Publié le 13 août 2013
Cloud computing has been around for a long time. Enterprise IT departments have been using data centers with success for decades. The novelty of cloud computing comes with the “sharing aspect” of data centers. Data centers are now being used by multiple users with ubiquitous public access to the Internet. By pooling resources, cloud service providers can offer dynamic services tailored to users’ requirements.
Now that we have covered the different types of connectivity and models of cloud deployment, we will now assess the cloud network architecture requirements needed to deliver cloud services. These requirements can be grouped into the following four categories:
Communication service providers (CSPs) or Carriers understand that they will need to provide more value-added services in order to increase their top-line profitability. There are a lot of different value-added services that could be added to the product portfolio of carriers, but as network and cloud access services are the basis of the quality equation, when it comes to cloud services, the evolution from CSP to cloud service provider is trivial.
Traditional telecom service providers are already trying to increase their top line by offering more managed services. However, these efforts must evolve to account for the fact that content and applications are what people value and are willing to pay for. Service providers need to find ways to pair their high-performance networks with cloud and content providers in ways that allow them to participate in current revenue streams. Doing so will require changes in terms of how they create, activate and assure services that let them interact with the cloud and content providers. They also need to increase their focused to the end service or application the user is buying.
In a recent report, Infonetics analysts interviewed 19 major telecom operators, cable operators, data center/content specialists and colocation providers with data centers containing 100 or more servers. Together, the respondent operators represent a significant 20% of the world’s telecom carrier revenue and 20% of the world’s telecom CAPEX, and are distributed across North America, EMEA (Europe, Middle East, Africa), and Asia Pacific.
According to Informa, more and more carriers are turning to cloud services for additional revenues. CSPs need to remember that cloud computing can and must defend their core broadband network. Cloud services must fulfill a primary function of securing additional revenues on the network assets that make carriers positively different from pure-play cloud-service providers.
When it comes to cloud challenges, QoE is at the top. Cloud users and cloud consumers (in this case defined as an organization or person that buys services from the cloud provider to use or run an application) are on the receiving end of QoE. Cloud providers are responsible for the cloud data center and transport connectivity. This responsibility translates into an SLA between the cloud provider and cloud consumer. The cloud provider does not own the carrier network, but leases transport connectivity from the cloud carrier with an attached SLA.
As mentioned earlier, cloud carriers are responsible for availability, reachability, bandwidth and service attributes, such as frame loss, latency and packet jitter.
Cloud providers need to take a closer look into the data center infrastructure. Virtual machine availability, server utilization and allocation, and storage capacity are all within the responsibilities.
As they connect the cloud users to the data center, they both need to ensure that the services are available to the users, that the Web response time is within the SLA, and that DNS service is accurate and performs as expected.
The most important shared responsibility is the time it takes to turn up a customer. Because most of the time required to turn-up a customer originates from activation of the cloud access service, carriers will need to streamline their operations to bring turn-up time down to a reasonable amount.
Once the customer order for the cloud access service has been received, the carrier will start the lifecycle of the service. The three major stages to the life cycle are:
Currently, there is only one standardized test methodology for testing services during service activation, and this methodology is recommendation Y.1564 from the ITU-T. As is true for all cloud connectivity, strict performance requirements are in place to ensure that applications run efficiently over Carrier Ethernet-based services.
Multiple services can be provided by cloud providers. Because each one of them can have its own class of service, a test methodology capable of measuring multiple key performance indicators (KPIs), such as frame delay, inter-frame delay variation and frame loss, is required on a per-class-of-service basis. For this type of measurement, ITU-T Y.1564, which is referred to as EtherSAM at EXFO, is the only standardized methodology capable of achieving this.
Y.1564 is a two-step methodology that validates the configuration and performance of the different services. During the configuration test, the test instruments will measure CIR/CBS, EIR/EBS, traffic policing and Ethernet-based service attributes, and for a single service at a time. This validates that the bandwidth profile and all major configurable parameters are properly configured on a per-service basis.
Once this step is completed, a second test, i.e., the performance test, will be conducted to test all configured services concurrently. By simulating all services simultaneously at their configured CIR, carriers will ensure that cloud services can be transported across the cloud access network to their maximum committed rate, and that the KPIs meet the service acceptance criteria for each of the services.
In application connectivity, the type of traffic being transmitted requires different service attributes. Because the virtual machine can be migrated from data center to data center, and large amounts of data need to be replicated at another location, the requirements from the services will be different. Fortunately, from a test-methodology perspective, the known methodologies are still applicable. High bandwidth, zero frame loss, and low latency can be measured with Y.1564.
Due to the large amounts of data being transferred, a TCP performance test can be performed to ensure that the files are transferred efficiently across the network. However, because the current service testing trend is based on the ITU-T Y.1564 methodology, it can only provide a reliable assessment of network performance if the applications running on it are UDP-based. If they are running on TCP, the methodology will only provide a general assessment of the network’s performance, and will not be able to measure the end user’s QoS.
For more information about TCP testing methodologies and tools that service providers can use to prove that their network is not at fault, watch the TCP Testing: Measuring True Customer Experience webinar and read the TCP Technology and Testing Methodologies white paper.