METHOD OF DETERMINING PATH MAXIMUM TRANSMISSION UNIT
First Claim
1. A method for performing by a proxy discovery of a maximum transmission unit of a path between a client and a server, the method comprising:
- (a) increasing, by a first proxy, a size of a path maximum transmission unit (PMTU) by a predetermined amount for transmitting network packets between a client and a server via the first proxy;
(b) repacketizing, by the first proxy, network packets received from the client for transmission to the server into packet sizes in accordance with the size of the PMTU;
(c) determining, by the first proxy, a first network packet of the repacketized network packets with a round trip time greater than a previous round trip time for networks packets transmitted to the server; and
(d) increasing, by the first proxy, the size of the PMTU by the predetermined amount responsive to receiving an acknowledgement for the first network packet without a fragmentation indication.
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Accused Products
Abstract
Network endpoints using TCP/IP operate to determine the maximum transmission unit (MTU) of the path between them. This determination is done so as to avoid the expensive IP fragmentation that will occur when transitting links with a smaller MTU size. The standard method of determining the path MTU (PMTU) has several known deficiencies, including: inefficient use of bandwidth as proper operation will likely result in the loss of one or more packets and difficulty of implementation as the reverse channel communication mechanism, reception of ICMP messages indicating the discarding of unfragmentable packets, is frequently blocked by firewalls and other security apparatus.
A method of determining the PMTU between intermediate proxies is disclosed that does not require reception of ICMP messages or the inefficient use of bandwidth due to the presumed dropping of packets with valid data.
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Citations
20 Claims
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1. A method for performing by a proxy discovery of a maximum transmission unit of a path between a client and a server, the method comprising:
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(a) increasing, by a first proxy, a size of a path maximum transmission unit (PMTU) by a predetermined amount for transmitting network packets between a client and a server via the first proxy; (b) repacketizing, by the first proxy, network packets received from the client for transmission to the server into packet sizes in accordance with the size of the PMTU; (c) determining, by the first proxy, a first network packet of the repacketized network packets with a round trip time greater than a previous round trip time for networks packets transmitted to the server; and (d) increasing, by the first proxy, the size of the PMTU by the predetermined amount responsive to receiving an acknowledgement for the first network packet without a fragmentation indication. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A system of proxies performing discovery of a maximum transmission unit of a path between a client and a server, the system comprising:
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a first proxy increasing a size of a path maximum transmission unit (PMTU) by a predetermined amount for transmitting network packets between a client and a server via the first proxy and the first proxy repacketing network packets received from the client for transmission to the server into packet sizes in accordance with the size of the PMTU; a second proxy detecting whether a first network packet from transmission of repacketized packets from the first proxy is fragmented and transmitting to the first proxy an acknowledgement of the first network packet without a fragment indicator; wherein the first proxy determines the first network packet of the repacketized network packets has a round trip time greater than a previous round trip time for networks packets transmitted to the server, and the first proxy increases the size of the PMTU by the predetermined amount responsive to receiving the acknowledgement for the first network packet without a fragmentation indication. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification