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Recital 15
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Third, measures going beyond such reasonable traffic management
measures might also be necessary to prevent impending network
congestion, that is, situations where congestion is about to
materialise, and to mitigate the effects of network congestion, where
such congestion occurs only temporarily or in exceptional
circumstances. The principle of proportionality requires that traffic
management measures based on that exception treat equivalent
categories of traffic equally. Temporary congestion should be
understood as referring to specific situations of short duration,
where a sudden increase in the number of users in addition to the
regular users, or a sudden increase in demand for specific content,
applications or services, may overflow the transmission capacity of
some elements of the network and make the rest of the network less
reactive. Temporary congestion might occur especially in mobile
networks, which are subject to more variable conditions, such as
physical obstructions, lower indoor coverage, or a variable number of
active users with changing location. While it may be predictable that
such temporary congestion might occur from time to time at certain
points in the network – such that it cannot be regarded as exceptional
– it might not recur so often or for such extensive periods that a
capacity expansion would be economically justified. Exceptional
congestion should be understood as referring to unpredictable and
unavoidable situations of congestion, both in mobile and fixed
networks. Possible causes of those situations include a technical
failure such as a service outage due to broken cables or other
infrastructure elements, unexpected changes in routing of traffic or
large increases in network traffic due to emergency or other
situations beyond the control of providers of internet access
services. Such congestion problems are likely to be infrequent but may
be severe, and are not necessarily of short duration. The need to
apply traffic management measures going beyond the reasonable traffic
management measures in order to prevent or mitigate the effects of
temporary or exceptional network congestion should not give providers
of internet access services the possibility to circumvent the general
prohibition on blocking, slowing down, altering, restricting,
interfering with, degrading or discriminating between specific
content, applications or services, or specific categories
thereof. Recurrent and more long-lasting network congestion which is
neither exceptional nor temporary should not benefit from that
exception but should rather be tackled through expansion of network
capacity.