Networking Concepts Lesson 11 - Enterprise & Distributed Networks - Eric Vanderburg

1. Chapter 11
Enterprise & Distributed Networks
Networking Concepts – Eric Vanderburg ©2005

2. Expanding Networks
 Modem
(Modulator/Demodulator)
 RJ11
phone port
 External modems use RS-232
(Recommended Standard 232) serial port
 Hayes-compatible – works with software
designed for the original Hayes modems in
the early 80’s
Networking Concepts – Eric
Vanderburg ©2005

3. Modems
Baud – number of sound wave oscillations per second
– old modems transferred 1 bit/baud
 ITU (International Telecommunications Union) –
created the V-series standards

•
•
•
•
•
V.22bis* – 2400baud, 2.4kbps
V.32 – 2400baud, 9.6kbps
V.32bis – 2400baud, 13.4kbps
V.32ter – 2400baud, 19.2kbps
V.FC (Fast Class) – 9600baud,
28.8kbps
•
•
•
•
•
V.34 – 9600baud, 28.8kbps
V.34bis – 9600baud, 33.6kbps
V.42bis – uses compression &
error correction, 28.8kbps
V.90 – 56k d/l, 22.6k u/l
V.92 – modem on hold, 56k
Networking respectively
*Bis & ter mean 2nd & 3rd revisionsConcepts – Eric
Vanderburg ©2005

4. Modems
Asynchronous – start and stop bits are placed before and after each byte
(8 bits + parity bit). More check data and more overhead.
 PCM (Pulse Code Modulation) – digitizing an analog signal on a modem



33.6 Kbps from modem to ISP
56 Kbps from ISP to modem
MNP Class 5 compression
 Synchronous – devices agree on a timing scheme utilizing sync bits and
transfer blocks of data (frames) accordingly. Less overhead, leased line
use. Also provide error checking.





SDLC (Synchronous Data Link Control)
HDLC (High-level Data Link Control)
Bisync (Binary Synchronous)
Transfer rates depend on



Line conditions
V standard
FCC regulations (max is 54kbps)
Networking Concepts – Eric
Vanderburg ©2005

5. Digital Modems

ISDN (Integrated Services Digital Network)





Cable


NT (Network Termination)
TA (Terminal Adapter)
BRI (Basic Rate Interface) – 2 B channels (64k) & 1 D channel (16k),
$50-$70
PRI (Primary Rate Interface) – 23 B channels, 1 D channel
(H10=1472 kb/s *see ch.7), $300-$1500
DOCSIS encrypts each connection to increase security.
DSL



Distance limitation between user and CO (17,500-23,000ft)
ADSL (Asymmetric Digital Subscriber Line) - 8 Mbps d/l, 1 Mbps u/l
SDSL (Symmetric Digital Subscriber Line) - equal d/l and u/l speeds
Networking Concepts – Eric
Vanderburg ©2005

6. Carriers
 Throughput
– how much data can be
sent over the line per second
 Distance
 Cost
Networking Concepts – Eric
Vanderburg ©2005

7. RRAS
 RRAS
Authentication
 Wizard
Networking Concepts – Eric
Vanderburg ©2005

8. RRAS & terms

RRAS




DUN (Dial-up Networking)
SLIP (Serial Line Internet Protocol)



Layer 1
Works with TCP/IP only
CSLIP (Compressed Serial Line Internet Protocol)


Max concurrent clients: 256
Called RAS (Remote Access Service) in NT
Same as SLIP but can compress data to increase speed
PPP (Point-to-Point Protocol)




Layers 1 & 2
Works with IP, IPX, & NetBEUI
Can compress & check for errors
Supports DHCP
Networking Concepts – Eric
Vanderburg ©2005

9. Other Vendors

Novell NetWare provides VPN server connections




Able to form VPN WAN by connecting corporate LANs over
VPN connections through the Internet
Mac OS version 9 and above support VPN client
connections to Windows servers using PPTP or IPSec
Mac OS X Server provides a VPN server service that
permits Mac OS, Windows, and Linux/Unix clients to
connect to the corporate LAN
Linux versions using L2TP may not be compatible with
Windows VPN solutions
Networking Concepts – Eric
Vanderburg ©2005

10. VPN
 Linux
supports VPN client and server
applications
 Not
compatible with Windows L2TP
 More difficult to use; may require a patch to
the kernel
 VPNs
are Less expensive than a modem
pool. Internet connection replaces direct
modem connection
Networking Concepts – Eric
Vanderburg ©2005

11. VLAN
 Implemented
on switches
 Requires a router also
 Divides ports into logical
sections
 Usually separated by
subnet
Networking Concepts – Eric
Vanderburg ©2005

12. Routing
 Static
routing – each path must be
manually entered – same path is used
each time
 Dynamic routing – router determines the
best route based on available info
Networking Concepts – Eric
Vanderburg ©2005

13. Brouters
 Routes
packets that use routable
protocols
 Forwards packets that are not routable
 Useful in hybrid network with mixture of
routable and nonroutable protocols
 May be identified as router with bridging
capabilities
Networking Concepts – Eric
Vanderburg ©2005

14. Gateway
 Operates
at layer 7
 Translates between most dissimilar
networks
 GSNW…
Networking Concepts – Eric
Vanderburg ©2005