Token Ring IEEE 802.5 Vs Ethernet IEEE 802.3

• Token Ring networks are deterministic in nature -nodes may only transmit at certain well defined times.Result is high bandwidth efficiency.Up to 90% in Token Ring, 40% in Ethernet.
• Guaranteed sequential access to network eliminates fluctuating response times experienced on other network topologies.
• Token Ring performance does not deteriorate to the same extent as Ethernet when network traffic increases.This means that at high loads, the presence of collisions of data frames on Ethernet networks becomes a major problem and can seriously affect the throughput.
• By its nature Token Ring has a higher reliability, the ring can continue normal operation in most cases despite any single fault.
• Ethernet has an advantage over Token Ring in that the cost of network equipment is lower for Ethernet.Token Ring networks tend to be more expensive to set up and maintain than Ethernet, although hardware costs for Token Ring are decreasing.
• Advances in Ethernet technology have tended to be much more rapid than Token Ring.Gigabit Ethernet being an example of this.Token Ring technologies are being developed however to allow data transfer rates of 100Mbps using technologies such as Token Ring Switching.

Token Ring IEEE 802.5 Vs Token Bus IEEE 802.4

• These standards although similar in some respects were developed with different applications in mind.Token Bus (IEEE 802.4), networks use a Bus technology and do not have a centralised active monitor.Token Bus was designed with large factories in mind where machines and equipment would be moving around under computer control.Network failures could have serious consequences and so had to be avoided at all costs.On the other hand the Token Ring network standard was designed with office automation in mind, where a failure once in a rare while could be tolerated as the price for simpler system.
• Token Bus is not as deterministic as Token Ring but like Token Ring it has excellent throughput and efficiency at high load.
• Token Bus uses broadband transmission and cabling which obviously gives it a bandwidth advantage over Token Ring but the downside is the equipment costs (modems, wideband amplifiers, etc).The IEEE 802.4 protocol is also extremely complex compared to IEEE 802.5 and it has a substantial delay at low loads.

In general Token Rings point to point connections, means that engineering is easy and can be fully digital.The standard twisted pair cable is cheap and simple to install. Also the Multistation Access Units as wire centres make Token Ring the only one of these Local Area Networks that can detect and eliminate cable failures automatically.

The major downside of Token Ring networks is the presence of a centralised monitor function (the active monitor),which introduces a critical component.A dead active monitor can be replaced by a standby monitor but a partially faulty monitor can slow down an entire network.

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