Download extract slides from KCC Basic Datacomm Course

ip addressing example work sheet
ROUTER (GateWay)
165.140.20.56/25
165.140.11.254/22
User PC A
Printer
ip 165.140.20.03
msk 255.255.255.128
g/w 165.140.20.56
ip 165.140.8.1
msk 255.255.252.0
g/w 165.140.11.254
Network
User PC B
ip 165.140.20.04
msk 255.255.255.128
g/w 165.140.20.56
ip 165.140.8.3
msk 255.255.252.0
g/w 165.140.11.254
User PC G
Network
User PC C
ip 165.140.20.100
msk 255.255.255.128
g/w 165.140.20.56
User PC H
ip 165.140.8.3
msk 255.255.252.0
g/w 165.140.11.254
NOTE
mask = 255.255.255.128
(25 bit network)
ie upto 126 local
connections
User PC K
ip 165.140.10.1
msk 255.255.252.0
g/w 165.140.11.254
NOTE
mask = 255.255.252.0 (22 bit network)
ie 1022 local connections
PC X
ip
msk
g/w
TO other networks,
Internet etc.
PC Z
ip
msk
g/w
COMPLETE THE CONFIGS FOR PC X, Z
KCC Feb 1998
Ethernet Reminder
PC
PC
PC
PC
PC
PC
PC
BRIDGE
PC
PC
with the use of layer2 bridges segments could be connected together.
each work group has its own collision domain. traffic is kept local
using the mac address. Unfortunately, broadcast traffic is sent to all
segments (all users in same broadcast domain). only one device in
each segment can use the cable at one time.
PC
PC
PC
PC
the original single segment network.
all devices share the same cable or
collision domain.
Remember Ethernet CSMA/CD =
Carrier Sense,Multiple Access,
Collision Detection…..
only one device can use the cable at
one time.
PC
PC
PC
PC
PC
ROUTER
PC
PC
PC
with the use of a layer 3 router the three segments become
separate networks with their own collision domain and
broadcast domain. The router can makes decisions based
upon protocol, company policy, traffic levels etc…
only one device in each segment can use the cable at one time.
KCC Feb 1998
Ethernet Reminder 2
PC
PC
PC
PC
PC
HUB
the hub or repeater (layer 1) extends the physical specification
and enables use of cabling over a greater distance. all devices still
are in same collision domain and same broadcast domain. only one
device can use the the above network at one time.
to/from other routers
and switches in the
company network
PC
PC
PC
PC
PC
PC4
PC
SW ITCH
the use of a simple ethernet switch provides an ethernet bridge for each port.
each switched port is a separate collision domain. the switch is a layer
2 device hence all ports are in the same broadcast domain.
PC5
PC6
ROUTER
use of more complex configurations can provide VLANs (virtual local
area networks) where PC 1,2,3,7 & 8 are in one vlan and PC 4,5,6 & 9
are in another. each vlan is a separate broadcast domain and each switch
port can provide a separate collision domain.
SW ITCH
interswitch link
SW ITCH
PC1
PC2
PC3
PC7
PC8
PC9
KCC Feb 1998
FRAME CONSTRUCTION EXAMPLE
LAYER 5
Example
FTP HEADER
FTP DATA
FTP session
LAYER 4
SEGMENT
Example
TCP HEADER
TCP DATA
TCP PORT # 21 = FTP content
LAYER 3
PACKET
IP HEADER
IP DATA
Example PROTOCOL #6 = TCP content
LAYER 2
FRAME
Example DIX frame
FRAME HEADER
DATA
TYPE #0800 = IP content
LAYER 1
Preamble
DATA SIGNAL
KCC August 1999
TCP SEGMENT CONSTRUCTION
0
4
8
16
19
source port
24
31
destination port
FLAGS;
U Urgent
A Acknowledgement
P Push
R Reset
S Synchronize SYN
F FIN
sequence number
acknowledgement number
offset
reserved
window
U A P R S F
checksum
options
urgent pointer
(variable length)
TCP = IP protocol # 6
padding
LAYER 4
data
UDP SEGMENT CONSTRUCTION
0
4
8
16
19
24
source port
destination port
length
UDP checksum
31
UDP = IP protocol # 17
LAYER 4
data
KCC August 1999
IP PACKET CONSTRUCTION
0
4
version
8
16
hdr length
TOS
24
31
total packet length
identification
TTL
19
flags
protocol #
fragment offset
header checksums
source address
LAYER 3
destination address
options
(variable length)
padding
data
LAYER 2
FRAME
FRAME HEADER
DATA
KCC August 1999
ETHERNET FRAME CONSTRUCTION
LAYER 2
64 to 1518 Bytes long
preamble/SD
8
destination mac address
source mac address
TYPE/LENGTH
6
6
2
L E N G T H
I N
802.2 SSAP/DSAP
4 (+5)
B Y T E S
DATA
FCS
4
41 to 1500
Bytes long
NOTE… Ethernet DIX frame preamble is 8 bytes long with no SD byte,
Ethernet DIX frame has TYPE field and no LENGTH or 802.2 fields.
Ethernet IEEE 802.3 frames have 7 byte preamble, 1 byte SD,
Ethernet IEEE 802.3 frames have LENGTH field and no TYPE field,
Ethernet IEEE 802.3 frames have 802.2 field for 2 byte DSAP, 2 byte SSAP, 2 control bytes and
5 byte SNAP (if used DSAP and SSAP = 0xAA).
Therefore the largest Ethernet frame size should be 1518 bytes and the minimum frame size should be 64 bytes
in order to stay within the Ethernet specification and be able to detect a collision. The frame size was extended
to 1522 bytes by a IEEE 802.3 committee workgroup (802.3ac) to support VLAN tagging using 802.1Q but
several manufactures equipment still will not support giant frames (larger than 1518). Frame sizes have been
pushed even further with the latest technologies. ISL (Inter Switch Link) VLAN tagging extends the frame
by an additional 30 Bytes, MPLS (Multi Protocol Label Switching) adds 4 Bytes for each label….. etc. etc. so
it is not unusual to see giant frames on today’s networks.
KCC August 1999
UTP & AUI Ethernet Cabling
LAYER 1
pin assignment;
pin #
RJ-45
1 2 3 4 5 6 7 8
SOCKET
1
2
3
6
MDI-X function
MDI function
Rx
Rx
Tx
Tx
Tx
Tx
Rx
Rx
+
+
-
+
+
-
VIEW
NOTE; most Ethernet equipment has MDI-X ports (Media Dependant Interface
Crossover) and some supply an MDI or switchable MDI/MDI-X to enable connection
of to 10BaseT devices without the use of a crossover cable.
NOTE: Chiron makes use of RJ-11 connectors for the Cat-3 cabling
for example an RJ-11 to RJ-45 cable ;
RJ-11 pin #
1
2
3
4
5
6
NOTES;
RJ-45 pin #
5
6
1
2
3
4
Some equipment uses the 15 pin D AUI connection ;
pin #
1
2
3
4
5
6
9
10
11
12
13
14
15
function
ground
CI-A
DO-A
ground
DI-A
VDC ground
CI-B
DO-B
ground
DI-B
VDC +12
ground
ground
KCC
Feb 1998