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Metacognition

Metacognition is defined as "cognition about cognition", or "knowing about knowing". It can take many forms; it includes knowledge about when and how to use particular strategies for learning or for problem solving.There are generally two components of metacognition: knowledge about cognition, and regulation of cognition.

Metamemory, defined as knowing about memory and mnemonic strategies, is an especially important form of metacognition. Differences in metacognitive processing across cultures have not been widely studied, but could provide better outcomes in cross-cultural learning between teachers and students.

Some evolutionary psychologists hypothesize that metacognition is used as a survival tool, which would make metacognition the same across cultures. Writings on metacognition can be traced back at least as far as De Anima and the Parva Naturalia of the Greek philosopher Aristotle.

 J. H. Flavell first used the word "metacognition".He describes it in these words:

    Metacognition refers to one’s knowledge concerning one's own cognitive processes and products or anything related to them, e.g., the learning-relevant properties of information or data. For example, I am engaging in metacognition if I notice that I am having more trouble learning A than B; [or] if it strikes me that I should double check C before accepting it as fact.
    —J. H. Flavell (1976, p. 232).

A. Demetriou, in his theory, one of the neo-Piagetian theories of cognitive development, used the term hypercognition to refer to self-monitoring, self-representation, and self-regulation processes, which are regarded as integral components of the human mind. Moreover, with his colleagues, he showed that these processes participate in general intelligence, together with processing efficiency and reasoning, which have traditionally been considered to compose fluid intelligence.

Metacognition also thinks about one's own thinking process such as study skills, memory capabilities, and the ability to monitor learning. This concept needs to be explicitly taught along with content instruction. Metacognitive knowledge is about our own cognitive processes and our understanding of how to regulate those processes to maximize learning. Some types of metacognitive knowledge would include: 1. Person knowledge (declarative knowledge) which is understanding one's own capabilities. 2. Task knowledge (procedural knowledge) which is how one perceives the difficulty of a task which is the content, length, and the type of assignment. 3. Strategic knowledge (conditional knowledge) which is one's own capability for using strategies to learn information. Young children are not particularly good at this; it is not until upper elementary where students start to develop the understanding of strategies that will be effective.

Different fields define metacognition very differently. Metacognition variously refers to the study of memory-monitoring and self-regulation, meta-reasoning, consciousness/awareness and auto-consciousness/self-awareness. In practice these capacities are used to regulate one's own cognition, to maximize one's potential to think, learn and to the evaluation of proper ethical/moral rules.

In the domain of experimental psychology, an influential distinction in metacognition (proposed by T. O. Nelson & L. Narens) is between Monitoring—making judgments about the strength of one's memories—and Control—using those judgments to guide behavior (in particular, to guide study choices). Dunlosky, Serra, and Baker (2007) covered this distinction in a review of metamemory research that focused on how findings from this domain can be applied to other areas of applied research.

In the domain of cognitive neuroscience, metacognitive monitoring and control has been viewed as a function of the prefrontal cortex, which receives (monitors) sensory signals from other cortical regions and through feedback loops implements control (see chapters by Schwartz & Bacon and Shimamura, in Dunlosky & Bjork, 2008).

Metacognition is studied in the domain of artificial intelligence and modelling. Therefore, it is the domain of interest of emergent systemics. It has been used, albeit off the original definition, to describe one's own knowledge that we will die. Writers in the 1990s involved with the musical "grunge" scene often used the term to describe self-awareness of mortality.[citation needed]
 
* Components
Metacognition is classified into three components:
 
Metacognitive knowledge (also called metacognitive awareness) is what individuals know about themselves and others as cognitive processors.Metacognitive regulation is the regulation of cognition and learning experiences through a set of activities that help people control their learning. Metacognitive experiences are those experiences that have something to do with the current, on-going cognitive endeavor.

Metacognition refers to a level of thinking that involves active control over the process of thinking that is used in learning situations. Planning the way to approach a learning task, monitoring comprehension, and evaluating the progress towards the completion of a task: these are skills that are metacognitive in their nature.

Metacognition includes at least three different types of metacognitive awareness when considering metacognitive knowledge:
 
Declarative Knowledge: refers to knowledge about oneself as a learner and about what factors can influence one's performance. Declarative knowledge can also be referred to as "world knowledge".
 
Procedural Knowledge: refers to knowledge about doing things. This type of knowledge is displayed as heuristics and strategies.A high degree of procedural knowledge can allow individuals to perform tasks more automatically. This is achieved through a large variety of strategies that can be accessed more efficiently.
 
Conditional knowledge: refers to knowing when and why to use declarative and procedural knowledge.It allows students to allocate their resources when using strategies. This in turn allows the strategies to become more effective.

Similar to metacognitive knowledge, metacognitive regulation or "regulation of cognition" contains three skills that are essential.
 
Planning: refers to the appropriate selection of strategies and the correct allocation of resources that affect task performance.

Monitoring: refers to one's awareness of comprehension and task performance 

Evaluating: refers to appraising the final product of a task and the efficiency at which the task was performed. This can include re-evaluating strategies that were used.

Similarly, maintaining motivation to see a task to completion is also a metacognitive skill. The ability to become aware of distracting stimuli – both internal and external – and sustain effort over time also involves metacognitive or executive functions. The theory that metacognition has a critical role to play in successful learning means it is important that it be demonstrated by both students and teachers.

Students who demonstrate a wide range of metacognitive skills perform better on exams and complete work more efficiently. They are self-regulated learners who utilize the "right tool for the job" and modify learning strategies and skills based on their awareness of effectiveness. Individuals with a high level of metacognitive knowledge and skill identify blocks to learning as early as possible and change "tools" or strategies to ensure goal attainment. Swanson (1990) found that metacognitive knowledge can compensate for IQ and lack of prior knowledge when comparing fifth and sixth grade students' problem solving. Students with a high-metacognition were reported to have used fewer strategies, but solved problems more effectively than low-metacognition students, regardless of IQ or prior knowledge.

Metacognologists are aware of their own strengths and weaknesses, the nature of the task at hand, and available "tools" or skills. A broader repertoire of "tools" also assists in goal attainment. When "tools" are general, generic, and context independent, they are more likely to be useful in different types of learning situations.

Another distinction in metacognition is executive management and strategic knowledge. Executive management processes involve planning, monitoring, evaluating and revising one's own thinking processes and products. Strategic knowledge involves knowing what (factual or declarative knowledge), knowing when and why (conditional or contextual knowledge) and knowing how (procedural or methodological knowledge). Both executive management and strategic knowledge metacognition are needed to self-regulate one's own thinking and learning.

Finally, there is no distinction between domain-general and domain-specific metacognitive skills. This means that metacognitive skills are domain-general in nature and there are no specific skills for certain subject areas. The metacognitive skills that are used to review an essay are the same as those that are used to verify an answer to a math question.

Metacognitive experience is responsible for creating an identity that matters to an individual. The creation of the identity with meta-cognitive experience is linked to the identity-based motivation (IBM) model. The identity-based motivation model implies that "identities matter because they provide a basis for meaning making and for action." A person decides also if the identity matters in two ways with meta-cognitive experience. First, a current or possible identity is either "part of the self and so worth pursuing" or the individual thinks that the identity is part of their self, yet it is conflicting with more important identities and the individual will decide if the identity is or is not worth pursuing. Second, it also helps an individual decide if an identity should be pursued or abandoned.

Usually, abandoning identity has been linked to meta-cognitive difficulty. Based on the identity-based motivation model there are naive theories describing difficulty as a way to continue to pursue an identity. The incremental theory of ability states that if "effort matters then difficulty is likely to be interpreted as meaning that more effort is needed." Here is an example, a woman who loves to play clarinet has come upon a hard piece. She knows that how much effort she puts into learning this piece is beneficial. The piece had difficulty so she knew the effort was needed. The identity the woman wants to pursue is to be a good clarinet player, having a metacognitive experience difficulty pushed her to learn the difficult piece to continue to identify with her identity. The entity theory of ability represents the opposite. This theory states that if "effort does not matter then difficulty is likely to be interpreted as meaning that ability is lacking so effort should be suspended." Based on the example of the woman playing the clarinet, if she did not want to identify herself as a good clarinet player, she would not have put in any effort to learn the difficult piece which is an example of using metacognitive experience difficulty to abandon an identity.
 
* Relation to sapience

Metacognologists believe that the ability to consciously think about thinking is unique to sapient species and indeed is one of the definitions of sapience.[citation needed] There is evidence that rhesus monkeys and apes can make accurate judgments about the strengths of their memories of fact and monitor their own uncertainty,while attempts to demonstrate metacognition in birds have been inconclusive. A 2007 study has provided some evidence for metacognition in rats, but further analysis suggested that they may have been following simple operant conditioning principles, or a behavioral economic model.

* Metacognitive strategies

Metacognitive-like processes are especially ubiquitous when it comes to the discussion of self-regulated learning. Being engaged in metacognition is a salient feature of good self-regulated learners[citation needed]. Groups reinforcing collective discussion of metacognition is a salient feature of self-critical and self-regulating social groups[citation needed]. The activities of strategy selection and application include those concerned with an ongoing attempt to plan, check, monitor, select, revise, evaluate, etc.

Metacognition is 'stable' in that learners' initial decisions derive from the pertinent fact about their cognition through years of learning experience. Simultaneously, it is also 'situated' in the sense that it depends on learners' familiarity with the task, motivation, emotion, and so forth. Individuals need to regulate their thoughts about the strategy they are using and adjust it based on the situation to which the strategy is being applied. At a professional level, this has led to emphasis on the development of reflective practice, particularly in the education and health-care professions.

Recently, the notion has been applied to the study of second language learners in the field of TESOL and applied linguistics in general (e.g., Wenden, 1987; Zhang, 2001, 2010). This new development has been much related to Flavell (1979), where the notion of metacognition is elaborated within a tripartite theoretical framework. Learner metacognition is defined and investigated by examining their person knowledge, task knowledge and strategy knowledge.

Wenden (1991) has proposed and used this framework and Zhang (2001) has adopted this approach and investigated second language learners' metacognition or metacognitive knowledge. In addition to exploring the relationships between learner metacognition and performance, researchers are also interested in the effects of metacognitively-oriented strategic instruction on reading comprehension (e.g., Garner, 1994, in first language contexts, and Chamot, 2005; Zhang, 2010). The efforts are aimed at developing learner autonomy, interdependence and self-regulation.

Metacognition helps people to perform many cognitive tasks more effectively.[1] Strategies for promoting metacognition include self-questioning (e.g. "What do I already know about this topic? How have I solved problems like this before?"), thinking aloud while performing a task, and making graphic representations (e.g. concept maps, flow charts, semantic webs) of one's thoughts and knowledge. Carr, 2002, argues that the physical act of writing plays a large part in the development of metacognitive skills.

Strategy Evaluation matrices (SEM) can help to improve the knowledge of cognition component of metacogntion. The SEM works by identifying the declarative (Column 1), procedural (Column 2) and conditional (Column 3 and 4) knowledge about specific strategies. The SEM can help individuals identify the strength and weaknesses about certain strategies as well as introduce them to new strategies that they can add to their repertoire.

A regulation checklist (RC) is a useful strategy for improving the regulation of cognition aspect of one’s metacognition. RCs help individuals to implement a sequence of thoughts that allow them to go over their own metacogntion.[32] King (1991) found that fifth-grade students who used a regulation checklist outperformed control students when looking at a variety of questions including written problem solving, asking strategic questions, and elaborating information.

Metacognitive strategies training can consist of coaching the students in thinking skills that will allow them to monitor their own learning. Examples of strategies that can be taught to students are word analysis skills, active reading strategies, listening skills, organizational skills and creating mnemonic devices.

* Meta-Strategic Knowledge
“Meta-Strategic Knowledge” (MSK) is a sub-component of metacognition that is defined as general knowledge about higher order thinking strategies. MSK had been defined as “general knowledge about the cognitive procedures that are being manipulated”. The knowledge involved in MSK consists of “making generalizations and drawing rules regarding a thinking strategy” and of “naming” the thinking strategy.

The important conscious act of a meta-strategic strategy is the “conscious” awareness that one is performing a form of higher order thinking. MSK is an awareness of the type of thinking strategies being used in specific instances and it consists of the following abilities: making generalizations and drawing rules regarding a thinking strategy, naming the thinking strategy, explaining when, why and how such a thinking strategy should be used, when it should not be used, what are the disadvantages of not using appropriate strategies, and what task characteristics call for the use of the strategy.[36]

MSK deals with the broader picture of the conceptual problem. It creates rules to describe and understand the physical world around the people who utilize these processes called Higher-order thinking. This is the capability of the individual to take apart complex problems in order to understand the components in problem. These are the building blocks to understanding the “big picture” (of the main problem) through reflection and problem solving.[37]

* Characteristics of Theory of Mind: Understanding the mind and the "mental world": 
False beliefs: understanding that a belief is only one of many and can be false.
Appearance–reality distinctions: something may look one way but may be something else.
Visual perspective taking: the views of physical objects differ based on perspective.
Introspection: children's awareness and understanding of their own thoughts.

* Mental Illness and Metacognition 
  Sparks of Interest

In the context of mental health, metacognition can be loosely defined as the process that "reinforces one's subjective sense of being a self and allows for becoming aware that some of one's thoughts and feelings are symptoms of an illness.[38]" The interest in metacognition emerged out of a concern for an individual’s ability to understand their own mental status compared to others as well as the ability to cope with the source of their distress. These insights into an individual's mental health status can have a profound affect on the over-all prognosis and recovery. Metacognition brings many unique insights into the normal daily functioning of a human being. It also demonstrates that a lack of these insights compromises ‘normal’ functioning. This leads to less healthy functioning. In the Autism spectrum, there is a profound inability to feel empathy towards the minds of other human beings. In people who identify as alcoholics, there is a belief that the need to control cognitions is an independent predictor of alcohol use over anxiety. Alcohol may be used as a coping strategy for controlling unwanted thoughts and emotions formed by negative perceptions. This is sometimes referred to as self medication.

* Implications
Well’s and Matthew’s theory proposes that when faced with an undesired choice, an individual can operate in two distinct modes: ‘object’ and ‘Metacognitive.’ Object mode interprets perceived stimuli as truth, where Metacognitive mode understands thoughts as cues that have to be weighted and evaluated. They are not as easily trusted. There are targeted interventions unique of each patient, that gives rise to the belief that assistance in increasing metacognition in people diagnosed with schizophrenia is possible through tailored psychotherapy. With a customized therapy in place clients then have the potential to develop greater ability to engage in complex self-reflection. This can ultimately be pivotal in the patient's recovery process. In the Obsessive Compulsive Disorder spectrum, cognitive formulations have greater attention to intrusive thoughts related to the disorder. "Cognitive Self-Consciousness" are the tendencies to focus attention on thought. Patients with OCD exemplify varying degrees of these ‘intrusive thoughts.’ Patients also suffering from Generalized Anxiety Disorder also show negative thought process in their cognition.

With any metacognition strategy, the general consensus is to believe that they are good. But in all actuality some may be very harmful. Cognitive-Attentional Syndrome (CAS) characterizes a Metacognitive model of emotion disorder. CAS is consistent with the constant with the attention strategy of excessively focusing on the source of a threat. This ultimately develops through the client’s own beliefs. Metacognitive therapy attempts to correct this change in the CAS. One of the techniques in this model is called Attention Training (ATT). It was designed to diminish the worry and anxiety by a sense of control and cognitive awareness. Also ATT trains clients to detect threats, test how controllable reality appears to be.

* Works of art as metacognitive artifacts
The concept of metacognition has also been applied to reader-response criticism. Narrative works of art, including novels, movies and musical compositions, can be characterized as metacognitive artifacts which are designed by the artist to anticipate and regulate the beliefs and cognitive processes of the recipient, for instance, how and in which order events and their causes and identities are revealed to the reader of a detective story. As Menakhem Perry has pointed out, mere order has profound effects on the aesthetical meaning of a text. Narrative works of art contain a representation of their own ideal reception process. They are something of a tool with which the creators of the work wish to attain certain aesthetical and even moral effects.

Courtesy of: http://en.wikipedia.org/wiki/Metacognition

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Job Description for Network Engineering

Network engineers are responsible for installing, maintaining and supporting computer communication networks within an organisation or between organisations. Their goal is to ensure the smooth operation of communication networks in order to provide maximum performance and availability for their users, such as staff, clients, customers and suppliers.

Network engineers may work internally as part of an organisation’s IT support team or externally as part of an IT networking consultancy firm working with a number of clients.

Other job titles used to refer to this kind of work include network support, support engineer, IT support engineer, helpdesk support, network administrator, first-line support, second-line support, security engineer and network architect.

Typical work activities

The work is influenced by the size and type of the employing organisation. In a large investment bank for example, a network engineer may have specific responsibility for one area of the system. In a small company, the engineer may be troubleshooter for almost any IT-related problem that arises.

* There are different types of network, such as:
 
  1. LANs - local area networks, linking a limited area such as a home, office or small group of buildings.
  2. MANs - metropolitan area networks, linking a large area such as a campus or city
  3. WANs - wide area networks, which link nationally or internationally
  4. GANs - global area networks, combining all of the above with satellite mobile-communication technologies.

* The type of network will affect the engineer's responsibilities. Typical tasks usually include:
  1. Installing, supporting and maintaining new server hardware and software infrastructure
  2. Managing email, anti-spam and virus protection
  3. Setting up user accounts, permissions and passwords
  4. Monitoring network usage
  5. Ensuring the most cost-effective and efficient use of servers
  6. Suggesting and providing IT solutions to business and management problems
  7. Ensuring that all IT equipment complies with industry standards
  8. Analysing and resolving faults, ranging from a major system crash to a forgotten password
  9. Undertaking routine preventative measures and implementing, maintaining and monitoring network security, particularly if the network connects to the internet
  10. Providing training and technical support for users with varying levels of IT knowledge and competence
  11. Supervising other staff, such as help-desk technicians
  12. Working closely with other departments/organisations and collaborating with other IT staff
  13. Planning and implementing future IT developments and undertaking project work
  14. Managing the website and keeping internal networks running
  15. Monitoring the use of the web by employees.
Posts entitled 'technical support' usually include responsibility for other IT equipment, such as printers and scanners 

Courtesy of : http://www.prospects.ac.uk/network_engineer_job_description.htm
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Arsitektur jaringan komputer

Model arsitektur menyediakan pendekatan dalam bentuk modular fungsional pada desain sebuah jaringan. Selain hirarki, modul digunakan untuk mengatur kumpulan perangkat server (server farm), manajemen jaringan, jaringan-jaringan kampus, Jaringan berskala WAN dan Internet.

* Model jaringan berbentuk hirarki   
  
Menurut  CCDA 640-864 Official Cert Guide (2011,p40), model berbentuk hirarki (Hierarchical model), memungkinkan kita untuk merancang internetworks, yang mengkombinasikan fungsi –fungsi, disesuaikan pada hirarki organisasi. Seperti menyederhanakan sebuah tugas-tugas desain untuk membangun jaringan, serta memenuhi kebutuhan saat ini dan dapat tumbuh untuk memenuhi kebutuhan masa depan.

Model hirarki menggunakan lapisan-lapisan (layers) untuk menyederhanakan tugas-tugas pada internetworking. Setiap lapisan fokus pada fungsi spesifik, memungkinkan Anda untuk memilih sistem dan fitur yang tepat, untuk setiap lapisan. Model hirarki berlaku baik untuk terminologi desain LAN dan WAN.

* Manfaat model hirarki
 
Manfaat menggunakan model hirarki untuk desain jaringan meliputi:
1.Penghematan biaya
2.Memudahkan pemahaman perancangan
3.Mudah mengembangkan jaringan karena berbasis modular
4.Memudahkan perawatan (maintenance), dalam melakukan isolasi pemulihan jaringan    

Manajer jaringan dapat dengan mudah mengerti dan menentukan awal perubahan (transisi) dalam jaringan, yang membantu mengidentifikasi sebuah kegagalan, karena akan lebih sulit memecahkan masalah, jika desain secara hirarki atau pembagian segment tidak digunakan.

* Desain jaringan berbentuk hirarki

Pada gambar 3.3 menunjukkan secara umum, desain hirarki yang diterapkan pada terminologi LAN, dan dibagi menjadi tiga lapisan (layers), menurut CCDA 640-864 Official Cert Guide: (2011,p41) :


Gambar 2.5: Model hirarki terdiri dari: Core, Distribution, and Access
Sumber: CCDA 640-864 Official Cert Guide: (2011,p41)

Adapun lapisan-lapisan yang membagi hirarki jaringan komputer berdasarkan CCDA 640-864 Official Cert Guide: (2011,p41) adalah:1.Core Layer (Lapisan Core)

Core layer (lapisan inti) adalah lapisan yang menangani switching berkecepatan tinggi dan sangat penting, karena menunjukkan karakteristik jaringan, bagi sebuah corporate atau perusahaan.

Ciri-ciri jaringan lapisan core (core layer):

a.Fast Transport
b.Kehandalan tinggi
c.Adanya redundansi
d.Toleransi kesalahan
e.Latensi rendah dan pengelolaan yang baik
f.Terbatas dan diameter yang konsisten
g.QOS (Quality Of Service)

Ketika jaringan menggunakan perangkat router, jumlah lompatan (hop) antara router yang satu dengan yang lainnya disebut diameter. Sebagai catatan, sangat dibutuhkan sebuah diameter yang konsisten diantara hirarki jaringan. Perjalanan dari satu stasiun (node) ke  stasiun (node) yang lain diantara backbone, harus memiliki jumlah hop yang sama. Jarak dari stasiun akhir (node) ke server dalam backbone juga harus konsisten.

Membatasi diameter internetwork, menyediakan kinerja yang dapat diprediksi dan kemudahan dalam troubleshooting. Kita dapat menambahkan router yang berjalan pada layer distribusi dan klien LAN  ke dalam model hirarki, tanpa meningkatkan diameter pada lapisan core.


2.Distribution layer (lapisan distribusi)

Lapisan distribusi didalam jaringan adalah titik isolasi di antara lapisan jaringan access dan lapisan core. Lapisan distribusi dapat memiliki banyak aturan, termasuk melaksanakan fungsi-fungsi dibawah ini:

a.Konektivitas berbasis kebijakan (misalnya, memastikan bahwa lalu lintas yang dikirim dari jaringan tertentu  diteruskan ke satu antarmuka, sementara semua lalu lintas lainnya diteruskan keluar antarmuka yang lain adanya access list.

b.Redundansi dan Load balancing
c.Agregasi antara jaringan LAN
d.Agregari antara koneksi WAN
e.Quality Of Service (QOS)
f.Filter keamanan
g.Broadcast atau multicast definisi domain
h.Routing antara Virtual LAN
i.Media Translasi (contoh, antara Ethernet dan Token Ring)
j.Redistribusi antara domain-domain routing (contoh, routing antara dua protokol yang berbeda
k.Sebagai pembatas antara protokol routing yang statik dan dinamis.

3.Access Layer (lapisan akses)


Lapisan akses menyediakan akses pengguna ke segmen-segmen lokal pada jaringan. Fungsi daripada access layer meliputi, yaitu:

a.Layer 2 switching
b.Ketersediaan yang tinggi
c.Keamanan port
d.Inspeksi protokol ARP (Address Resolution Protocol)
e.Spanning Tree
f.Power over ethernet (PoE)
g.Pembatasan rate traffic/policy
h.Virtual access control lists (VACL)
i.Auxiliary VLAN

Pada gambar 2.6 mendeskripsikan layanan switching pada desain jaringan dengan model hirarki:


 Gambar 2.6: Layanan switching pada model hirarki jaringan
Sumber: CCDA 640-864 Official Cert Guide: (2011,p46)

 Pada gambar 2.7 mendeskripsikan layanan routing pada desain jaringan dengan model berhirarki:


Gambar 2.7: Layanan routing pada model hirarki jaringan
Sumber: CCDA 640-864 Official Cert Guide: (2011,p46)


Keuntungan lainnya di dalam penerapan jaringan berbasis hirarki adalah, pemisahan broadcast domain sesuai dengan segment nya masing-masing, sehingga pemanfaatan kapasitas bandwidth dapat di optimalkan.

Gambar 2.8: Jaringan menggunakan perangkat switch yang rata (flat)
Sehingga menghasilkan suatu broadcast domain yang besar
Sumber: CCNA Discovery Learning Guide: (2008, p4)

 
Pada gambar 2.9 dibawah ini menunjukan jaringan yang menggunakan model hirarki, dan terlihat bahwa pembagian broadcast domain di lakukan secara terpisah. 


Gambar 2.9: Jaringan menggunakan hirarki dan pembagian broadcast domain dilakukan secara terpisah
Sumber: CCNA Discovery Learning Guide: (2008, p4)

Menerapkan saluran yang memiliki redundansi (backup) pada lapisan core, bertujuan untuk memberikan jalur alternatif, jika terjadi kegagalan dan kerusakan pada saluran utama. Ketika perangkat-perangkat layer 3 ditempatkan pada layer core, jalur redundansi ini dapat digunakan untuk mengatur load balancing dalam hal menyediakan backup. Melalui penambahan protokol STP (Spanning Tree Protocol) jalur backup akan di matikan terlebih dahulu (disable), terkecuali ketika jalur utama putus, maka secara otomatis jalur backup akan menjadi aktif kembali. 


Gambar 2.10: Redundansi dalam topologi mesh yang berbasis hirarki
Sumber: CCNA Discovery Learning Guide: (2008, p12)
 

Br
Zaid Amin

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Topologi Cisco EtherChannel

Pada gambar 2.1 menunjukkan beberapa penerapan umum teknologi Cisco EtherChannel, dan bagaimana teknologi Cisco EtherChannel ini memecahkan persoalan kebutuhan bandwidth. Fast EtherChannel dan Fast Ethernet Link akan digunakan di seluruh contoh ini. Gambar 2.1 menunjukkan jaringan yang menggunakan koneksi Cisco EtherChannel. Bandwidth antara wiring closets dan data center telah digandakan, dari 200 Mbps sampai 400 Mbps. Selain peningkatan bandwidth, ketahanan dalam saluran di sediakan untuk konvergensi subseconds jika salah satu link mengalami kegagalan.
Gambar 2.1: Penambahan kinerja (Cisco EtherChannel) diantara Wiring Closets dan Data Center
Sumber: (Cisco EtherChannel Technology: 2003, p4)


Pada Gambar 2.2  menunjukkan topologi, dimana manajer jaringan telah meningkatkan bandwidth antara data center dan wiring closets, untuk sebuah link agregate menjadi 800 Mbps. Serta menambahkan diversity (backup) berupa kabel fiber optic, untuk mengurangi kemungkinan adanya kegagalan jaringan, menggunakan koneksi teknologi Cisco EtherChannel yang terdiri dari empat Fast Ethernet Link, dan dua kabel fiber optic yang  berjalan di sisi timur bangunan, yang menyediakan 400 Mbps, dan sisi barat bangunan menyediakan sisanya 400 Mbps. Dalam contoh ini, jika sebuah serat ada yang dipotong di satu sisi bangunan, maka sisi yang tersisa akan mengambil lalu lintas dalam waktu kurang dari satu detik, tanpa memutus sesi koneksi client yang terhubung dengan wiring closets.

Gambar 2.2: Penambahan Bandwidth dengan ketahanan jaringan (Resilience)
Sumber: (Cisco EtherChannel Technology: 2003, p4)

Pada Gambar 2.3 menunjukkan konfigurasi dimana sebuah switch telah dikonfigurasi dengan dua koneksi Cisco EtherChannel pada setiap link. Karena saluran terpisah adalah terpisah, maka Spanning Tree Protocol akan memblokir salah satu konfigurasi di kedua saluran untuk menghindari adanya looping lalu lintas.

Gambar 2.3: Ketahanan Cisco EtherChannel dengan teknologi Spanning Tree Protocol
Sumber: (Cisco EtherChannel Technology: 2003, p5)

Pada Gambar 2.4 menunjukkan desain jaringan lengkap yang didasarkan pada teknologi Cisco EtherChannel. Seperti pada contoh sebelumnya, link dari wiring closets dibawa ke data center menggunakan saluran 400 Mbps, menyediakan bandwidth dan ketahanan. Di data center, router saling berhubungan dengan koneksi EtherChannel, memberikan peningkatan kinerja dengan memiliki lebih banyak ketersediaan bandwidth untuk melakukan routing antara subnet. Pada contoh ini, router dikonfigurasi dengan dua koneksi  dual-link EtherChannel untuk memberikan 400 Mbps bandwidth pada masing-masing subnet. Teknologi EtherChannel menyediakan mekanisme load balancing antara dua link dalam saluran berdasarkan alamat IP (IP Address), dan link dalam saluran dapat menggunakan protokol enkapsulasi ISL untuk mendukung beberapa subnet per link. Komponen terakhir di dalam desain jaringan ini adalah sebuah server yang terpasang melalui koneksi empat link EtherChannel, yang menyediakan 800 Mbps bandwidth untuk jaringan. Platform khusus yang membutuhkan bandwidth tersebut adalah seperti High-end Pentium Pro server, Enterprise Server, teknologi grafis serta server untuk multimedia. Seperti yang ditunjukkan pada gambar 2.4, server terhubung melalui Multiple-link EtherChannel.


Gambar 2.4: Interkoneksi teknologi Cisco EtherChannel, yang menghubungkan server, switch dan router
Sumber: (Cisco EtherChannel Technology: 2003, p5)

Teknologi Cisco EtherChannel memanfaatkan standar berbasis protokol Ethernet Links, yang digunakan dalam topologi paralel saat ini, dan mengambil keuntungan dari teknologi tersebut untuk menyediakan bandwidth tambahan yang diperlukan, oleh jaringan backbone.
Teknologi EtherChannel menyediakan bandwidth yang fleksibel, dapat ditingkatkan,  dengan ketahanan dan load sharing  pada switch, router dan server. Teknologi EtherChannel menyediakan  tools untuk manajer jaringan, untuk membangun jaringan backbone berkecepatan tinggi didalam menggunakan kabel dan jaringan perangkat infrastruktur. Teknologi EtherChannel dapat menggabungkan semua jenis kecepatan Ethernet link, dari 10 Mbps hingga 10 Gbps.

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Zaid Amin
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Link Agregasi Menggunakan Cisco EtherChannel

Menurut Conlan (2009, p57), EtherChannel adalah sebuah teknik antara switch dengan switch (switch to switch), yang memberikan beberapa layanan link secara multipleks melalui port-port switch pada fast atau gigabit ethernet (kartu jaringan), ke satu jalur logikal. EtherChannel dapat digunakan untuk meningkatkan kapasitas bandwidth pada sebuah koneksi ke single server. EtherChannel adalah sebuah metode lintas platform yang mendukung load balancing, diantara perangkat servers, switches dan routers. EtherChannel dapat melakukan kombinasi dua, empat, atau delapan port (tergantung daripada platform switch) menjadi satu logikal link yang terhubung dan dapat juga sekaligus sebagai redundant (backup link).

Etherchannel adalah suatu teknologi trunking  yang digunakan oleh switch Cisco catalyst dimana sejumlah fisikal port pada device digabung menjadi satu jalur logika saja, dalam satu buah port group. Fungsinya adalah untuk meningkatkan kecepatan koneksi antar switch, router ataupun server, dan jika salah satu port atau jalur rusak atau mengalami failover, maka port group akan tetap bekerja menggunakan jalur atau port yang lain.

EtherChannel adalah istilah untuk teknologi berbasis perangkat Cisco yang memungkinkan pembuatan link hingga delapan fisik ethernet link, ke satu link logis. Pada awalnya teknologi ini disebut dengan Fast EtherChannel (FEC), atau saat teknologi Ethernet hanya tersedia di Fast Ethernet. Teknologi ini juga disebut Gigabit EtherChannel (GEC), atau lebih umum, hanya disebut dengan istilah Port Channel. Untuk vendor umum diluar perangkat Cisco istilah yang digunakan untuk link agregasi tersebut adalah Link Aggregation, atau disingkat dengan LAG.

Melalui protokol EtherChannel, kecepatan satu link tunggal Logis, sama untuk agregat kecepatan semua link fisik yang digunakan. Sebagai contoh, jika Anda membuat EtherChannel dari empat 100 Mbps Ethernet Link, maka EtherChannel akan memiliki kecepatan 400 Mbps.

1. Keuntungan EtherChannel

Menurut (Cisco System,Inc) adapun keuntungan daripada teknologi EtherChannel ini adalah:
a.Berbasis Standards IEEE 802.3 -compliant Ethernet
Teknologi Cisco EtherChannel dibangun berdasarkan protokol IEEE 802.3-compliant Ethernet, dengan pengelompokan beberapa full-duplex point-to-point link secara bersama-sama. Teknologi EtherChannel menggunakan mekanisme IEEE 802.3 untuk full-duplex autonegotiation, dan autosensing ketika layanan tersebut dibutuhkan.

b.Multiple platforms
Teknologi Cisco EtherChannel  sangatlah fleksibel dan dapat digunakan di mana saja, bahkan dalam jaringan yang sering terjadi hambatan. Dapat digunakan di jaringan untuk meningkatkan bandwidth antara switch, dan antara router dan switch, serta menyediakan scalable bandwidth untuk server jaringan, seperti server UNIX atau PC berbasis Web server.

c.Fleksibel dalam meningkatkan bandwidth
Teknologi Cisco EtherChannel menyediakan agregasi bandwidth dalam kelipatan dari 100 Mbps, 1 Gbps atau 10 Gbps, tergantung pada kecepatan link agregat. Sebagai contoh, admin jaringan dapat menerapkan teknologi EtherChannel yang terdiri dari pasangan Fast Ethernet Link full-duplex untuk memberikan lebih dari 400 Mbps antara kabel dan data center. Di data center, bandwidth hingga 800 Mbps dapat disediakan antara server dan jaringan tulang punggung (backbone) untuk memberikan dan meningkatkan sejumlah bandwidth yang scalable.

d.Load Balancing
Teknologi Cisco EtherChannel terdiri dari beberapa Fast Ethernet Link dan mampu melakukan load balancing lalu lintas link tersebut, baik itu dengan metode Unicast, Broadcast, dan Multicast hingga merata di seluruh link, memberikan kinerja yang lebih tinggi dan jalur paralel backup. Ketika link mengalami kegagalan, lalu lintas diarahkan ke link yang tersisa tanpa campur tangan pengguna (user) dan dengan paket hilang (packet loss) yang minimal.

e.Ketahanan dan konvergensi yang cepat
Ketika link mengalami kegagalan, teknologi Cisco EtherChannel menyediakan pemulihan otomatis oleh redistributing beban di seluruh link tersisa. Ketika link gagal, teknologi Cisco EtherChannel akan mengarahkan lalu lintas dari link gagal ke link tersisa, dalam waktu kurang dari satu detik. Konvergensi ini merupakan bersifat transparan kepada pengguna (user).

f.Kemudahan manajemen
Teknologi Cisco EtherChannel mengambil keuntungan dari pengalaman produk Cisco, yang dikembangkan selama bertahun-tahun dalam pemecahan masalah, dan mempertahankan jaringan Ethernet. Ada banyak terdapat jaringan yang digunakan untuk manajemen lalu lintas dan melakukan pemecahan masalah, dan aplikasi manajemen seperti CiscoWorks dan aplikasi manajemen pihak ketiga yang sekarang mengakui teknologi EtherChannel.

g.Transparan untuk aplikasi jaringan
Teknologi Cisco EtherChannel tidak memerlukan perubahan aplikasi jaringan. Ketika EtherChannel digunakan dalam kampus, switch dan router akan menyediakan load balancing beberapa link yang bersifat transparan untuk pengguna jaringan. Untuk mendukung teknologi EtherChannel pada kelas enterprise server dan kartu antarmuka jaringan, perangkat lunak smart driver dapat mengkoordinasikan distribusi beban di beberapa antarmuka jaringan.

h.Compatible dengan Cisco IOS ® Software
Cisco EtherChannel memiliki koneksi yang kompatibel sepenuhnya dengan Cisco IOS virtual LAN (VLAN) dan routing teknologi. Inter-Switch Link (ISL) VLAN Trunking Protocol (VTP) dapat membawa beberapa VLAN pada EtherChannel link.

i.Kompabilitas 100 Megabit, 1 Gigabit, dan 10 Gigabit Ethernet
Teknologi Cisco EtherChannel tersedia dalam semua kecepatan Ethernet link. Teknologi EtherChannel memungkinkan admin jaringan untuk menyebarkan jaringan dengan lancar melalui dukungan ketersediaan teknologi generasi berikutnya, berbasis standar Ethernet protocol.

j.Dukungan kompabilitas dengan konverter antarmuka Gigabit Coarse Wavelength Division Multiplexing (CWDM), Secara bersamaan menerapkan teknologi Gigabit EtherChannel dan CWDM, admin jaringan dapat meningkatkan link bandwidth mereka tanpa harus berinvestasi menggunakan media fiber optic. CWDM teknologi memungkinkan lalu lintas yang dikumpulkan oleh Cisco EtherChannel link ke multiplexed pada satu kabel fiber optic.

2. Komponen-komponen EtherChannel

Menurut (Cisco System,Inc), teknologi Cisco EtherChannel terdiri dari beberapa elemen-elemen penting, diantaranya adalah:

a.Fast Ethernet Link
Koneksi Cisco EtherChannel, dapat terdiri dari satu sampai delapan standar industri Fast Ethernet link untuk memuat bandwidth hingga 80 Gbps pada pembagian lalu lintas. Koneksi EtherChannel, dapat melakukan interkoneksi antara LAN switch, router, server dan klien. Dikarenakan load balancing sudah terintegrasi dengan arsitektur Cisco Catalyst ® LAN, maka tidak ada penurunan kinerja ketika admin menambahkan link ke saluran, throughput yang tinggi dan latency rendah dapat dipertahankan sebelum mendapatkan ketersediaan bandwidth yang lebih. Teknologi EtherChannel menyediakan ketahanan link dalam saluran, jika salah satu link gagal, maka lalu lintas langsung diarahkan ke link tersisa. Kesimpulannya adalah teknologi EtherChannel bukanlah tergantung pada jenis medianya. Teknologi EtherChannel  dapat digunakan dengan Ethernet yang berjalan pada kabel unshielded twisted pair (UTP), atau single mode dan multimode fiber optic.

b.Teknologi Cisco EtherChannel merupakan fitur standar di seluruh seri Cisco Catalyst switch, dan Cisco IOS ® yang berbasis perangkat lunak router. Menggunakan algoritma load-sharing yang digunakan secara bervariasi antar platform, yang memungkinkan untuk menjalankan keputusan berdasarkan sumber atau tujuan melalui pengalamatan berbasis Media Access Control (MAC), IP Address, atau penomoran berbasis port TCP/UDP.

c.Redundansi
Teknologi Cisco EtherChannel tidak memerlukan penggunaan 802.1 D (Spanning Tree Protocol), untuk mempertahankan keadaan topologi dalam saluran. Sebaliknya, ia menggunakan sebuah protokol peer-to-peer, yang menyediakan autokonfigurasi dan konvergensi berbasis subseconds untuk link yang paralel, namun juga memungkinkan protokol tingkat yang lebih tinggi (seperti Spanning Tree Protocol) atau protokol-protokol routing yang digunakan untuk mempertahankan topologi. Pendekatan ini memungkinkan teknologi EtherChannel, menggunakan fitur pemulihan jaringan tanpa menambahkan kompleksitas, atau menciptakan tidak kompatibel nya dengan alat-alat hardware & software dari pihak ketiga.

d.Manajemen
Teknologi Cisco EtherChannel mudah dikonfigurasi dengan antarmuka baris perintah (CLI/Command Line Interface), atau oleh aplikasi berbasis SNMP monitoring seperti CiscoWorks. Seorang manajer jaringan perlu mengidentifikasi, dan menentukan jumlah port yang akan dibuat saluran, dan kemudian menghubungkan perangkat-perangkat tersebut dengan mudah. CiscoWorks untuk perangkat berbasis Switch Internetworks, akan menampilkan grafis keadaan  EtherChannel yang memperlihatkan koneksi antar perangkat, mengumpulkan informasi statistik untuk kedua individu Ethernet Link dalam saluran, dan statistik gabungan untuk sambungan agregat EtherChannel. Kemudahan lain pada proses manajemen adalah, teknologi EtherChannel sudah secara terintegrasi memiliki kemampuan untuk mendeteksi, melaporkan, dan mencegah penggunaan salah pemasangan interface dalam saluran, baik itu dikarenakan adanya missmatched kecepatan antara link, dan secara konsisten memonitor konfigurasi yang diterapkan, agar dipastikan aktif pada keseluruhan jaringan.

Br
Zaid Amin










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Metode Perancangan Jaringan dengan Model PPDIOO

Dengan kebutuhan layanan jaringan yang semakin kompleks, maka diperlukan suatu metodologi yang mendukung perancangan arsitektur dan disain jaringan. Cisco memperkenalkan sebuah metode perancangan jaringan dengan model PPDIOO (Cisco: 2011,p8)  yaitu, Prepare, Plan, Design, Implement, Operate, and Optimize.

Model siklus hidup metode pengembangan jaringan dengan konsep PPDIOO ini, memberikan langkah-langkah kunci dalam keberhasilan perencanaan jaringan, baik itu pada tahapan desain, implementasi dan operasional nantinya. Pendekatan dengan model top-down design, mengarahkan infrastruktur jaringan untuk beradaptasi pada aplikasi-aplikasi apa saja yang dibutuhkan oleh suatu jaringan.

Menurut CCDA 640-864 Official Cert Guide (2011,p11), Cisco telah menghasilkan sebuah formula siklus hidup perencanaan jaringan, menjadi enam fase: Prepare (persiapan), Plan (Perencanaan), Design (Desain), Implement (Implementasi), Operate (Operasi) dan Optimize (Optimasi). Fase-fase ini dikenal dengan istilah PPDIOO. PPDIOO menghasilkan empat manfaat utama, yaitu:

1.Menurunkan total biaya yang harus dikeluarkan oleh organisasi/perusahaan, dengan melakukan validasi persyaratan-persyaratan teknologi, perencanaan perubahan infrastruktur dan kebutuhan akan berbagai macam sumber daya.

2.Meningkatkan ketersediaan layanan jaringan, dengan menghasilkan desain jaringan dan melakukan validasi operasi-operasi di dalam jaringan.

3.Meningkatkan kemampuan percepatan kemajuan bisnis, dengan mempersiapkan kebutuhan yang berorientasi bisnis, yang didukung oleh strategi penerapan teknologi.

4.Meningkatkan kecepatan akses ke aplikasi-aplikasi (software) dan layanan (services), dengan meningkatkan keandalan, ketersediaan, keamanan, skalabilitas dan kinerja.

Pada gambar 3.2 mendeskripsikan sebuah model siklus hidup jaringan dengan konsep PPDIOO yaitu, Prepare (persiapan), Plan (Perencanaan), Design (Desain), Implement (Implementasi), Operate (Operasi) dan Optimize (Optimasi).

Adapun pemahaman detail mengenai tiap-tiap fase pada metode pengembangan jaringan PPDIOO adalah sebagai berikut Cisco, Inc ( 2011,p13):

1.Fase Prepare (Persiapan)
Fase Prepare (persiapan), menetapkan kebutuhan organisasi dan  bisnis, mengembangkan strategi jaringan, dan mengusulkan konsep arsitektur dengan level tingkat tinggi, untuk mendukung suatu strategi, yang didukung dengan kemampuan keuangan pada organisasi atau perusahaan tersebut.

2.Fase Plan (Perencanaan)
Fase Plan (perencanaan) mengidentifikasi persyaratan jaringan berdasarkan tujuan, fasilitas, dan kebutuhan pengguna. Fase ini mendeskripsikan karakteristik suatu jaringan, yang bertujuan untuk menilai jaringan tersebut, melakukan gap analisis pada perancangan terbaik sebuah arsitektur, dengan melihat perilaku dari lingkungan operasional. Sebuah perencanaan proyek dikembangkan untuk mengelola tugas-tugas (tasks), pihak-pihak yang bertanggung jawab, batu pijakan (milestones), dan semua sumber daya untuk melakukan desain dan implementasi. Perencanaan proyek harus sejalan dengan ruang lingkup (batasan), biaya dan parameter sumber daya yang disesuaikan dengan kebutuhan bisnis . Rencana proyek ini diikuti (dan diperbarui) selama fase-fase dalam siklus.

3.Fase Design (Desain)
Desain jaringan dikembangkan berdasarkan persyaratan teknis, dan bisnis yang diperoleh dari kondisi sebelumnya. Spesifikasi desain jaringan adalah desain yang bersifat komprehensif dan terperinci, yang memenuhi persyaratan teknis dan bisnis saat ini. Jaringan tersebut haruslah menyediakan ketersediaan, kehandalan, keamanan, skalabilitas dan kinerja. Hasil desain termasuk diagram jaringan, dan daftar peralatan-peralatan. Rencana proyek harus terus diperbarui, dengan informasi yang lebih terperinci untuk diimplementasikan. Setelah tahap desain disetujui, fase implementasi dimulai.

4.Fase Implement (Implementasi)
Pada fase ini, peralatan-peralatan baru dilakukan instalasi dan di konfigurasi, sesuai spesifikasi desain. Perangkat-perangkat baru ini akan mengganti atau menambah infrastruktur yang ada. Perencanaan proyek juga harus diikuti selama fase ini, jika ada perubahan seharusnya disampaikan dalam pertemuan (meeting), dengan persetujuan yang diperlukan untuk dilanjutkan. Setiap langkah dalam implementasi, harus menyertakan deskripsi, rincian pedoman pelaksanaan, perkiraan waktu untuk penerapan, evaluasi (rollback) langkah-langkah jika terdapat kegagalan, dan informasi-informasi lainnya sebagai referensi tambahan. Seiring perubahan yang telah di implementasikan, tahapan ini juga menjadi langkah pengujian, sebelum pindah ke fase operasional (operate phase).

5.Fase Operate (operasional)
Fase operasional adalah mempertahankan ketahahan kegiatan sehari-hari jaringan. Operasional meliputi pengelolaan dan memonitor komponen-komponan jaringan, pemeliharaan routing, mengelola kegiatan upgrade, mengelola kinerja, mengidentifikasi dan mengoreksi kesalahan jaringan. Tahapan ini adalah ujian akhir bagi tahapan desain. Selama operasi, manajemen jaringan harus memantau stabilitas dan kinerja jaringan, Deteksi kesalahan, koreksi konfigurasi, dan kegiatan-kegiatan pemantauan kinerja, yang menyediakan data awal untuk fase selanjutnya, yaitu fase optimalisasi (optimize phase).

6.Fase Optimize (Optimalisasi)
Fase optimalisasi, melibatkan kesadaran proaktif seorang manajemen jaringan dengan mengidentifikasi dan menyelesaikan masalah, sebelum persoalan tersebut mempengaruhi jaringan. Fase optimalisasi, memungkinkan untuk memodifikasi desain jaringan, jika terlalu banyak masalah jaringan yang timbul, kemudian juga untuk memperbaiki masalah kinerja, atau untuk menyelesaikan masalah-masalah pada aplikasi (software). Persyaratan-persayaratan untuk desain jaringan yang dimodifikasi mengarahkan perkembangan jaringan tersebut, kembali ke awal siklus hidup dalam model fase PPDIOO.

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Zaid Amin







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Wireless Charging

Inductive charging (also known as "wireless charging") uses an electromagnetic field to transfer energy between two objects. This is usually done with a charging station. Energy is sent through an inductive coupling to an electrical device, which can then use that energy to charge batteries or run the device.

Induction chargers typically use an induction coil to create an alternating electromagnetic field from within a charging base station, and a second induction coil in the portable device takes power from the electromagnetic field and converts it back into electrical current to charge the battery. The two induction coils in proximity combine to form an electrical transformer.Greater distances between sender and receiver coils can be achieved when the inductive charging system uses resonant inductive coupling.

* Advantages

1. Protected connections - no corrosion when the electronics are all enclosed, away from water or oxygen in the atmosphere.
2. Safer for medical implants - for embedded medical devices, allows recharging/powering through the skin rather than having wires penetrate the skin, which would increase the risk of infection.
3. Durability - Without the need to constantly plug and unplug the device, there is significantly less wear and tear on the socket of the device and the attaching cable.

* Disadvantages

1. Lower efficiency, waste heat - The main disadvantages of inductive charging are its lower efficiency and increased resistive heating in comparison to direct contact. Implementations using lower frequencies or older drive technologies charge more slowly and generate heat within most portable electronics.

2. Slower charging - due to the lower efficiency, devices can take longer to charge when supplied power is equal.

3. More costly - Inductive charging also requires drive electronics and coils in both device and charger, increasing the complexity and cost of manufacturing.

4. Inconvenience - When a mobile device is connected to a cable, it can be freely moved around and operated while charging. In current implementations of inductive charging (such as the Qi standard), the mobile device must be left on a pad, and thus can't be moved around or easily operated while charging.

5. Newer approaches reduce transfer losses through the use of ultra thin coils, higher frequencies, and optimized drive electronics. This results in more efficient and compact chargers and receivers, facilitating their integration into mobile devices or batteries with minimal changes required. These technologies provide charging times comparable to wired approaches, and they are rapidly finding their way into mobile devices.

For example, the Magne Charge vehicle recharger system employs high-frequency induction to deliver high power at an efficiency of 86% (6.6 kW power delivery from a 7.68 kW power draw).

Courtesy of :  http://en.wikipedia.org/wiki/Inductive_charging
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My first DLSR - Canon EOS 650D ;)

Canon meluncurkan kamera DSLR terbaru EOS 650D yang menjadi DSLR entry-level pertama yang dipersenjatai dengan prosesor gambar DIGIC 5. Disandingkan dengan sensor APS-C Hybrid CMOS beresolusi 18 megapixel, 650D mampu menghasilkan gambar berukuran poster yang mendetail dan kaya warna. Kemampuan continuous shooting mengalami peningkatan menjadi 5 fps dengan resolusi penuh.

EOS 650D menjadi kamera EOS pertama yang menggunakan sistem AF ganda. Sistem ini mampu memperkaya detail foto dan menawarkan continuous AF tracking selama proses rekam video berlangsung. Sebagai tambahan, sistem AF dengan 9 titik cross type, serta sistem AF  Hybrid yang menawarkan continuous AF selama rekam video dan pengambilan gambar melalui mode Live View, telah dibenamkan dalam EOS 650D.

Layar LCD yang digunakan dalam EOS 650D mengalami pembaruan yang signifikan dibanding pendahulunya. Walaupun masih menggunakan ukuran 3 inci yang sama dan badan layar yang dapat disesuaikan dengan sudut pandang pengguna, EOS 650D menggunakan layar sentuh yang menawarkan pengalaman fotografi yang lebih menarik.

Melalui mode Live View, pengguna dapat memilih titik AF, melakukan face tracking, dan menyempurnakan pengaturan foto hanya dengan menyentuh layar beresolusi 1.040k-dot tersebut. Layar EOS 650D juga mendukung gestur multi-touch, seperti pinch-zooming dan swipping ketika melihat ulang hasil foto.


Dengan setiap pembaruan yang dilakukan, kemampuan rekam video 1080p, dan kehadiran fitur Creative Filters yang membantu menghasilkan foto-foto dengan efek unik, tampaknya EOS 650D dapat menjadi kamera DSLR entry-level yang tepat. Kamera ini dibanderol dengan harga USD849 (body), USD949 dengan lensa IS 18-55mm, atau USD1199 dengan lensa IS 18-135mm.

Courtesy of:
http://www.jagatreview.com/2012/06/canon-eos-650d-dslr-entry-level-dengan-sistem-af-hybrid-dan-layar-sentuh/

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"Banker to the Poor"

Professor Muhammad Yunus established the Grameen Bank in Bangladesh in 1983, fueled by the belief that credit is a fundamental human right. His objective was to help poor people escape from poverty by providing loans on terms suitable to them and by teaching them a few sound financial principles so they could help themselves.

From Dr. Yunus' personal loan of small amounts of money to destitute basketweavers in Bangladesh in the mid-70s, the Grameen Bank has advanced to the forefront of a burgeoning world movement toward eradicating poverty through microlending. Replicas of the Grameen Bank model operate in more than 100 countries worldwide.

Born in 1940 in the seaport city of Chittagong, Professor Yunus studied at Dhaka University in Bangladesh, then received a Fulbright scholarship to study economics at Vanderbilt University. He received his Ph.D. in economics from Vanderbilt in 1969 and the following year became an assistant professor of economics at Middle Tennessee State University. Returning to Bangladesh, Yunus headed the economics department at Chittagong University.

From 1993 to 1995, Professor Yunus was a member of the International Advisory Group for the Fourth World Conference on Women, a post to which he was appointed by the UN secretary general. He has served on the Global Commission of Women's Health, the Advisory Council for Sustainable Economic Development and the UN Expert Group on Women and Finance.

Professor Yunus is the recipient of numerous international awards for his ideas and endeavors, including the Mohamed Shabdeen Award for Science (1993), Sri Lanka; Humanitarian Award (1993), CARE, USA; World Food Prize (1994), World Food Prize Foundation, USA; lndependence Day Award (1987), Bangladesh's highest award; King Hussein Humanitarian Leadership Award (2000), King Hussien Foundation, Jordan; Volvo Environment Prize (2003), Volvo Environment Prize Foundation, Sweden; Nikkei Asia Prize for Regional Growth (2004), Nihon Keizai Shimbun, Japan; Franklin D. Roosevelt Freedom Award (2006), Roosevelt Institute of The Netherlands; and the Seoul Peace Prize (2006), Seoul Peace Prize Cultural Foundation, Seoul, Korea. He is a member of the board of the United Nations Foundation.

From Les Prix Nobel. The Nobel Prizes 2006, Editor Karl Grandin, [Nobel Foundation], Stockholm, 2007

This autobiography/biography was written at the time of the award and later published in the book series Les Prix Nobel/Nobel Lectures. The information is sometimes updated with an addendum submitted by the Laureate.

Copyright © The Nobel Foundation 2006

http://www.nobelprize.org/nobel_prizes/peace/laureates/2006/yunus-bio.html#
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Konfigurasi DHCP Server pada Mikrotik Router OS

Ketika kondisi jaringan membutuhkan konfigurasi IP Address secara otomatis, maka sebaiknya alternatif solusi yang kita berikan adalah dengan menambahkan layanan DHCP Server, dimana server ini akan melakukan leased pada scope IP yang telah kita tentukan. Konfigurasi pengalamatan dengan menggunakan layanan ini akan memudahkan seorang administrator jaringan dalam mengkonfigurasi IP Address jika kebutuhan host relatif besar. Kebutuhan akan pengalamatan secara otomatis ini juga dapat diterapkan pada media jaringan dengan koneksi berbasis wireless, dimana host akan melakukan request IP Dynamic untuk dapat terhubung dan dikenali oleh perangkat Access Point untuk melakukan share ke segment jaringan (internet) yg lainnya.

Adapun langkah-langkah di dalam melakukan konfigurasi Mikrotik Router OS untuk membuat layanan DHCP Server adalah sebagai berikut:

1. Masuk ke winbox -> pilih IP -> Pilih DHCP Server

















2. Pilih DHCP Setup -> Pilih NIC (interface yang akan dijadikan DHCP Server)


















3. Menentukan network yang akan menggunakan layanan DHCP (dalam case ini saya menggunakan network 192.168.0.0 prefix /28 (255.255.255.240)

















4. Menentukan IP gateway (dalam case ini saya memasang server NAT plus DHCP server)


















5. Menentukan range IP Address yang disewakan (note penting: tidak termasuk IP DHCP Server)


















6. Menentukan DNS Server (dalam case ini mesin DNS server juga saya integrasikan dengan layanan DHCP Server)

















7. Menentukan leased duration time (waktu maksimum untuk melakukan lease IP dynamic tersebut/dalam case ini saya memberikan leased untuk rolled back setiap 2 jam sekali)
















8. Konfigurasi DHCP Server Selesai














9. Terlihat layanan DHCP Server telah dipakai oleh salah satu client dg IP 192.168.0.3/28 dengan nama host "zaid", dengan leased duration yang telah ditentukan.













Sekian dan selamat mencoba :)

Br







Zaid Amin



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