ccna book 200-301 pdf

ccna book 200-301 pdf.8.1.2 VPN Topology8.1.2.1 Site-to-Site VPNs and Remote Access VPNsThere are two basic types of VPN networks: site-to-site and remote access. When devices on both sides of a VPN connection have prior knowledge of the VPN configuration, a site-to-site VPNOVPN is established that remains static and the internal hosts are unaware of the VPN's existence. Frame Relay, ATM, GRE, and MPLSVPN are all site-to-site VPNoRemote access VPNs are established when the VPN information is not statically configured, but allows connection information to be dynamically changed and can be enabled and disabled as needed o Consider a remote office worker who needs to access company data through a VPN on the Internet. The telecommuter does not need the VPN connection to be always present; his PC is responsible for establishing the VPN o The information needed to establish the VPN connection, such as the IP address, changes dynamically with the telecommuter's location.8.1.2.2 Site-to-Site VPNsA site-to-site VPN is an extension of a traditional WAN network that connects entire networks to each other. For example, a site-to-site VPN can connect a branch office network to an enterprise's headquarters network. In the past, leased lines or frame relay links were required to connect sites; since most enterprises now have access to the Internet, these connections can be replaced with site-to-site VPNs.In a site-to-site VPN, hosts send and receive normal TCP/IP traffic through a VPN gateway. The VPN gateway can be a router, firewall, CiscoVPN concentrator, or CiscoASAoVPN gateway that encapsulates and encrypts outbound traffic from a specific site and sends it through a VPN tunnel on the Internet± to a peer VPN gateway at the destination site. Upon receipt of the traffic, the peer VPN gateway strips the packet headers, decrypts the contents, and forwards the packet to the destination host inside its private network.8.1.2.3 Remote Access VPNsRemote access VPNs evolved from circuit-switched networks such as Plain Old Telephone Service (POTS) or ISDN. remote access VPNs support a client/server architecture where a VPN client (remote host) needs to securely access the corporate network through a VPN server device at the network boundary.In the past, enterprises used dial-up networks and ISDNs to support remote users. With a VPN, mobile users only need access to the Internet to communicate with the home office. Telecommuters typically use broadband connections to provide Internet connectivity.