30 VIP-4R/4T Installation and Configuration
VIP Port Adapter Functions
Token Ring Overview
The following sections describe Token Ring specifications, physical connections, connection
equipment, and cables and connectors. Figure 14 shows the 4R port adapter installed on the
VIP-4R/4T.
Figure 14
VIP with One 4R and One 4T Port Adapter Installed (Horizontal Orientation Shown)
Note
Current VIP configurations support only one 4R port adapter and one 4T port adapter. Single
and dual 4R configurations are not available. Port adapters have a handle attached, but this handle is
not shown to allow a full view of detail on each port adapter’s faceplate.
Token Ring Specifications and Physical Connections
The term Token Ring refers to both IBM’s Token Ring Network, which IBM developed in the 1970s,
and to IEEE 802.5 networks. The IEEE 802.5 specification was modeled after, and still closely
shadows, IBM’s network. The two types are compatible, although the specifications differ slightly.
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.
H5985
DRAM
SIMMs
Microcode
ROM U1 7
Bus connector
EN
TD
TC
RD
RC
LB CD
FAST SERIAL
EN
TD
TC
RD
RC
LB CD
TD
TC
RD
RC
LB CD
TD
TC
RD
RC
LB CD
TD
TC
RD
RC
LB CD
4R in port
adapter
slot 0
4T in port
adapter
slot 1
Port adapter
handles not shown