33
Chapter 6. Interfaces and Subnets
This chapter covers the setup of Ethernet interfaces and the definition of subnets that are present on those
interfaces.
For information about other types of 'interfaces', refer to the following chapters :-
• Point-to-Point Protocol over Ethernet (PPPoE) - Chapter 10
• Tunnels, including FB105 tunnels - Chapter 11
6.1. Relationship between Interfaces and
Physical Ports
The FB6000 features four Gigabit Ethernet (1Gb/s) ports that can also operate at 10Mb/s and 100Mb/s speeds.
Auto-negotiation of link speed is enabled by default, so when connected to auto-negotation capable equipment,
the ports operate at the highest speed that both ends of the link can run at. In some situations, auto-negotiation
is not supported by connected equipment, and so the FB6000 provides control of port behaviour to allow the
port to work with such equipment.
Each port features a green and amber LED, the functions of which can be chosen from a range of options
indicating link speed and/or traffic activity.
The exact function of the ports is flexible, and controlled by the configuration of the FB6000.
6.1.1. Port groups
Up to four port groups can be defined, with each group comprising a set of one or more physical ports that
doesn't overlap with any other group. The ports within the group work as a conventional Ethernet switch,
directly transferring traffic at wire-speed that is destined for a MAC address that is present on one of the other
ports in the group.
6.1.2. Interfaces
In the FB6000, an interface is a logical equivalent of a physical Ethernet interface adapter. Each interface
normally exists in a distinct broadcast domain, and is associated with at most one port group. It is referred to as
a logical interface, since Virtual LAN (VLAN) support allows multiple logical interfaces to be implemented on
one physical port group. If you are unfamiliar with VLANs or the concept of broadcast domains, Appendix D
contains a brief overview.
Table 6.1 shows the logical to physical associations that are possible :-
Table 6.1. Physical port usage options
Association
Notes
A single physical port
a
implements one interface
VLANs are not in use on the port, and so only untagged
packets are present.
A user-defined group of physical ports implements one
interface
The ports in the group work as a conventional Layer
2 Ethernet switch, directly transferring traffic at wire-
speed that is destined for a MAC address that is present
on one of the other ports in the group.
