Cambium Networks PTP 820S, Техническое описание, Страница: 81 / 208

Chapter 4: Feature Description Ethernet Features
Ethernet Interfaces
The PTP 820S switching fabric distinguishes between physical interfaces and logical interfaces.
Physical and logical interfaces serve different purposes in the switching fabric.
The concept of a physical interface refers to the physical characteristics of the interface, such as
speed, duplex, auto-negotiation, master/slave and standard RMON statistics.
A logical interface can consist of a single physical interface or a group of physical interfaces that
share the same function. Examples of the latter are protection groups and link aggregation groups.
Switching and QoS functionality are implemented on the logical interface level.
It is important to understand that the PTP 820S switching fabric regards all traffic interfaces as
regular physical interfaces, distinguished only by the media type the interface uses, e.g., RJ-45,
SFP or Radio.
From the user’s point of view, the creation of the logical interface is simultaneous with the creation
of the physical interface. For example, when the user enables a radio interface, both the physical
and the logical radio interfaces come into being at the same time.
Once the interface is created, the user configures both the physical and the logical interface. In
other words, the user configures the same interface on two levels, the physical level and the
logical level.
The following figure shows physical and logical interfaces in a one-to-one relationship in which
each physical interface is connected to a single logical interface, without grouping.
Figure 49 Physical and Logical Interfaces
SP
SP
SP
SP Physical Interface 2
Physical Interface 1
Logical Interface
Logical Interface
Service
Physical Interface 3
Physical Interface 4
Logical Interface
Logical Interface
Note
For simplicity only, this figure represents a unidirectional rather than a bi-directional
traffic flow.
The next figure illustrates the grouping of two or more physical interfaces into a logical interface, a
link aggregation group (LAG) in this example. The two physical interfaces on the ingress side send
traffic into a single logical interface. The user configures each physical interface separately and
configures the logical interface as a single logical entity. For example, the user might configure
each physical interface to 100 Mbps, full duplex, with auto-negotiation off. On the group level, the
user might limit the group to a rate of 200 Mbps by configuring the rate meter on the logical
interface level.
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