Allied Telesis AT-MR912TX - Manual (Page 38)

Installation
18
Rack mounting
Rack mounting will require use of the rackmount installation kit which is
provided. The 19-inch rackmount kit, standard with all models, consists of two
brackets and eight panhead screws. The installation of these brackets is
shown below. Note that, for clarification, the illustration shows the back side of
the hub.
Figure 13: Rackmount Brackets
For additional information about rackmount installation kits, please contact
your ATI sales representative.Cascading With Fast Ethernet
Two AT-MR912TX hubs can be cascaded to enable support for up to a
maximum of 22 network port connections.
The Two-Repeater Rule
Because of the Two Repeater Rule for IEEE 802.3u, the maximum number of
Class II hubs allowed in a cascaded configuration is two.
That is, the IEEE 802.3u standard provides general rules for 100Base-TX
cable length and network connections on single segments of cable or on point-
to-point links with media attenuation and signal propagation delays. The basic
rule is that, in a Class II installation, each hub in the network is viewed as a
standalone hub and, therefore, the maximum number of hubs in the data path
between any two nodes cannot exceed two.