Jaycee's Networking

August 10, 2009

Anycast DNS

Filed under: BGP, Information — Tags: — Jaycee @ 9:24 pm

DNS Anycast Service-Provision Architecture

IPv4 Anycast Routing

* Local and global nodes:

a. Anycast deployment on the Internet differs between local and global nodes:

1) Local nodes are often more intended to provide benefit for the direct local community.

2) Local node announcements are often announced with the no-export BGP community to prevent peers from announcing them to their peers (i.e. the announcement is kept in the local area).

3) Where both local and global nodes are deployed, the announcements from global nodes are often AS prepended (i.e. the AS is added a few more times) to make the path longer so that a local node announcement is preferred over a global node announcement.


May 4, 2009

Cloud Computing

Filed under: Information — Tags: — Jaycee @ 1:00 am

Cloud computing is a style of computing in which dynamically scalable and often virtualized resources are provided as a service over the Internet. Users need not have knowledge of or control over the technology infrastructure “in the cloud” that supports them.

Cloud computing services usually provide common business applications online that are accessed from a web browser, while the software and data are stored on the servers. The concept incorporates CaaS, IaaS, PaaS and SaaS that have the common theme of reliance(依靠) on the Internet for satisfying the computing needs of the users.

The majority of cloud computing infrastructure consists of reliable services delivered through data centers and built on servers with different levels of virtualization technologies. The services are accessible anywhere that has access to networking infrastructure.

The Cloud appears as a single point of access for all the computing needs of consumers. Commercial offerings need to meet the quality of service requirements of customers and typically offer SLA (service level agreements). IBM, Amazon, Google, Microsoft or Yahoo are some of the major cloud computing service providers.


1. Cloud computing has been criticized for limiting the freedom of users and making them dependent on the cloud computing provider. Users had no freedom to install new applications and needed approval from the administrator to achieve certain tasks. Overall, it limited both freedom and creativity.

2. Cloud computing endangers liberties because users sacrifice their privacy and personal data to a third party.

3. The Cloud spans many borders and “may be the ultimate form of globalization.” As such it becomes subject to complex geopolitical issues: providers must satisfy myriad regulatory environments in order to deliver service to a global market.as of 2009[update] providers such as Amazon Web Services cater to the major markets (typically the United States and the European Union) by deploying local infrastructure and allowing customers to select “availability zones.”

4. Seven security issues should discuss with a cloud-computing vendor:

(1) Privileged user access—inquire about who has specialized access to data and about the hiring and management of such administrators

(2) Regulatory compliance(承諾)—make sure a vendor is willing to undergo external audits and/or security certifications

(3) Data location—ask if a provider allows for any control over the location of data

(4) Data segregation(隔離)—make sure that encryption is available at all stages and that these “encryption schemes were designed and tested by experienced professionals”

(5) Recovery—find out what will happen to data in the case of a disaster; do they offer complete restoration and, if so, how long that would take

(6) Investigative Support—inquire whether a vendor has the ability to investigate any inappropriate or illegal activity

(7) Long-term viability—ask what will happen to data if the company goes out of business; how will data be returned and in what format


1. Cost— Pricing on a utility computing basis with usage-based options.

2. Device and location independence— users access systems using a web browser regardless of their location or what device they are using

3. Multi-tenancy— sharing of resources and costs amoung a large pool of users:

(1) Centralization of infrastructure— lower real estate, electricity costs
(2) Peak-load capacity increases— users need not engineer for highest possible load-levels
(3) Utilization and efficiency

4. Reliability— improves through the use of multiple redundant sites

5. Scalability— via dynamic (“on-demand”) provisioning of resources on a fine-grained, self-service basis near real-time, without users having to engineer for peak loads. Performance is monitored and consistent and loosely-coupled architectures are constructed using web services as the system interface.

6. Security— Due to centralization of data, increased security-focused resources. Providers are able to devote resources to solving security issues that many customers cannot afford. Providers typically log accesses, but accessing the audit logs themselves can be difficult or impossible.

7. Sustainability(持續性)–comes about through improved resource utilization, more efficient systems.

<Six layers components of cloud computing>

1. Client— A cloud client consists of computer hardware and/or computer software which relies on cloud computing for application delivery, or which is specifically designed for delivery of cloud services and which, in either case, is essentially useless without it.

2. Services— A cloud service includes “products, services and solutions that are delivered and consumed in real-time over the Internet”. For example, Web Services (“software system[s] designed to support interoperable machine-to-machine interaction over a network”) which may be accessed by other cloud computing components, software, or end users directly.

3. Application— A cloud application leverages the Cloud in software architecture, often eliminating the need to install and run the application on the customer’s own computer, thus alleviating the burden of software maintenance, ongoing operation, and support.

4. Platform— A cloud platform, such as PaaS, the delivery of a computing platform, and/or solution stack as a service, facilitates deployment of applications without the cost and complexity of buying and managing the underlying hardware and software layers.

5. Storage Cloud storage involves the delivery of data storage as a service, including database-like services, often billed on a utility computing basis, e.g., per gigabyte per month.

6. Infrastructure Cloud infrastructure, such as IaaS, is the delivery of computer infrastructure, typically a platform virtualization environment, as a service.


  • Client
    • Browsers (AJAX)
    • Offline (HTML 5)
  • Service
  • Application
  • Platform
    • Solution stacks (LAMP)
  • Implementations
    • Virtualization (OVF)


The systems architecture of the software systems involved in the delivery of cloud computing, comprises hardware and software designed by a cloud architect who typically works for a cloud integrator. It typically involves multiple cloud components communicating with each other over application programming interfaces, usually web services.

This closely resembles the Unix philosophy of having multiple programs doing one thing well and working together over universal interfaces. Complexity is controlled and the resulting systems are more manageable than their monolithic counterparts.

Cloud architecture extends to the client, where web browsers and/or software applications access cloud applications.

Cloud storage architecture is loosely coupled, where metadata operations are centralized enabling the data nodes to scale into the hundreds, each independently delivering data to applications or users.

<Cloud Computing Providers>

Akamai Technologies
Amazon Web Services


A cloud computing provider or cloud computing service provider owns and operates live cloud computing systems to deliver service to third parties. Usually this requires significant resources and expertise in building and managing next-generation data centers. Some organizations realize a subset of the benefits of cloud computing by becoming “internal” cloud providers and servicing themselves, although they do not benefit from the same economies of scale and still have to engineer for peak loads.

The barrier to entry is also significantly higher with capital expenditure required and billing and management creates some overhead. Nonetheless, significant operational efficiency and agility advantages can be realised, even by small organisations, and server consolidation and virtualization rollouts are already well underway.

Amazon.com was the first such provider, modernising its data centers which, like most computer networks, were using as little as 10% of its capacity at any one time just to leave room for occasional spikes. This allowed small, fast-moving groups to add new features faster and easier, and they went on to open it up to outsiders as Amazon Web Services in 2002 on a utility computing basis.

<Cloud Computing Vendor>

Some vendors sells or gives products and services that facilitate the delivery, adoption and use of cloud computing.For example:

April 23, 2009

Everything as a service

Filed under: Information — Tags: — Jaycee @ 12:35 am

1. CaaS (Communication as a service):

delivery of Voice over IP (VaaS), instant messaging, and video conferencing applications using fixed and mobile devices

2. IaaS (Infrastructure as a service)

Delivery of computer infrastructure: platform virtualization environment for running client specified virtual machines, computer hardware, computer network ( including firewalls, load balancing), internet connectivity

3. SaaS (Software as a service):

SaaS software vendors may host the application on their own web servers or download the application to the consumer device, disabling it after use or after the on-demand contract expires. The on-demand function may be handled internally to share licenses within a firm or by a third-party application service provider (ASP) sharing licenses between firms. Examples of SaaS vendors include SAP Business ByDesign and Google Apps which provide common business applications online that are accessed from a web browser, while the software and data are stored on the servers.


a. Data transfers take place at Internet, rather than local Ethernet speeds; the provider may go bankrupt and the firewall may not permit integration with back end systems. It may not be easy to judge the importance of such issues when an implementation is first started, however they are largely resolved by the Hybrid SaaS model.

b. Widespread implementation of SaaS requires well defined services. That can achieve an economy of scale and the capacity to balance supply and demand. This requires areas of IT that are ubiquitous and commodity-like. SaaS is therefore not suitable for innovative or highly specialized niche systems, though SaaS may be used to provide one or more components in such systems.

c. As with manufacturing, a lack of substitutability and second sourcing options with any commodity creates a strategic weakness for any customer in terms of security, competition and pricing. Various forms of this weakness, such as “vendor lock-in”, are often cited as a barrier to adoption of SaaS as the current industry lacks portability and interoperability between vendors. This means that to change from one vendor to another will take a considerable amount of effort and time, although no more time then required to convert or migrate from one traditional, installed software package to another. This situation is resolvable by the introduction of open sourced standards and the development of markets based upon such standards.

d. Many vendors counter the concerns over potential security and operational risk with the argument that the professionals operating SaaS applications may have much better security and redundancy tools available to them. One vendor of SaaS document and process automation has for many years offered a “data-return guarantee” that allows clients to receive their documents and data upon cancellation of service.

e. SaaS applications pose some difficulty for businesses that need extensive customization is countered with the claim that many vendors have made progress with both customization and publication of their programming interfaces. Customization will reduce substitutability and given that SaaS applications are sometimes deployed for non-strategic business activities, the strategic benefit of customization is somewhat questionable.

f. The availability of open-source applications, inexpensive hardware and low-cost bandwidth combine to offer compelling economic reasons for businesses to operate their own software applications, particularly as open-source solutions have increased in quality and become easier to install. SaaS providers can offer a higher level of service and support then most open source solutions but the level of that service in any delivery model depends greatly on the orientation of the software vendor. For example, development-centric vendors that are highly technical tend to deliver the lowest level of user support whether in terms of technical support or implementation. Conversely, companies that are services-oriented tend to offer much more developed plans for technical support, user training, even supporting services such as data capture which make the application more usable.

g. Users and purchasers of any SaaS application need to establish a strong confidence in the provider of the service, particularly if the application stores the user’s data. This confidence can be enhanced and enforced by a balanced Service Agreement that gives the provider opportunities to correct issues but within limits that the client can accept. The provider needs to be trusted with both the intention and the ability to safeguard this information. Thus internet security procedures such as SSL or other encryption technologies should be required by all SaaS consumers.

4. PaaS (Platform as a service):

Delivery of a computing platform and solution stack as a service. It facilitates deployment of applications without the cost and complexity of buying and managing the underlying hardware and software layers, providing all of the facilities required to support the complete life cycle of building and delivering web applications and services entirely available from the Internet—with no software downloads or installation for developers, IT managers or end-users. It’s also known as cloud computing, in which dynamically scalable and often virtualized resources are provided as a service over the Internet. Users need not have knowledge of, expertise in, or control over the technology infrastructure “in the cloud” that supports them.

Blog at WordPress.com.