cisco ccna routing

cisco ccna routing.Step 3. R2 performs the same operation as R1. R2 strips the link-layer headers and tails, processes the IP packet headers, and queries the routing table to discover the next-hop device to host B. After checking the routing table, R2 learns that Host B is directly connected to the local machine, which means that the local F0/2 interface belongs to the same broadcast domain as Host B. So, R2 encapsulates the packet into an Ethernet frame and sends it directly to host Bo.After receiving the Ethernet frame, Host B strips the Ethernet frame header and tail, and parses the header of the IP packet. Since Host B is the destination host of the IP packet, it strips the IP packet header first and passes the net load to a higher-level protocol for further processing. The above process for routing packets is similar for both IPv4 and IPv6 packets. This section continues to explain the process of routingThe process of routing IPv4 packets is similar for both IPv4 and IPv6 packets. The process of routing IPv6 packets will be discussed in the next section.1.4.1 IPv4 Packet Headers An IP packet consists of an IP packet header, which contains information about how to handle packets generated by the IP protocol, and an IP netload, which contains Layer 4 PDUs (e.g., TCP packet segments). The length of the IP packet header is 20.60 bytes, depending on which options are present in the IP packet header. Figure 1-44 shows the format of an IPv4 packet header.I ---------------------------------------------------------4 bytes ----------------------------------------------------------------1kISIP version number P packet header length DS and ECN fields Total IP packet lengthPacket ID Tag Slice OffsetSurvival Time Protocol Type Packet Header ChecksumSource IP address