blank.gif (43 bytes)

Church Of The
Swimming Elephant

Search: Timestamp and Timestamp Reply: RFC-792 Connected: An Internet Encyclopedia Timestamp and Timestamp Reply: RFC-792

Up: Connected: An Internet Encyclopedia
Up: Requests For Comments
Up: RFC 1122
Up: 3.2.2 Internet Control Message Protocol -- ICMP
Prev: Information Request/Reply: RFC-792
Next: Address Mask Request/Reply: RFC-950 Timestamp and Timestamp Reply: RFC-792 Timestamp and Timestamp Reply: RFC-792

A host MAY implement Timestamp and Timestamp Reply. If they are implemented, the following rules MUST be followed.

  • The ICMP Timestamp server function returns a Timestamp Reply to every Timestamp message that is received. If this function is implemented, it SHOULD be designed for minimum variability in delay (e.g., implemented in the kernel to avoid delay in scheduling a user process).

The following cases for Timestamp are to be handled according to the corresponding rules for ICMP Echo:

  • An ICMP Timestamp Request message to an IP broadcast or IP multicast address MAY be silently discarded.

  • The IP source address in an ICMP Timestamp Reply MUST be the same as the specific-destination address of the corresponding Timestamp Request message.

  • If a Source-route option is received in an ICMP Echo Request, the return route MUST be reversed and used as a Source Route option for the Timestamp Reply message.

  • If a Record Route and/or Timestamp option is received in a Timestamp Request, this (these) option(s) SHOULD be updated to include the current host and included in the IP header of the Timestamp Reply message.

  • Incoming Timestamp Reply messages MUST be passed up to the ICMP user interface.

The preferred form for a timestamp value (the "standard value") is in units of milliseconds since midnight Universal Time. However, it may be difficult to provide this value with millisecond resolution. For example, many systems use clocks that update only at line frequency, 50 or 60 times per second. Therefore, some latitude is allowed in a "standard value":

  1. A "standard value" MUST be updated at least 15 times per second (i.e., at most the six low-order bits of the value may be undefined).

  2. The accuracy of a "standard value" MUST approximate that of operator-set CPU clocks, i.e., correct within a few minutes.

Next: Address Mask Request/Reply: RFC-950

Connected: An Internet Encyclopedia Timestamp and Timestamp Reply: RFC-792


Protect yourself from cyberstalkers, identity thieves, and those who would snoop on you.
Stop spam from invading your inbox without losing the mail you want. We give you more control over your e-mail than any other service.
Block popups, ads, and malicious scripts while you surf the net through our anonymous proxies.
Participate in Usenet, host your web files, easily send anonymous messages, and more, much more.
All private, all encrypted, all secure, all in an easy to use service, and all for only $5.95 a month!

Service Details

Have you gone to church today?
All pages ©1999, 2000, 2001, 2002, 2003 Church of the Swimming Elephant unless otherwise stated
Church of the Swimming Elephant©1999, 2000, 2001, 2002, 2003 is a wholly owned subsidiary of Packetderm, LLC.

Packetderm, LLC
210 Park Ave #308
Worcester, MA 01609