Information Technology Reference
In-Depth Information
Another important setting to consider when looking at Frame Relay networks is the initial encapsulation
type used when the protocol is activated on an interface. This setting must be consistent between end
devices on the internetwork. If you are connecting Cisco-only devices, Cisco encapsulation may be used.
This is the default encapsulation type on Cisco routers. If you are connecting to hardware from other
vendors, IETF encapsulation should be used.
Network Implementation
Frame Relay can be used as an interface to either a publicly available carrier-provided service or to a
network of privately owned equipment. A typical means of private network implementation is to equip
traditional T1 multiplexers with Frame Relay interfaces for data devices, as well as non-Frame Relay
interfaces for other applications such as voice and video/teleconferencing. Figure 18-5 shows this
configuration.
Figure18-5 A Hybrid Frame Relay Network
Token
Ring
Router
Frame Relay
interface
Ethernet
WAN
T1 MUX
Non-Frame Relay
interface
T1 MUX
PBX
Non-Frame Relay
interface
Frame Relay
interface
Token
Ring
Router
Ethernet
Video/teleconference
A public Frame Relay service is deployed by putting Frame Relay switching equipment in the central
offices of a telecommunications carrier. In this case, users can realize economic benefits from
traffic-sensitive charging rates and are relieved from the work necessary to administer and maintain the
network equipment and service.
In either type of network, the lines that connect user devices to the network equipment can operate at a
speed selected from a broad range of data rates. Speeds between 56 kbps and 2 Mbps are typical,
although Frame Relay can support lower and higher speeds.
Whether in a public or private network, the support of Frame Relay interfaces to user devices does not
necessarily dictate that the Frame Relay protocol is used between the network devices. No standards for
interconnecting equipment inside a Frame Relay network currently exist. Thus, traditional
circuit-switching, packet-switching, or a hybrid approach combining these technologies can be used.
