What is encapsulation in network protocols?
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Data encapsulation is the process that adds additional protocol header information to the data before transmission. In most forms of data communications, the original data is encapsulated or wrapped in several protocols before being transmitted. Show When sending messages on a network, the protocol stack on a host operates from top to bottom. In the web server example, we can use the TCP/IP model to illustrate the process of sending an HTML web page to a client. The application layer protocol, HTTP, begins the process by delivering the HTML formatted web page data to the transport layer. There the application data is broken into TCP segments. Each TCP segment is given a label, called a header, containing information about which process running on the destination computer should receive the message. It also contains the information that enables the destination process to reassemble the data back to its original format. The transport layer encapsulates the web page HTML data within the segment and sends it to the internet layer, where the IP protocol is implemented. Here the entire TCP segment is encapsulated within an IP packet, which adds another label, called the IP header. The IP header contains source and destination host IP addresses, as well as information necessary to deliver the packet to its corresponding destination process. Next, the IP packet is sent to the network access layer where it is encapsulated within a frame header and trailer. Each frame header contains a source and destination physical address. The physical address uniquely identifies the devices on the local network. The trailer contains error checking information. Finally the bits are encoded onto the media by the server network interface card (NIC). Click the Play button in the figure to see the encapsulation process. Table Of ContentsEncapsulation Protocols Encapsulation protocols connect the layer- 2 (link layer) protocol with the layer-3 (network layer) protocol. For an ASE to analyze network-layer protocols, it must know how to access them above the link layer. Toward this end, you can set the ASE's encapsulation protocol. Note  An encapsulation protocol is not always necessary on a communications link, however, typically, it is used to carry more than one layer-3 protocol over a link. For example, you can configure a Frame Relay link to send only IP packets, in which case no encapsulation protocol is required. However, if the link were configured to also send IPX, an EtherType or RFC1490-type encapsulation protocol must be used. The encapsulation protocol selections (such as IP) are not all proper encapsulation protocols. Instead, they tell the ASE what to look for above the link layer. IP means IP immediately follows the Frame Relay header and no encapsulation protocol is used. The encapsulation offset in the protocol-definition window (titled Beginning n octets after the frame header) works in conjunction with the encapsulation protocol. This mechanism instructs the ASE to skip a certain number of octets after the link-layer headers before it attempts to decode the packet further using the encapsulation protocol: • • You also can use the offset for data in an encapsulation protocol that is not supported in Cisco WAPMS. The offset then instructs the ASE to ignore the specified number of octets because the ASE would not be able to recognize the encapsulation protocol. For example, you may know that on your line the IP packet begins ten octets after the link-layer header. Therefore, setting an encapsulation of IP with an offset of ten would work—the ASE would simply ignore the ten octets between the header and the IP protocol. Table B-1 lists the encapsulation protocols available for configuration through Cisco WAPMS.
Table B-1 Encapsulation Protocol and Network Layer Settings
1This is a common setting for Frame Relay with an offset of zero. However, you can use it when an unsupported encapsulation protocol is in use but the user knows the line is carrying EtherType formatted frames. In this case, configure the offset with the appropriate number of octets to skip between the link-layer header and the beginning of the EtherType frame. 2Use this setting when no encapsulation protocol in use and the specified network address is the only one in use on the link. Or, you can use this setting when an unsupported encapsulation protocol is in use, in which case you must determine the offset from the link-layer header to reach the specified protocol. The ASE would therefore skip the analysis of the encapsulation protocol and jump to the network-layer protocol. What are encapsulation protocols?Encapsulation protocols connect the layer- 2 (link layer) protocol with the layer-3 (network layer) protocol. For an ASE to analyze network-layer protocols, it must know how to access them above the link layer. Toward this end, you can set the ASE's encapsulation protocol.
What is encapsulation in networking example?1. With networking, encapsulation is taking data from one protocol and translating it into another protocol, so the data can continue across a network. For example, a TCP/IP packet contained in an ATM frame is a form of encapsulation.
What is data encapsulation in networking?In computer networking, encapsulation is a method of designing modular communication protocols in which logically separate functions in the network are abstracted from their underlying structures by inclusion or information hiding within higher-level objects.
What is encapsulation and encapsulation in network operations?Encapsulation adds information to a packet as it travels to its destination. Decapsulation reverses the process by removing the info, so a destination device can read the original data.
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