Справочник по сетевым протоколам

RFC1661 - часть 22

Implementation Note:

The Restart timer SHOULD be based on the speed of the link.

The default value is designed for low speed (2,400 to 9,600

bps), high switching latency links (typical telephone lines).

Higher speed links, or links with low switching latency, SHOULD

have correspondingly faster retransmission times.

Instead of a constant value, the Restart timer MAY begin at an

initial small value and increase to the configured final value.

Each successive value less than the final value SHOULD be at

least twice the previous value. The initial value SHOULD be

large enough to account for the size of the packets, twice the

round trip time for transmission at the link speed, and at

least an additional 100 milliseconds to allow the peer to

process the packets before responding. Some circuits add

another 200 milliseconds of satellite delay. Round trip times

for modems operating at 14,400 bps have been measured in the

range of 160 to more than 600 milliseconds.


There is one required restart counter for Terminate-Requests.

Max-Terminate indicates the number of Terminate-Request packets

sent without receiving a Terminate-Ack before assuming that the

peer is unable to respond. Max-Terminate MUST be configurable,

but SHOULD default to two (2) transmissions.


A similar counter is recommended for Configure-Requests. Max-

Configure indicates the number of Configure-Request packets sent

without receiving a valid Configure-Ack, Configure-Nak or

Configure-Reject before assuming that the peer is unable to

respond. Max-Configure MUST be configurable, but SHOULD default

to ten (10) transmissions.

Simpson [Page 24]

RFC 1661 Point-to-Point Protocol July 1994


A related counter is recommended for Configure-Nak. Max-Failure

indicates the number of Configure-Nak packets sent without sending

a Configure-Ack before assuming that configuration is not

converging. Any further Configure-Nak packets for peer requested

options are converted to Configure-Reject packets, and locally

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