Cisco 7000 Series Hardware Installation And Maintenance Manual page 90

Preparing Network Connections
Table 2-14
Network Type Data Rates
IBM Token Ring 4, 16 Mbps
network
IEEE 802.5 4, 16 Mbps
network
In the typical Token Ring network shown in Figure 2-19, lobe cables connect each Token Ring
station (TRIP port) to the MSAU (or MAU), and patch cables connect adjacent MSAUs (or MAUs)
to form one large ring.
Figure 2-19
Token Ring and IEEE 802.5 are token-passing networks, which move a small frame (called a token)
around the network. Possession of the token grants the right to transmit; a station with information
to transmit must wait until it detects a free token passing by.
When all stations on the ring are idle, the token packet is labeled as a free token. If the station
receiving the token has no information to send, it simply passes the free token to the next station. A
station that does have information to transmit seizes the token, alters a bit of the token frame (which
changes the free token to a busy token), appends the information it wishes to transmit, and then sends
this information to the next station on the ring. The busy token, with the information frame,
circulates the ring until it reaches the intended destination station, which copies the information for
further processing and passes the busy token and information frame back out to the ring.
2-30 Cisco 7010 Hardware Installation and Maintenance
IBM Token Ring and IEEE 802.5 Comparison
Stations/ Segment
260 shielded twisted pair
72 unshielded twisted pair
250
Token Ring Network Physical Connections
MAU or MSAU
Ring
in 1 2 3 4 5 6
Stations
MAU or MSAU
Ring
in 1 2 3 4 5 6
Stations
Topology Media
Star Twisted pair
Not specified Not specified Baseband
Ring Ring
7 8 out in 1
Patch
cables
Ring Ring
7 8 out in 1
Lobe
cables
Access
Signaling Method
Baseband Token
passing
Token
passing
MAU or MSAU
Ring
2 3 4 5 6 7 8
Stations
MAU or MSAU
Ring
2 3 4 5 6 7 8
Stations
Encoding
Differential
Manchester
Differential
Manchester
out
out