ccna 9tut question

ccna 9tut question.The lack of QoS is a key consideration when deploying VPNs across the Internet or public network. Where possible, QoS must be addressed by the provider by providing a service level agreement (SLA). An SLA is a document that describes in detail the QoS parameters that packets transmitted in the provider's network should have.Voice communications do not work well (or sometimes not at all) if there is latency. Because of the need to protect VPN encrypted data, throughput bottlenecks can occur when packets are processed through encryption algorithms. This problem is usually further exacerbated by increased security.There is full compatibility between VoIP and DES or 3DES. provided that the VPN can provide the necessary throughput. Large international companies may have to deal with other issues affecting voice communications. The US commercial sector can restrict the export of certain encryption technologies. Typically, DES is exportable, while 3DES is not. Nevertheless, regulation of these 3DES technologies takes many forms, ranging from a complete ban on exports to certain countries to allowing 3DES exports to specific industries and users. Most companies that use VPN connections outside of the U.S. mainland will have to figure out whether their VPN provider has exportable products and how export controls will affect the use of these products to build their networks.6.4.5.4 Hardening Voice DevicesWhen protecting voice traffic, don't forget to protect the voice application servers. The latest release of Cisco Unified Communications Manager disables unnecessary services, disables default user names, allows only signed images to be installed, and supports secure management protocols. IP phones should also be protected. IP phones should use only signed firmware and configuration. Also, the PC port, settingbuttonspeakerphone, and Web access should be disabled unless absolutely necessary. A highly secure IP telephony communications environment can be provided by integrating the transport provided by secure LANs, firewalls, VPNs, and the application and host security features available with Cisco Unified Communications Manager and Cisco IP phones.6.4 Wireless, VoIP, and SAN Security 1796.4.6 SAN Security Considerations6.4.6.1 Introduction to SANsA SAN is a specialized network for fast and reliable access to resources such as servers and external storage. In a SAN, a storage device is not the exclusive property of any one server. Instead, a storage device is a peer-to-peer resource shared by all network servers. Just as a LAN can be used to connect clients to servers, a SAN can be used to connect servers to storage, as well as to enable interconnection between servers and between storage and storage.A SAN does not need to be a physically segmented network. It can be a dedicated subnet used only to carry business-critical I/O traffic between servers and storage devices. For example, a SAN should not carry traffic for general-purpose purposes, such as email or other end-application-related traffic. It is restricted to carry I/O traffic, such as reading files from or writing files to disk. This network approach helps avoid unacceptable hazards and performance degradation. When only a single network is used for all applications, and these potential hazards and performance degradation are unavoidable.