-= Cisco CCNA Diary =-

[coolnezz]

---

ur on the right track... aside from security and network IT. good luck!

as for me, i think i'm going for the SP

yeah i'm more into VoIP, which interest me a lot. and it's one of the hot certs right now since a lot of companies are now implementing VoIP.
currently, i am also taking Network Security class in conjunction with my CCNA courses, in preparation for CompTIA Security+ Cert. Security is a very broad field so i think i would prefer a non-vendor specific certification for now.

we use this book for our Security+ class:
Security+ Guide to Network Security Fundamentals: Mark Ciampa

[coolnezz]

CISCO Certification – a Great Career Option


Acquiring an IT certification is a highly recommended step for any individual planning a career in Information Technology. There are various kinds of certifications that one can go for. The kind of certification depends on the specific field chosen in IT. There are different certifications available for programming professionals, networking professionals, and technicians.

In the field of networking, Cisco is a company well known for its hardware equipment. Cisco systems form the backbone of many a computer networks across the world. Cashing in on this expertise, Cisco has also devised a system of certifications. CISCO certifications test an individual on various aspects of computer networking.

The basic certification level in Cisco is CCNA, which is an acronym for Cisco Certified Network Associate. This certification is designed to check skills such as installation and configuration of Cisco products. This is the basic certification that a candidate needs to acquire before progressing to CCNP and finally the CCIE.

The CCNA certification exam is designed in such a way that it attempts to test all basic aspects of networking specifically in respect to Cisco networks. The exam is a combination of various theory and practice-oriented questions. The CCNA exam generally covers concepts such as:

TCP/IP
LAN Technology
WAN Technology
OSI Model
Communication Protocols

Just as other certification exams, the CCNA exam is an online exam, consisting of a set of multiple-choice questions. The result is declared immediately on completion of the exam. The minimum passing percentage is 84.9%, which means the candidate must get 849 questions right out of a total of 1000.

In the arena of computer networking, CCNA is a highly sought after qualification. Individuals possessing the CCNA certification are able to manage lucrative positions for themselves. Cisco networking equipment is use very widely across the world; hence there is a huge requirement of professionals trained on their use and operation. Moreover, the holding of CCNA by a candidate provides the potential employer a reasonable level of assurance that the person in question has a sound knowledge of Cisco networking devices.

CCNA even provides a tremendous scope for individuals planning to start up their own Network support services. There are millions of small companies around the world who do not employ full-time network engineers, but have a high dependence upon networking. These companies prefer to engage CCNA certified professionals to manage and support their systems on requirement basis.

Once a candidate clears the CCNA exam, he/she becomes eligible to appear for the next level of Cisco certification, i.e., Cisco Certified Networking Professional (CCNP). The CCNP certification exam tests the networking professional’s ability to install and configure large networks typically covering 100 to 500 nodes. It covers technologies such as Broadband and VPNs.

The number of professionals holding CCNP is comparatively less, which is one reason that employers aggressively hunt around for them, and pay them handsomely. The major reason for this hot demand for CCNP professionals is that they possess demonstrated knowledge about high-end concepts such as routers, switches and even wireless networking applications.

The last and the most prestigious level of Cisco certification is the CCIE (Cisco Certified Internetworking Expert). It is an Expert level certification provided by Cisco. Although there are no formal prerequisites, it is recommended by experts that the candidate must have around 3-5 years of networking experience before attempting the CCIE exam. As of September 2006, there were only 13,756 CCIE qualified individuals in the world.

Though it is quite a challenge to clear the CCIE certification exam, it is indeed very rewarding. Owing to the high level of complexity of the CCIE exam, it is assumed by the industry that a CCIE certified professional has an in-depth and expert level knowledge about the networking concepts. It is therefore not surprising that the salary levels of CCIE professionals often cross the $100,000 mark.

Besides the ones detailed above, there are some more certifications that fall under the Cisco brand:

Cisco Certified Design Professional (CCDP): This certification is designed to test advanced knowledge of Cisco devices and network design.
Cisco Certified Security Professional (CCSP): This certification is designed to test advanced knowledge of Cisco network security issues.
Cisco Certified Internetwork Professional (CCIP): This certification is designed to test the use of protocols covering large networks.
Cisco Certified Voice Professional (CCVP): This certification is designed to test all aspects of Internet telephony.

Since it is not easy to acquire a Cisco certification, experts recommend that the candidate must take adequate coaching and guidance before appearing for any such exam. Equally important is a fair amount of practical exposure to the networking industry. Cisco certifications undoubtedly provide a valuable boost to the career of any individual who is involved the computer-networking field.

[IPsuite]

sir coolnezz, i am one of those aspirants. but i am only a beginner. I have questions, I am planning to set up a home lab for me to practice, coz mag self study lang ko, unsa need nako na resources to start like routers kanang barato ra..tnx

[coolnezz]

sir coolnezz, i am one of those aspirants. but i am only a beginner. I have questions, I am planning to set up a home lab for me to practice, coz mag self study lang ko, unsa need nako na resources to start like routers kanang barato ra..tnx

just to give you an idea follow the link below:

Cisco CCNA LAB items



.

[coolnezz]

Open Shortest Path First (OSPF) is a link-state routing protocol that was developed as a replacement for the distance vector routing protocol RIP. RIP was an acceptable routing protocol in the early days of networking and the Internet, but its reliance on hop count as the only measure for choosing the best route quickly became unacceptable in larger networks that needed a more robust routing solution. OSPF is a classless routing protocol that uses the concept of areas for scalability. RFC 2328 defines the OSPF metric as an arbitrary value called cost. The Cisco IOS uses bandwidth as the OSPF cost metric.

OSPF's major advantages over RIP are its fast convergence and its scalability to much larger network implementations. In this final chapter of the Routing Protocols and Concepts course, you will learn basic, single-area OSPF implementations and configurations. More complex OSPF configurations and concepts are reserved for CCNP-level courses.

OSPF packet Type 1 is the OSPF Hello packet. Hello packets are used to:
Discover OSPF neighbors and establish neighbor adjacencies.
Advertise parameters on which two routers must agree to become neighbors.
Elect the Designated Router (DR) and Backup Designated Router (BDR) on multiaccess networks like Ethernet and Frame Relay.

Important fields shown in the figure include:

Type: OSPF Packet Type: Hello (1), DD (2), LS Request (3), LS Update (4), LS ACK (5)
Router ID: ID of the originating router
Area ID: area from which the packet originated
Network Mask: Subnet mask associated with the sending interface
Hello Interval: number of seconds between the sending router's hellos
Router Priority: Used in DR/BDR election (discussed later)
Designated Router (DR): Router ID of the DR, if any
Backup Designated Router (BDR): Router ID of the BDR, if any
List of Neighbors: lists the OSPF Router ID of the neighboring router(s)

Neighbor Establishment

Before an OSPF router can flood its link-states to other routers, it must first determine if there are any other OSPF neighbors on any of its links. In the figure, the OSPF routers are sending Hello packets on all OSPF-enabled interfaces to determine if there are any neighbors on those links. The information in the OSPF Hello includes the OSPF Router ID of the router sending the Hello packet (Router ID is discussed later in the chapter). Receiving an OSPF Hello packet on an interface confirms for a router that there is another OSPF router on this link. OSPF then establishes adjacency with the neighbor. For example, in the figure, R1will establish adjacencies with R2 and R3.

OSPF Hello and Dead Intervals

Before two routers can form an OSPF neighbor adjacency, they must agree on three values: Hello interval, Dead interval, and network type. The OSPF Hello interval indicates how often an OSPF router transmits its Hello packets. By default, OSPF Hello packets are sent every 10 seconds on multiaccess and point-to-point segments and every 30 seconds on non-broadcast multiaccess (NBMA) segments (Frame Relay, X.25, ATM).

In most cases, OSPF Hello packets are sent as multicast to an address reserved for ALLSPFRouters at 224.0.0.5. Using a multicast address allows a device to ignore the packet if its interface is not enabled to accept OSPF packets. This saves CPU processing time on non-OSPF devices.

The Dead interval is the period, expressed in seconds, that the router will wait to receive a Hello packet before declaring the neighbor "down." Cisco uses a default of four times the Hello interval. For multiaccess and point-to-point segments, this period is 40 seconds. For NBMA networks, the Dead interval is 120 seconds.

If the Dead interval expires before the routers receive a Hello packet, OSPF will remove that neighbor from its link-state database. The router floods the link-state information about the "down" neighbor out all OSPF enabled interfaces.

Electing a DR and BDR

To reduce the amount of OSPF traffic on multiaccess networks, OSPF elects a Designated Router (DR) and Backup Designated Router (BDR). The DR is responsible for updating all other OSPF routers (called DROthers) when a change occurs in the multiaccess network. The BDR monitors the DR and takes over as DR if the current DR fails.

Note: The Hello packet is discussed in more detail in CCNP along with the other types of OSPF packets.

[netcommando]

OSPF States:

down, attempt, init, 2-way, Extart, Exchange, loading, full.
Full state - means all the routers database within the AS has already synchronized

[coolnezz]

When OSPF adjacency is formed, a router goes through several state changes before it becomes fully adjacent with its neighbor. Those states are defined in the OSPF RFC 2328 , section 10.1. The states are Down, Attempt, Init, 2-Way, Exstart, Exchange, Loading, and Full. This document describes each state in detail.


Down

This is the first OSPF neighbor state. It means that no information (hellos) has been received from this neighbor, but hello packets can still be sent to the neighbor in this state.

During the fully adjacent neighbor state, if a router doesn't receive hello packet from a neighbor within the RouterDeadInterval time (RouterDeadInterval = 4*HelloInterval by default) or if the manually configured neighbor is being removed from the configuration, then the neighbor state changes from Full to Down.

Attempt

This state is only valid for manually configured neighbors in an NBMA environment. In Attempt state, the router sends unicast hello packets every poll interval to the neighbor, from which hellos have not been received within the dead interval.

Init

This state specifies that the router has received a hello packet from its neighbor, but the receiving router's ID was not included in the hello packet. When a router receives a hello packet from a neighbor, it should list the sender's router ID in its hello packet as an acknowledgment that it received a valid hello packet.

2-Way

This state designates that bi-directional communication has been established between two routers. Bi-directional means that each router has seen the other's hello packet. This state is attained when the router receiving the hello packet sees its own Router ID within the received hello packet's neighbor field. At this state, a router decides whether to become adjacent with this neighbor. On broadcast media and non-broadcast multiaccess networks, a router becomes full only with the designated router (DR) and the backup designated router (BDR); it stays in the 2-way state with all other neighbors. On Point-to-point and Point-to-multipoint networks, a router becomes full with all connected routers.

At the end of this stage, the DR and BDR for broadcast and non-broadcast multiacess networks are elected. For more information on the DR election process, refer to DR Election.

Note: Receiving a Database Descriptor (DBD) packet from a neighbor in the init state will also a cause a transition to 2-way state.

Exstart

Once the DR and BDR are elected, the actual process of exchanging link state information can start between the routers and their DR and BDR.

In this state, the routers and their DR and BDR establish a master-slave relationship and choose the initial sequence number for adjacency formation. The router with the higher router ID becomes the master and starts the exchange, and as such, is the only router that can increment the sequence number. Note that one would logically conclude that the DR/BDR with the highest router ID will become the master during this process of master-slave relation. Remember that the DR/BDR election might be purely by virtue of a higher priority configured on the router instead of highest router ID. Thus, it is possible that a DR plays the role of slave. And also note that master/slave election is on a per-neighbor basis.

Exchange

In the exchange state, OSPF routers exchange database descriptor (DBD) packets. Database descriptors contain link-state advertisement (LSA) headers only and describe the contents of the entire link-state database. Each DBD packet has a sequence number which can be incremented only by master which is explicitly acknowledged by slave. Routers also send link-state request packets and link-state update packets (which contain the entire LSA) in this state. The contents of the DBD received are compared to the information contained in the routers link-state database to check if new or more current link-state information is available with the neighbor.

Loading

In this state, the actual exchange of link state information occurs. Based on the information provided by the DBDs, routers send link-state request packets. The neighbor then provides the requested link-state information in link-state update packets. During the adjacency, if a router receives an outdated or missing LSA, it requests that LSA by sending a link-state request packet. All link-state update packets are acknowledged.

Full

In this state, routers are fully adjacent with each other. All the router and network LSAs are exchanged and the routers' databases are fully synchronized.

Full is the normal state for an OSPF router. If a router is stuck in another state, it's an indication that there are problems in forming adjacencies. The only exception to this is the 2-way state, which is normal in a broadcast network. Routers achieve the full state with their DR and BDR only. Neighbors always see each other as 2-way.

[hemp_republic]

nice.. nice.. thanks mga masters.. followers lang ko ninyo.. LOL..

[netcommando]

@coolnezz;

how you may differentiate routing protocols and routed protocols?

[coolnezz]

@coolnezz;

how you may differentiate routing protocols and routed protocols?

Routing Protocols are RIP, OSPF, EIGRP, BGP, these are the protocols that are doing the routing, used for communication between routers to update routing tables.

Routed Protocols are Internet Protocol (IP) and Internetwork Packet Exchange (IPX), the protocols that are being routed.