LAN Cabling, Standards, and Topologies

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Cisco CCNA Study Guide	By Cbrzana
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LAN Cabling, Standards, and Topologies

Network Topologies

Physical = How the cabling/devices are physically setup

Logical = How the data actually flows

Coaxial = Physical bus/Logical bus

Hub use = Physical Star/Logical bus

Switch use = Physical Star/Logical Star

Token Ring Hub (Multistation Access Unit) = Physical Star/Logical Ring

- > Star also known as hub-and-spoke topology

- > Extended Star is simply an extension of the star topology

- > Full-mesh is every device connected to every other, partial is not 100% connected

• Frame relays often referred to partial/full mesh due to PVCs

- >Dual rings on Token ring are used for failover/redundancy

Cabling and Connectors

UTP Standards

UTP Category	Max Speed	Description
1	--	Used for POTS
2	4 Mbps	Originally designed for Token Ring.
3	10 Mbps	Can be used for telephones.
4	16 Mbps	Intended for fast Token Ring speed.
5	1 Gbps	Very popular desktop cabling.
5e	1 Gbps	Lower emissions, better for Gigabit Ethernet.
6	1 Gbps+	Intended as a replacement for Cat5e, capability to support multigigabit speeds (when standards are created).

UTP = RJ-45 Connectors

Coaxial Cabling: Used for 10Base2 and 10Base5

10Base5 = Thicknet, vampire taps and Attachment Unit Interfaces (AUI) connectors, 500m max length.

10Base2 = Thinnet, BNS connectors with T-connector/transceiver to connect to each machine, 185 meters max

Fiber-Optic Cabling and Connectors for Ethernet

• Longer distances supported
• More expensive
• Secure
• Less interference than electrical cabling
• Only type of cabling to support 10 Gigabit Ethernet

- > Dark fiber is when fiber cabling is lease from a service provider

Two Categories of Optical Cabling

Multimode (MM): Use LEDs, shorter distances, less expensive

Singlemode (SM): Use lasers, Small diameter optical fiber, require more precision when being made, more expensive, greater distances.

- > Fiber cabling is made from fiberglass, has extra protection from plastic and Kevlar coating.

- > Light hits the outer wall of the core/inner wall of the cladding, "bounces" until destination reached

Optical Connectors for Ethernet

To transmit data in both directions, need a pair of fiber strands. No need to twist the strands together, since there is no magnetic interference.

ST Connector (BNC style), SC Connector (2 strands attach to single connector), MT-RJ Connector (same plastic mold as RJ-45)

Summary

	Max Length	Max Speed	Cost	Pros	Cons
UTP	100m	1 Gbps	Low	Easy to install, commonly available	Susceptible to interference, limited distance
STP	100m	100 Mbps	Medium	Low emissions, less interference	Difficult to work with, limited distance.
Coaxial	500m (Thicknet) 185m (Thinnet)	100 Mbps	Medium	Least susceptible to interference of all copper media.	Single cable problem fails entire network
Fiber	10km+ (SM) 2 km+ (MM)	100 Gbps (SM) 10 Gbps (MM)	High	More secure, long distances, highest speeds	Difficult to terminate, expensive

Ethernet Cabling Standards

Standard	Cabling	Maximum Length
10Base5	Thick coaxial	500m
10Base2	Thin coaxial	185m
10Base-T	UTP CAT 3,5,5e,6	100m
100Base-FX	Two strands, multimode	400m
100Base-T	UTP CAT3,5,5e,6, 2-pair	100m
100Base-T4	UTP CAT3,5,5e,6, 4-pair	100m
100Base-TX	UTP CAT3,5,5e,6, or STP, 2-pair	100m
1000Base-LX	Long-wavelength, MM or SM	10 km (SM) 3 km (MM)
1000Base-SX	Short-wavelength, MM	220m with 62.5 micron fiber; 550m with 50-micron fiber
1000Base-ZX	Extended wavelength, SM	100km
1000Base-CS	STP, 2-pair	25m
1000Base-T	UTP CAT5,5e,6	100m

10-Gigabit Ethernet: defined in IEEE 803.ae

• Allows only point-to-point topology (intended for connectivity between switches)
• Only full-duplex communication
• Specifies only optical cabling

IEEE 802.11 Wireless LANs: Known informally as Wi-Fi, only one station can effectively transmit at a time (within the range)

• 802.11 requires different MAC header than 802.3 header
• 802.11a = 5 GHz, 54 Mbps
• 802.11b = 2.4 GHz, 11 Mbps
• 802.11c = 2.4 GHz, 54 Mbps

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