Data Center Network Architectures and Research Problems

Data centers have progressively become an essential part of Internet services and networking.  This has resulted in setting key demands for the current data center network architecture. Demands like support for cloud computing, competence, scalability and efficiency results in appealing confronts from network architecture’s perspective. Like other sciences, research in data centers is essential to keep the center running smoothly.  Research projects must be paid keen attention for the purpose of quick improvement. Agility is the key. The more agile a data-center network is, the more efficient the deployment of money and resources is. During the research process there is a whole gamut of challenges. The major ones include – formulating ideas, setting out detailed designs to code up and implement, bringing together all the equipment to run the experiments and make them real.

There are several research problems or hitches in data center. Some of them are enlisted below:

Cost:

It is essential to understand the cost structure in a data center. There are various components in a data center which eat up the costs. Some components include – Servers, Infrastructure, Electrical utility costs and lastly the Network (Links, transit, equipment). Power associated expenses are similar to the networks. IT devices consume 59% of each watt brought, 8% to delivery losses and 33% for cooling purposes. Cooling costs could be brought down by permitting the data centers to run hotter, which may need the network to be more flexible in nature. Important fraction of network related costs is spent on networking equipment. Other fraction of the total costs of the network recount to wide area networking that includes traffic to end users, traffic between data centers and regional services.

Cloud Servicing:

Data centers supporting cloud services vary from distinctive enterprise data centers. Cloud service data centers need automation, unlike enterprise data center where automation is inequitable. Cloud service data centers support large economies of scale. Scaling out dispense workload to small cost hardware, in contrast to updating lofty cost hardware. The enterprise networking architectures were initially developed for much smaller data centers, in contrast to the ones active today. The limitations of the conventional architecture have resulted in quite a few workarounds and squares for the protocols to keep up with the new anxieties on data centers.

Unnecessary subscription of resource and fragmentation:

Unnecessary subscription ratio means the ratio of subscriptions to what is offered restricted server-to-server capacity limits the data center capacity and fragments the server pool. This is because idle resources cannot be allotted where they it is required. To evade this trouble all applications should be placed carefully also taking the impact of the traffic into consideration.  However, in practice this is challenging. Partial server-to-server capacity guides to designers clustering the servers around one another in the ladder, because the distance in the ladder influences the performance and cost of the communication

Reliability, utilization and fault tolerance:

Data centers undergo pitiable reliability and utilization. In case some component of the data center is unsuccessful, there must be some means to keep the data center working. Typically in data centers, counterpart elements exist. When an access router fails for example the counterpart handles the load. However, this leads to elements use only 50% of greatest capacity. Multiple paths are not successfully used in current data center network capacity. A vast majority of data centers use TCP (Transmission Control Protocol) for communication. This communication usually takes place among the nodes and Incast. This occurs in many to single environment, which is dissimilar from the usual assumptions TCP based its design. In simple and more understandable words, TCP is unsuitable for a special data center environment with low latencies and high bandwidths thus limiting the optimum use of all capacity. In casting a receiver, requests data from multiple senders. Upon receiving the demand, the senders start sending out data to the original receiver simultaneously with the other senders. Nevertheless, in the middle of the connection from sender to receiver, is a bottleneck link resulting in a fall down in the receiver receiving the data. The result is network jamming from using the same bottleneck link. Advancing and increasing the buffer sizes of switches and routers hinders congestion, but in high latency and bandwidth data center environment, the buffers can still fill up in a short phase. In addition, large buffer switches and routers are costly.

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Advantages of Cloud Based Network Test System

Cloud-based networking solutions are services that establish cost efficiency and scalability benefits to the networking sphere. It is a system where software programs and storage space can be accessed through the Internet. Hence companies use this service to outsource the ownership and management of certain areas of its IT functionality like storage, mail room, web sites, etc within the cloud. Users may not be aware of what software or hardware is being used or what operating system it is running on, but they do not need to. It is similar to software as a service (SaaS) in the market. This is also an enterprise application. Multi-tenant architecture based SaaS applications like SalesforceTM has changed the status quo in the Customer Relationship Management space. Cloud-based networking has brought about the same upheaval in the networking space.

Cloud-based networking has created waves in the internet sphere. It is an innovative way to roll out distributed venture networks that convey enterprise-class network capabilities around the world. The process is carried out via vastly resilient, multi-tenant applications that involve no principal investment in networking equipment. Unlike conventional hardware-based solutions, cloud-based networking is extremely simple, enabling enterprises to install remote locations in less time and operate their distributed networks through a cloud-based application. It also provides unique levels of centralized control and network visibility. Such services are also subscription based which the users can opt.

The two major features of the cloud computing are:
(i) It is modular and it compartmentalizes software applications ,associated hardware and the infrastructure
(ii) It is uniform and utilizes the same possessions that clients share. A business using cloud computing can keep away from large outlays of capital expense as well as everlasting maintenance costs. This results in the cash flow with total system cost.

Apart from the above mentioned, there are other benefits to cloud computing. The major one being it supporting data centers in every aspect. Data centers can at times be too bunched up for comfort. Virtualizing the servers has met with only limited triumph. Over time, there will be a smooth transition to measurable computing, based on the cloud. The future of computing is going to be a blend of service orientation, service management, and cloud computing. Some of the reasons being -

• Customers can access applications and data from anywhere at any time through the internet. Data will be stored offsite rather than being stored on a hard drive of a user’s computer or a corporation’s internal network.

• Another important aspect is that the hardware costs would decline as cloud computing systems would lessen the need for advanced, expensive hardware on the client side. The cost of buying, installing and supporting a system network will dramatically decline.

• The need for expensive memory or even large hard drives is undesirable. Rather, everyone would buy an reasonably priced computer terminal, a monitor, input components such as a keyboard and mouse, and only enough processing power to run the middleware essential to connect to the cloud system. Computer components have to be purchased in large quantities in IT. But buying hardware in large volume, cloud suppliers get better pricing on each purchase.

Cloud computing is a subscription based system. Enterprises would not have to buy software or software licenses for each employee in the company. Instead, the company would pay for what they use. It is more like the way an open source software functions. In a broader sense, cloud computing infrastructures are fabricated from open source components as the cloud providers are uncertain to make huge investments without knowing the outcome.

When cloud computing system’s back end is a grid computing system, customers could make optimum use of the entire network’s processing power. For example, researchers who work with extremely complicated computation can dispatch the computation to the cloud for processing purpose. The cloud system would make use of the processing power of all available computers on the back end and considerably speed up the results. Cloud computing offers a way to outsource non-critical applications to business. It also results in better performance, allowing IT to hub on critical applications.

Another advantage of using Cloud computing is the usage of man power. Cloud providers are more resourceful at IT operations, using fewer man-hours for criterion tasks.

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A Modern Twist on Malware Production

Malware has always been a threat to companies and computer users since the early days of the internet, however while prior malware was often created by individuals and small groups for leisure and fame, today malware makers are operating at an organizational capacity similar to legitimate corporations. This industry has been coined Crime as a Service and as the name implies, encompasses a whole new class of malware creators who do not just create the malware, but provide:  toll free support lines, ongoing updates to take advantage of zero day attacks, integrated product activation to protect against piracy, easy to use control panels complete with statistics about infection rates, and much more.

To get a better idea of the malware landscape, I interviewed Ziv Mador, the director of malware security labs for M86 Security.

Origin and Demographics of Attacks

According to Ziv, the majority of malware development originates in:  Russia, Romania, and a few Eastern European countries mainly because of weak and corrupt governments which are not able to keep organized crime in check. Additionally, many of the support, sales, and logistics of:  malware kits, stolen data, and more also are handled within these regions due to the lax government climate.

As far as attack targets go, while malware typically knows no bounds, Ziv mentioned that in most of his findings Western countries are the most targeted heavily for their wealth. In particular, bank fraud tends to have the highest reward for attackers by allowing them to access large sums of money in the shortest amounts of time. Because of the easy access to funds and limited fraud protection, on the black markets, bank account information tends to sell at prices significantly higher than credit/debit card numbers.

Additionally, as many malware makers prefer to have ongoing revenue, fake antivirus products and pay per install spyware often are integral to many malware makers by providing a fairly simple but effective way of monetizing their victims.

Attack Vectors

Although web browsers have been and remain the largest vulnerability point for end users, recent malware attacks have been shifting towards third party plug-ins such as Flash, Java, and Adobe Acrobat because the plugins tend to be less hardened and therefore provide better closer access to critical system files. Additionally, deploying updates for third-party programs on enterprise networks is significantly harder due to compatibility issues, making them a perfect target for attackers who are aiming for a high infection rate.

Even if you stay away from questionable sites normally associated with malware, today there is a new attack angle which allows infections to spread throughout legitimate websites without the owner or end user knowing. According to Ziv, this new form of attack is known as an iFrame injection and consists of a website being hacked and having a small code injection. Unlike the common depiction of hackers trashing websites and replacing them with obscene pages, today many infections occur in the background without notice. By using malicious code to inject hidden iFrames into a compromised website, malicious parties are able to have scripts download files to visitors in the background without warning.

This type of attack is so prevalent that according to Ziv, before launching an infection campaign, many groups will collect statistics from a few compromised servers and use that data to better target their attacks. While in the past malware used to be most prevalent on pornography and piracy websites, today even visiting a site as respectable as Facebook or Twitter could lead to an infection if a breach were to occur. Currently however, this form of attack is more prevalent on smaller independent websites where the owners fail to update and apply patches in a timely fashion.

Commercialization of Malware

As mentioned earlier in this article, the malware industry has gone from small groups of “hackers” to an industry with estimated transaction values of well over $1 billion USD. In particular the biggest sources of revenue have come from brokering stolen data and also selling malware kits. While in the past creating a virus used to require extensive technical knowledge – today, for around $1,000 USD, you can purchase a “malware kit” complete with:  a GUI for changing settings, ongoing updates for continuing effectiveness,  internal statistics to better target attacks,  and even product activation integrated by the creators to protect their creations from piracy.

This commercialization is not limited to malware.  Today brokers handling stolen data provide toll free support lines to handle reissuing data if it is flagged for fraud (common with credit and debit cards), and call centers exist to  provide criminals access to phone operators with any accent desired.  A crucial service for helping to expedite fraudulent transactions over the phone.

Closing Words

Overall, the details mentioned above are just a small sampling of today’s chaotic environment in computer security. As malware continues to be commercialized and commoditized information technology professionals of virtually every breed will have to learn to place security in the fore front of all projects. Although this article is more of an overview piece, at the least this article should alert you to the fact that today malware is not just being produced by lone wolf hackers. Rather syndicates now control the sphere, and as such, security must be given top priority to combat the increased threat.

Please leave your views and comments on the article in the Data Center Talk Forum

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IPv6 Readiness for Datacenter

IPv6 is a subsequent generation internet protocol that is designed to substitute IPv4, the internet protocol mainly used all through the world and is the base for most of the internet connections. IPv4 addresses are rapidly going out and transitioning to IPv6 will rapidly turn out to be an obligation for all ventures networks. IPv6 facilitates important growth of the IP address that is required to provide accommodation of the constantly rising numeral of universal internet consumers, and offers an extra safety features for the internet passage.
IPv6 preparation and operations component mechanically evaluate the IPv6 readiness for the present network tools and forecasts the impact of IPv4 to IPv6 relocation on network presentation and safety.

The key advantages of IPv6 readiness for data center technologies are:

  • Settle on IPv6 system readiness with the help of a methodical, system based legalization of all devices compatibility with IPv6 characteristics such as routing, addressing, QoS, security, multicast, operating system necessities, and changeover apparatus characteristics.
  • Influence and comprehensive information to rapidly recognize obedient and disobedient equipment, and necessary hardware or software improvements.
  • Evaluation of what-if circumstances as well as capability and design changes, apparatus improvement, and the use of channels and double heaped devices.
  • Mechanically generation of network designs to make a change from IPv4 to IPv6 through describing the subnets that need relocation, the planned change methods and other explanation metrics
  • Clearly visualization of non-routable travel streams and services that are beginning from the relocation in a brief report.
  • Examination of IPv6 network plan to make sure survivability and safety.
  • Authentication of planned IPv6 pattern changes earlier to consumption or deployment.

Despite these features, the main challenge for IPv6 readiness for data center technologies is that IPv6 addresses are not compatible with IPv4 addresses. It signifies that if you do not take the essential ladder to improve, you will finally practice:

  •  Incapability to advertise goods and services or bring your substance to IPv6 consumers
  • Incapability to access the right of entry on internet based appliances, similar to chat and SaaS applications.
  • Incapability to start the latest websites

Since the internet grown up and its existence enlarging more and more quickly with the quick acceptance of movable devices change in system communications, software, services, and customer support are essential. IPv6 readiness plan provides network machinists with the chance to expand and build familiarity with this fresh standard on their individual network and also in a genuine world experiment surroundings.

The IPv6 readiness provide initiative and permits right of entry to the width of data center technologies, IPv6 ready DNS (Domain Name System) and DHCP software for experiment reasons. IPv6 experiment protocols and without charge in-person, phone, and electronic mail technological support provide you all the possessions you require to make sure a winning system and test. The IPv6 readiness for data center technologies gives all of the software that is necessary for data center technologies.

Compatibility and linking with IPv6 networking is primarily a software problem. But many of the old hardware’s that can in chiefly be improved are probably to be restored in its place. The majority of computers running latest operating systems are IPv6 ready at data center technologies.

Data Center Talk keeps you updated on the latest news from the data center world. Visit us. Please leave your views and comments on DCT Forum.

 

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Colocation Pricing Trends

Data Centers are growing very fast. The Reason is all information is managed in these only and these are now business critical. It is very vital to keep the cost of IT related expenses for organization. All companies need to have dedicated data centers as it might not have proper Return on investment. Colocation is solution to such companies and businesses. Building your own datacenter need lots of efforts, Time and money. In Colocation, Service provider provides you facility and some bundled services at affordable price.

Colocation provides some and more of following services to you to have datacenter established.

  • Space: It can be measured as Rack space or Square fts.
  • Cooling: Cooling remains one of basic necessity along with space.
  • Power: Electric power along with appropriate Power backup is also part of bundle service.
  • Physical Security: Only authorized people will have access to colocation area.
  • Facility related Services like fire safety, battery room, cleaning, sanitation etc are part of real estate and offered along with colocation.
  • Internet Links and other Communication services are charged separately and optional.
  • Managed Services like managing your servers and other infrastructure pieces are also offered.

Colocation cost varies from $1000 to $2600 per cabinet/Rack. It also depends on all factors we considered.

This list is very specific to Service provider or Colocation service and most of times these services are customized for customers so that it suits best to customer requirement.

As the trend for colocation is increasing day by day, these services are becoming more affordable and have better return on investment. Factors mentioned above influence the cost for colocation services. There are few more factors which affects the
costing offered by services provider:

Geographical Location of Colocation Data center:

Location of datacenter influences the real estate value of datacenter hence impacts rental value for colocation. Also how suitable is facility for the Disaster Recovery is considered factors.

How much do you need?:

More space you need provider will give better pricing. It is same as retail vs wholesales services.

Diversity Provided by Colocation provide for Communication links:

Are the internet, WAN and other telecom related links have robust and redundant paths. To provide this kind of facility, service providers have common area for Telecom service providers. This enables customer to select from multiple options.

Term or duration for which customer is looking for Colocation services.

Contract time duration also affects cost offered by Colocation service provider. Longer you stay more economical services are.

Scope for future growth and expansion

Colocation Service provider also enables you to expand or modify your space as and when needed. This keeps you out from worries of capacity planning for future.

Conclusion:

Most of times colocation is one of the best options for housing your business critical systems. With time Colocation service are getting more effective and affordable. It helps to keep your IT budget low compared to having your own data center. Colocation Service provider also provides better professional services for facility, Security, Cooling, Power, Power backup etc. Also have scope for future growth as needed.

With time colocation is becoming more and more competitive and cost effective. The Future is Colocation for small and medium sized businesses.

For more updates on data centers, visit Data Center Talk.

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SURVEY OF DATA CENTER : AREAS OF INTEREST

While choosing site for data center, some points shall be pondered. Completed study with following area of interest will help you to indentify best location for your data center.

Physical Security

External

  • Anonymity
  • Protection (Barriers, Patrols)
  • Observation (Lights, Cameras and Monitoring Station)
  • Entry Points
  • Locks, Guards, Logs, Mantraps

Internal

  • Access Control (Passkeys, Compartmentalization, Creation and Review of Logs, Identification and Escort Requirements, Use of Cages/Rooms)
  • Observation (Cameras, Video Recording, Tape Maintenance and Review)

Environment Controls

  • Detection of smoke, heat, sound, water, humidity
  • Fire suppression systems
  • HVAC systems
  • Power plant (multiple power supplies, internal distribution and switching systems, UPS systems, testing)

Telecommunications

  • Multiple carriers
  • Internal distribution and switching systems
  • Control Center (location, staffing, scope of responsibility, monitoring systems, escalation procedures)
  • Testing

Network Management

  • Control Center (location, staffing, scope of responsibility, monitoring systems, escalation procedures)

System Configuration

  • Redundancy
  • Logical security (firewalls, IDS, DMZ, log management, backups)
  • Change management (plan review, authorization, testing)Capacity Planning
  • Performance characteristics
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Data Center Migration,Move and Relocation Project Timeline Checklists

Data Center Migration, Move and Relocation Project Timeline

Data Center Migration Planning Phase
1. Define Roles and Responsibility.

  • Create a team and assign responsibilities for all aspects of the move
  • Make sure all areas of expertise are covered
  • Make sure that you may have to look outside of IT for some areas

2. Prepare documentation, policy, and procedures

  • Ensure that assets and inventory documentation is properly managed.
  • Here is where you find out how good or bad your assets documentation is.

Data Center Migration Blueprint Phase

1. Design a layout for your new data center.

  • Get familiar with the dimensions of the new location and determine where everything will be located.

2. Develop a schedule.

  • A complex data center move is all about timing. Divide and conquer by breaking the task into manageable subtasks.

3. Set up services.

  • Contact service providers for all the utilities you’ll need, such as WAN services. Do this well in advance of your move, but even then be
    prepared for possible delays.

4. Make business interruption plans.

  • Plan the timing for shutting down and bringing back essential applications and services. Leave plenty of time for testing.

Data Center Migration Relocation Phase

The move will quickly reveal whether your months of planning bear fruit. Here are some tips:

  • Only personnel involved in the move should be present at this time.
  • Have contact numbers for all your vendors handy.
  • If you are moving into a newly constructed building, try to have representatives from the construction firm present.
  • A data center move means a lot of work getting done in a short amount of time. Make sure you have resources on “standby” in case you
    require more help.
  • Have plenty of help desk staff available to help users get their PCs and network configurations set up. If your entire business is moving, you will have lots of users asking for help.
  • Test your critical applications and hardware once everything is in place. Is your hardware operating properly?
  • Are your critical applications running without a hitch , or are there configuration problems to be resolved ? Is your networking equipment
    operating properly ?
  • Act to correct any problems revealed by your testing. Document any problems thoroughly and file the report in a safe place. After all, you never know when you might be moving again!

Lots of more in our tool section.. http://datacentertalk.com/category/data-center-tools/

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Facility and Site Selections Guidelines for Data Center

While looking for Facility and site for Data center, some points should be kept in mind:

Locations Related Security Guidelines.

1. Avoid the following:

  • Iconic, trophy, historic, listed, or high-profile sites and/or locations near such sites.
  • Uncontrolled public facilities for vehicles (e.g., tunnels, parking areas, etc.) directly beneath or adjacent to the site.
  • Avoid politically unstable areas.

2. Seek the following:

  • Maximum setback from the street on all facades
  • Maximum physical separation from neighboring buildings
  • Convenient external assembly points
  • Close proximity to emergency services
  • Easy access to major roads or arteries

Facility-related security guidelines

Seek the following in conjunction with a proper facility risk
assessment
before signing a lease:

  • Sole building occupancy or sole floor occupancy at a minimum
  • Physical access-controlled building entrances and exits to include parking facilities
  • Structural designs that minimize the risk of progressive collapse in the event of an explosive incident
  • Buildings with appropriate blast mitigation measures
  • Effective acoustic isolation for internal offices/conference rooms next to non-company-controlled space
  • Provisions for proper visitor access and control
  • Elevated and physically secured HVAC air intakes
  • Fire detection/prevention and life safety systems that meet company standards as well as all applicable codes
  • Adequate emergency escape routes
  • Internal space with the potential for segregated mail sorting/distribution
  • Appropriate access controls for on-site parking and preferably not located beneath the building if a multi-tenant facility
  • Provisions for secure equipment storage

For more Please refer our tool section ….

http://datacentertalk.com/category/data-center-tools/

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OPEN SHORTEST PATH FIRST (OSPF) – AN IGP PROTOCOL

KEYWORDS: OSPF , CCNA, CCNP , LSA, LSDB , Dijkstra , MPLS, DBD

 

Do you recall  Dijkstra’s algorithm, shortest path first algorithm in your engineering and CCNA preparation . Its time to know its one of the  interesting application .

OSPF is an interior gateway protocol that helps to facilitate the routing information in for the form of LSA (Link state Advertisement) within a single routing domain. It gathers LSA from available routers and constructs a topology map of the network.The same topology map is shared between all the devices with an Area .  OSPF was designed to support (VLSM) or (CIDR) addressing models.

OSPF senses changes in the state of the link , such as link failures, quickly and converges on a new loop-free routing structure. It uses the Dijkstra’s algorithm to find the shortest path tree for each route.

The link-state information is maintained on each router as a link-state database (LSDB) which is a tree-image of the entire network topology. Identical copies of the LSDB are periodically updated through flooding on all OSPF routers.

The best routes are selected by the OSPF by discovering the paths with the lowest cost to a destination. The route cost includes the cost which is configured on interface on which the Link State Advertisement is received by the OSPF and the cost configured on the outbound links operating between the destination network and the router.

A close look inside a OSPF packet suggests the field that constitutes the OSPF packet .

 

 

The fields on the OSPF header are as follows:

  • Version number – Version for IPv4 .I.E 2
  • Type –There are different types of ospsf packets (Hello, DBD, LSR, LSU, LSack)
  • Packet Length – length of the OSPF packet
  • Router ID – Router ID of source Router
  • Area ID – The OSPF area in which the packets originated
  • Check sum – Used in error detection.
  • Authentication Type – Describes either no authentication, cleartext passwords, or encrypted Message Digest 5 (MD5) for router authentication.
  • Authentication – Used with authentication type.
  • Data – Contains different information, depending on the OSPF packet type:
    • Hello – A list of known neighbors.
    • DBD – Summary of the LSDB, which includes all known router IDs and their last sequence number, among a number of other fields.
    • LSR - Contains the type of LSU needed and the router ID of the router that has the needed LSU
    • LSU – Contains the full LSA entries. Multiple LSA entries can fit in one OSPF update packet.
    • LSack – Empty.

 

 

How to Configure OSPF on Cisco Router?

Following commands should be entered in Router configuration mode on Cisco router to enable OSPF,

Router(config)# router ospf 1 (this command enables OSPF on router where 1 is the process ID)

Router(config-router)# network 10.1.1.1 0.0.0.255 area 0 (network specified in this command on which OSPF has to be enabled)

Router(config-router)# network 10.2.1.1 0.0.0.255 area 0 (network specified in this command on which OSPF has to be enabled)

OSPF Neighbor states in case of Adjacency

In order to determine the neighbor state of OSPF, you have to run the following command,

Rotuer# Show ip ospf neighbor

OSPF Multicast Address

OSPF routers sends and listens OSPF message on following multicast address .

  • 224.0.0.5 –all OSPF routers Multicast Address
  • 224.0.0.6 –the DR and BDR multicast Address

 

OSPF Challenges and Troueblshooting

Most of the engineers find it difficult to troubleshoot the OSPF if the goes down or is not coming up . Although from Practical expereince it is not difficult if you know how OSPF works and what happens of each stage.

 

 

OSPF Neighbor Adjacency States

  1. Down State An OSPF intial process before any exchange of information starts .The exchange process begins when router sending a hello out each interface that is configured for OSPF. The hello packet is sent out multicast address 224.0.0.5.
  2. Init State  An ospf speaking router receives a packet from another OSPF router . These routers will add the originating router to their list of neighbors. This state is the init state.
  3. Two-way State  When the originating router obtains the hello back from the neighbors as well, it notices that its ownRouter ID is included in the list of neighbors. At this point a two-way state is reached. They now have two way communication.
  4. On a broadcast link type, such as an Ethernet LAN and multi-access medium, a DR and BDR must be elected. The DR will form a bi-directional adjacency with each routers on the LAN link.
  • If a new router joins the broadcast network in which a DR and BDR already exist, it will get to the two-way state with all the routers, including the DR and BDR, and those that are DROTHER. The new router will form a bidirectional adjacency with only the DR and BDR.
  1. Every 10 seconds, the routers exchange hello packets to ensure there is still communication established.

 

  • The routers proceeds in the exstart state once the DR and BDR are elected. After that they exchange LSAs and populate the LSDBs.
  • Loading Stateif the router finds that the DBD contains a more updated information, it sends an LSR to the other router. The process of sending the LSR is called the loading state.
  • The routers are considered synchronized and in full state once all LSRs have been received and updated.

 

From troubleshooting perspective you can run the command “ Sh ip ospf nei “ . it will show the the neighbor states and their status.

 

Wish you a happy learning !!!

 

For more updates on the Data Center world,visit Data Center Talk.

 

 

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“In Service Software Upgrade” : Vital Tool

“I have a mission critical switch and I had an issue which cause problem in my production data center, I think, I need to upgrade my switch code software. I cannot ask for outage window from the clients. What should I do?”

What shall you as Data Center Planner do to avoid getting into such condition?

What Should I plan before I built data center?

Plan to have high availability, redundant and resilient core and distribution and critical piece of network in data center. Always try having redundant Routing Engines. With this you pursue a approach with minimum downtime.

What does ISSU stand for?

ISSU stand for “In Service Software Upgrade”. This is meant for upgrading software of switches without affecting production services. In Service Software Upgrade significantly reduces the impact planned software upgrades and maintenance can have on service availability. The risk assessment criteria are also changed, since impact to users is much less than before.

What should be typical design for high available switch where ISSU can be used?

Following diagram highlights main component of high available switch to utilize benefits for ISSU. Switch have two Routing Engine (Processors) which provide you capability to switch over to backup Routing engine whenever there is problem or failure in Active Routing engine. This is taken care in Control Plane and Data plane remains un-impacted. It means line cards will not get impact of routing engine failure.

ISSU for Cisco iOS:

Cisco Supports and uses ISSU to provide you high availability and upgrade without any interruption. Cisco IOS 12.2SB and above supports ISSU provided hardware/platform you are using supports the same.

Following document guides and provide information related to ISS. It is recommended by Cisco to check for ISSU compatibility using Cisco Online compatibility tool.

http://www.cisco.com/en/US/prod/collateral/iosswrel/ps6537/ps6550/prod_white_paper0900aecd80456d57.pdf

ISSU for Juniper OS:

Juniper also supports ISSU and provides resilience towards any such hardware failures. Again hardware compatibility and OS
compatibility should be checked before ISSU is used.

http://www.juniper.net/us/en/local/pdf/whitepapers/2000280-en.pdf

General Recommendations:

Upgrade frequency needs to be considered for each component when designing a system for ISSU. If frequent microcode changes are not required for a particular component, the ISSU process could omit that component entirely. However, managing such a process would be difficult given the constant need to track which components should be included in which upgrades. In other cases it might only be necessary to upgrade one component. An example would be a software issue that needed to be fixed within the control plane.

Two basic questions need to be answered before deciding on an appropriate ISSU design:

  • What if some components of the forwarding path are not redundant?
  • If the new release does not change a given component, should that component be omitted from the ISSU design so the process completes without resetting it?

The answers to these questions depend on the software and hardware architecture of the system and the quality of the operating system development effort. An ISSU design is determined by the quantity and functionality of each component and the interdependence between components.

Conclusion

ISSU is vital tool in performing upgrades for enterprise and service provider networks. Study in detail about your environment and ISSU features supported by your hardware vendor. The selection of an ISSU design requires a comprehensive approach, one that considers the advantages and disadvantages of various permutations of redundant and non-redundant router architectures.

You can also keep up to date with current trends and technology by visiting Data Centre Talk where we keep you informed on important changes as they occur.

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