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Computer Networks : Delays and Loss
1)Propagation delay
Queuing delay
Transmission delay are faced by the packet in travelling from one end system to another.
2) For a 10Mbps Ethernet link, if the length of the packet is 32bits, the transmission delay is(in milliseconds) is 3.2. Explanation: Transmission rate = length / transmission rate = 32/10 = 3.2milli seconds.
3)The time required to examine the packet’s header and determine where to direct the packet is part of Processing delay.
4)Traffic intensity is given by, where L = number of bits in the packet a = average rate R = transmission rate La/R.
5)In the transfer of file between server and client, if the transmission rates along the path is 10Mbps, 20Mbps, 30Mbps, 40Mbps. The throughput is usually 10Mbps.
Explanation: The throughput is generally the transmission rate of bottleneck link.
6) If end to end delay is given by dend-end = N(dproc + dtrans + dprop) is a non congested network. The number of routers between source and destination is N-1.
7)The total nodal delay is given by dnodal = dproc + dqueue + dtrans + dprop.
8)In a network, If P is the only packet being transmitted and there was no earlier transmission, Queuing delays could be zero.
9)Transmission delay does not depend on Distance between the routers.
Explanation: Transmission delay = packet length / transmission rate.
10)Propagation delay depends on Distance between the routers.
Explanation: Propagation delay is the time it takes a bit to propagate from one router to the next.
Network Attacks
1)The attackers a network of compromised devices known as Botnet.
2)Vulnerability attack
Bandwidth flooding
Connection flooding are form of DoS attack.
3)The DoS attack is which the attacker establishes a large number of half-open or fully open TCP connections at the target host :- Connection flooding.
4)The DoS attack is which the attacker sends deluge of packets to the targeted host :- Bandwidth flooding.
5)Packet sniffers involve Passive receiver.
Explanation: They do not inject packets into the channel.
6)Sniffers can be deployed in
Wired environment
WiFi
Ethernet LAN
7) Firewalls are often configured to block UDP traffic.
