Network considerations in cloud computing

The impact of networking on cloud computing is best understood by considering public and private cloud applications in one dimension and cloud access versus intra-cloud networking in the other.

Cloud computing is a technique of resource sharing where servers and storage in multiple locations are connected...

by networks to create a pool of resources. When applications are run, resources are allocated from this pool and connected to the user as needed. The missions of connecting the resources (servers and storage) into a resource pool and then connecting users to the correct resources create the network's mission in cloud computing.

For many cloud computing applications, network performance will be the key to cloud computing performance. The implications are best understood by considering a kind of issue matrix: Public and private cloud applications in one dimension and cloud access versus intra-cloud networking in the other.

Public cloud access networking
First, public cloud access networking is most often through the Internet, though some cloud providers may be able to support virtual private networks (VPNs) for large customers. Accessing public cloud services will always create a tension between security and performance. Not all cloud computing providers will support encrypted tunnels, so your information may be sent in the open on the Internet. Where encryption is available, using it will certainly increase delay and may impact performance.

The only way to reduce delay without compromising security is by minimizing transit "hops". The Internet is a complex federation of interconnected providers, and reaching a given cloud computing service may involve transiting several provider networks. You will need to determine how your cloud provider choices are connected to other ISPs, particularly those you use regularly. The best cloud/ISP combination in terms of delay will almost always be one with the smallest number of hops.

Private cloud access networking
The second network consideration is private cloud access networking. Most often, enterprises will access their own private clouds using the same technology they employed for access to their data centers. This may include an Internet VPN or VPN service from a network operator. If application access was satisfactory in a "pre-cloud" configuration, a transition to private cloud computing is not likely to impact access performance.

Intra-cloud networking for public cloud services
Our third network application in cloud computing is intra-cloud networking for public cloud services. Public cloud computing networks are internal and thus not visible to the user, so when you secure public cloud computing services, it is very important to understand how your provider interconnects its cloud computing elements. The key issue to look for is the difference in network quality of service across the geography of the resource pool. If your cloud provider allows you to geographically narrow the range of resources that can be assigned to your application, then the performance variation across that narrower range should be examined. You'll want to include the intra-cloud network performance of public cloud providers in your cloud computing SLA.

Private intra-cloud networking
The final and most complicated issue for networking in cloud computing is private intra-cloud networking. What makes this particular issue so complex is that it depends on how much intra-cloud connectivity is associated with the applications being run. At a minimum, all cloud computing implementations will rely on intra-cloud networking to link users with the resource to which their application was assigned. Once the resource linkage is made, the extent to which intra-cloud networking is used depends on whether the application is componentized among multiple systems.

If the principle of service-oriented architecture (SOA) is followed, then traffic may move between components of the application, as well as between application and user. The performance of those connections will then impact cloud computing performance overall. Private intra-cloud networking is usually supported over company-leased trunks between the major data center sites. It is important that these trunks have high enough capacity to insure that there are minimal network delays no matter where in the private cloud a given application is run. In fact, the ability of a company to create an effective private cloud will depend in large part on the quality of the network connections between the major data centers that make up the cloud. This is why it is usually more important to design the intra-cloud network in private cloud computing than to design the cloud access network.

While network performance is important to cloud computing, it's also important not to become obsessive about measuring and guaranteeing it. The key thing to look for in exploring the impact of networks on cloud computing performance is the differences that exist between your current application/network relationships and those that will exist under the cloud. Those differences are what will impact your users.

Tom Nolle, is president of CIMI Corporation, a strategic consulting firm specializing in telecommunications and data communications since 1982. He is a member of the IEEE, ACM, Telemanagement Forum, and the IPsphere Forum, and is the publisher of Netwatcher, a journal in advanced telecommunications strategy issues.  


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