HDLC
One sub-interface per VLANA compatible trunking protocol encapsulation for each sub-interfaceOne IP network or sub-network for each sub-interface
Protocol
protocol data unit
The ISL protocol can be used in Cisco routers when configuring the subinterfaces.
IPV5....i am not sure
The answer is Protocol's. Protocol is the set of rules for formatting the data across the network.
To allow the subnet configured on that interface to be advertised through a dynamic routing protocol without having that interface participate in the protocol.
there may be the issue with the layer 2 protocol like hdlc or ppp is not configured or wrongly configured if the interface is serial interface.
The difference between a link and an interface is the protocol used.
A: protocol
By encapsulation process data is put in a nutshell with all basic protocol information at each and every OSI layer. During this phase of network layer each layer conveys and exchange information to its neighboring layer. This is done utilizing Protocol Data Units.
The Internet Protocol (IP) is a protocol used for communicating data across a packet-switched internetwork using the Internet Protocol Suite, also referred to as TCP/IP. IP is the primary protocol in the Internet Layer of the Internet Protocol Suite and has the task of delivering distinguished protocol datagrams (packets) from the source host to the destination host solely based on their addresses. For this purpose the Internet Protocol defines addressing methods and structures for datagram encapsulation. The first major version of addressing structure, now referred to as Internet Protocol Version 4 (IPv4) is still the dominant protocol of the Internet, although the successor, Internet Protocol Version 6 (IPv6) is being deployed actively worldwide.