Internet DRAFT - draft-eip-arch
draft-eip-arch
WG Working Group S. Salsano
Internet-Draft Univ. of Rome Tor Vergata / CNIT
Intended status: Informational H. ElBakoury
Expires: 23 June 2024 Consultant
D. Lopez
Telefonica, I+D
21 December 2023
Extensible In-band Processing (EIP) Architecture and Framework
draft-eip-arch-03
Abstract
Extensible In-band Processing (EIP) extends the functionality of the
IPv6 protocol considering the needs of future Internet services / 6G
networks. This document discusses the architecture and framework of
EIP. Two separate documents respectively analyze a number of use
cases for EIP and provide the protocol specifications of EIP.
About This Document
This note is to be removed before publishing as an RFC.
The latest revision of this draft can be found at https://eip-
home.github.io/eip-arch/draft-eip-arch.html. Status information for
this document may be found at https://datatracker.ietf.org/doc/draft-
eip-arch/.
Discussion of this document takes place on the EIP SIG mailing list
(mailto:eip@cnit.it), which is archived at http://postino.cnit.it/
cgi-bin/mailman/private/eip/.
Source for this draft and an issue tracker can be found at
https://github.com/eip-home/eip-arch.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
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This Internet-Draft will expire on 23 June 2024.
Copyright Notice
Copyright (c) 2023 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Basic principles for EIP . . . . . . . . . . . . . . . . . . 3
3. Benefits of a common EIP header for multiple use cases. . . . 4
4. Review of standardized and proposed evolutions of IPv6 . . . 5
4.1. Consideration on Hop-by-hop Options allocation . . . . . 7
5. Conventions and Definitions . . . . . . . . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . 7
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
8.1. Normative References . . . . . . . . . . . . . . . . . . 8
8.2. Informative References . . . . . . . . . . . . . . . . . 8
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction
Networking architectures need to evolve to support the needs of
future Internet services and 6G networks. The networking research
and standardization communities have considered different approaches
for this evolution, that can be broadly classified in 3 different
categories:
1. Clean slate and "revolutionary" solutions. Throw away the legacy
IP networking layer.
2. Solutions above the layer 3. Do not touch the legacy networking
layer (IP).
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3. Evolutionary solutions. Improve the IP layer (and try to
preserve backward compatibility).
The proposed EIP (Extensible In-band Processing) solution belongs to
the third category, it extends the current IPv6 architecture without
requiring a clean-slate revolution.
The use cases for EIP are discussed in [id-eip-use-cases]. The
specification of the EIP header format is provided in
[id-eip-headers].
2. Basic principles for EIP
An ongoing trend is extending the functionality of the IPv6
networking layer, going beyond the plain packet forwarding. An
example of this trend is the rise of the SRv6 "network programming"
model. With the SRv6 network programming model, the routers can
implement "complex" functionalities and they can be controlled by a
"network program" that is embedded in IPv6 packet headers. Another
example is the INT (IN band Telemetry) solution for monitoring.
These (and other) examples are further discussed in Section 4.
The EIP solution is aligned with this trend, which will ensure a
future proof evolution of networking architectures. EIP supports a
feature-rich and extensible IPv6 networking layer, in which complex
dataplane functions can be executed by end-hosts, routers, virtual
functions, servers in datacenters so that services can be implemented
in the smartest and more efficient way.
The EIP solution foresees the introduction of an EIP header in the
IPv6 packet header. The proposed EIP header is extensible and it is
meant to support a number of different use cases. In general, both
end-hosts and transit routers can read and write the content of this
header. Depending of the specific use-case, only specific nodes will
be capable and interested in reading or writing the EIP header. The
use of the EIP header can be confined to a single domain or to a set
of cooperating domains, so there is no need of a global, Internet-
wide support of the new header for its introduction. Moreover, there
can be usage scenarios in which legacy nodes can simply ignore the
EIP header and provide transit to packets containing the EIP header.
An important usage scenario considers the transport of user packets
over a provider network. In this scenario, we consider the network
portion from the provider ingress edge node to the provider egress
edge node. The ingress edge node can encapsulate the user packet
coming from an access network into an outer packet. The outer packet
travels in the provider network until the egress edge node, which
will decapsulate the inner packet and deliver it to the destination
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access network or to another transit network, depending on the
specific topology and service. Assuming that the IPv6/SRv6 dataplane
is used in the provider network, the ingress edge node will be the
source of an outer IPv6 packet in which it is possible to add the EIP
header. The outer IPv6 packet (containing the EIP header) will be
processed inside the "limited domain" (see [RFC8799]) of the provider
network, so that the operator can make sure that all the transit
routers either are EIP aware or at least they can forward packets
containing the EIP header. In this usage scenario, the EIP framework
operates "edge-to-edge" and the end-user packets are "tunneled" over
the EIP domain.
The architectural framework for EIP is depicted in Figure 1. We
refer to nodes that are not EIP capable as legacy nodes. An EIP
domain is made up by EIP aware routers (EIP R) and can also include
legacy routers (LEG R). At the border of the EIP domain, EIP edge
nodes (EIP ER) are used to interact with legacy End Hosts / Servers
(LEG H) and with other domains. It is also possible that an End Host
/ Server is EIP aware (EIP H), in this case the EIP framework could
operate "edge-to-end" or "end-to-end".
LEG domain
+------------+
+---+ +---+ +---+ +---+
|EIP|_ _|EIP|______|EIP| ___|LEG|
| H | \__+---+__/ | R | | R |__ +---+__/ | R | ...
+---+ |EIP| +---+ +---+ \__|EIP| +---+
__|ER |__ | | __|ER |__
+---+_/ +---+ \_+---+ +---+__/ +---+ \___+---+
|LEG| |LEG|______|LEG| |EIP|
| H | | R | | R | |ER | ...
+---+ +---+ +---+ +---+
+-----------------------------+ +------------+
EIP domain EIP domain
Figure 1: EIP framwork
As shown in Figure 1, an EIP domain can communicate with other
domains, which can be legacy domains or EIP capable domains.
3. Benefits of a common EIP header for multiple use cases.
The EIP header will carry different EIP Information Elements that are
defined to support the different use cases. There are reasons why it
is beneficial to define a common EIP header that supports multiple
use cases.
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1. The number of available Option Types in HBH header is limited,
likewise the number of available TLVs in the Segment Routing
Header (SRH) is limited. Defining multiple Option Types or SRH
TLVs for multiple use case is not scalable and puts pressure on
the allocation of such codepoints. This aspect is further
discussed in Section 4.
2. The definition and standardization of specific EIP Information
Elements for the different use cases will be simplified, compared
to the need of requiring the definition of a new Option Type or
SRH TLVs.
3. Different use cases may share a subset of common EIP Information
Elements.
4. Efficient mechanism for the processing of the EIP header (both in
software and in hardware) can be defined when the different EIP
Information Elements are carried inside the same EIP header.
4. Review of standardized and proposed evolutions of IPv6
In the last few years, we have witnessed important innovations in
IPv6 networking, centered around the emergence of Segment Routing for
IPv6 (SRv6) [RFC8754] and of the SRv6 "Network Programming model"
[RFC8986]. With SRv6 it is possible to insert a _Network program_,
i.e. a sequence of instructions (called _segments_), in a header of
the IPv6 protocol, called Segment Routing Header (SRH).
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Another recent activity that proposed to extend the networking layer
to support more complex functions, concerns the network monitoring.
The concept of INT "In-band Network Telemetry" has been proposed
since 2015 [onf-int] in the context of the definition of use cases
for P4 based data plane programmability. The latest version of INT
specifications dates November 2020 [int-spec]. [int-spec] specifies
the format of headers that carry monitoring instructions and
monitoring information along with data plane packets. The specific
location for INT Headers is intentionally not specified: an INT
Header can be inserted as an option or payload of any encapsulation
type. The In-band Telemetry concept has been adopted by the IPPM
IETF Working Group, renaming it "In-situ Operations, Administration,
and Maintenance" (IOAM). The internet draft
[I-D.ietf-ippm-ioam-data] is about to become an IETF RFC. Note that
IOAM is focused on "limited domains" as defined in [RFC8799]. The
in-situ OAM data fields can be encapsulated in a variety of
protocols, including IPv6. The specification details for carrying
IOAM data inside IPv6 headers are provided in draft
[I-D.ietf-ippm-ioam-ipv6-options], which is also close to becoming an
RFC. In particular, IOAM data fields can be encapsulated in IPv6
using either Hop-by-Hop Options header or Destination options header.
Another example of extensions to IPv6 for network monitoring is
specified in [RFC8250], which defines an IPv6 Destination Options
header called Performance and Diagnostic Metrics (PDM). The PDM
option header provides sequence numbers and timing information as a
basis for measurements.
The "Alternate Marking Method" is a recently proposed performance
measurement approach described in [RFC8321]. The draft
[I-D.draft-ietf-6man-ipv6-alt-mark] (also close to becoming an RFC)
defines a new Hop-by-Hop Option to support this approach.
"Path Tracing" [I-D.draft-filsfils-spring-path-tracing] proposes an
efficient solution for recording the route taken by a packet
(including timestamps and load information taken at each hop along
the route). This solution needs a new Hop-by-Hop Option to be
defined.
[RFC8558] analyses the evolution of transport protocols. It
recommends that explicit signals should be used when the endpoints
desire that network elements along the path become aware of events
related to trasport protocol. Among the solutions, [RFC8558]
considers the use of explicit signals at the network layer, and in
particular it mentions that IPv6 hop-by-hop headers might suit this
purpose.
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The Internet Draft [I-D.draft-ietf-6man-mtu-option] specifies a new
IPv6 Hop-by-Hop option that is used to record the minimum Path MTU
between a source and a destination. This draft is close to become an
RFC.
The Internet Draft [I-D.draft-ietf-6man-enhanced-vpn-vtn-id] proposes
a new Hop-by-Hop option of IPv6 extension header to carry the Virtual
Transport Network (VTN) identifier, which could be used to identify
the set of network resources allocated to a VTN and the rules for
packet processing. The procedure of processing the VTN option is
also specified.
4.1. Consideration on Hop-by-hop Options allocation
We have listed several proposals or already standardized solutions
that use the IPv6 Hop-by-Hop Options. These Options are represented
with a 8 bits code. The first two bits represent the action to be
taken if the Options is unknown to a node that receives it, the third
bit is used to specify if the content of the Options can be changed
in flight. In particular the Option Types that start with 001 should
be ignored if unknown and can be changed in flight, which is the most
common combination. The current IANA allocation for Option Types
starting with 001 is (see https://www.iana.org/assignments/ipv6-
parameters/ipv6-parameters.xhtml)
32 possible Option Types starting with 001
2 allocated by RFCs
2 temporary allocated by Internet Drafts
1 allocated for RFC3692-style Experiment
27 not allocated
We observe that there is a potential scarcity of the code points, as
there are many scenarios that could require the definition of a new
Hop-by-hop option. We also observe that having only 1 code point
allocated for experiments is a very restrictive limitation.
5. Conventions and Definitions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
6. Security Considerations
TODO Security
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7. IANA Considerations
The definition of the EIP header as an Option for IPv6 Hop-by-hop
Extension header requires the allocation of a codepoint from the
"Destination Options and Hop-by-Hop Options" registry in the
"Internet Protocol Version 6 (IPv6) Parameters"
(https://www.iana.org/assignments/ipv6-parameters/
ipv6-parameters.xhtm).
The definition of the EIP header as a TLV in the Segment Routing
Header requires the allocation of a codepoint from the "Segment
Routing Header TLVs" registry in the "Internet Protocol Version 6
(IPv6) Parameters" (https://www.iana.org/assignments/ipv6-parameters/
ipv6-parameters.xhtm).
The definition of EIP Information Elements in the EIP header will
require the definition of a IANA registry.
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/rfc/rfc2119>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.
8.2. Informative References
[I-D.draft-filsfils-spring-path-tracing]
Filsfils, C., Abdelsalam, A., Camarillo, P., Yufit, M.,
Graf, T., Su, Y., Matsushima, S., Valentine, M., and
Dhamija, "Path Tracing in SRv6 networks", Work in
Progress, Internet-Draft, draft-filsfils-spring-path-
tracing-05, 23 October 2023,
<https://datatracker.ietf.org/doc/html/draft-filsfils-
spring-path-tracing-05>.
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[I-D.draft-ietf-6man-enhanced-vpn-vtn-id]
Dong, J., Li, Z., Xie, C., Ma, C., and G. S. Mishra,
"Carrying Virtual Transport Network (VTN) Information in
IPv6 Extension Header", Work in Progress, Internet-Draft,
draft-ietf-6man-enhanced-vpn-vtn-id-05, 6 July 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-6man-
enhanced-vpn-vtn-id-05>.
[I-D.draft-ietf-6man-ipv6-alt-mark]
Fioccola, G., Zhou, T., Cociglio, M., Qin, F., and R.
Pang, "IPv6 Application of the Alternate-Marking Method",
Work in Progress, Internet-Draft, draft-ietf-6man-ipv6-
alt-mark-17, 27 September 2022,
<https://datatracker.ietf.org/doc/html/draft-ietf-6man-
ipv6-alt-mark-17>.
[I-D.draft-ietf-6man-mtu-option]
Hinden, R. M. and G. Fairhurst, "IPv6 Minimum Path MTU
Hop-by-Hop Option", Work in Progress, Internet-Draft,
draft-ietf-6man-mtu-option-15, 10 May 2022,
<https://datatracker.ietf.org/doc/html/draft-ietf-6man-
mtu-option-15>.
[I-D.ietf-ippm-ioam-data]
Brockners, F., Bhandari, S., and T. Mizrahi, "Data Fields
for In Situ Operations, Administration, and Maintenance
(IOAM)", Work in Progress, Internet-Draft, draft-ietf-
ippm-ioam-data-17, 13 December 2021,
<https://datatracker.ietf.org/doc/html/draft-ietf-ippm-
ioam-data-17>.
[I-D.ietf-ippm-ioam-ipv6-options]
Bhandari, S. and F. Brockners, "IPv6 Options for In Situ
Operations, Administration, and Maintenance (IOAM)", Work
in Progress, Internet-Draft, draft-ietf-ippm-ioam-ipv6-
options-12, 7 May 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-ippm-
ioam-ipv6-options-12>.
[id-eip-headers]
Salsano, S. and H. ElBakoury, "Extensible In-band
Processing (EIP) Headers Definitions", 2022, <https://eip-
home.github.io/eip-headers/draft-eip-headers-
definitions.txt>.
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[id-eip-use-cases]
Salsano, S. and H. ElBakoury, "Extensible In-band
Processing (EIP) Use Cases", 2022, <https://eip-
home.github.io/use-cases/draft-eip-use-cases.txt>.
[int-spec] Group, T. P. A. W., "In-band Network Telemetry (INT)
Dataplane Specification, version 2.1", n.d.,
<https://p4.org/p4-spec/docs/INT v2 1.pdf>.
[onf-int] P4.org, "Improving Network Monitoring and Management with
Programmable Data Planes", 2015,
<https://opennetworking.org/news-and-events/blog/
improving-network-monitoring-and-management-with-
programmable-data-planes/>.
[RFC8250] Elkins, N., Hamilton, R., and M. Ackermann, "IPv6
Performance and Diagnostic Metrics (PDM) Destination
Option", RFC 8250, DOI 10.17487/RFC8250, September 2017,
<https://www.rfc-editor.org/rfc/rfc8250>.
[RFC8321] Fioccola, G., Ed., Capello, A., Cociglio, M., Castaldelli,
L., Chen, M., Zheng, L., Mirsky, G., and T. Mizrahi,
"Alternate-Marking Method for Passive and Hybrid
Performance Monitoring", RFC 8321, DOI 10.17487/RFC8321,
January 2018, <https://www.rfc-editor.org/rfc/rfc8321>.
[RFC8558] Hardie, T., Ed., "Transport Protocol Path Signals",
RFC 8558, DOI 10.17487/RFC8558, April 2019,
<https://www.rfc-editor.org/rfc/rfc8558>.
[RFC8754] Filsfils, C., Ed., Dukes, D., Ed., Previdi, S., Leddy, J.,
Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header
(SRH)", RFC 8754, DOI 10.17487/RFC8754, March 2020,
<https://www.rfc-editor.org/rfc/rfc8754>.
[RFC8799] Carpenter, B. and B. Liu, "Limited Domains and Internet
Protocols", RFC 8799, DOI 10.17487/RFC8799, July 2020,
<https://www.rfc-editor.org/rfc/rfc8799>.
[RFC8986] Filsfils, C., Ed., Camarillo, P., Ed., Leddy, J., Voyer,
D., Matsushima, S., and Z. Li, "Segment Routing over IPv6
(SRv6) Network Programming", RFC 8986,
DOI 10.17487/RFC8986, February 2021,
<https://www.rfc-editor.org/rfc/rfc8986>.
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Acknowledgments
TODO acknowledge.
Authors' Addresses
Stefano Salsano
Univ. of Rome Tor Vergata / CNIT
Email: stefano.salsano@uniroma2.it
Hesham ElBakoury
Consultant
Email: helbakoury@gmail.com
Diego R. Lopez
Telefonica, I+D
Email: diego.r.lopez@telefonica.com
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