WANs
Chapter 5
Networking Essentials – Eric Vanderburg © 2005
DSL
DSL is layer 1
 ATM can be used on top of DSL
 PPPoE


CHAP authentication
 IP address assignment




DSLAM (DSL...
Cable Modem
Datalink protocol is MCNS (Multimedia
Cable Network Systems) – Identifies
each modem so shared data is only
pr...
Cable Modem


Downstream data


QAM (Quadrature Amplitude Modulation)
 QAM



64 & QAM 256

Upstream data
QPSK (Quater...
DCE & DTE
CSU/DSU is considered DCE (Data
Communications Equipment) because it
does clocking
 Router is considered DTE (D...
HDLC (High level Data Link
Control)
Cisco uses a proprietary version with a
type field in the header.
 Default for Serial...
PPP (Point to Point Protocol)
FCS in trailer
 Type field
 LCP (Link Control Protocol) - used with
dialed links to bring ...
PPP (Point to Point Protocol)
Magic Number looped link detection
 Supports multilink
 PAP & CHAP support
 Synchronous o...
ISDN
B & D channels
 LAPD (Link Access Procedure D
channel)


used to set up and bring down circuits.
 Q.931 specifies ...
ISDN





B channels are digital so an analog line is
used for the DTMF (Dual Tone Multifrequency) tones
BRI for reside...
ISDN DDR


DDR (Dial on Demand Routing) dials a
link if traffic is waiting to go to a site that
is not currently connecte...
Frame Relay
Frame switching service
 Leased lines from router to FR switch
 Layer 2 address – DLCI (Datalink
connection ...
Frame Relay
PVC (Permanent Virtual Circuit) – link
between 2 devices on a FR network.
PVCs are set up between the devices
...
Frame Relay


LMI (Local Management Interface) – used for
messages sent between router & switch.
Encoding type must be sa...
ATM
Layer 2 protocol using fixed length cells
 Usually runs on top of SONET,
sometimes DSL
 VPI (Virtual Path Identifier...
X.25
Operates on layers 2 & 3
 Reliable with high overhead
 Used in many foreign countries

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CCNA Routing and Switching Lesson 05 - WANs - Eric Vanderburg

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CCNA Routing and Switching Lesson 05 - WANs - Eric Vanderburg

  1. 1. WANs Chapter 5 Networking Essentials – Eric Vanderburg © 2005
  2. 2. DSL DSL is layer 1  ATM can be used on top of DSL  PPPoE  CHAP authentication  IP address assignment   DSLAM (DSL Access Multiplexer) Connection at ISP for DSL. Separates voice from data.  Data is sent over the ISP’s data network rather than the PSTN. 
  3. 3. Cable Modem Datalink protocol is MCNS (Multimedia Cable Network Systems) – Identifies each modem so shared data is only processed by the designated modem.  Different channels are used for upstream & downstream data. 
  4. 4. Cable Modem  Downstream data  QAM (Quadrature Amplitude Modulation)  QAM  64 & QAM 256 Upstream data QPSK (Quaternary Phase Shift Keying)  QAM 16  Same frequency range as other uses (can collide) 
  5. 5. DCE & DTE CSU/DSU is considered DCE (Data Communications Equipment) because it does clocking  Router is considered DTE (Data Terminal Equipment)  Connecting 2 routers directly  Use DTE to DCE cable  One router must have clocking configured 
  6. 6. HDLC (High level Data Link Control) Cisco uses a proprietary version with a type field in the header.  Default for Serial ports  FCS in trailer. Error frames are discarded  Synchronous, sends receiver ready frames when there is no data to synch the line (keep timing for 1’s & 0’s) 
  7. 7. PPP (Point to Point Protocol) FCS in trailer  Type field  LCP (Link Control Protocol) - used with dialed links to bring the connection up  IPCP (IP Control Protocol) allows IP addresses to be assigned over PPP  PPP Callback - incoming connections are disconnected & called back to verify number and stop roaming or unauthorized access 
  8. 8. PPP (Point to Point Protocol) Magic Number looped link detection  Supports multilink  PAP & CHAP support  Synchronous or Asynchronous (used mainly for dial-up)  LQM (Link Quality Monitoring) – takes down links with too many errors  Supports compression but tasks router processor 
  9. 9. ISDN B & D channels  LAPD (Link Access Procedure D channel)  used to set up and bring down circuits.  Q.931 specifies the setup & teardown messages  Circuit switching. Can connect to many sites but circuits are set up by dialing.  SPID (Service Profile Identifier) – provided by the ISP for authenticating B channels. 
  10. 10. ISDN    B channels are digital so an analog line is used for the DTMF (Dual Tone Multifrequency) tones BRI for residential use (2B+D), D channel 16k PRI for business use, D channel 64k   T1 (23B+D), uses AMI (Alternate Mark Inversion) or B8ZS (Binary 8 with Zero Substitution) encoding E1 (30B+D), uses HDB3 (High Density Bipolar 3) encoding
  11. 11. ISDN DDR  DDR (Dial on Demand Routing) dials a link if traffic is waiting to go to a site that is not currently connected Interesting & boring traffic (interesting traffic “triggers the dial”)  Dial mapping - DDR needs to be configured with the networks on each link (static route) & their phone numbers  Idle timeouts allow unused connections to be taken down. 
  12. 12. Frame Relay Frame switching service  Leased lines from router to FR switch  Layer 2 address – DLCI (Datalink connection Identifier), only a place for one DLCI number in FR frames. Changed by switches at destination.  Encapsulation type must be same between routers (Cisco & IETF). Use IETF if both routers are not Cisco. 
  13. 13. Frame Relay PVC (Permanent Virtual Circuit) – link between 2 devices on a FR network. PVCs are set up between the devices you own on the FR network. (Set up by provider)  CIR (Committed Information Rate) – minimum bandwidth specified 
  14. 14. Frame Relay  LMI (Local Management Interface) – used for messages sent between router & switch. Encoding type must be same       Sends keepalive messages Status messages can be used to find DLCI numbers of other routers Cisco LMI uses DLCI 1023 ANSI T1.617-D & ITU Q.933-A LMI’s use DLCI 0 LMI autosense Inverse ARP maps IP addresses to DLCI numbers. Routers send their IP address
  15. 15. ATM Layer 2 protocol using fixed length cells  Usually runs on top of SONET, sometimes DSL  VPI (Virtual Path Identifier) & VCI (Virtual Channel Identifier) – used to switch cells 
  16. 16. X.25 Operates on layers 2 & 3  Reliable with high overhead  Used in many foreign countries 
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