Specifications

Propagation Delay 8-3
Propagation Delay Example
3. Now that you have the equipment delay times, you must calculate the
total delay for each media type. To do this, make a list of each media
type found in the signal path and add up the total length, in meters, of
each. Now, multiply this number by the appropriate media delay time
for each media type found in Table 8-1, to get the delay time for each
length of media found in the signal path.
4. Add up the equipment delay times, calculated in step 2, to find the
total equipment delay for this signal path.
5. Add up the media delay times, calculated in step 3, to find the total
media delay for this signal path.
6. Add the numbers found in step 4 and step 5. This is the total one-way
propagation delay time for this network. Multiply this number by two
to get the round trip propagation delay time.
By IEEE definition, the one way propagation delay time must be less than
or equal to 25.6 µs. Your result from this exercise should be 23.45 µs. Since
this value is less than the IEEE maximum, the network is within
specification. If you didn’t come up with 23.45 µs, refer to Table 8-2 and
Table 8-3 to see where you went wrong.
The values contained in Table 8-1 are maximum values. It is possible that
certain grades of cable will have a higher velocity of propagation which will
result in a smaller delay per meter.
NOTE