Home > Articles > Cisco Network Technology > General Networking > Network Virtualization: A Basic Virtualized Enterprise

Network Virtualization: A Basic Virtualized Enterprise

  • Sample Chapter is provided courtesy of Cisco Press.
  • Date: Oct 6, 2006.

Chapter Description

The authors of Network Virtualization define the technical requirements posed by the need to virtualize the network. Based on these requirements, they propose an architectural framework comprised of the functional areas necessary to successfully support concurrent virtual networks (VNs) over a shared enterprise physical network.

From the Book

Network Virtualization

Network Virtualization

$70.00

In this chapter, we define the technical requirements posed by the need to virtualize the network. Based on these requirements, we propose and architectural framework comprised of the functional areas necessary to successfully support concurrent virtual networks (VNs) over a shared enterprise physical network.

Networks enable users to access services and resources distributed throughout the enterprise. Some of these services and resources are public: those accessed over the Internet, and others that are private and internal to the enterprise. Every enterprise has unique security and service level policies that govern the connectivity to the different services, whether these are public or private.

One of the basic building blocks behind the virtualized network and, in fact, a key driver is security. An important element of an enterprise's security policy is the definition of a network perimeter. In general, the level of trust inside and outside of the network perimeter differs, with end stations inside the perimeter being generally trusted and any access from outside the perimeter being untrusted by default. Communications between the inside and the outside of the perimeter must happen through a checkpoint. At the checkpoint, firewalls and other security devices ensure that all traffic that enters or leaves the enterprise is tightly controlled. Therefore, we refer to the point of entry/exit to/from the enterprise network as the network perimeter.

To provide the required connectivity, create a secure perimeter and enforce the necessary policies, it is recommended that an enterprise network be based on certain functional blocks. Figure 3-1 depicts a modular enterprise network and its perimeter. The recommended functional blocks are as follows:

  • The LAN/MAN transport (core and distribution)
  • The LAN edge or access layer
  • The Internet access module
  • The data center access module
  • The WAN aggregation module
  • The WAN transport
  • The branch

When a single enterprise network must service many different groups, it is often necessary to create virtual networks (VNs) so that each group can enjoy

  • Private connectivity over a shared infrastructure.
  • A dedicated perimeter in which independent policies can be enforced per group.
  • User mobility (ubiquitous access to the appropriate virtual network regardless of the user's location).
nv100301.gif

Figure 3-1 The Modular Enterprise Network and Its Perimeter

At the risk of oversimplifying, a VN can be seen as a security zone. All devices within the security zone trust each other and communicate freely with each other. Meanwhile, any communication with other security zones, or other networks, must happen in a controlled manner over a highly secured perimeter or checkpoint. Thus, a virtualized enterprise network will simultaneously host many security zones, and their dedicated perimeters, over a shared infrastructure.

The Virtual Enterprise

A virtual enterprise network must provide each group with the same services as a traditional dedicated enterprise network would. The experience from an end-user perspective should be that of being connected to a dedicated network that provides connectivity to all the resources the user requires. The experience from the perspective of the network administrator is that they can easily create and modify virtual work environments for the different groups of users and adapt to changing business requirements in a much easier way. The latter derives from the ability to create security zones that are governed by policies enforced centrally. Because policies are centrally enforced, adding or removing users and services to or from a VN does not require any policy reconfiguration. Meanwhile, new policies affecting an entire group can be deployed centrally at the VN perimeter. To virtualize an enterprise network, the basic functional blocks of the modular enterprise must be enhanced to provide the following functionality:

  • Dynamically authenticate and authorize users into groups
  • Isolate connectivity to guarantee privacy between groups
  • Create well-defined and controllable ingress/egress points at the perimeter of each VN
  • Enforce independent security policies for each group at the perimeter
  • Centralize the enforcement of the perimeter security policies for the different VNs by
    - Allowing secure collaboration mechanisms among groups
    - Allowing secure sharing of common resources
  • Provide basic networking services for the different groups, either shared or dedicated
  • Provide independent routing domains and address spaces to each group

You could use many different technologies to solve the listed challenges. The technologies available and how these can be used to meet the above requirements are the topic of the remaining chapters in the book.

From an architectural perspective, the previous requirements can be addressed by segmenting the network pervasively into VNs and centralizing the application of network policies at the perimeter of each VN. These are, of course, the policies for ingress and egress to the VN or security zone. The formation of a trusted security zone relies on traffic-isolation mechanisms rather than a distributed policy. Because traffic internal to a zone is trusted, policies are required only at the perimeter to control the access to external resources that could in many cases be shared. Figure 3-2 illustrates this concept.

nv100302.gif

Figure 3-2 Virtual Networks with Centralized Policies at the Perimeter

Regardless of where a user is connected, its traffic should always use the same VN and be directed through a central site of policy enforcement (VN perimeter), should it need to exit the VN. This makes users mobile and ensures that regardless of their location they will always be subject to the same policies. To ensure that users are always connected to the right VN, dynamic authentication and authorization mechanisms are required. These allow the identification of devices, users, or even applications so that these can be authorized onto the correct virtual segment and thus inherit the segment's policies.

The virtualization architecture described so far can be organized into functional areas. These functional areas provide a framework for the virtualization of networks:

  • Transport virtualization
  • Edge authorization
  • Central services access (VN perimeter)

As you will see throughout the book, this modular framework gives the network architect a wide choice of technologies for each functional area. A key element in achieving this degree of flexibility is the definition of clear communication interfaces between the different areas.

VLANs provide an example of a communication interface between functional areas. The edge authorization module assigns a user to a VLAN, and the transport module maps that VLAN to a VN. At the destination, the transport module maps the VPN back to a VLAN. If the destination is outside the VN perimeter, the transport module hands off a VLAN to the central services access module, which maps the VLAN to the necessary virtual services. As you progress through the book, you learn that the interface between modules could very well be a label or a policy.

Figure 3-3 shows the functional areas of the virtualized enterprise. As shown, you can use a variety of technologies for each different area.

nv100303.gif

Figure 3-3 Virtualized Enterprise Network Functional Areas

A useful way to look at Figure 3-3 and understand the role of the different functional areas is to look at it from the top down. Starting at the top, the endpoints connected to the network are authenticated and as a result of the authentication are authorized onto a specific VLAN (edge authorization). Each VLAN maintains its traffic separate from other VLANs and is mapped to a virtual routing and forwarding instance (VRF).

Each VRF is connected to other VRFs in its VN and keeps its traffic separate from VRFs that belong to other VNs (transport virtualization). When traffic is destined to a resource outside the VN (for example, the data center), it is routed to the VN perimeter, where virtual services, such as firewalling and load balancers, are applied to each group (central services access—VN perimeter). Traffic destined to a subnet over the WAN is kept separate from traffic in other VNs through the virtualization of the WAN transport (transport virtualizaton).

2. Transport VirtualizationVNs | Next Section

Cisco Press Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from Cisco Press and its family of brands. I can unsubscribe at any time.

Overview

Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about Cisco Press products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information

To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites; develop new products and services; conduct educational research; and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@ciscopress.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information

Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security

Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children

This site is not directed to children under the age of 13.

Marketing

Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information

If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out

Users can always make an informed choice as to whether they should proceed with certain services offered by Cisco Press. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.ciscopress.com/u.aspx.

Sale of Personal Information

Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents

California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure

Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links

This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact

Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice

We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020