TCS Placement: Sample Questions 343 - 344 of 502

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Question 343

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Describe in Detail

Essay▾

What is BGP (Border Gateway Protocol) ?

Explanation

  • Border gateway protocol is an inter-autonomous system routing protocol to advertise reachable networks within an autonomous system.
  • Enables information to be shared with the autonomous system- exchange network reachability information with other BGP systems.
  • Newer than EGP (Exterior Gateway Protocol) .
  • Manages packets routed across the internet through the exchange of routing and reachability information between edge routers. Routes packets between autonomous systems (AS) under one service provider.
  • Traffic routed within a single network AS is referred to as internal BGP, or iBGP.
  • BGP connecting one AS to other AS is referred as external BGP, or eBGP.
  • BGP rule is that an AS advertises only those routes that it uses.
  • BGP runs over a reliable transport protocol and uses TCP port for establishing its connections.
The Border Gateway Protocol (BGP)

Question 344

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Describe in Detail

Essay▾

What is protocol Data Unit?

Explanation

  • A protocol data unit is information delivered as a unit among peer entities of networks containing control information, address information, or data.
  • PDU represents a unit of data specified in the protocol of a given layer, which consists of protocol control information and user data.
  • PDU is related to the initial four layers of the OSI model. In Layer 1, PDU is a bit, in Layer 2 it is a frame, in Layer 3 it is a packet and in Layer 4 it is a segment. In Layer 5 and above, PDU is referred to as data.
  • Contains four fields:
    • Destination service access point (DSAP)
    • Source service access point (SSAP)
    • Control field
    • Information field
  • DSAP, SSAP are addresses used by the LLC to identify the protocol stacks on the receiving and sending machines that are generating and using the data.
  • The control field specifies whether the PDU frame is an information frame (I - frame) , a supervisory frame (S - frame) , or an unnumbered frame (U - frame) .
Given the Image is Define the Protocol Data Unit (PDU)

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