Functions of OSI and TCP/IP Layers Q.34
Consider three IP networks A, B and C. Host HA in network A sends messages each containing 180 bytes of application data to a host HC in network C. The TCP layer prefixes a 20 byte header to the message. This passes through an intermediate network B. The maximum packet size, including 20 byte IP header, in each network is
A : 1000 bytes
B : 100 bytes
C : 1000 bytes
The network A and B are connected through a 1 Mbps link, while B and C are connected by a 512 Kbps link (bps = bits per second).
- Option : D
- Explanation : Packet A sends an IP packet of 180 bytes of data
+20 bytes of TCP header +20 bytes of IP header
to B.
Ip layer of B now removes 20 bytes of IP header and has 200 bytes of data.
So, it makes 3 IP packets – (80 + 20, 80 + 20, 40 + 20) and sends to C as the Ip packet size of B is 100. So, C receives 260 bytes of data which includes 60 bytes of Ip headers and 20 bytes of TCP header.
