Specifications

Ethernet Network Design 7-7
10BASE5 Ethernet Network Design
Inter-Repeater Link (IRL)
Repeaters can be used to connect up to 3 coaxial segments before special
considerations need to be taken into account. If it is necessary to connect
more than 3 coaxial segments together, then an Inter-Repeater Link (IRL)
must be used (see Figure 7-7). An IRL is a segment that spans between two
repeaters with no other devices attached to it. It can be made up of thin
coaxial (185 m), thick coaxial (500 m), fiber optic cable (2/5 km) or twisted
pair cable (200 m) with the appropriate media limitations being observed.
IEEE states that if IRLs are used, the maximum network size can be up to 4
repeaters with 5 segments, giving a total linear distance of 2,500 m (if just
10BASE5 coaxial is used), not including AUI cables. IEEE has determined
that this is the maximum network size that will allow the round trip
propagation delay budget to be met. Propagation delay is discussed in
Chapter 8, Propagation Delay.
Figure 7-7. Using Inter-Repeater Links
Inter Repeater Link
NETWORK 1
(Up to 1,024 devices)
NETWORK 2
(Up to 1,024 devices)
Repeaters
(length dependent
on media type)
1913-24
In multiple segment networks, each coaxial segment must be grounded at
only one point. All exposed metallic connectors and terminators must be
insulated from ground to prevent ground loops.
NOTE