Hawking HBB1, Руководство пользователя

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through the high-priority packets. This means that a high-priority
VoIP packet does not have to wait for large FTP packets to be sent
before leaving the modem.
Assuming that all of the data streams are correctly prioritized, the
user can still run into problems. Many people believe that the
delays they see while using online applications is caused by the
internet itself. However, most latency and jitter is actually caused
by the behavior of the modem on the user’s home network. The
maximum throughput of the router’s WAN port is usually much
larger than the throughput of the modem’s uplink. Modems are
designed to handle this by using a very large buffer that stores the
packets sent by the fast WAN port of the router before they can be
transmitted by the modem to the ISP. Once a packet is stored in
the modem’s packet buffer, the priority of the packet cannot be
changed. This is shown in Figure 2. If the router sends more
packets to the modem than the buffer can hold, these packets may
be lost.
Figure 2: Broadband modem rate adaptation buffer and its
effect on QoS