ccna certification in hyderabad

ccna certification in hyderabad.Tunneling (Tunnel) is a technology that encapsulates one protocol into another protocol for transmission. Tunneling only requires devices at both ends of the tunnel to support both IPv4 and IPv6 protocol stacks. The IPv4 tunneling technology uses the existing IPv4 network to provide connectivity to the independent IPv6 network, and IPv6 packets are encapsulated in IPv4 packets to traverse the IPv4 network for transparent transmission of IPv6 packets. The advantage of this technique is that only the border devices of the network are required to implement IPv4/IPv6 dual stack and tunneling, and other nodes do not need to support dual stack, which can protect the existing IPv4 network investment to the maximum extent. However, tunneling does not enable direct communication between IPv4 hosts and IPv6 hosts. Tunnels can be configured manually or automatically, and which method is used depends on the requirements for scalability and management overhead, etc. The main tunneling techniques used for IPv6 traversing IPv4 networks are described below.(1) IPv6 Manual TunnelingIPv6 manual tunnels have manually configured source and destination addresses and configure IPv6 addresses for the tunnel interfaces to provide a stable connection to the IPv6 network separated by the IPv4network separated by an IPv6 network to provide stable point-to-point connectivity. If a border device is to establish a manual tunnel with multiple devices..22 . Cisco Networking Lab CCNA Lab Guide (Release 2)it is necessary to configure multiple tunnels on the device. The operating mode of the manual tunnel is ipv6ip,which corresponds to the value of the IPv4 protocol field of 41. which can be obtained by using the command debugippacket detail.(2) GRE TunnelingGRE tunnels are very similar to manual tunnels in that they can also provide stable point-to-point connectivity to IPv6 networks separated by IPv4 networks. It requires manual configuration of the tunnel source and destination addresses and the tunnel interface IPv6 address. On Cisco routers, the default mode of operation for tunnels is greip, which corresponds to an IPv4 protocol field value of 47.(3) 6to4 TunnelingA 6to4 tunnel is an automatic tunnel that is also used to connect isolated IPv6 networks through an IPv4 network, but it can be multipoint. Border devices use IPv4 addresses embedded in IPv6 addresses to automatically create the tunnel. 6to4 tunnels use a dedicated address range 2002::/16, and a 6to4 network can be represented as a 2002:IPv4 address ::/48, for example, a border device with an IPv4 address of 192.168.99.1 (c0a86301 in hex) would have an IPv6 address prefix of 2002:c0a8:6301::/ The source IPv4 address of the 48o6to4 tunnel is specified manually, and the destination address of the tunnel is determined by the packets forwarded through the tunnel. If the destination address of an IPv6 packet is a 6to4 address, the IPv4 address is extracted from the destination address of the packet as the destination address of the tunnel. The biggest disadvantage of 6to4 tunnels is that they can only use static routes or BGP, because other routing protocols use link-local addresses to establish neighbor relationships and exchange routing information.