초록 ▼

A local system issues an ICMP echo request packet with a size based on an initial PMTU value corresponding to that of the local system's interface MTU. When an ICMP needfrag error packet is received by the local system, this signifies that the initial PMTU value was too large for packets of correspo

A local system issues an ICMP echo request packet with a size based on an initial PMTU value corresponding to that of the local system's interface MTU. When an ICMP needfrag error packet is received by the local system, this signifies that the initial PMTU value was too large for packets of corresponding size to be transmitted through the Internet without fragmentation. The value is accordingly decreased by the local system and a next ICMP echo request packet transmitted through the Internet. The process iterates until an ICMP echo request packet is successfully transmitted through the Internet to a target system. In response thereto, the target system transmits an ICMP echo response packet back through the Internet to the local system, thereby indicating that the last-sent ICMP echo request packet from the local system had the correct PMTU value which is thereafter assumed to be the correct PMTU. An MTU application, MTU table, and corresponding application program interfaces and controls are provided in the system for dynamically maintaining PMTU value estimates and for providing next estimates of PMTU. These next estimates are accessed from the table in next ICMP echo request packet transmissions when an ICMP needfrag error packet does not contain an MTU value returned from a router in the Internet.

대표청구항 ▼

[ We claim:] [1.] A method for dynamically obtaining a PMTU estimate in a multimedia Internet system having a plurality of routers, said system having a local system, intermediate routers at least one of wich may include an intermediate routing table of intermediate PMTU estimates and a target syste

[ We claim:] [1.] A method for dynamically obtaining a PMTU estimate in a multimedia Internet system having a plurality of routers, said system having a local system, intermediate routers at least one of wich may include an intermediate routing table of intermediate PMTU estimates and a target system, said method comprising the following steps:(a) maintaining a local table of common Pre-exisinq PMTU estimates at said local system;(b) transmitting an ICMP echo request packet from said local system onto said Internet corresponding to a first PMTU estimate;(c) receiving from one of said routers an ICMP needfrag error packet;(d) accessing said local table in response to said receiving said needfrag error packet to select a next PMTU estimate non-functionally related to said PMTU estimates of said intermediate routing table;(e) transmitting a next ICMP echo request packet from said local system onto said Internet corresponding to said next PMTU estimate; and(f) repeating steps (b) through (e) sequentially, wherein each time a said ICMP echo request packet is transmitted from said local system, it corresponds to a successive said next PMTU estimate from said local table smaller or larger than that of a PMTU estimate in an immediately preceding transmitted ICMP echo request packet.