The IT Stuff

Cisco IOS (originally Internetwork Operating System) is the software used on the  Cisco Systems routers and all current Cisco network switches.

IOS is a package of routing, switching, internetworking and telecommunications functions tightly integrated with a multitasking operating system.

The core of the fiber optic cable is made of very pure and clear material for the easy reflection of light. Mostly glass is used as the core of the fiber optic cable. However plastic may also be used as the core for short distance transmission. The glass of the fiber optic cable is almost always made from pure silica along with other materials like chalcogenide, fluorozirconate and fluoroaluminate which are suitable for longer wavelength infrared applications.

Advantages:

• Offers high speed & large carrying capacity.
• Smaller maintenance costs.
• Provides greater resistance to electromagnetic noise from motors, radios and the neighboring cables, especially power cables.
• Use  light as a transmission medium.
• Suitable for carrying transmission at both long and short distances.

OSPF Packets:

OSPFv3 has five types of packets: hello, DD, LSR, LSU, and LSAck.

OSPF does not use UDP or TCP for transmitting its packets. Instead, it runs directly over IP (IP protocol 89) using an OSPF header. One field in this header identifies the type of packet being carried.

Hello—Identifies neighbors and serves as a keepalive and to elect the DR/BDR,

Database Description (DBD)—A summary of the LSDB, including the RID and sequence number of each LSA in the LSDB  for database synchronization, contents in DD packets including the header of each LSA (uniquely representing a LSA). The LSA header occupies small part of an LSA to reduce traffic between routers. The recipient checks whether the LSA is available using the LSA header.

Link State Request (LSR)—A request for an Link State Update (LSU). Contains the type of LSU requested and the ID of the router requesting it.

Link State Update (LSU)—LSU (Link State Update) packets are used to send the requested LSAs to peers, and each packet carries a collection of LSAs

Link State Acknowledgment (LSAck)—Acknowledges all other OSPF packets (except hellos).

OSPF traffic is multicast to either of two addresses: 224.0.0.5 for all OSPF routers or 224.0.0.6 for all OSPF DRs.

Denial-of-Service Attack:
In DOS Attack after gaining access to your network, the attacker can do any of the following:

• Randomize the attention of your internal Information Systems staff so that they do not see the intrusion immediately, which allows the attacker to make more attacks during the diversion.
• Send invalid data to applications or network services, which causes abnormal termination or behavior of the applications or services.
• Flood a computer or the entire network with traffic until a shutdown occurs because of the overload.
• Block traffic, which results in a loss of access to network resources by authorized users.

Intrusion:
The most common attacks on your systems are intrusions; with intrusions, people are actually able to use your computers. Most attackers want to use your computers as if they were legitimate users.

Buffer Overflows:
Buffer overflows are caused by users entering huge amounts of data into the forms of your website. This data is sent to the server an can cause the server to crash unexpectedly.

Session Hijacking:
A session is a link created once a user provides authentication (ie username and password) to gain access to a system or website. Session Hijacking is performed using tools that allow the hacker to take the authenticated user offline and then take over their session.

• As streaming media applications such as video and multi-media become common, the demands for faster data rates will increase and create new applications that will benefit from the higher bandwidth offered by category 6.
• Difference between category 5e and category 6 is in the transmission performance, and extension of the allowed bandwidth from 100 MHz for category 5e to 200 MHz for category 6.
• Cat6 gives better insertion loss, near end crosstalk (NEXT), return loss, and equal level far end crosstalk (ELFEXT).
• Because of its greater transmission performance and better immunity from external noise, systems operating over 6 cabling will have fewer errors vs. category 5e for current applications.