Frequently Asked Questions (FAQ)

1:

Will IP-VPNs replace traditional WAN services, such as ATM or Frame Relay?

A1:

Although VPNs do offer flexibility for communications planners, they also enable the consumer to retain better control of security and communications policy management, rather than turning those controls over to a third-party as is the case with Frame Relay networks. The feature that attracts most consumers to VPNs in WANs is the low cost.

The concern with widespread acceptance of IP-VPNs replacing traditional WAN services is twofold:

  1. The Quality of Service (QoS), Service Level Agreements (SLAs), and QoS Service Level Guarantees (SLGs) of the IP Network Service Providers carrying the IP traffic and whether the providers will have these levels of quality and meet the service agreements. Currently, customers aren't willing to accept the replacement of WAN services with VPNs because they aren't convinced that ISPs are providing QoS, SLAs, and SLGs.

  2. The VPN parameters themselves (authentication, tunneling, and encryption) must be agreed upon by all VPN network sites.

These concerns are being addressed by IP-VPN vendors, network service providers, and customers alike and it is expected that widespread acceptance and use of IP-VPNs will coincide with the same widespread acceptance of IP, version 6 (IPv6). IPv6, originally called IP Next Generation (IPng), increases the address space from 32 to 128 bits, providing for a nearly unlimited (2128, or 3.4028236692093846346337460743177e+38, unique addresses) number of networks and systems. IPv6 enables QoS parameters for real-time audio and video.

2:

What is QoS and why is it important?

A2:

QoS is the ability to define a level of performance in a network. For example, ATM networks specify modes of service that ensure optimum performance for traffic such as real-time voice and video. QoS is a major issue on the Internet as well as in enterprise networks, because voice and video are more often transported over IP-based data networks that were not designed for continuous speech or video. Thus, transmissions are broken into packets that can travel different routes and arrive at different times, causing "choppy" conversations.

There is no better QoS than that offered by the plain old telephone system (POTS), which provides the highest quality of service in the world for voice calls. This circuit-switched system provides a continuous channel between two parties until one hangs up.

It is important to realize the difference between QoS and Class of Service (CoS). QoS refers to the mechanisms in the network software that determine which packets have priority. CoS refers to feature sets, or groups of services, that are assigned to users based on an organization's policy.

3:

Are there issues with router-based VPNs?

A3:

There are two concerns with router-based VPNs:

  • Interoperability If a connection to a suppliers' VPN is required, will both the site router and suppliers' router operate with one another and create the VPN?

  • Encapsulation Will non-IP protocols, such as IPX or SNA, be transported? Some router manufacturers only encrypt; they do not encapsulate.

Although processor load also is a concern, many routers now use application-specific integrated circuit (ASIC) hardware, enabling the router to dedicate certain processors for specific tasks, preventing any one router activity from overloading the router.



Network Sales and Services Handbook
Network Sales and Services Handbook (Cisco Press Networking Technology)
ISBN: 1587050900
EAN: 2147483647
Year: 2005
Pages: 269

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