Syngress - Eleventh Hour Network+ Exam N10-004 Study Guide (11 ...

110 CHAPTER 7 Wide Area Networking
■ In Europe, Australia, and other parts of the world, PRI provides 30 B
channels plus one 64 Kbps D channel and a total interface rate of
2.048 Mbps.
■ ISDN comprises digital telephony and data transport services offered by
regional telephone carriers using preexisting telephone wiring.
■ FDDI FDDI is debated to be a local area network (LAN) versus WAN technology.
FDDI is generally used as a backbone technology due to its redundant
design and high speed.
■ FDDI is based on fiber and is the standard for a 100 Mbps dual ring token
passing technology.
■ It can also be based on copper cable, which is called Copper Distributed
Data Interface (CDDI).
■ FDDI works using a dial ring token passing architecture that allows for
bidirectional traffic – traffic traveling opposite directions – which is also
called counter rotation.
■ FDDI and its primary and secondary rings are based on providing highspeed
service reliably. The dual rings offer redundancy; in case of failure,
the traffic can traverse the other link.
■ Frame Relay Frame Relay is a packet-switching protocol for connecting
devices on a WAN. Frame Relay is based on the older X.25 packet-switching
technology, which was designed for transmitting analog data such as voice
conversations, and is the skeleton for the MPLS solutions that are being
used in most enterprises today.
■ Frame Relay networks in the United States support data transfer rates
at T1 (1.544 Mbps) and T3 (45 Mbps) speeds and can be purchased as
DS0s.
■ Frame Relay, when used in the WAN, is often used between a company’s
core and remote sites and can be sized perfectly to whatever bandwidth
is needed between the sites.
■ Frame Relay allows for bursting which is when the carrier allows you to
use some of the space on the rest of the whole line if available.
■ Frame Relay has a high transmission speed, very low network delay if
configured properly and sized correctly, and it is fairly reliable.
■ MPLS MPLS is a new WAN technology that is becoming very popular
because of its many benefits, including its pure Layer 3 design and the fact
that it is IP-based. Furthermore, MPLS allows you to label data to have a
specific priority based on the application type. The quality of service (QoS)
mechanisms in MPLS are quite sophisticated. MPLS is able to use labels
to mark packets as they enter and exit the MPLS network. When the packets
enter the MPLS network fabric, it is quickly routed to its destination
based on its label and what that label specifies. MPLS operates at Layer 3
of the OSI model and is an excellent choice for voice and video applications.
Request for Comments (RFC) 3031 (www.faqs.org/rfcs/rfc3031.html)
shows many fine details on the inner workings of the technology and how
MPLS operates.