As per Relevance of the word delivery, we have this rfc below:
Network Working Group S.
Request for Comments: 1702 NetSmiths, Ltd
Category: Informational T.
D.
P.
cisco
October 1994
Generic Routing Encapsulation over IPv4
Status of this
This memo provides information for the Internet community. This
does not specify an Internet standard of any kind. Distribution
this memo is unlimited
In an earlier memo [RFC 1701], we described GRE, a mechanism
encapsulating arbitrary packets within an arbitrary
protocol. This is a companion memo which describes the use of
with IP. This memo addresses the case of using IP as the
protocol or the payload protocol and the special case of IP as
the delivery and payload. This memo also describes using
addresses and autonomous system numbers as part of a GRE
route
IP as a delivery
GRE packets which are encapsulated within IP will use IP
type 47.
IP as a payload
IP packets will be encapsulated with a Protocol Type field of 0x800.
For the Address Family value of 0x800, the Routing Information
will consist of a list of IP addresses and indicates an IP
route. The first octet of the Routing Information field constitute
8 bit integer offset from the start of the Source Route Entry (SRE),
called the SRE Offset. The SRE Offset indicates the first octet
the next IP address. The SRE Length field consists of the
length of the IP Address List in octets
Hanks, Li, Farinacci & Traina [Page 1]
RFC 1702 GRE over IPv4 networks October 1994
This has the form
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Address Family | SRE Offset | SRE Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IP Address List ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
For the Address Family value of 0xfffe, the Routing Information
will consist of a list of Autonomous System numbers and indicates
AS source route. The third octet of the Routing Information
contains an 8 bit unsigned integer offset from the start of
Source Route Entry (SRE), called the SRE Offset. The SRE
indicates the first octet of the next AS number. THe SRE
field consists of the total length of the AS Number list in octets
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Address Family | SRE Offset | SRE Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AS Number List ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
IP as both delivery and payload
When IP is encapsulated in IP, the TTL, TOS, and IP security
MAY be copied from the payload packet into the same fields in
delivery packet. The payload packet's TTL MUST be decremented
the packet is decapsulated to insure that no packet lives forever
IP source
When a system is processing a SRE with an Address Family
an IP source route, it MUST use the SRE Offset to determine the
destination IP address. If the next IP destination is this system
the SRE Offset field should be increased by four (the size of an
address). If the SRE Offset is equal to the SRE Length in this SRE
then the Offset field in the GRE header should be adjusted to
to the next SRE (if any). This should be repeated until the next
destination is not this system or until the entire SRE has
processed
If the source route is incomplete, then the Strict Source Route
is checked. If the source route is a strict source route and
next IP destination is NOT an adjacent system, the packet MUST
Hanks, Li, Farinacci & Traina [Page 2]
RFC 1702 GRE over IPv4 networks October 1994
dropped. Otherwise, the system should use the IP address
by the Offset field to replace the destination address in
delivery header and forward the packet
Autonomous system source
When a system is processing a SRE with an Address Family
an AS source route, it MUST use the SRE Offset field to determine
next autonomous system. If the next autonomous system is the
autonomous system, the SRE Offset field should be increased by
(the size of an autonomous system number). If the SRE Offset
equal to the SRE Length in this SRE, then the Offset field in the
header should be adjusted to point to the next SRE (if any).
should be repeated until the next autonomous system number is
equal to the local autonomous system number or until the entire
has been processed
If the source route is incomplete, then the Strict Source Route
is checked. If the source route is a strict source route and
next autonomous system is NOT an adjacent autonomous system,
packet should be dropped. Otherwise, the system should use
autonomous system number indicated by the SRE Offset field to
the destination address in the delivery header and forward
packet. The exact mechanism for determining the next
destination address given the AS number is outside of the scope
this document
Security
Security issues are not discussed in this memo
Hanks, Li, Farinacci & Traina [Page 3]
RFC 1702 GRE over IPv4 networks October 1994
Authors'
Stan
NetSmiths, Ltd
2025 Lincoln
Edison, NJ 08817
EMail: stan@netsmiths.
Tony
cisco Systems, Inc
1525 O'Brien
Menlo Park, CA 94025
EMail: tli@cisco.
Dino
cisco Systems, Inc
1525 O'Brien
Menlo Park, CA 94025
EMail: dino@cisco.
Paul
cisco Systems, Inc
1525 O'Brien
Menlo Park, CA 94025
EMail: pst@cisco.
RFC 1701
Hanks, S., Li, T, Farinacci, D., and P. Traina, "Generic
Encapsulation", RFC 1701, NetSmiths, Ltd., and cisco Systems
October 1994.
Hanks, Li, Farinacci & Traina [Page 4]
if you see any problems within the linking, don't worry be happy,
this is version 0.1 of the Relevance System and you gotta expect some crappy subroutines sometimes,
just be content we did not write this in Java, which would have made this "bigger and better" HAHAHHA.
RFC documents can be found at I.E.T.F.
Relevance System Copyright © 2002 Spectrum WorldResearch
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