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Saturday, October 5, 2013

Identifying Migration Risks


After the decision has been made to migrate to a colocation facility in Houston, it is vital to develop a comprehensive migration plan. This plan must look at each aspect of the migration and identify all the possible problems that may occur. It is vital to identify as many of the potential risks as possible and fully understand them before you migrate. This article will look at the possible problems that a migration may encounter with regards to each of the seven layers that make up the Open System Interconnection (OSI). These seven layers are:

  1. Physical layer
  2. Datalink layer
  3. Network layer
  4. Transport layer
  5. Session Layer
  6. Presentation Layer
  7. Application Layer
The OSI model sets out a standard framework for the transfer of messages between the various points in a telecommunications network and the implementation of protocols within it. Most migration specialists will construct a plan following this process from bottom to top.

Physical layer

This layer concerns the flow of data through the network at the electrical and mechanical level. Cabling the private suite or even an individual rack in a Dallas colocation center can lead to a number of potentially costly problems. These include:
  • incorrectly calculating the total amount of cable required,
  • insufficiently calculating the port density,
  • insufficient pre-migration testing, and
  • improper or lack of labeling.
If at all possible, any budget should include a structured cabling design including a Main Distribution Frame (MDF) and Independent Distribution Frames (IDF).

Datalink layer

The datalink layer involves two areas - Media Access Control (MAC) and Logical Link Control (LLC). These are fairly low-level functions; however, there are a number of potential problems that can come into play. When changing the IP address, it is important to remember to clear the ARP cache on any switches or routers. Pre-knowledge of all the hubs and switches that will be present in the migration is crucial. If the migration does not correctly perform the VLAN configuration of switches, some network segments will be unable to communicate with each other.

Network layer

In most Houston colocation facilities the migration will involve Internet Protocol (IP). Many configuration issues are involved and this can be one of the most problematic areas.  Any problems that arise within the network will affect all subsequent areas of the migration. DNS issues associated in the networking process will be one of the most challenging areas.

A common approach to migration, when it is necessary to renumber an IP address, is to reconfigure Time to Live settings for DNS zones. This will force updates to DNS servers all around the world. It will be necessary to allow at least 72 hours for replication even if the Time to Live is very low.  The firewall and other security related devices will also be affected by changing IP addresses. Consider any intrusion detection or prevention devices that will be added to your network by the Houston colocation facility, and what configurations will be required to keep any false positives reported to a minimum.

Transport layer

The transport layer provides the end-to-end control and error-checking. It will involve both TCP and UDP protocols. TCP/IP is actually a number of protocols working together. It must be identified which applications are connection-oriented and which rely on receiving packets broadcast onto the network. It is also important to be aware of any security features involved in this stage of production.

Session Layer

Protocols in this layer deal with establishing conversations throughout the network. Protocols that should be considered include NetBIOS and Session Control Protocol.

Presentation Layer 

This area is generally the least problematic in a migration to a Houston colocation facility. Technologies present in this part of the migration include QuickTime, GIF, JPEG, and MPEG. If switching from one platform to another, there are many conversion tools available that can be used to simplify the process.

Application Layer

This area will have the most obvious impact as it directly affects the end users. Changing from FTP to SCP, or Telnet to SSH, will require extra training. The impact of this in terms of both money and time should be accounted for in the migration plan. Provision for end-user training should be built into any plan as it will have a direct effect on daily operations.

By identifying the risks at each layer in the OSI, all potential risks can be analyzed and planned against.

This will lead to a more comprehensive plan and a greater chance of the migration to the Houston colocation facility running smoothly. Countering any possible problems before migration will lead to a seamless transition and avoid costly downtime benefiting the organization and its customers.
Featured images:
  •  License: Image author owned 
  •  License: Image author owned 
James Crowl writes about colocation services in the Houston Area.  He believes colocation should be considered by any company looking for data security. James discusses the benefits of colocation and data centers for companies large and small.  The  Houston Data Center he recommends is further discussed at http://www.datafoundry.com/data-centers/houston-data-center/
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