R&M Data Center Handbook

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In contrast to user ports, the transmission and receiving line for the uplink port of a switch are interchanged. In
modern devices, ports are equipped with functionality known as auto uplink (or Auto MDI-X). This allows them to
recognize, on their own, whether it is necessary to exchange the transmission and receiving line, so separate
uplink ports or crossover cables are unnecessary. Connecting switches in series by using uplinks is known as cascading.
The following illustration demonstrates cascading from the Access to the Aggregation area. In the left
image, these connections are established over permanently installed cables, and by means of patch cords over
the cable duct in the right image.
PATCH
PATCH
PATCH
PATCH
PATCH
PATCH
PATCH
PATCH
PATCH
Aggregation
& Core
Aggregation
& Core
SAN Connection
LAN Connection
KVM Connection
Redunancy
Uplink
SAN Switch
LAN Switch
KVM Switch
These variants can be a sensible option for short distances, especially since there are two fewer connections in
between and at the same time patch panels can be saved.
Arranging Patch Panels
It is not a must that patch panels be installed horizontally, or installed in the rack in general. There are attractive
alternatives to doing this, just from the viewpoint of the efficient use of the otherwise already scarce free spaces in
the data center.
Vertical mounting
Floor box
PATCH
PATCH
PATCH
PATCH
PATCH
PATCH
SAN Connection
LAN Connection
KVM Connection
PATCH
PATCH
PATCH
Page 64 of 156 © 08/2011 Reichle & De-Massari AG R&M Data Center Handbook V2.0