by Ilya Gregorik
Latency: the time from the source sending a packet to the destination receiving it
- Propagation Delay: Amount of time required for a message to travel from the sender to receiver, which
is a function of distance over speed with which the signal propagates.
- usually within a small constant factor of the speed of light
- Transmission Delay: Amount of time required to push all the packet’s bits into the link, which is a func‐
tion of the packet’s length and data rate of the link.
- determined by the available data rate of the transmitting link
- Processing Delay: Amount of time required to process the packet header, check for bit-level errors,
and determine the packet’s destination.
- once the packet arrives at the router, the router must examine the packet header to determine the outgoing route and check other properties for the data
- Queuing Delay Amount of time the incoming packet is waiting in the queue until it can be pro‐
cessed.
- if the packets are arriving at a faster rate than the router is capable of processing, the packets are queued inside an incoming buffer
Total latency is the sum of all of the delays listed above.