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Session Protocols

2008-11-30T06:10:00.000-08:00

There are 2 different types of protocols:

Connectionless

No session set-up

No session tear-down

No acknowledgements

No sequencing

No flow control

No keep alives

Connection Oriented

Session set-up

Session tear-down

Acknowledgements

Sequencing

Flow control

A TCP client has to set-up a session with a server before sending data. (handshaking).

Also when completion of transmission the client/server has to 'handshake' to teardown session.

Sessions can use 'sliding windows' if the vendor has set-up the option, used in send / acknowledgement of data.

You would have to set-up the send/receive window, flow control buffer and keep alive state.

The Sliding Windows option makes data transmission fast because the server doesn't have to keep acknowledging each window.

The Client is always in control of the session.

LAN PROTOCOLS

2008-11-29T16:29:00.002-08:00

Local Area Network protocols used in today's network environment are:

Ethernet / Fast Ethernet

Half Duplex:
1. Supported by all 10BaseX and 100BaseX standards
2. Stations listen for collisions whilst transmitting data
3. Single cable type is similar to a narrow one way bridge
Three IEEE 100BaseX standards

TX:
1. Uses same 2 twisted pair as 10mb
2. Supports full duplex
3. 4b5b encoding

FX:
1. Half Duplex - MM 412 metres
2. Full Duplex - MM 2km or SM 10km
3. 4b5b encoding

T4:
(Uses 4 pairs)
1. 3 pairs for Tx and Rx
2. 1 pair for collision detection
3. 8b6t encoding
4. Does not support full duplex mode

Full Duplex
No Collisions
Requires a dedicated point to point connection between two devices
Supported by 10 and 100Base TX and FX standards
Both ends must support full duplex at the software and hardware level
Max distance limitations based on media
Must disable the transceivers loopback and collision detection function
Four Ethernet Encapsulations
Industry Naming
Cisco Naming
Ethernet II
Arpa
Ethernet 802.3
Novell Ether
IEEE Compliant frames
Ethernet 802.3
SAP
Ethernet SNAP
SNAP

Token Ring:
More resilient under heavy data transfer loads
Data runs in a ring formation, each station receives and then repeats the signal to its downstream neighbours
Collisions don't happen because stations can't transmit unless they have a token

FDDI: (File Distributed Data Interface)
Running like token ring
Can run very long distances
Very high speed data transfers

LAN TECHNOLOGIES

2008-11-29T16:29:00.001-08:00

LAN TECHNOLOGIES

LAN devices used in today's networking environment include:
Repeaters / Hubs / Concentrators
Physical layer device
Used to extend the distance of the network
Amplifies and bit repeats
Protocol independent
No traffic segmentation
Generates a new preable (used to sequence devices and know what is data)

Bridges / Switches
Exist as layer 2 devices
Floods, then forwards data
Uses destination hardware address to make decisions about forwarding
Learns where devices are from source hardware address
Protocol independent
Used for Non routable protocols i.e. NetBEUI
Do not filter broadcast or multicast traffic
Do not define separate networks
Each port on a bridge / switch defines a separate Collision Domain.

Bridges:
Store and forward devices
Examines the frame and performs a CRC (Cyclic Redundancy Check)
Does not pass on bad frames
Set-up the 'spanning tree' option to avoid network 'loops' if your bridge has this option.

Switches:
3 main switching methods are:
Cut Through - looks at the first 6 bytes of the destination MAC address only
Fragment free cut through - looks at the first 64 bytes only
Store and forward - looks at the entire frame
Routers and Brouters:
Protocol independent - understand protocol used network layer 3
Network orientated - where to send the data
Used to connect for example, Token Ring to Ethernet
Brouter - router that can bridge traffic (NetBEUI - no layer 3 info)

VLAN's - Virtual LAN's
Set-up by user using switches assigning ports to different networks running different speeds.
Switches have to be linked to a router to assign across an inter-network

Gateway:

Converts one language to another i.e. Microsoft protocol to Novell's protocol, across a network

OSI Model:

2008-11-29T16:28:00.000-08:00

The Open System Interconnect (OSI) model consists of 7 layers:
Layer 7 Application (e-mail, Accessing remote files, printers & databases)
Layer 6 Presentation (Protocol conversion, Data Translation)
Layer 5 Session (Establishes communication connection, Transmit length, time)
Layer 4 Transport (Error handling, Flow control ? Buffer availability)
Layer 3 Network (Route taken, addressing messages)
Layer 2 Data-Link (Frame transmission, acknowledgement)
Layer 1 Physical (Cabling types, Network Interface Cards)
The Application Layer:
Provides applications with network and inter-network services
File and print services
E-Mail (Electronic Mail)
WWW / HTTP (World Wide Web / Hyper Text Transport Protocol)
TELNET (see RFC854)
FTP (File Transfer Protocol)
The Presentation Layer:
Data conversion and translation
Encryption, Decryption
ASCII to EBCDIC (American Standard Code for Information Interchange / Extended binary coded decimal interchange code)
Multimedia - TIFF/JPEG/PICT (Image formats)
Sound - MIDI/MPEG/Quicktime (Sound formats)
The Session Layer:
Controls dialog between 2 applications on different hosts
NFS (Network File Service)
SQL (Structured Query Language)
X Windows (Multi-tasking windowing and graphics system)
NetBIOS (Network basic input/output system)
RFC (Request For Comments)
The Transport Layer:
Controls end to end communications between 2 processes running on different hosts
Provides connection oriented or connection-less services to upper layers
Uses client and server port addresses to identify processes running within a host
Client ports: Are randomly chosen from range above 1024
Server ports: Well known port range 0 - 255, Proprietary ports range 256 - 1023
The Network Layer:
IP, IPX, and DDP (Internet Protocol / Inter-network Packet Exchange / Datagram Delivery Protocol)
Logical addressing
Routers
Routing protocols:
RIP (Routing Information Protocol)
OSPF (Open Shortest Path First)
IGRP (Interior Gateway Routing Protocol)
EIGRP (Enhanced IGRP)

The Data Link Layer:

2 sub-layers: Defined by IEEE (Institute of Electrical and Electronics Engineers)
LLC (802.2) (Logical Link Control)
MAC (Media Access Control)
Layer 2 devices use MAC addresses
Bridges
Switches
The Physical Layer:
Electrical and Mechanical characteristics
Signal Encoding
Synchronisation

--Session Protocols

Session Protocols There are 2 different types of protocols: Connectionless

No session set-up

No session tear-down

No acknowledgements

No sequencing

No flow control

No keep alives

Connection Oriented

Session set-up

Session tear-down

Acknowledgements

Sequencing

Flow control

A TCP client has to set-up a session with a server before sending data. (handshaking).

Also when completion of transmission the client/server has to 'handshake' to teardown session.

Sessions can use 'sliding windows' if the vendor has set-up the option, used in send / acknowledgement of data.

You would have to set-up the send/receive window, flow control buffer and keep alive state.

The Sliding Windows option makes data transmission fast because the server doesn't have to keep acknowledging each window.

The Client is always in control of the session.

Introduction: Course notes taken by Craig Ellis, qualified CCNA+MCP TCP/IP-NT4)

2008-11-29T16:27:00.000-08:00

Covered in the exam course notes will be OSI model definitions, LAN technologies, traffic segmentation, CISCO router components, IP addressing, configuring your router and WAN technologies. What you will need to help you study for this exam is:
2 CISCO 2501 routers with IP and IPX software feature set.
2 DTE / DCE v.35 cables 2 Ethernet transceivers
2 Console cables with adapters
The Exam: There is one exam to take for the CISCO CCNA course (Exam Number 640-801). Your are asked between 55 to 65 questions (three simulation), you have 90 minutes to complete the test, a apx. score of 849 needed to pass. The cost of the exam is approximately £125 (UK).