Residential access: point to point access

1
Residential access point to point access

• Dialup via modem
• up to 56Kbps direct access to router (often less)

• ADSL asymmetric digital subscriber line
• up to 1 Mbps upstream (today typically lt 256
  kbps)
• up to 8 Mbps downstream (today typically lt 1
  Mbps)
• FDM 50 kHz - 1 MHz for downstream
• 4 kHz - 50 kHz for upstream
• 0 kHz - 4 kHz for ordinary
  telephone

2

• Use existing telephone lines
• transmitting higher frequency signals
• Interpret higher frequency signals

3
Residential access cable modems

• HFC hybrid fiber coax
• asymmetric up to 30Mbps downstream, 2 Mbps
  upstream
• network of cable and fiber attaches homes to ISP
  router
• homes share access to router
• deployment available via cable TV companies

4
Cable Network Architecture Overview
Typically 500 to 5,000 homes
cable headend
home
cable distribution network (simplified)
5
Cable modem placement
6
Company access local area networks

• company/univ local area network (LAN) connects
  end system to edge router
• Ethernet
• Shared (hub) or dedicated (switched) link
  connects end system and router
• 10 Mbs, 100Mbps, Gigabit Ethernet
• LANs chapter 5

7
Switch, hub examples

• Suppose C sends frame to D (A, B, C, MAC
  Address)

address
interface
switch
1
1 2 2 3 1
A D E G C
3
2
hub
hub
hub
A
I
F
D
G
B
C
H
E

• Switch receives frame from from C
• notes in bridge table that C is on interface 1
• because D is in table, switch forwards frame into
  interface 2
• frame received by D

8
Wireless access networks

• shared wireless access network connects end
  system to router
• via base station aka access point
• wireless LANs
• 802.11b (WiFi) 11 Mbps
• wider-area wireless access
• provided by telco operator
• 3G 384 kbps
• Will it happen??
• WAP/GPRS in Europe

9
Cellular standards brief survey

• 2.5 G systems voice and data channels
• for those who cant wait for 3G service 2G
  extensions
• general packet radio service (GPRS)
• evolved from GSM
• data sent on multiple channels (if available)
• enhanced data rates for global evolution (EDGE)
• also evolved from GSM, using enhanced modulation
• Date rates up to 384K
• CDMA-2000 (phase 1)
• data rates up to 144K
• evolved from IS-95

10
Cellular standards brief survey

• 3G systems voice/data
• Universal Mobile Telecommunications Service
  (UMTS)
• GSM next step, but using CDMA
• CDMA-2000
• .. more (and more interesting) cellular
  topics due to mobility (stay tuned for details)

11
Home networks

• Typical home network components
• ADSL or cable modem
• router/firewall/NAT
• Ethernet
• wireless access
• point

wireless laptops
to/from cable headend
cable modem
router/ firewall
wireless access point
Ethernet