Chapter 2
Computer Network Technology
Network Management Principles and Practice
Vikas Singh, CSIS Dept., BITS Pilani
1
Technology and Management
• What are the technologies that need to managed?
• Challenges of technological progress on
network management
Vikas Singh, CSIS Dept., BITS Pilani
2
Computer Network Technology
• Network
comprises
• Nodes
• Links
• Topology: How they’re configured
• LAN
• WAN
• Question: Distinction between LAN and WAN?
Vikas Singh, CSIS Dept., BITS Pilani
3
LANs
•Type of LANs
• Ethernet
• Fast Ethernet
• Gigabit Ethernet
• Half-duplex vs Full-duplex
• Switched Ethernet
•VLAN
• Token ring
• FDDI
• ATM / LANE
•Token ring, FDDI and ATM/LANE not used in newer
implementation!
Vikas Singh, CSIS Dept., BITS Pilani
4
Nodes
• Hubs
• Bridges
• Remote bridges
• Routers
• Gateways
• Half bridge / half router
• Switches
Vikas Singh, CSIS Dept., BITS Pilani
5
• Facilities / Media
WANs
• Wired
• Copper
• Coaxial
• Fiber
• Wireless
• Terrestrial
• Satellite
• Mode: Digital, Analog
• Services
• POTS
• ISDN
• Broadband: Frame Relay, ATM, MPLS VPNs etc
•Wireless services
Vikas Singh, CSIS Dept., BITS Pilani
6
Basic LAN Topologies
DTE
DTE
DTE
E th e rn e t
DTE
DTE
F ig u re 2 .1 (a ) B u s T o p o lo g y
DTE
DTE
DTE
DTE
F ig u re 2 .1 (b ) R in g T o p o lo g y
• Bus topology
• Used in Ethernet LAN family
• Common shared medium
• Randomized access (CSMA/CD)
• Easy to implement
• Lower utilization under heavy traffic 30%-40%
• Single culprit could effect the entire LAN
•A malfunctioning cable
canCSIS
disrupt
thePilani
entire communications on
Vikas Singh,
Dept., BITS
7
the Ethernet segment
Basic LAN Topologies
DTE
DTE
DTE
E th e rn e t
DTE
DTE
F ig u re 2 .1 (a ) B u s T o p o lo g y
DTE
DTE
DTE
DTE
F ig u re 2 .1 (b ) R in g T o p o lo g y
• Ring Topology
• Used in token ring and FDDI
• Shared medium
• Deterministic access
• Master DTE has control
• High utilization >90%
Vikas Singh, CSIS Dept., BITS Pilani
8
Star & Hybrid LAN Topologies
DTE
DTE
DTE
DTE
DTE
DTE
F ig u re 2 .1 (c ) S ta r T o p o lo g y
DTE
DTE
DTE
DTE
DTE
DTE
DTE
DTE
E th e rn e t H u b
T o k e n R in g H u b
F ig u re 2 .1 (d ) H u b C o n fig u ra tio n s
• Star topology used with bus and ring topology
• Hub is “LAN in a box”
• What does the electronic LAN inside the box
look like?
• Why has hub become so popular?
Vikas Singh, CSIS Dept., BITS Pilani
9
A Campus Network
1 0 .1 .1 .2
1 0 .1 .1 .3
1 0 .1 .1 .4
1 0 .1 .1 .5
E th e rn e t 1 0 .1 .1 .0
1 0 .1 .1 .1
B rid g e
1 0 .1 .2 .6
E th e rn e t 1 0 .1 .2 .0
1 0 .1 .2 .2
1 0 .1 .2 .3
1 0 .1 .2 .4
1 0 .1 .2 .5
F D D I R in g
1 0 .1 0 .0 .0
E x te rn a l
N e tw o rk
R o u te r
R o u te r
H a lf - R o u t e r
R o u te r
H a lf - R o u t e r
E th e rn e t 1 0 .3 .1 .0
1 0 .1 .2 .1
T o k e n -rin g
1 0 .2 .1 .0
R o u te r
A T M E L A N 1 0 .4 .1 .0
F ig u r e 2 .3 C a m p u s N e tw o r k o f L A N s
• ATM VLAN an alternative to FDDI backbone
•The Ethernet advances in Hub/switching technology and speed
have unified the LAN/MAN,
since
in the
Vikas Singh,
CSIS even
Dept., BITS
Pilanibackbone one can
use Fast Ethernet or gig Ethernet.
10
WAN Topologies
N1
N2
N1
N3
N5
N2
N6
N3
N4
N4
N5
N6
F ig u r e 2 .2 (a ) M e s h T o p o lo g y
F ig u r e 2 .2 (b ) T r e e T o p o lo g y
• Mesh topology
• Implemented in network layer level
• Multiple paths between nodes
• Flat topology
• Redundancy
• Load balancing
• Shortest path
• Tree topology
• Used with Ethernet bridges
• Hierarchical
• Efficient for small networks and
special purpose networks
Vikas Singh, CSIS Dept., BITS Pilani
11
Ethernet
T a b le 2 .1 E th e rn e t L A N T o p o lo g y L im its
TYPE
D E S C R IP T IO N
SEG M ENT LENG TH
DRO P CABLE
10Base2
T h in c o a x (0 .2 5 ”)
2 0 0 m e te rs
N o t a llo w e d
10Base5
T h ic k C o a x (0 .5 ”)
5 0 0 m e te rs
T w is te d p a ir: 5 0 m e te rs
1 0 B a s e -T
H u b to p o lo g y
N /A
T w is te d p a ir: 1 0 0
m e te rs
1 0 B a s e -F
H u b to p o lo g y
N /A
2 km
Notes
• IEEE 802.3 standard
• 10 Mbps data rate
• Collision - analogy of hollow pipe
• Principle of operation; CSMA/CD
• Segment length and drop cable length
• Minimum size of packet 64 bytes
• Maximum size of packet 1500 bytes
• Hub configuration Vikas Singh, CSIS Dept., BITS Pilani
12
Ethernet Cont’d)
•
In Thin Ethernet the workstations etc are daisy chained. Hence a Coax cable
problem in a segment can partition the segment in 2, and disrupt the
communications.
• The disdvantages of the Bus topology?
Vikas Singh, CSIS Dept., BITS Pilani
13
Ethernet Cont’d)
• In any new networks the 10Base2 and 10base 5 Ethernets
are not used
• In practice Ethernets based on Hub technology are used
• Advantages
– Star topology
– Uses standard Cat 3 wiring
– A break in the wiring only affects a single user
– Easy to trouble shoot
Vikas Singh, CSIS Dept., BITS Pilani
14
Fast Ethernet
N e tw o rk
D a ta L in k
LLC
M A C S u b la y e r
P h y s ic a l
C o n v e rg e n c e L a y e r
P M D S u b la y e r
L L C L o g ic a l L in k c o n tro l
M A C M e d iu m A c c e s s C o n tro l
P M D P h y s ic a l M e d iu m D e p e n d e n t
F ig u re 2 .4 1 0 0 B a s e -T F a s t E th e rn e t P ro to c o l A rc h ite c tu re
Hub
Station
4-pair UTP
• Rationale
• Max drop length 100m => Max round-trip
time 1/10 of Ethernet; hence 10 times data rate
• Standard 100Base-T4
• Compatibility with 10BaseT
• UTP limitation; Use 4-pair UTP @ 25 Mbps/pair
• Alternatives: 2-pair 100BaseTX Cat 5(Max 100 m)
and 100Base FX optical fiber
km)
Vikas(Max
Singh, 2
CSIS
Dept., BITS Pilani
15
LAN Data Rate Race
E’Net
10Mbps
FDDI
100 Mbps
Fast E’Net
100Mbps
Gbit E’Net
1 Gbps
Duplex
E’nets
Vikas Singh, CSIS Dept., BITS Pilani
ATM
155.52 Mbps
ATM
OC-n
16
Gigbit Ethernet
T a b le 2 .2 G ig a b it E th e rn e t T o p o lo g y L im its
9
m icro n
S in g le Mode
50
m icro n
S in g le
Mode
5 0 m icro n
M u ltim o d e
6 2 .5
m icro n
M u ltim o d e
B a la n ce
S h ie ld e d
C a b le
UTP
1 0 0 0 B A S E -L X
1 0 km
3 km
550 m
440 m
-
-
1 0 0 0 B A S E -S X
-
550 m
260 m
-
-
1 0 0 0 B A S E -C X
-
-
-
25 m
-
1 0 0 0 B A S E -T
-
-
-
-
100 m
• Packet size 512 bytes, slot size 4.096 microseconds
• Minimum frame size 64 bytes for backward compatibility; Slot filled
with carrier extension
• Packet bursts with no idle time between frames
increases efficiency
Vikas Singh, CSIS Dept., BITS Pilani
17
Switched Ethernet
DTE
DTE
DTE
DTE
S w itc h e d
hub
DTE
DTE
DTE
DTE
F ig u re 2 .8 S w itc h e d E th e rn e t H u b
• Maximum throughput increased ~N/2 in N-port hub
Vikas Singh, CSIS Dept., BITS Pilani
18
Client/Server Configuration using
Switched Hub
S e rv e r
100 Mbps
10 Mbps
10 Mbps
S w it c h e d h u b
10 Mbps
W o rk s t a tio n
W o rk s t a tio n
W o rk s t a tio n
F ig u re 2 .9 S w itc h e d H u b in C lie n t-S e r v e r C o n fig u ra tio n
Vikas Singh, CSIS Dept., BITS Pilani
19
Virtual LAN
DTE 1
DTE 2
R o u te r
DTE 3
S w itc h e d H u b
P o rt fo r S u b n e ts
2 0 0 .1 0 0 .1 5 0 .1
&
2 0 0 .1 0 0 .1 6 0 .1
DTE 4
DTE 5
VLAN
VLAN
2 0 0 .1 0 0 .1 5 0 .1 2 0 0 .1 0 0 .1 6 0 .1
F ig u r e 2 .1 0 V ir tu a l L A N s
• Switched hub enables establishing virtual LANs
• Permits switching stations between LANs without
physical moving of equipment
• Walk through scenario
Vikas Singh, CSIS Dept., BITS Pilani
20
Token Ring
DTE 4
3 to 1 A C K
DTE 1
D TE 1 has
to k e n c o n tro l
T oken
R in g
DTE 3
1 to 3 M S G
DTE 2
F ig u re 2 .1 1 T o k e n R in g L A N
• Adopted by IBM
• IEEE 802.5 standard
• Data rates of 4Mbps and 16 Mbps
• Single and dual ring LANs
Vikas Singh, CSIS Dept., BITS Pilani
21
Dual Ring TR LAN
DTE 4
DTE 1
P rim a ry
R in g
R edundant
DTE 3
R in g
DTE 2
F ig u re 2 .1 2 (a ) T o k e n R in g D u a l R in g M a n a g e m e n t
Vikas Singh, CSIS Dept., BITS Pilani
22
Failure Recovery in TR LAN
DTE 4
DTE 1
DTE 3
F a ile d S ta tio n
DTE 2
F ig u r e 2 .1 2 (b ) T o k e n R in g D T E Is o la tio n
DTE 4
DTE 1
DTE 3
DTE 2
F ig u r e 2 .1 2 (c ) T o k e n R in g S e g m e n t Is o la tio n
• Station failure recovery
• Link failure recovery
Vikas Singh, CSIS Dept., BITS Pilani
23
FDDI
DAS
SAS
SAS
DAS
S A S S in g le A tta c h e d S ta tio n
D A S D u a l A tta c h e d S ta tio n
F ig u r e 2 .1 3 (a ) D u a l R in g F D D I N e tw o r k C o n fig u r a tio n
• Uses fiber optics medium
• Modified token ring protocol
• Data rate 100 Mbps
• Segment length 100 km
• 500 stations in the ring with max separation of 2 km
• Single and dual attached stations
• Dual attached stations load share the two rings
Vikas Singh, CSIS Dept., BITS Pilani
24
Basic Network Nodes
ATM
ATM
A T M S w itc h
F ig u r e 2 .1 4 (a ) S w itc h
Local LAN
E th e rn e t
P a c k e ts
R o u tin g
F ilte r
B rid g e
E x te rn a l L A N
E th e rn e t
P a c k e ts
F ig u r e 2 .1 4 (b ) B r id g e
L o c a l N e tw o rk
IP P a c k e ts
R o u tin g
F ilte r
E x te rn a l N e tw o rk
IP P a c k e ts
R o u te r
F ig u r e 2 .1 4 (c ) R o u te r
IP
N e tw o rk
P a c k e ts
F o rm a t
change
X .2 5
N e tw o rk
P a c k e ts
G a te w a y
F ig u r e 2 .1 4 (d ) R o u te r
F ig u r e 2 .1 4 B a s ic N e tw o r k N o d e C o m p o n e n ts
Vikas Singh, CSIS Dept., BITS Pilani
25
Network Node Components
D ia l-u p
N e tw o rk
H a lf
R o u te r
R o u te r
S w itc h e d
Hub
E x te rn a l
N e tw o rk
G a te w a y
ATM
S w itc h
Hub
B rid g e
E x te rn a l
N e tw o rk
R e m o te
B rid g e
W o rk s ta tio n
Hub
R o u te r
Hub
F ig u r e 2 .1 5 N e tw o r k e d C o m p o n e n ts
• Hubs
• Bridges
• Remote bridges
• Routers
• Gateways
• Half bridge / half router
• Switches
Vikas Singh, CSIS Dept., BITS Pilani
26
Hubs
DTE
DTE
DTE
DTE
P a tc h P a n e l
Hub
W irin g C lo s e t
F ig u re 2 .1 6 (a ) H u b C o n fig u ra tio n
Notes
• Hub is a platform
• Function dependent on what is housed
• LAN
• Switched LAN
• Bridge
Vikas Singh, CSIS Dept., BITS Pilani
27
Hub 1
To DTEs
Stacked Hubs
B a c k p la n e
In te rc o n n e c tio n
Hub 2
F ig u re 2 .1 6 (b ) S ta c k e d H u b
Notes
• Hub ports can be scaled up using stacked hubs
• Stacked hub
• extend back plane
• connected as daisy chain
Vikas Singh, CSIS Dept., BITS Pilani
28
Bridges
Bridge
Local Bridge
Simple
Remote Bridge
Multiport
Multiport
Multi-protocol
• Bridges two nodes at data link control layer
• Ethernet: tree topology, transparent bridge
• Token ring:mesh topology, source routing bridge
• Remote bridge uses WAN interface cards;
same protocol used at both ends
• Ethernet bridge is a learning bridge
Vikas Singh, CSIS Dept., BITS Pilani
29
Routers
N e tw o rk A
P ro to c o l P
N e tw o rk B
P ro to c o l P
R o u te r
R o u te r
TP
P ro to c o l in te rfa c e
TP
NP
NP
NP
NP
DP
DP
DP'
DP'
Phy
Phy
Phy'
Phy'
P h y s ic a l m e d iu m A
P h y s ic a l m e d iu m B
F ig u re 2 .2 1 R o u te r C o n fig u ra tio n
• Routers operate at network layer
• Routes packets between nodes of similar
network protocols
• Routing table used to route packets
• DLC and Physical layers could be different
under the same common network layer protocol
Vikas Singh, CSIS Dept., BITS Pilani
30
Gateway
N e tw o rk A
P ro to c o l P
N e tw o rk B
P ro to c o l Q
G a te w a y
G a te w a y
TP
P ro to c o l in te rfa c e
TP
NP
NP
NP'
NP'
DP
DP
DP'
DP'
Phy
Phy
Phy'
Phy'
P h y s ic a l m e d iu m
F ig u re 2 .2 2 G a te w a y C o n fig u ra tio n
• Gateway is router connecting two networks with dissimilar network
protocols
• Gateway does the protocol conversion at the network layer
• Protocol converter does the conversion at the application layer
Vikas Singh, CSIS Dept., BITS Pilani
31
X .2 5
IP
Tunnel
M u ltip ro to c o l
R o u te r
IP
M u ltip ro to c o l
R o u te r
E th e rn e t
E th e rn e t
Tunneling
F ig u r e 2 .2 4 T u n n e lin g U s in g M u ltip r o to c o l R o u te r s
Joe’s Mobile
Loc: Seattle
Home LAN
NY
Foreign
Tunneling
Agent
Sally
L.A
• Tunneling is transmission of packets (via multiprotocol routers) by
encapsulation
• In Figure 2.24, packets are encapsulated and transmitted through X.25
network in a serial mode
• In the mobile environment, Joe and his home agent in NY communicate
Joe’s Seattle location to the foreign agent. His communication with Sally in
LA is tunneled
•Other examples of tunneling are layer 2 tunneling protocol (L2TP), used
for dial up services offeredVikas
by Singh,
ISPsCSIS Dept., BITS Pilani
32
S e ria l
O u tp u t
R o u te r
P P P /M P
B rid g e
E th e rn e t
Half-Bridge
F ig u r e 2 .2 5 H a lf-B r id g e C o n fig u r a tio n
• Half-bridge (also referred to as half-router) is for point-to-point
communication
• Uses PPP protocol
• Helps low-end users to communicate with ISP on dial-up link
saving the expense of dedicated link
• Router encapsulates packets in PPP frames and puts serial
outputs to the bridge, and vice-versa
Vikas Singh, CSIS Dept., BITS Pilani
33
Switched Networks
P k t3
P k t2
P k t1
DTE A
P k t1
P k t3
P k t2
B
P k t2
A
P k t3
P k t1
P k t2
D
DTE Z
P k t2
C
F ig u r e 2 .2 6 (a ) D a ta g r a m C o n fig u r a tio n
P k t1
P k t3
P k t2
P k t2
P k t1
DTE A
P k t3
B
A
P k t3
D
P k t2
P k t1
DTE Z
C
F ig u re 2 .2 6 (b ) V irtu a l C irc u it C o n fig u ra tio n
• Switches are embedded in bridges and routers
• Switched network used in WAN
• Two types of switched networks
• Circuit-switched
• Packet-switched
• Datagram service
• Virtual circuit
Vikas Singh, CSIS Dept., BITS Pilani
34
Transmission Technology
Transmission Technology
Medium
Wired
LAN
WAN
Mode
Wireless
LAN
Mobile
Digital
Analog
Satellite
• Physical transport media
• UTP
• Coax
• Fiber
• Terrestrial wireless
• Satellite transmission
Vikas Singh, CSIS Dept., BITS Pilani
35
Transmission Modes
Channel
channel 2
channel 24
T im e
B a n d w id th
T im e
D iv is io n
M u ltip le x in g
(T D M )
channel 1
U ser 24
U ser 1
U ser 2
U ser 3
U ser 4
T im e
Packet
M u ltip le x in g
B a n d w id th
F ig u re 2 .2 7 (a ) T 1 T im e D iv is io n M u ltip le x in g (T D M ) T ra n s m is s io n
U ser 1
U ser 2
U ser 3
U ser 4
U ser 5
T im e
1
s
e
r
4
U
s
U
s
U
e
r
e
r
e
s
r
1
5
1
3
U
U
s
e
r
U
s
e
r
U
s
e
e
s
r
2
5
1
4
r
3
U
U
s
e
r
1
r
e
s
U
C e ll
M u ltip le x in g
B a n d w id th
F ig u re 2 .2 7 (b ) P a c k e t T ra n s m is s io n ( X .2 5 )
T im e
F ig u re 2 .2 7 (c ) C e ll T ra n s m is s io n (A T M )
Vikas Singh, CSIS Dept., BITS Pilani
36
Questions
• What kind of switching is used in
conjunction with TDM? With Cell
transmission?
• Is there any other mode we have missed in
last slide?
Vikas Singh, CSIS Dept., BITS Pilani
37
Broadband Services
R e s id e n tia l
C u s to m e r
N e tw o rk
S e rv ic e
P ro v id e rs
C am pus
ATM / LAN
N e tw o rk
B ro a d b a n d
Access
G a te w a y
B ro a d b a n d
Access
R e s id e n tia l
C u s to m e r
N e tw o rk
O C -n /
S T S -n
L in k
C am pus
ATM / LAN
N e tw o rk
SDH / SONET
WAN
O C -n /
S T S -n
L in k
F ig u re 2 .2 8 B ro a d b a n d S e rv ic e s N e tw o rk
• Integrated services: Voice, video, and data
• Narrow band ISDN (Integrated Services Digital Net.)
• Basic rate:2B + D (B channel 64 kbps and
D channel 16 kbps
• Primary rate: 23B + D channels
• Broadband (ISDN) Services uses ATM technology
• SONET (Synchronous Optical Network) or
SDH (Synchronous Digital Hierarchy)
• Data rate OC-n
• OC-1 51.84 Mbps
• OC-3 155.52 Mbps
• Access technologies:
• HFC (Hybrid Fiber Coaxial) / Cable modem
• ADSL (Asymmetric
Digital Subscriber Line)
Vikas Singh, CSIS Dept., BITS Pilani
38