DCN386 SDLC RIPv1 compile

SDLC - HDLC - FrameRelay - PPP

SDLC - Synchronous Data Link Control

SDLC - Datalink Protocol which are Point to Point protocols

The Bank and customer start a PPP so their is no Network Layer Involved

Website for SDLC frame and ALL information:

http://www.cisco.com/univercd/cc/td/doc/cisintwk/ito_doc/sdlcetc.htm

Below will Summerize what was talked about in class:

SDLC + HDLC + PPP have one thing in common

Variable Datasize
- the protocol does not specify the maximum data unit

SDLC Fields

Flag |- 8 bits of information - 01111110 -|

The first zero start bit last zero end bit.

Why? - To know when the message is over because its variable datasize

Start and End bits - Marks between data.

To ward off mixed data when the bits have a consecutive 6 1bits SDLC will put an artificial 0 at the end aka bitstuffing.
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Control Field |- 8 bits of informaiton -|

A three bit frame format field: Info Frame, Supervisory Frame, Unnumbered Frame

Info Frame
0 - in the control field, means information is being transmitted
Supervisory Frame
1 - Supervisory frame
- positive ack
- Negative ack
- Flow control Feature
Unnumbered - Used For Network Management Functions
- Shut down & restart "Banke Machines...."
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Still in the control field
|Sequence Number| - 3 bits - Can send 7 frames before an ack is demanaded
000 - Received SN
000 - Send SN
Error checking is done for the seven frames

If they are all correct their will be a supervisory frame of 111 for completeness

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Supervisory Frame
|Function Code| - 00 = means no errors
01 = errors
11 = stop sending data
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Unnumbered Frame - 5 bits -
| function code |
- Bring up down reset
- Done by a Network Manager Person
- Preforms network management functions
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Info | Supervisory | Unnumbered
| Poll Final |
- 1 bit 2 functions
- Depends on direction
We call computers usings these protocols
Central Units & Primary Units

Primary unit - control the ordered delivery of data

Polling will ask each primary unit if it has data

- When it is coming from the final primary unit a final bit is indicated
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Thats it for SDLC at this time.

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RIPv1 - Request Ip address | Hop Count | Interface ...depending on the Hop count it will choose the lowest one as its main route to destination
- Every 20 seconds a request is made
- Does not address Subnets
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