Abstract: A communication system capable of high-quality routing and improved in operability. An IPsec tunneling control section sets up an IPsec tunnel on the Internet between the device in which it is provided and a remote router, by using an ISAKMP default route. A routing registration section has a routing table in which local IP addresses as destination addresses are statically registered and also a second router is statically registered as an IP default route for addresses other than the registered local IP addresses. When the IPsec tunnel is set up, the routing registration section identifies a global IP address of the remote router and dynamically registers the global IP address in the routing table in association with the corresponding local IP address. A packet transfer section transfers packets in accordance with the routing table.

Abstract: In a method, an apparatus, and a system for a bandwidth control, a packet is held in a buffer, the held packet is read at a line bandwidth, and a read timing of a next packet is controlled, based on a packet length of a counted packet in order that a difference between the line bandwidth and a setting bandwidth assumes a packet interval. Also, by a flow control combined therewith, a bandwidth control is realized as a system without discarding any packet or with a low packet discarding rate.