported point-to-point links at 100 Mbps and, later, 1,000 Mbps. In full-duplex switched operation, the normal token-passing process was suspended. These speeds were specialized DTR implementations, not typical shared Token Ring networks.
Is Token Ring Still Used Today?
Token Ring is mostly obsolete. Almost all businesses and homes use Ethernet instead. You may still find Token Ring in some old systems, in museum-style collections, and in networking classes.
Why Did Token Ring Become Obsolete?
Ethernet became faster and cheaper, and switches made it simple to set up. Organizations could upgrade without buying special Token Ring hardware. As more people chose Ethernet, fewer companies built Token Ring products. The IEEE has also withdrawn its older 802.5 standards.
Is Token Ring Still Worth Learning?
Yes, especially for students. It shows how devices share a medium, how MAC rules control sending, and how a logical layout can differ from the physical one. It also makes the move to modern Ethernet easier to understand.
Token Ring vs Other Token-Based Technologies
Token Ring is related to other token-passing technologies, but they are different systems.
Token Ring vs Token Bus
Token Ring is defined by IEEE 802.5. Token Bus is defined by IEEE 802.4. Both pass a token. Token Bus runs on a bus cable but passes the token in a logical ring order.
Token Ring vs FDDI
Fiber Distributed Data Interface (FDDI) also uses token passing. It was built for fiber-optic cable and ran at 100 Mbps. It used two rings that run in opposite directions, which helped the network recover from some failures. Classic Token Ring usually ran over copper cable at 4 or 16 Mbps.
Frequently Asked Questions About Token Ring
What does a token ring do?
A token ring connects computers and other devices in a LAN. It uses a token to decide which device may send data. This lets devices share the network in an orderly way.
What is a token in a token ring network?
A token is a three-byte control frame. It gives a station permission to transmit. A station must capture a free token before it can send data.
How does a token ring network work?
A free token travels around a logical ring. A station that has data captures the token and sends a frame. The frame goes to its destination and returns to the sender, which removes it and releases a new token.
What is the difference between Token Ring and Ethernet?
Token Ring uses token passing to control access. Old shared Ethernet used CSMA/CD, and modern Ethernet uses switches with full-duplex links. Ethernet is faster, cheaper, and far more common.
How fast was Token Ring?
Most Token Ring networks ran at 4 Mbps or 16 Mbps. Later Dedicated Token Ring standards covered 100 Mbps and 1,000 Mbps.
What is a Token Ring MAU?
A multistation access unit (MAU) is the central device that connects stations in a typical IBM Token Ring network. It links them in a logical ring and can bypass stations that are offline.
Does anyone still use Token Ring?
Rarely. Most organizations use Ethernet. Token Ring may still appear in older systems and in networking courses.
What are the advantages of Token Ring?
It offered controlled access, predictable turns, priority support, and no collisions on a shared ring. These traits suited many business networks of its time.
What are the disadvantages of Token Ring?
It cost more, ran at lower common speeds, needed special hardware, and was harder to troubleshoot. It also lacked the wide vendor support Ethernet had.
What is IEEE 802.5?
IEEE 802.5 is the standard for Token Ring. It defines the access method and the physical layer. The older versions of the standard are now withdrawn or superseded.
Conclusion
A token ring is a LAN technology in which devices take turns sending data by holding a token. IBM introduced it in 1984, and IEEE 802.5 standardized it. Its logical ring and MAU-based wiring gave businesses an orderly way to share a network.
Ethernet eventually replaced it because Ethernet became faster, cheaper, and easier to expand. Today Token Ring is mainly a legacy technology. It is still a helpful lesson in how networks control access.
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I’m Emma Rose, the founder of Punstation. I cover technology, digital trends, business, and online tools, creating practical guides and thoughtful reviews to help readers understand their options and make informed decisions. For more on how I approach my content, see our Editorial Standards.