Routing Protocols

In determining the best route to a destination, different routing protocols use a number of different measurements. These measurements are called metrics. Each routing protocol uses one or more metric to calculate the best route to a particular destination. The most common metrics include path length (hop count), reliability, delay, bandwidth, load, and financial cost of a link.

Another major difference between routing protocols is how they handle updating each other with current information. There are many methods of doing this. Given these major differences, routing protocols are broken into two main categories: Distance Vector and Link State.
Distance Vector protocols include RIP and IGRP. They send their entire routing tables out in all directions at regularly scheduled intervals.

Link State protocols are more advanced than distance vector protocols because, unlike distance vector, they do not send periodic routing updates. Link State protocols include OSPF, NLSP, BGP, and IS-IS.

They send partial routing tables (of their own networks) to everyone and then send updates when necessary.

Cisco Hierarchical Internetworking Model

Cisco characterizes networks by using a three-level hierarchical model. This helps clarify the purpose of each device in the network. Cisco calls them the Access, Distribution, and Core levels. They are described here:

Access level
Where end (user) nodes access the network. These are closet or desktop routers or switches. If the network is designed well, a good portion of the intra-workgroup traffic will remain at the Access level. VLANs are implemented at this level. Some basic filtering can happen here, but it is usually implemented at the distribution level. If there are WAN connections, they would connect the Access level to the Distribution level.

Distribution level
Aggregates the Access level connections to the Core level. Oversubscription of bandwidth happens here (150 10Mbps access-level users do not require a T1 to the Core, because they will not all use this bandwidth at the same time). Most Access Lists, compression, and encryption should be implemented here. Devices at this level are almost exclusively routers.

Core level
Concentrates all traffic that needs to transverse the network. The focus here is switching traffic as fast as possible. ATM, Gigabit, SONET, and other high-speed technologies are usually implemented here (although it is becoming more common to see higher speeds closer to the Access level, as equipment prices drop).

OSI Layer [ MUST REMEMBER ]

OSI MODEL [ hell important, MUST REMEMBER! ]

7. Application Away
6. Presentation Pizza
5. Session Sossej
4. Transport Throw
3. Network Not
2. Data link Do
1. Physical Please


PHYSICAL = Binary Transmission
- Wires, connectors, voltages, data rates.

DATA LINK = Direct Link Control, Access to Media
- Provides connectivity between two host.
- No error correction, best effort delivery.

NETWORK = Network Address and Best Path Determination
- Provides reliable transfer of data across media.
- Physical addressing, network topology, error notification,
flow control.

TRANSPORT = End to end connection
- Concerned with transportation issues between host.
- Data transport reliability.
- Establish, maintain, terminate virtual circuit.
- Fault detection and recovery information flow control.

SESSION = Interhost Session
- Establishes, manages and terminates sessions between applications.


PRESENTATION = Data Presentation
- Ensure that the data is readable when receiving the system.
- Format of data.
- Data structures.
- Nagiotates data transfer syntax for application layer.


APPLICATION = Network Processor to Application
- Provides network services to application processes such as
electronic mail, file transfer and terminal emulasion.

Protection on Network Attack

PROTECTION ON NETWORK ATTACK :)

Encryption
Policy ( Rules) - obey the rules.
Software - antivirus, spyware software,password.
Hardware - thumb scan, finger print.
Physical Control - ownself protection of the belonging such as using laptop lock
[ am not very sure what its been called act.. hihihi=)

above are the method used for the vital protection.

ENCRYPTION :

the READABLE text/plain change to unreadable text.

DECRYPTION :

change the UNREADABLE text to plain text.

TYPE OF ENCRYTION:

3 Chipping Step
counting three step forward of the alphabet to become new alphabet.
extra info !!
pioneer of 3 step chipping is Julies Ceasar.


Streganography
hidden word in one extra block of text.
can be break using software called GIF IT UP.
a combination of text and graphic, after being encrypt get the info.
extra info!!
using by AL QAEDA to crush the World Trade Centre.

Digital Drop Box
secret info in the draft email.

Network Security Notes

NETWORK SECURITY

1st level INFORMATION SECURITY = if hardcopy its been written P&C.
[private & confidental]

2nd level NETWORK SECURITY = unable to surf on some pages/access denied.


3rd level PC/DEVICE SECURITY = firewall, antivirus, ZIP folders, password.


NETWORK SECURITY can be ATTACK by 4 ways :-


INTERRUPTION = block the signal. receiver don't get the information that being send
via sender.


INTERSEPTION = view the vital/private information before its being send to
the receiver.


MODIFICATION = alter/twist the info to be wrongly understood for receiver.


FABRICATION = create/fabricate fake/independent information to the sender which
is the info never mean to be send/state for receiver.


SOCIAL ENGINEERING ATTACK = pretend to be someone else to take advantages or
to get an information. [ BEWARE !!! ]