Project ForgeComputer Networks
OSI/TCP-IP Layers & Routing
GATE 2013
Medium
Assume that source S and destination D are connected through two intermediate routers labeled R. Determine how many times each packet has to visit the network layer and the data link layer during a transmission from S to D.
- ANetwork layer – 4 times and Data link layer – 4 times
- BNetwork layer – 4 times and Data link layer – 3 times
- Network layer – 4 times and Data link layer – 6 times
- DNetwork layer – 2 times and Data link layer – 6 times
Explanation
The path S–R–R–D has 4 nodes (S, R, R, D), each of which processes the packet at the network layer once: 4 network-layer visits. There are 3 physical links (S-R, R-R, R-D), and the data link layer is used twice per link (once at each end): 3×2 = 6 data-link-layer visits.
Source: GATE CS 2013 (2013)
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