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RFC1661 - часть 34


specific to the Configuration Option. The format and length of

the Data field is determined by the Type and Length fields.

When the Data field is indicated by the Length to extend beyond

the end of the Information field, the entire packet is silently

discarded without affecting the automaton.

Simpson [Page 40]

RFC 1661 Point-to-Point Protocol July 1994

6.1. Maximum-Receive-Unit (MRU)

Description

This Configuration Option may be sent to inform the peer that the

implementation can receive larger packets, or to request that the

peer send smaller packets.

The default value is 1500 octets. If smaller packets are

requested, an implementation MUST still be able to receive the

full 1500 octet information field in case link synchronization is

lost.

Implementation Note:

This option is used to indicate an implementation capability.

The peer is not required to maximize the use of the capacity.

For example, when a MRU is indicated which is 2048 octets, the

peer is not required to send any packet with 2048 octets. The

peer need not Configure-Nak to indicate that it will only send

smaller packets, since the implementation will always require

support for at least 1500 octets.

A summary of the Maximum-Receive-Unit Configuration Option format is

shown below. The fields are transmitted from left to right.

0 1 2 3

0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

| Type | Length | Maximum-Receive-Unit |

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Type

1

Length

4

Maximum-Receive-Unit

The Maximum-Receive-Unit field is two octets, and specifies the

maximum number of octets in the Information and Padding fields.

It does not include the framing, Protocol field, FCS, nor any

transparency bits or bytes.

Simpson [Page 41]

RFC 1661 Point-to-Point Protocol July 1994

6.2. Authentication-Protocol

Description

On some links it may be desirable to require a peer to




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