Compressed SID (CSID) for SRv6 SFC
draft-lh-spring-srv6-sfc-csid-04
This document is an Internet-Draft (I-D).
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| Document | Type | Active Internet-Draft (individual) | |
|---|---|---|---|
| Authors | Cheng Li , Weiqiang Cheng , Hongyi Huang | ||
| Last updated | 2025-04-22 | ||
| RFC stream | (None) | ||
| Intended RFC status | (None) | ||
| Formats | |||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
| IESG | IESG state | I-D Exists | |
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| Send notices to | (None) |
draft-lh-spring-srv6-sfc-csid-04
SPRING Working Group C. Li, Ed.
Internet-Draft Huawei
Intended status: Standards Track W. Cheng
Expires: 24 October 2025 China Mobile
H. Huang, Ed.
Huawei
22 April 2025
Compressed SID (CSID) for SRv6 SFC
draft-lh-spring-srv6-sfc-csid-04
Abstract
In SRv6, an SRv6 SID is a 128-bit value. When too many 128-bit SRv6
SIDs are included in an SRH, the introduced overhead will affect the
transmission efficiency of payload. In order to address this
problem, Compressed SID(CSID) is proposed. This document defines new
behaviors for service segments with REPLACE-CSID and NEXT-CSID
flavors to enable compressed SRv6 service programming.
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/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 24 October 2025.
Copyright Notice
Copyright (c) 2025 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/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
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extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
2. SR Proxy Behaviors . . . . . . . . . . . . . . . . . . . . . 4
2.1. Static SR Proxy . . . . . . . . . . . . . . . . . . . . . 4
2.1.1. Static Proxy for Inner Type Ethernet . . . . . . . . 4
2.1.2. Static Proxy for Inner Type IPv4 . . . . . . . . . . 6
2.1.3. Static Proxy for Inner Type IPv6 . . . . . . . . . . 7
2.2. Dynamic SR Proxy . . . . . . . . . . . . . . . . . . . . 8
2.2.1. Dynamic Proxy for Inner Type Ethernet . . . . . . . . 8
2.2.2. Dynamic Proxy for Inner Type IPv4 . . . . . . . . . . 10
2.2.3. Dynamic Proxy for Inner Type IPv6 . . . . . . . . . . 11
2.3. Shared Memory SR Proxy . . . . . . . . . . . . . . . . . 12
2.4. Masquerading SR Proxy . . . . . . . . . . . . . . . . . . 12
2.4.1. SRv6 Masquerading Proxy Pseudocode . . . . . . . . . 13
2.4.2. Destination NAT Flavor . . . . . . . . . . . . . . . 14
2.4.3. Cache Flavor . . . . . . . . . . . . . . . . . . . . 15
3. Security Considerations . . . . . . . . . . . . . . . . . . . 15
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
4.1. SRv6 Endpoint Behaviors . . . . . . . . . . . . . . . . . 15
5. References . . . . . . . . . . . . . . . . . . . . . . . . . 16
5.1. Normative References . . . . . . . . . . . . . . . . . . 16
5.2. Informative References . . . . . . . . . . . . . . . . . 17
Appendix A. Complete Pseudocodes . . . . . . . . . . . . . . . . 17
A.1. REPLACE-CSID Flavor for Static Proxy for Inner Type
Ethernet . . . . . . . . . . . . . . . . . . . . . . . . 17
A.2. NEXT-CSID Flavor for Static Proxy for Inner Type
Ethernet . . . . . . . . . . . . . . . . . . . . . . . . 18
A.3. REPLACE-CSID Flavor for Static Proxy for Inner Type
IPv4 . . . . . . . . . . . . . . . . . . . . . . . . . . 20
A.4. NEXT-CSID Flavor for Static Proxy for Inner Type IPv4 . . 21
A.5. REPLACE-CSID Flavor for Static Proxy for Inner Type
IPv6 . . . . . . . . . . . . . . . . . . . . . . . . . . 23
A.6. NEXT-CSID Flavor for Static Proxy for Inner Type IPv6 . . 24
A.7. REPLACE-CSID Flavor for Dynamic Proxy for Inner Type
Ethernet . . . . . . . . . . . . . . . . . . . . . . . . 26
A.8. NEXT-CSID Flavor for Dynamic Proxy for Inner Type
Ethernet . . . . . . . . . . . . . . . . . . . . . . . . 27
A.9. REPLACE-CSID Flavor for Dynamic Proxy for Inner Type
IPv4 . . . . . . . . . . . . . . . . . . . . . . . . . . 28
A.10. NEXT-CSID Flavor for Dynamic Proxy for Inner Type IPv4 . 30
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A.11. REPLACE-CSID Flavor for Dynamic Proxy for Inner Type
IPv6 . . . . . . . . . . . . . . . . . . . . . . . . . . 31
A.12. NEXT-CSID Flavor for Dynamic Proxy for Inner Type IPv6 . 32
A.13. REPLACE-CSID Flavor for SRv6 Masquerading Proxy . . . . . 33
A.14. REPLACE-CSID Flavor for SRv6 De-masquerading Proxy . . . 35
A.15. NEXT-CSID Flavor for SRv6 Masquerading Proxy . . . . . . 35
A.16. NEXT-CSID Flavor for SRv6 De-masquerading Proxy . . . . . 37
A.17. REPLACE-CSID Flavor for Destination NAT Flavor . . . . . 37
A.18. NEXT-CSID Flavor for Destination NAT Flavor . . . . . . . 38
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 39
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 39
1. Introduction
Segment Routing [RFC8402] is a source routing paradigm to support
steering packets through a programmed path at the ingress node.
Currently, two data planes are defined for Segment Routing: MPLS and
IPv6. When IPv6 data plane is used in Segment Routing, it is called
SRv6 [RFC8754] . [RFC8754] defines a new extension header in IPv6,
called Segment Routing Header (SRH), to support SRv6. To support
SRv6 network programming, [RFC8986] defines a framework to build a
network program with topological and service segments carried in a
Segment Routing header (SRH) [RFC8754].
A Service Function Chain (SFC) [RFC7665] defines an ordered set of
abstract service functions and ordering constraints that must be
applied to packets and/or frames and/or flows.
A service function chain can be implemented by SRv6 by using a
sequence of SRv6 SIDs including service segments defined in
[I-D.ietf-spring-sr-service-programming].
However, when too many 128-bit SRv6 SIDs are included in an SRH, the
overhead of the SRH will affect the transmission efficiency of the
payload. [I-D.ietf-spring-compression-requirement] points out the
problem of long SRv6 SID lists reduce payload efficiency. To
mitigate such overhead, [I-D.ietf-spring-srv6-srh-compression]
defines new flavors for basic SR endpoint behaviors defined in
[RFC8986]. Using the new flavored behavior SID, a 128-bit SRv6 SID
can be compressed to be an 32-bit or 16-bit Compressed SID (CSID),
which reduces a lot of size of the SRv6 header.
To enable SRv6 SID lists compression for service function chaining
(SFC), this document defines new behaviors of service segments with
flavors defined in [I-D.ietf-spring-srv6-srh-compression].
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1.1. Requirements Language
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.
1.2. Terminology
This document leverages the terms defined in [RFC8402], [RFC8754],
[RFC8986], [I-D.ietf-spring-srv6-srh-compression] and
[I-D.ietf-spring-sr-service-programming]. The reader is assumed to
be familiar with this terminology. This document does not introduce
any new terms.
2. SR Proxy Behaviors
[I-D.ietf-spring-sr-service-programming] defines several SRv6
endpoint behaviors for service proxy segments. A service proxy
segment ID is represented as an 128-bit value just like other SIDs
defined in [RFC8986]. This section defines some new behaviors of
those service proxy segments by combining the existing service proxy
segment behaviors with CSID flavors, such as REPLACE-CSID flavor and
NEXT-CSID flavor.
The main difference between behaviors are the forwarding
instructions. Therefore, when CSID compression mechanism applies to
SR Proxy behaviors, the pseudo code of the new behaviors can be
generated by updating the forwarding instructions of CSID to SR proxy
forwarding instructions. The following sections define the details
of the pseudo code of new behaviors.
2.1. Static SR Proxy
In [I-D.ietf-spring-sr-service-programming], an End.AS - Static proxy
endpoint behavior is defined for the static SR proxy. According to
the traffic type encapsulated in the SRv6 payload, the pseudo code of
Ethernet, IPv4 and IPv6 is described as well in
[I-D.ietf-spring-sr-service-programming]. This section defines the
new behaviors of associate the NEXT-CSID and REPLACE-CSID Flavor to
END.AS.
2.1.1. Static Proxy for Inner Type Ethernet
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2.1.1.1. REPLACE-CSID Flavor
When processing an IPv6 packet that matches a FIB entry locally
instantiated as an SRv6 static proxy SID with the REPLACE-CSID flavor
(a.k.a End.AS with REPLACE-CSID) for Ethernet traffic, the procedure
described in Section 4.2.1 of [I-D.ietf-spring-srv6-srh-compression]
is executed except for line R10 and R21 that are both replaced as
follows.
P01. If (Upper-layer header type != 143 (Ethernet)) {
P02. Resubmit the packet to the IPv6 module for transmission to
the new destination.
P03. }
P04. Perform IPv6 decapsulation.
P05. Submit the frame to the Ethernet module for transmission via
interface IFACE-OUT.
A rendering of the complete pseudocode is provided in Appendix A.1.
The upper-layer header processing is unchanged as per Section 6.1.2.1
of [I-D.ietf-spring-sr-service-programming].
When processing an Ethernet frame received on the interface IFACE-IN
and with a destination MAC address that is neither a broadcast
address nor matches the address of IFACE-IN, as per Section 6.1.2.1
of [I-D.ietf-spring-sr-service-programming].
2.1.1.2. NEXT-CSID Flavor
When processing an IPv6 packet that matches a FIB entry locally
instantiated as an SRv6 static proxy SID with the NEXT-CSID flavor
(a.k.a End.AS with NEXT-CSID) for Ethernet traffic, the procedure
described in Section 4.1.1 of [I-D.ietf-spring-srv6-srh-compression]
is executed except for line N08 of that and line S15 of Section 4.1
of [RFC8986] that are both replaced as follows.
Q01. If (Upper-layer header type != 143 (Ethernet)) {
Q02. Resubmit the packet to the IPv6 module for transmission to
the new destination.
Q03. }
Q04. Perform IPv6 decapsulation.
Q05. Submit the frame to the Ethernet module for transmission via
interface IFACE-OUT.
A rendering of the complete pseudocode is provided in Appendix A.2.
The upper-layer header processing is unchanged as per Section 6.1.2.1
of [I-D.ietf-spring-sr-service-programming].
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When processing an Ethernet frame received on the interface IFACE-IN
and with a destination MAC address that is neither a broadcast
address nor matches the address of IFACE-IN, as per Section 6.1.2.1
of [I-D.ietf-spring-sr-service-programming].
2.1.2. Static Proxy for Inner Type IPv4
2.1.2.1. REPLACE-CSID Flavor
When processing an IPv6 packet that matches a FIB entry locally
instantiated as an SRv6 static proxy SID with the REPLACE-CSID flavor
(a.k.a End.AS with REPLACE-CSID) for IPv4 traffic, the procedure
described in Section 4.2.1 of [I-D.ietf-spring-srv6-srh-compression]
is executed except for line R10 and R21 that are both replaced as
follows.
P01. If (Upper-layer header type != 4 (IPv4)) {
P02. Resubmit the packet to the IPv6 module for transmission to
the new destination.
P03. }
P04. Perform IPv6 decapsulation.
P05. Submit the packet to the IPv4 module for transmission on
interface IFACE-OUT via NH-ADDR.
A rendering of the complete pseudocode is provided in Appendix A.3.
The upper-layer header processing is unchanged as per Section 6.1.2.2
of [I-D.ietf-spring-sr-service-programming].
When processing an IPv4 packet received on the interface IFACE-IN and
with a destination address that does not match any address of IFACE-
IN, as per Section 6.1.2.2 of
[I-D.ietf-spring-sr-service-programming].
2.1.2.2. NEXT-CSID Flavor
When processing an IPv6 packet that matches a FIB entry locally
instantiated as an SRv6 static proxy SID with the NEXT-CSID flavor
(a.k.a End.AS with NEXT-CSID) for IPv4 traffic, the procedure
described in Section 4.1.1 of [I-D.ietf-spring-srv6-srh-compression]
is executed except for line N08 of that and line S15 of Section 4.1
of [RFC8986] that are both replaced as follows.
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Q01. If (Upper-layer header type != 4 (IPv4)) {
Q02. Resubmit the packet to the IPv6 module for transmission to
the new destination.
Q03. }
Q04. Perform IPv6 decapsulation.
Q05. Submit the packet to the IPv4 module for transmission on
interface IFACE-OUT via NH-ADDR.
A rendering of the complete pseudocode is provided in Appendix A.4.
The upper-layer header processing is unchanged as per Section 6.1.2.2
of [I-D.ietf-spring-sr-service-programming].
When processing an IPv4 packet received on the interface IFACE-IN and
with a destination address that does not match any address of IFACE-
IN, as per Section 6.1.2.2 of
[I-D.ietf-spring-sr-service-programming].
2.1.3. Static Proxy for Inner Type IPv6
2.1.3.1. REPLACE-CSID Flavor
When processing an IPv6 packet that matches a FIB entry locally
instantiated as an SRv6 static proxy SID with the REPLACE-CSID flavor
(a.k.a End.AS with REPLACE-CSID) for IPv6 traffic, the procedure
described in Section 4.2.1 of [I-D.ietf-spring-srv6-srh-compression]
is executed except for line R10 and R21 that are both replaced as
follows.
P01. If (Upper-layer header type != 41 (IPv6)) {
P02. Resubmit the packet to the IPv6 module for transmission to
the new destination.
P03. }
P04. Perform IPv6 decapsulation.
P05. Submit the packet to the IPv6 module for transmission on
interface IFACE-OUT via NH-ADDR.
A rendering of the complete pseudocode is provided in Appendix A.5.
The upper-layer header processing is unchanged as per Section 6.1.2.3
of [I-D.ietf-spring-sr-service-programming].
When processing an IPv6 packet received on the interface IFACE-IN and
with a destination address that does not match any address of IFACE-
IN, as per Section 6.1.2.3 of
[I-D.ietf-spring-sr-service-programming].
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2.1.3.2. NEXT-CSID Flavor
When processing an IPv6 packet that matches a FIB entry locally
instantiated as an SRv6 static proxy SID with the NEXT-CSID flavor
(a.k.a End.AS with NEXT-CSID) for IPv6 traffic, the procedure
described in Section 4.1.1 of [I-D.ietf-spring-srv6-srh-compression]
is executed except for line N08 of that and line S15 of Section 4.1
of [RFC8986] that are both replaced as follows.
Q01. If (Upper-layer header type != 41 (IPv6)) {
Q02. Resubmit the packet to the IPv6 module for transmission to
the new destination.
Q03. }
Q04. Perform IPv6 decapsulation.
Q05. Submit the packet to the IPv6 module for transmission on
interface IFACE-OUT via NH-ADDR.
A rendering of the complete pseudocode is provided in Appendix A.6.
The upper-layer header processing is unchanged as per Section 6.1.2.3
of [I-D.ietf-spring-sr-service-programming].
When processing an IPv6 packet received on the interface IFACE-IN and
with a destination address that does not match any address of IFACE-
IN, as per Section 6.1.2.3 of
[I-D.ietf-spring-sr-service-programming].
2.2. Dynamic SR Proxy
In [I-D.ietf-spring-sr-service-programming], an End.AD - Dynamic
proxy endpoint behavior is defined for the dynamic SR proxy.
According to the traffic type encapsulated in the SRv6 payload, the
pseudo code of Ethernet, IPv4 and IPv6 is described as well in
[I-D.ietf-spring-sr-service-programming]. This section defines the
new behaviors of associate the NEXT-CSID and REPLACE-CSID Flavor to
END.AD.
2.2.1. Dynamic Proxy for Inner Type Ethernet
2.2.1.1. REPLACE-CSID Flavor
When processing an IPv6 packet that matches a FIB entry locally
instantiated as an SRv6 dynamic proxy SID with the REPLACE-CSID
flavor (a.k.a End.AD with REPLACE-CSID) for Ethernet traffic, the
procedure described in Section 4.2.1 of
[I-D.ietf-spring-srv6-srh-compression] is executed except for line
R10 and R21 that are both replaced as follows.
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P01. If (Upper-layer header type != 143 (Ethernet)) {
P02. Resubmit the packet to the IPv6 module for transmission to
the new destination.
P03. }
P04. Copy the IPv6 encapsulation in a CACHE entry associated with
the interface IFACE-IN.
P05. Perform IPv6 decapsulation.
P06. Submit the frame to the Ethernet module for transmission via
interface IFACE-OUT.
A rendering of the complete pseudocode is provided in Appendix A.7.
The upper-layer header processing is unchanged as per Section 6.2.2
of [I-D.ietf-spring-sr-service-programming].
When processing an Ethernet frame received on the interface IFACE-IN
and with a destination MAC address that is neither a broadcast
address nor matches the address of IFACE-IN, as per Section 6.2.2 of
[I-D.ietf-spring-sr-service-programming].
2.2.1.2. NEXT-CSID Flavor
When processing an IPv6 packet that matches a FIB entry locally
instantiated as an SRv6 dynamic proxy SID with the NEXT-CSID flavor
(a.k.a End.AD with NEXT-CSID) for Ethernet traffic, the procedure
described in Section 4.1.1 of [I-D.ietf-spring-srv6-srh-compression]
is executed except for line N08 of that and line S15 of Section 4.1
of [RFC8986] that are both replaced as follows.
Q01. If (Upper-layer header type != 143 (Ethernet)) {
Q02. Resubmit the packet to the IPv6 module for transmission to
the new destination.
Q03. }
Q04. Copy the IPv6 encapsulation in a CACHE entry associated with
the interface IFACE-IN.
Q05. Perform IPv6 decapsulation.
Q06. Submit the frame to the Ethernet module for transmission via
interface IFACE-OUT.
A rendering of the complete pseudocode is provided in Appendix A.8.
The upper-layer header processing is unchanged as per Section 6.2.2
of [I-D.ietf-spring-sr-service-programming].
When processing an Ethernet frame received on the interface IFACE-IN
and with a destination MAC address that is neither a broadcast
address nor matches the address of IFACE-IN, as per Section 6.2.2 of
[I-D.ietf-spring-sr-service-programming].
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2.2.2. Dynamic Proxy for Inner Type IPv4
2.2.2.1. REPLACE-CSID Flavor
When processing an IPv6 packet that matches a FIB entry locally
instantiated as an SRv6 dynamic proxy SID with the REPLACE-CSID
flavor (a.k.a End.AD with REPLACE-CSID) for IPv4 traffic, the
procedure described in Section 4.2.1 of
[I-D.ietf-spring-srv6-srh-compression] is executed except for line
R10 and R21 that are both replaced as follows.
P01. If (Upper-layer header type != 4 (IPv4)) {
P02. Resubmit the packet to the IPv6 module for transmission to
the new destination.
P03. }
P04. Copy the IPv6 encapsulation in a CACHE entry associated with
the interface IFACE-IN.
P05. Perform IPv6 decapsulation.
P06. Submit the frame to the IPv4 module for transmission via
interface IFACE-OUT via NH-ADDR.
A rendering of the complete pseudocode is provided in Appendix A.9.
The upper-layer header processing is unchanged as per Section 6.2.2
of [I-D.ietf-spring-sr-service-programming].
When processing an IPv4 packet received on the interface IFACE-IN and
with a destination address that does not match any address of IFACE-
IN, as per Section 6.2.2 of [I-D.ietf-spring-sr-service-programming].
2.2.2.2. NEXT-CSID Flavor
When processing an IPv6 packet that matches a FIB entry locally
instantiated as an SRv6 dynamic proxy SID with the NEXT-CSID flavor
(a.k.a End.AD with NEXT-CSID) for IPv4 traffic, the procedure
described in Section 4.1.1 of [I-D.ietf-spring-srv6-srh-compression]
is executed except for line N08 of that and line S15 of Section 4.1
of [RFC8986] that are both replaced as follows.
Q01. If (Upper-layer header type != 4 (IPv4)) {
Q02. Resubmit the packet to the IPv6 module for transmission to
the new destination.
Q03. }
Q04. Copy the IPv6 encapsulation in a CACHE entry associated with
the interface IFACE-IN.
Q05. Perform IPv6 decapsulation.
Q06. Submit the frame to the IPv4 module for transmission via
interface IFACE-OUT via NH-ADDR.
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A rendering of the complete pseudocode is provided in Appendix A.10.
The upper-layer header processing is unchanged as per Section 6.2.2
of [I-D.ietf-spring-sr-service-programming].
When processing an IPv4 packet received on the interface IFACE-IN and
with a destination address that does not match any address of IFACE-
IN, as per Section 6.2.2 of [I-D.ietf-spring-sr-service-programming].
2.2.3. Dynamic Proxy for Inner Type IPv6
2.2.3.1. REPLACE-CSID Flavor
When processing an IPv6 packet that matches a FIB entry locally
instantiated as an SRv6 dynamic proxy SID with the REPLACE-CSID
flavor (a.k.a End.AD with REPLACE-CSID) for IPv6 traffic, the
procedure described in Section 4.2.1 of
[I-D.ietf-spring-srv6-srh-compression] is executed except for line
R10 and R21 that are both replaced as follows.
P01. If (Upper-layer header type != 41 (IPv6)) {
P02. Resubmit the packet to the IPv6 module for transmission to
the new destination.
P03. }
P04. Copy the IPv6 encapsulation in a CACHE entry associated with
the interface IFACE-IN.
P05. Perform IPv6 decapsulation.
P06. Submit the frame to the IPv6 module for transmission via
interface IFACE-OUT via NH-ADDR.
A rendering of the complete pseudocode is provided in Appendix A.11.
The upper-layer header processing is unchanged as per Section 6.2.2
of [I-D.ietf-spring-sr-service-programming].
When processing an IPv6 packet received on the interface IFACE-IN and
with a destination address that does not match any address of IFACE-
IN, as per Section 6.2.2 of [I-D.ietf-spring-sr-service-programming].
2.2.3.2. NEXT-CSID Flavor
When processing an IPv6 packet that matches a FIB entry locally
instantiated as an SRv6 dynamic proxy SID with the NEXT-CSID flavor
(a.k.a End.AD with NEXT-CSID) for IPv6 traffic, the procedure
described in Section 4.1.1 of [I-D.ietf-spring-srv6-srh-compression]
is executed except for line N08 of that and line S15 of Section 4.1
of [RFC8986] that are both replaced as follows.
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Q01. If (Upper-layer header type != 41 (IPv6)) {
Q02. Resubmit the packet to the IPv6 module for transmission to
the new destination.
Q03. }
Q04. Copy the IPv6 encapsulation in a CACHE entry associated with
the interface IFACE-IN.
Q05. Perform IPv6 decapsulation.
Q06. Submit the frame to the IPv6 module for transmission via
interface IFACE-OUT via NH-ADDR.
A rendering of the complete pseudocode is provided in Appendix A.12.
The upper-layer header processing is unchanged as per Section 6.2.2
of [I-D.ietf-spring-sr-service-programming].
When processing an IPv6 packet received on the interface IFACE-IN and
with a destination address that does not match any address of IFACE-
IN, as per Section 6.2.2 of [I-D.ietf-spring-sr-service-programming].
2.3. Shared Memory SR Proxy
This document does not need to define new flavors for shared proxy
behavior as the processing will be executed by using the shared
memory Section 6.3 of [I-D.ietf-spring-sr-service-programming].
2.4. Masquerading SR Proxy
As per [I-D.ietf-spring-sr-service-programming], when forwarding
packets to SR-unaware SFs, masquerading SR proxy sets the destination
address of the IPv6 header as segment list[0] which is the original
final destination address. When receiving the traffic returning from
the service, de-masquerading sets the destination address as segment
list[Segment Left].
To be consistent with the behavior of masquerading proxy, it's
required that any segment list containing one or more masquerading
proxy CSID MUST NOT apply any compression encoding to the last
segment (segment list[0]).
Note: The service receiving an IPv6 packet from the proxy uses the
destination address (copied from last segment) as final destination
and could apply certain actions based on that. In order to process
and forward packets correctly, it is required that the last segment
not be compressed.
To be consistent with the behavior of masquerading proxy, when
processing an IPv6 packet matching a FIB entry locally instantiated
as an SRv6 masquerading CSID, it's required that the updated
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destination address MUST be cached in the proxy by adding a dynamic
caching mechanism similar to the one described in Section 6.2 of
[I-D.ietf-spring-sr-service-programming] in case that segment
list[Segment Left] is a compressed SID.
When processing an IPv6 packet received on the interface IFACE-IN and
with a destination address that does not match any address of IFACE-
IN, the destination address MUST be recovered from CACHE in case that
segment list[Segment Left] could be a CSID container.
2.4.1. SRv6 Masquerading Proxy Pseudocode
In [I-D.ietf-spring-sr-service-programming], an End.AM - Masquerading
proxy endpoint behavior is defined for the Masquerading SR proxy.
According to the traffic type encapsulated in the SRv6 payload, the
pseudo code of Ethernet, IPv4 and IPv6 is described as well in
[I-D.ietf-spring-sr-service-programming]. This section defines the
new behaviors of associate the NEXT-CSID and REPLACE-CSID Flavor to
END.AM.
2.4.1.1. REPLACE-CSID Flavor
When processing an IPv6 packet that matches a FIB entry locally
instantiated as an SRv6 masquerading proxy SID with the REPLACE-CSID
flavor (a.k.a End.AM with REPLACE-CSID), the procedure described in
Figure 23 from Section 4.2.1 of
[I-D.ietf-spring-srv6-srh-compression] is executed except for line
R10 and R21 that are both replaced as follows.
P01. Copy the IPv6 Destination Address in a CACHE entry associated
with the interface IFACE-IN.
P02. Copy Segment List[0] from the SRH to the Destination Address
of the IPv6 header.
P03. Submit the packet to the IPv6 module for transmission on
interface IFACE-OUT via NH-ADDR.
A rendering of the complete pseudocode is provided in Appendix A.13.
*De-masquerading*: When processing an IPv6 packet received on the
interface IFACE-IN and with a destination address that does not match
any address of IFACE-IN, the procedure described in Figure 24 from
Section 6.4.1 of [I-D.ietf-spring-sr-service-programming] is executed
except for line S10 that is replaced as follows.
D01. Retrieve the CACHE entry associated with IFACE-IN.
D02. If the CACHE entry is not empty {
D03. Destination Address of the IPv6 header is set to CACHE.
D04. }
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A rendering of the complete pseudocode is provided in Appendix A.14.
2.4.1.2. NEXT-CSID Flavor
When processing an IPv6 packet that matches a FIB entry locally
instantiated as an SRv6 masquerading proxy SID with the NEXT-CSID
flavor (a.k.a End.AM with NEXT-CSID), the procedure described in
Section 4.1.1 of [I-D.ietf-spring-srv6-srh-compression] is executed
except for line N08 of that and line S15 of Section 4.1 of [RFC8986]
that are both replaced as follows.
Q01. Copy the IPv6 Destination Address in a CACHE entry associated
with the interface IFACE-IN.
Q02. Copy Segment List[0] from the SRH to the Destination Address
of the IPv6 header.
Q03. Submit the packet to the IPv6 module for transmission on
interface IFACE-OUT via NH-ADDR.
A rendering of the complete pseudocode is provided in Appendix A.15}.
*De-masquerading*: When processing an IPv6 packet received on the
interface IFACE-IN and with a destination address that does not match
any address of IFACE-IN, the procedure described in Section 6.4.1 of
[I-D.ietf-spring-sr-service-programming] is executed except for line
S10 that is replaced as follows.
E01. Retrieve the CACHE entry associated with IFACE-IN.
E02. If the CACHE entry is not empty {
E03. Destination Address of the IPv6 header is set to CACHE.
E04. }
A rendering of the complete pseudocode is provided in Appendix A.16.
2.4.2. Destination NAT Flavor
2.4.2.1. REPLACE-CSID Flavor
The Destination NAT flavor of the SRv6 masquerading proxy with the
REPLACE-CSID (a.k.a End.AM- Masquerading proxy with NAT with REPLACE-
CSID, End.AMN with REPLACE-CSID for short) is executed except for
line S09.1 and S10 in Section 6.4.2 of
[I-D.ietf-spring-sr-service-programming] replaced as follows.
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P01. Copy the Destination Address of the IPv6 header to the
Segment List[0] entry of the SRH.
P02. Retrieve the CACHE entry associated with IFACE-IN.
P03. If the CACHE entry is not empty {
P04. Destination Address of the IPv6 header is set to CACHE.
P05. }
A rendering of the complete pseudocode is provided in Appendix A.17.
2.4.2.2. NEXT-CSID Flavor
The Destination NAT flavor of the SRv6 masquerading proxy with the
NEXT-CSID (a.k.a End.AM- Masquerading proxy with NAT with NEXT-CSID,
End.AMN with NEXT-CSID for short) is executed except for line S09.1
and S10 in Section 6.4.2 of [I-D.ietf-spring-sr-service-programming]
replaced as follows.
Q01. Copy the Destination Address of the IPv6 header to the
Segment List[0] entry of the SRH.
Q02. Retrieve the CACHE entry associated with IFACE-IN.
Q03. If the CACHE entry is not empty {
Q04. Destination Address of the IPv6 header is set to CACHE.
Q05. }
A rendering of the complete pseudocode is provided in Appendix A.18.
2.4.3. Cache Flavor
The caching flavor of the SRv6 masquerading proxy with CSID is
enabled as per Section 6.4.3 of
[I-D.ietf-spring-sr-service-programming] without any modification.
3. Security Considerations
The security requirements and mechanisms described in [RFC8402] and
[RFC8754] also apply to this document.
This document does not introduce any new security considerations.
4. IANA Considerations
4.1. SRv6 Endpoint Behaviors
This document requests the IANA to allocate, within the "SRv6
Endpoint Behaviors" sub-registry belonging to the top-level "Segment-
routing with IPv6 dataplane (SRv6) Parameters" registry, the
following allocations:
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Value Description Reference
--------------------------------------------------------------
180 End.AS with REPLACE-CSID [This.ID]
181 End.AS with NEXT-CSID [This.ID]
182 End.AD with REPLACE-CSID [This.ID]
183 End.AD with NEXT-CSID [This.ID]
184 End.AM with REPLACE-CSID [This.ID]
185 End.AM with NEXT-CSID [This.ID]
186 End.AMN with REPLACE-CSID [This.ID]
187 End.AMN with NEXT-CSID [This.ID]
5. References
5.1. 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>.
[RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
July 2018, <https://www.rfc-editor.org/rfc/rfc8402>.
[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>.
[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>.
[I-D.ietf-spring-srv6-srh-compression]
Cheng, W., Filsfils, C., Li, Z., Decraene, B., and F.
Clad, "Compressed SRv6 Segment List Encoding (CSID)", Work
in Progress, Internet-Draft, draft-ietf-spring-srv6-srh-
compression-23, 6 February 2025,
<https://datatracker.ietf.org/doc/html/draft-ietf-spring-
srv6-srh-compression-23>.
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[I-D.ietf-spring-sr-service-programming]
Clad, F., Xu, X., Filsfils, C., Bernier, D., Li, C.,
Decraene, B., Ma, S., Yadlapalli, C., Henderickx, W., and
S. Salsano, "Service Programming with Segment Routing",
Work in Progress, Internet-Draft, draft-ietf-spring-sr-
service-programming-11, 23 February 2025,
<https://datatracker.ietf.org/doc/html/draft-ietf-spring-
sr-service-programming-11>.
5.2. Informative References
[RFC7665] Halpern, J., Ed. and C. Pignataro, Ed., "Service Function
Chaining (SFC) Architecture", RFC 7665,
DOI 10.17487/RFC7665, October 2015,
<https://www.rfc-editor.org/rfc/rfc7665>.
[I-D.ietf-spring-compression-requirement]
Cheng, W., Xie, C., Bonica, R., Dukes, D., Li, C., Peng,
S., and W. Henderickx, "Compressed SRv6 SID List
Requirements", Work in Progress, Internet-Draft, draft-
ietf-spring-compression-requirement-03, 3 April 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-spring-
compression-requirement-03>.
Appendix A. Complete Pseudocodes
A.1. REPLACE-CSID Flavor for Static Proxy for Inner Type Ethernet
When processing the SRH of a packet matching a FIB entry locally
instantiated as an SRv6 static proxy SID with the REPLACE-CSID flavor
for Ethernet traffic:
S01. When an SRH is processed {
S02. If (Segments Left == 0 and (DA.Arg.Index == 0 or
Segment List[0][DA.Arg.Index-1] == 0)) {
S03. Stop processing the SRH, and proceed to process the next
header in the packet, whose type is identified by
the Next Header field in the routing header.
S04. }
S05. If (IPv6 Hop Limit <= 1) {
S06. Send an ICMP Time Exceeded message to the Source Address,
Code 0 (Hop limit exceeded in transit),
interrupt packet processing and discard the packet.
S07. }
S08. max_LE = (Hdr Ext Len / 2) - 1
R01. If (DA.Arg.Index != 0) {
R02. If ((Last Entry > max_LE) or (Segments Left > Last Entry)) {
R03. Send an ICMP Parameter Problem to the Source Address,
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Code 0 (Erroneous header field encountered),
Pointer set to the Segments Left field,
interrupt packet processing and discard the packet.
R04. }
R05. Decrement DA.Arg.Index by 1.
R06. If (Segment List[Segments Left][DA.Arg.Index] == 0) {
R07. Decrement Segments Left by 1.
R08. Decrement IPv6 Hop Limit by 1.
R09. Update IPv6 DA with Segment List[Segments Left]
P01. If (Upper-layer header type != 143 (Ethernet)) {
P02. Resubmit the packet to the IPv6 module for
transmission to the new destination.
P03. }
P04. Perform IPv6 decapsulation.
P05. Submit the frame to the Ethernet module for transmission
via interface IFACE-OUT.
R11. }
R12. } Else {
R13. If((Last Entry > max_LE) or (Segments Left > Last Entry+1)){
R14. Send an ICMP Parameter Problem to the Source Address,
Code 0 (Erroneous header field encountered),
Pointer set to the Segments Left field,
interrupt packet processing and discard the packet.
R15. }
R16. Decrement Segments Left by 1.
R17. Set DA.Arg.Index to (128/LNFL - 1).
R18. }
R19. Decrement IPv6 Hop Limit by 1.
R20. Write Segment List[Segments Left][DA.Arg.Index] into the bits
[LBL..LBL+LNFL-1] of the Destination Address of the IPv6
header.
P01. If (Upper-layer header type != 143 (Ethernet)) {
P02. Resubmit the packet to the IPv6 module for transmission to
the new destination.
P03. }
P04. Perform IPv6 decapsulation.
P05. Submit the frame to the Ethernet module for transmission via
interface IFACE-OUT.
S16. }
A.2. NEXT-CSID Flavor for Static Proxy for Inner Type Ethernet
When processing an IPv6 packet that matches a FIB entry locally
instantiated as an SRv6 static proxy SID with the NEXT-CSID flavor
for Ethernet traffic:
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N01. If (DA.Argument != 0) {
N02. If (IPv6 Hop Limit <= 1) {
N03. Send an ICMP Time Exceeded message to the Source Address
with Code 0 (Hop limit exceeded in transit),
interrupt packet processing, and discard the packet.
N04. }
N05. Copy the value of DA.Argument into the bits [LBL..(LBL+AL-1)]
of the Destination Address.
N06. Set the bits [(LBL+AL)..127] of the Destination Address to
zero.
N07. Decrement IPv6 Hop Limit by 1.
Q01. If (Upper-layer header type != 143 (Ethernet)) {
Q02. Resubmit the packet to the IPv6 module for transmission to
the new destination.
Q03. }
Q04. Perform IPv6 decapsulation.
Q05. Submit the frame to the Ethernet module for transmission via
interface IFACE-OUT.
N09. }
S02. If (Segments Left == 0) {
S03. Stop processing the SRH, and proceed to process the next
header in the packet, whose type is identified by
the Next Header field in the routing header.
S04. }
S05. If (IPv6 Hop Limit <= 1) {
S06. Send an ICMP Time Exceeded message to the Source Address
with Code 0 (Hop limit exceeded in transit),
interrupt packet processing, and discard the packet.
S07. }
S08. max_LE = (Hdr Ext Len / 2) - 1
S09. If ((Last Entry > max_LE) or (Segments Left > Last Entry+1)) {
S10. Send an ICMP Parameter Problem to the Source Address
with Code 0 (Erroneous header field encountered)
and Pointer set to the Segments Left field,
interrupt packet processing, and discard the packet.
S11. }
S12. Decrement IPv6 Hop Limit by 1.
S13. Decrement Segments Left by 1.
S14. Update IPv6 DA with Segment List[Segments Left].
Q01. If (Upper-layer header type != 143 (Ethernet)) {
Q02. Resubmit the packet to the IPv6 module for transmission to
the new destination.
Q03. }
Q04. Perform IPv6 decapsulation.
Q05. Submit the frame to the Ethernet module for transmission via
interface IFACE-OUT.
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A.3. REPLACE-CSID Flavor for Static Proxy for Inner Type IPv4
When processing an IPv6 packet that matches a FIB entry locally
instantiated as an SRv6 static proxy SID with the REPLACE-CSID flavor
for IPv4 traffic:
S01. When an SRH is processed {
S02. If (Segments Left == 0 and (DA.Arg.Index == 0 or
Segment List[0][DA.Arg.Index-1] == 0)) {
S03. Stop processing the SRH, and proceed to process the next
header in the packet, whose type is identified by
the Next Header field in the routing header.
S04. }
S05. If (IPv6 Hop Limit <= 1) {
S06. Send an ICMP Time Exceeded message to the Source Address,
Code 0 (Hop limit exceeded in transit),
interrupt packet processing and discard the packet.
S07. }
S08. max_LE = (Hdr Ext Len / 2) - 1
R01. If (DA.Arg.Index != 0) {
R02. If ((Last Entry > max_LE) or (Segments Left > Last Entry)) {
R03. Send an ICMP Parameter Problem to the Source Address,
Code 0 (Erroneous header field encountered),
Pointer set to the Segments Left field,
interrupt packet processing and discard the packet.
R04. }
R05. Decrement DA.Arg.Index by 1.
R06. If (Segment List[Segments Left][DA.Arg.Index] == 0) {
R07. Decrement Segments Left by 1.
R08. Decrement IPv6 Hop Limit by 1.
R09. Update IPv6 DA with Segment List[Segments Left]
P01. If (Upper-layer header type != 4 (IPv4)) {
P02. Resubmit the packet to the IPv6 module for transmission
to the new destination.
P03. }
P04. Perform IPv6 decapsulation.
P05. Submit the packet to the IPv4 module for transmission on
interface IFACE-OUT via NH-ADDR.
R11. }
R12. } Else {
R13. If((Last Entry > max_LE) or (Segments Left > Last Entry+1)){
R14. Send an ICMP Parameter Problem to the Source Address,
Code 0 (Erroneous header field encountered),
Pointer set to the Segments Left field,
interrupt packet processing and discard the packet.
R15. }
R16. Decrement Segments Left by 1.
R17. Set DA.Arg.Index to (128/LNFL - 1).
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R18. }
R19. Decrement IPv6 Hop Limit by 1.
R20. Write Segment List[Segments Left][DA.Arg.Index] into the bits
[LBL..LBL+LNFL-1] of the Destination Address of the IPv6
header.
P01. If (Upper-layer header type != 4 (IPv4)) {
P02. Resubmit the packet to the IPv6 module for transmission to
the new destination.
P03. }
P04. Perform IPv6 decapsulation.
P05. Submit the packet to the IPv4 module for transmission on
interface IFACE-OUT via NH-ADDR.
S16. }
A.4. NEXT-CSID Flavor for Static Proxy for Inner Type IPv4
When processing an IPv6 packet that matches a FIB entry locally
instantiated as an SRv6 static proxy SID with the NEXT-CSID flavor
for IPv4 traffic:
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N01. If (DA.Argument != 0) {
N02. If (IPv6 Hop Limit <= 1) {
N03. Send an ICMP Time Exceeded message to the Source Address
with Code 0 (Hop limit exceeded in transit),
interrupt packet processing, and discard the packet.
N04. }
N05. Copy the value of DA.Argument into the bits [LBL..(LBL+AL-1)]
of the Destination Address.
N06. Set the bits [(LBL+AL)..127] of the Destination Address to
zero.
N07. Decrement IPv6 Hop Limit by 1.
Q01. If (Upper-layer header type != 4 (IPv4)) {
Q02. Resubmit the packet to the IPv6 module for transmission to
the new destination.
Q03. }
Q04. Perform IPv6 decapsulation.
Q05. Submit the packet to the IPv4 module for transmission on
interface IFACE-OUT via NH-ADDR.
N09. }
S02. If (Segments Left == 0) {
S03. Stop processing the SRH, and proceed to process the next
header in the packet, whose type is identified by
the Next Header field in the routing header.
S04. }
S05. If (IPv6 Hop Limit <= 1) {
S06. Send an ICMP Time Exceeded message to the Source Address
with Code 0 (Hop limit exceeded in transit),
interrupt packet processing, and discard the packet.
S07. }
S08. max_LE = (Hdr Ext Len / 2) - 1
S09. If ((Last Entry > max_LE) or (Segments Left > Last Entry+1)) {
S10. Send an ICMP Parameter Problem to the Source Address
with Code 0 (Erroneous header field encountered)
and Pointer set to the Segments Left field,
interrupt packet processing, and discard the packet.
S11. }
S12. Decrement IPv6 Hop Limit by 1.
S13. Decrement Segments Left by 1.
S14. Update IPv6 DA with Segment List[Segments Left].
Q01. If (Upper-layer header type != 4 (IPv4)) {
Q02. Resubmit the packet to the IPv6 module for transmission to
the new destination.
Q03. }
Q04. Perform IPv6 decapsulation.
Q05. Submit the packet to the IPv4 module for transmission on
interface IFACE-OUT via NH-ADDR.
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A.5. REPLACE-CSID Flavor for Static Proxy for Inner Type IPv6
When processing an IPv6 packet that matches a FIB entry locally
instantiated as an SRv6 static proxy SID with the REPLACE-CSID flavor
for IPv6 traffic:
S01. When an SRH is processed {
S02. If (Segments Left == 0 and (DA.Arg.Index == 0 or
Segment List[0][DA.Arg.Index-1] == 0)) {
S03. Stop processing the SRH, and proceed to process the next
header in the packet, whose type is identified by
the Next Header field in the routing header.
S04. }
S05. If (IPv6 Hop Limit <= 1) {
S06. Send an ICMP Time Exceeded message to the Source Address,
Code 0 (Hop limit exceeded in transit),
interrupt packet processing and discard the packet.
S07. }
S08. max_LE = (Hdr Ext Len / 2) - 1
R01. If (DA.Arg.Index != 0) {
R02. If ((Last Entry > max_LE) or (Segments Left > Last Entry)) {
R03. Send an ICMP Parameter Problem to the Source Address,
Code 0 (Erroneous header field encountered),
Pointer set to the Segments Left field,
interrupt packet processing and discard the packet.
R04. }
R05. Decrement DA.Arg.Index by 1.
R06. If (Segment List[Segments Left][DA.Arg.Index] == 0) {
R07. Decrement Segments Left by 1.
R08. Decrement IPv6 Hop Limit by 1.
R09. Update IPv6 DA with Segment List[Segments Left]
P01. If (Upper-layer header type != 41 (IPv6)) {
P02. Resubmit the packet to the IPv6 module for transmission to
the new destination.
P03. }
P04. Perform IPv6 decapsulation.
P05. Submit the packet to the IPv6 module for transmission on
interface IFACE-OUT via NH-ADDR.
R11. }
R12. } Else {
R13. If((Last Entry > max_LE) or (Segments Left > Last Entry+1)){
R14. Send an ICMP Parameter Problem to the Source Address,
Code 0 (Erroneous header field encountered),
Pointer set to the Segments Left field,
interrupt packet processing and discard the packet.
R15. }
R16. Decrement Segments Left by 1.
R17. Set DA.Arg.Index to (128/LNFL - 1).
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R18. }
R19. Decrement IPv6 Hop Limit by 1.
R20. Write Segment List[Segments Left][DA.Arg.Index] into the bits
[LBL..LBL+LNFL-1] of the Destination Address of the IPv6
header.
P01. If (Upper-layer header type != 41 (IPv6)) {
P02. Resubmit the packet to the IPv6 module for transmission to
the new destination.
P03. }
P04. Perform IPv6 decapsulation.
P05. Submit the packet to the IPv6 module for transmission on
interface IFACE-OUT via NH-ADDR.
S16. }
A.6. NEXT-CSID Flavor for Static Proxy for Inner Type IPv6
When processing an IPv6 packet that matches a FIB entry locally
instantiated as an SRv6 static proxy SID with the NEXT-CSID flavor
for IPv6 traffic:
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N01. If (DA.Argument != 0) {
N02. If (IPv6 Hop Limit <= 1) {
N03. Send an ICMP Time Exceeded message to the Source Address
with Code 0 (Hop limit exceeded in transit),
interrupt packet processing, and discard the packet.
N04. }
N05. Copy the value of DA.Argument into the bits [LBL..(LBL+AL-1)]
of the Destination Address.
N06. Set the bits [(LBL+AL)..127] of the Destination Address to
zero.
N07. Decrement IPv6 Hop Limit by 1.
Q01. If (Upper-layer header type != 41 (IPv6)) {
Q02. Resubmit the packet to the IPv6 module for transmission to
the new destination.
Q03. }
Q04. Perform IPv6 decapsulation.
Q05. Submit the packet to the IPv6 module for transmission on
interface IFACE-OUT via NH-ADDR.
N09. }
S02. If (Segments Left == 0) {
S03. Stop processing the SRH, and proceed to process the next
header in the packet, whose type is identified by
the Next Header field in the routing header.
S04. }
S05. If (IPv6 Hop Limit <= 1) {
S06. Send an ICMP Time Exceeded message to the Source Address
with Code 0 (Hop limit exceeded in transit),
interrupt packet processing, and discard the packet.
S07. }
S08. max_LE = (Hdr Ext Len / 2) - 1
S09. If ((Last Entry > max_LE) or (Segments Left > Last Entry+1)) {
S10. Send an ICMP Parameter Problem to the Source Address
with Code 0 (Erroneous header field encountered)
and Pointer set to the Segments Left field,
interrupt packet processing, and discard the packet.
S11. }
S12. Decrement IPv6 Hop Limit by 1.
S13. Decrement Segments Left by 1.
S14. Update IPv6 DA with Segment List[Segments Left].
Q01. If (Upper-layer header type != 41 (IPv6)) {
Q02. Resubmit the packet to the IPv6 module for transmission to
the new destination.
Q03. }
Q04. Perform IPv6 decapsulation.
Q05. Submit the packet to the IPv6 module for transmission on
interface IFACE-OUT via NH-ADDR.
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A.7. REPLACE-CSID Flavor for Dynamic Proxy for Inner Type Ethernet
When processing an IPv6 packet that matches a FIB entry locally
instantiated as an SRv6 dynamic proxy SID with the REPLACE-CSID
flavor for Ethernet traffic:
S01. When an SRH is processed {
S02. If (Segments Left == 0 and (DA.Arg.Index == 0 or
Segment List[0][DA.Arg.Index-1] == 0)) {
S03. Stop processing the SRH, and proceed to process the next
header in the packet, whose type is identified by
the Next Header field in the routing header.
S04. }
S05. If (IPv6 Hop Limit <= 1) {
S06. Send an ICMP Time Exceeded message to the Source Address,
Code 0 (Hop limit exceeded in transit),
interrupt packet processing and discard the packet.
S07. }
S08. max_LE = (Hdr Ext Len / 2) - 1
R01. If (DA.Arg.Index != 0) {
R02. If ((Last Entry > max_LE) or (Segments Left > Last Entry)) {
R03. Send an ICMP Parameter Problem to the Source Address,
Code 0 (Erroneous header field encountered),
Pointer set to the Segments Left field,
interrupt packet processing and discard the packet.
R04. }
R05. Decrement DA.Arg.Index by 1.
R06. If (Segment List[Segments Left][DA.Arg.Index] == 0) {
R07. Decrement Segments Left by 1.
R08. Decrement IPv6 Hop Limit by 1.
R09. Update IPv6 DA with Segment List[Segments Left]
P01. If (Upper-layer header type != 143 (Ethernet)) {
P02. Resubmit the packet to the IPv6 module for transmission to
the new destination.
P03. }
P04. Copy the IPv6 encapsulation in a CACHE entry associated with
the interface IFACE-IN.
P05. Perform IPv6 decapsulation.
P06. Submit the frame to the Ethernet module for transmission via
interface IFACE-OUT.
R11. }
R12. } Else {
R13. If((Last Entry > max_LE) or (Segments Left > Last Entry+1)){
R14. Send an ICMP Parameter Problem to the Source Address,
Code 0 (Erroneous header field encountered),
Pointer set to the Segments Left field,
interrupt packet processing and discard the packet.
R15. }
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R16. Decrement Segments Left by 1.
R17. Set DA.Arg.Index to (128/LNFL - 1).
R18. }
R19. Decrement IPv6 Hop Limit by 1.
R20. Write Segment List[Segments Left][DA.Arg.Index] into the bits
[LBL..LBL+LNFL-1] of the Destination Address of the IPv6
header.
P01. If (Upper-layer header type != 143 (Ethernet)) {
P02. Resubmit the packet to the IPv6 module for transmission to
the new destination.
P03. }
P04. Copy the IPv6 encapsulation in a CACHE entry associated with
the interface IFACE-IN.
P05. Perform IPv6 decapsulation.
P06. Submit the frame to the Ethernet module for transmission via
interface IFACE-OUT.
S16. }
A.8. NEXT-CSID Flavor for Dynamic Proxy for Inner Type Ethernet
When processing an IPv6 packet that matches a FIB entry locally
instantiated as an SRv6 dynamic proxy SID with the NEXT-CSID flavor
for Ethernet traffic:
N01. If (DA.Argument != 0) {
N02. If (IPv6 Hop Limit <= 1) {
N03. Send an ICMP Time Exceeded message to the Source Address
with Code 0 (Hop limit exceeded in transit),
interrupt packet processing, and discard the packet.
N04. }
N05. Copy the value of DA.Argument into the bits [LBL..(LBL+AL-1)]
of the Destination Address.
N06. Set the bits [(LBL+AL)..127] of the Destination Address to
zero.
N07. Decrement IPv6 Hop Limit by 1.
Q01. If (Upper-layer header type != 143 (Ethernet)) {
Q02. Resubmit the packet to the IPv6 module for transmission to
the new destination.
Q03. }
Q04. Copy the IPv6 encapsulation in a CACHE entry associated with
the interface IFACE-IN.
Q05. Perform IPv6 decapsulation.
Q06. Submit the frame to the Ethernet module for transmission via
interface IFACE-OUT.
N09. }
S02. If (Segments Left == 0) {
S03. Stop processing the SRH, and proceed to process the next
header in the packet, whose type is identified by
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the Next Header field in the routing header.
S04. }
S05. If (IPv6 Hop Limit <= 1) {
S06. Send an ICMP Time Exceeded message to the Source Address
with Code 0 (Hop limit exceeded in transit),
interrupt packet processing, and discard the packet.
S07. }
S08. max_LE = (Hdr Ext Len / 2) - 1
S09. If ((Last Entry > max_LE) or (Segments Left > Last Entry+1)) {
S10. Send an ICMP Parameter Problem to the Source Address
with Code 0 (Erroneous header field encountered)
and Pointer set to the Segments Left field,
interrupt packet processing, and discard the packet.
S11. }
S12. Decrement IPv6 Hop Limit by 1.
S13. Decrement Segments Left by 1.
S14. Update IPv6 DA with Segment List[Segments Left].
Q01. If (Upper-layer header type != 143 (Ethernet)) {
Q02. Resubmit the packet to the IPv6 module for transmission to
the new destination.
Q03. }
Q04. Copy the IPv6 encapsulation in a CACHE entry associated with
the interface IFACE-IN.
Q05. Perform IPv6 decapsulation.
Q06. Submit the frame to the Ethernet module for transmission via
interface IFACE-OUT.
A.9. REPLACE-CSID Flavor for Dynamic Proxy for Inner Type IPv4
When processing an IPv6 packet that matches a FIB entry locally
instantiated as an SRv6 dynamic proxy SID with the REPLACE-CSID
flavor for IPv4 traffic:
S01. When an SRH is processed {
S02. If (Segments Left == 0 and (DA.Arg.Index == 0 or
Segment List[0][DA.Arg.Index-1] == 0)) {
S03. Stop processing the SRH, and proceed to process the next
header in the packet, whose type is identified by
the Next Header field in the routing header.
S04. }
S05. If (IPv6 Hop Limit <= 1) {
S06. Send an ICMP Time Exceeded message to the Source Address,
Code 0 (Hop limit exceeded in transit),
interrupt packet processing and discard the packet.
S07. }
S08. max_LE = (Hdr Ext Len / 2) - 1
R01. If (DA.Arg.Index != 0) {
R02. If ((Last Entry > max_LE) or (Segments Left > Last Entry)) {
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R03. Send an ICMP Parameter Problem to the Source Address,
Code 0 (Erroneous header field encountered),
Pointer set to the Segments Left field,
interrupt packet processing and discard the packet.
R04. }
R05. Decrement DA.Arg.Index by 1.
R06. If (Segment List[Segments Left][DA.Arg.Index] == 0) {
R07. Decrement Segments Left by 1.
R08. Decrement IPv6 Hop Limit by 1.
R09. Update IPv6 DA with Segment List[Segments Left]
P01. If (Upper-layer header type != 4 (IPv4)) {
P02. Resubmit the packet to the IPv6 module for transmission to
the new destination.
P03. }
P04. Copy the IPv6 encapsulation in a CACHE entry associated with
the interface IFACE-IN.
P05. Perform IPv6 decapsulation.
P06. Submit the frame to the IPv4 module for transmission via
interface IFACE-OUT via NH-ADDR.
R11. }
R12. } Else {
R13. If((Last Entry > max_LE) or (Segments Left > Last Entry+1)){
R14. Send an ICMP Parameter Problem to the Source Address,
Code 0 (Erroneous header field encountered),
Pointer set to the Segments Left field,
interrupt packet processing and discard the packet.
R15. }
R16. Decrement Segments Left by 1.
R17. Set DA.Arg.Index to (128/LNFL - 1).
R18. }
R19. Decrement IPv6 Hop Limit by 1.
R20. Write Segment List[Segments Left][DA.Arg.Index] into the bits
[LBL..LBL+LNFL-1] of the Destination Address of the IPv6
header.
P01. If (Upper-layer header type != 4 (IPv4)) {
P02. Resubmit the packet to the IPv6 module for transmission to
the new destination.
P03. }
P04. Copy the IPv6 encapsulation in a CACHE entry associated with
the interface IFACE-IN.
P05. Perform IPv6 decapsulation.
P06. Submit the frame to the IPv4 module for transmission via
interface IFACE-OUT via NH-ADDR.
S16. }
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A.10. NEXT-CSID Flavor for Dynamic Proxy for Inner Type IPv4
When processing an IPv6 packet that matches a FIB entry locally
instantiated as an SRv6 dynamic proxy SID with the NEXT-CSID flavor
for IPv4 traffic:
N01. If (DA.Argument != 0) {
N02. If (IPv6 Hop Limit <= 1) {
N03. Send an ICMP Time Exceeded message to the Source Address
with Code 0 (Hop limit exceeded in transit),
interrupt packet processing, and discard the packet.
N04. }
N05. Copy the value of DA.Argument into the bits [LBL..(LBL+AL-1)]
of the Destination Address.
N06. Set the bits [(LBL+AL)..127] of the Destination Address to
zero.
N07. Decrement IPv6 Hop Limit by 1.
Q01. If (Upper-layer header type != 4 (IPv4)) {
Q02. Resubmit the packet to the IPv6 module for transmission to
the new destination.
Q03. }
Q04. Copy the IPv6 encapsulation in a CACHE entry associated with
the interface IFACE-IN.
Q05. Perform IPv6 decapsulation.
Q06. Submit the frame to the IPv4 module for transmission via
interface IFACE-OUT via NH-ADDR.
N09. }
S02. If (Segments Left == 0) {
S03. Stop processing the SRH, and proceed to process the next
header in the packet, whose type is identified by
the Next Header field in the routing header.
S04. }
S05. If (IPv6 Hop Limit <= 1) {
S06. Send an ICMP Time Exceeded message to the Source Address
with Code 0 (Hop limit exceeded in transit),
interrupt packet processing, and discard the packet.
S07. }
S08. max_LE = (Hdr Ext Len / 2) - 1
S09. If ((Last Entry > max_LE) or (Segments Left > Last Entry+1)) {
S10. Send an ICMP Parameter Problem to the Source Address
with Code 0 (Erroneous header field encountered)
and Pointer set to the Segments Left field,
interrupt packet processing, and discard the packet.
S11. }
S12. Decrement IPv6 Hop Limit by 1.
S13. Decrement Segments Left by 1.
S14. Update IPv6 DA with Segment List[Segments Left].
Q01. If (Upper-layer header type != 4 (IPv4)) {
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Q02. Resubmit the packet to the IPv6 module for transmission to
the new destination.
Q03. }
Q04. Copy the IPv6 encapsulation in a CACHE entry associated with
the interface IFACE-IN.
Q05. Perform IPv6 decapsulation.
Q06. Submit the frame to the IPv4 module for transmission via
interface IFACE-OUT via NH-ADDR.
A.11. REPLACE-CSID Flavor for Dynamic Proxy for Inner Type IPv6
When processing an IPv6 packet that matches a FIB entry locally
instantiated as an SRv6 dynamic proxy SID with the REPLACE-CSID
flavor for IPv6 traffic:
S01. When an SRH is processed {
S02. If (Segments Left == 0 and (DA.Arg.Index == 0 or
Segment List[0][DA.Arg.Index-1] == 0)) {
S03. Stop processing the SRH, and proceed to process the next
header in the packet, whose type is identified by
the Next Header field in the routing header.
S04. }
S05. If (IPv6 Hop Limit <= 1) {
S06. Send an ICMP Time Exceeded message to the Source Address,
Code 0 (Hop limit exceeded in transit),
interrupt packet processing and discard the packet.
S07. }
S08. max_LE = (Hdr Ext Len / 2) - 1
R01. If (DA.Arg.Index != 0) {
R02. If ((Last Entry > max_LE) or (Segments Left > Last Entry)) {
R03. Send an ICMP Parameter Problem to the Source Address,
Code 0 (Erroneous header field encountered),
Pointer set to the Segments Left field,
interrupt packet processing and discard the packet.
R04. }
R05. Decrement DA.Arg.Index by 1.
R06. If (Segment List[Segments Left][DA.Arg.Index] == 0) {
R07. Decrement Segments Left by 1.
R08. Decrement IPv6 Hop Limit by 1.
R09. Update IPv6 DA with Segment List[Segments Left]
P01. If (Upper-layer header type != 41 (IPv6)) {
P02. Resubmit the packet to the IPv6 module for transmission to
the new destination.
P03. }
P04. Copy the IPv6 encapsulation in a CACHE entry associated with
the interface IFACE-IN.
P05. Perform IPv6 decapsulation.
P06. Submit the frame to the IPv6 module for transmission via
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interface IFACE-OUT via NH-ADDR.
R11. }
R12. } Else {
R13. If((Last Entry > max_LE) or (Segments Left > Last Entry+1)){
R14. Send an ICMP Parameter Problem to the Source Address,
Code 0 (Erroneous header field encountered),
Pointer set to the Segments Left field,
interrupt packet processing and discard the packet.
R15. }
R16. Decrement Segments Left by 1.
R17. Set DA.Arg.Index to (128/LNFL - 1).
R18. }
R19. Decrement IPv6 Hop Limit by 1.
R20. Write Segment List[Segments Left][DA.Arg.Index] into the bits
[LBL..LBL+LNFL-1] of the Destination Address of the IPv6
header.
P01. If (Upper-layer header type != 41 (IPv6)) {
P02. Resubmit the packet to the IPv6 module for transmission to
the new destination.
P03. }
P04. Copy the IPv6 encapsulation in a CACHE entry associated with
the interface IFACE-IN.
P05. Perform IPv6 decapsulation.
P06. Submit the frame to the IPv6 module for transmission via
interface IFACE-OUT via NH-ADDR.
S16. }
A.12. NEXT-CSID Flavor for Dynamic Proxy for Inner Type IPv6
When processing an IPv6 packet that matches a FIB entry locally
instantiated as an SRv6 dynamic proxy SID with the NEXT-CSID flavor
for IPv6 traffic:
N01. If (DA.Argument != 0) {
N02. If (IPv6 Hop Limit <= 1) {
N03. Send an ICMP Time Exceeded message to the Source Address
with Code 0 (Hop limit exceeded in transit),
interrupt packet processing, and discard the packet.
N04. }
N05. Copy the value of DA.Argument into the bits [LBL..(LBL+AL-1)]
of the Destination Address.
N06. Set the bits [(LBL+AL)..127] of the Destination Address to
zero.
N07. Decrement IPv6 Hop Limit by 1.
Q01. If (Upper-layer header type != 41 (IPv6)) {
Q02. Resubmit the packet to the IPv6 module for transmission to
the new destination.
Q03. }
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Q04. Copy the IPv6 encapsulation in a CACHE entry associated with
the interface IFACE-IN.
Q05. Perform IPv6 decapsulation.
Q06. Submit the frame to the IPv6 module for transmission via
interface IFACE-OUT via NH-ADDR.
N09. }
S02. If (Segments Left == 0) {
S03. Stop processing the SRH, and proceed to process the next
header in the packet, whose type is identified by
the Next Header field in the routing header.
S04. }
S05. If (IPv6 Hop Limit <= 1) {
S06. Send an ICMP Time Exceeded message to the Source Address
with Code 0 (Hop limit exceeded in transit),
interrupt packet processing, and discard the packet.
S07. }
S08. max_LE = (Hdr Ext Len / 2) - 1
S09. If ((Last Entry > max_LE) or (Segments Left > Last Entry+1)) {
S10. Send an ICMP Parameter Problem to the Source Address
with Code 0 (Erroneous header field encountered)
and Pointer set to the Segments Left field,
interrupt packet processing, and discard the packet.
S11. }
S12. Decrement IPv6 Hop Limit by 1.
S13. Decrement Segments Left by 1.
S14. Update IPv6 DA with Segment List[Segments Left].
Q01. If (Upper-layer header type != 41 (IPv6)) {
Q02. Resubmit the packet to the IPv6 module for transmission to
the new destination.
Q03. }
Q04. Copy the IPv6 encapsulation in a CACHE entry associated with
the interface IFACE-IN.
Q05. Perform IPv6 decapsulation.
Q06. Submit the frame to the IPv6 module for transmission via
interface IFACE-OUT via NH-ADDR.
A.13. REPLACE-CSID Flavor for SRv6 Masquerading Proxy
When processing an IPv6 packet that matches a FIB entry locally
instantiated as an SRv6 masquerading proxy SID with the REPLACE-CSID
flavor:
S01. When an SRH is processed {
S02. If (Segments Left == 0 and (DA.Arg.Index == 0 or
Segment List[0][DA.Arg.Index-1] == 0)) {
S03. Stop processing the SRH, and proceed to process the next
header in the packet, whose type is identified by
the Next Header field in the routing header.
Li, et al. Expires 24 October 2025 [Page 33]
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S04. }
S05. If (IPv6 Hop Limit <= 1) {
S06. Send an ICMP Time Exceeded message to the Source Address,
Code 0 (Hop limit exceeded in transit),
interrupt packet processing and discard the packet.
S07. }
S08. max_LE = (Hdr Ext Len / 2) - 1
R01. If (DA.Arg.Index != 0) {
R02. If ((Last Entry > max_LE) or (Segments Left > Last Entry)) {
R03. Send an ICMP Parameter Problem to the Source Address,
Code 0 (Erroneous header field encountered),
Pointer set to the Segments Left field,
interrupt packet processing and discard the packet.
R04. }
R05. Decrement DA.Arg.Index by 1.
R06. If (Segment List[Segments Left][DA.Arg.Index] == 0) {
R07. Decrement Segments Left by 1.
R08. Decrement IPv6 Hop Limit by 1.
R09. Update IPv6 DA with Segment List[Segments Left]
P01. Copy the IPv6 Destination Address in a CACHE entry associated
with the interface IFACE-IN.
P02. Copy Segment List[0] from the SRH to the Destination Address
of the IPv6 header.
P03. Submit the packet to the IPv6 module for transmission on
interface IFACE-OUT via NH-ADDR.
R11. }
R12. } Else {
R13. If((Last Entry > max_LE) or (Segments Left > Last Entry+1)){
R14. Send an ICMP Parameter Problem to the Source Address,
Code 0 (Erroneous header field encountered),
Pointer set to the Segments Left field,
interrupt packet processing and discard the packet.
R15. }
R16. Decrement Segments Left by 1.
R17. Set DA.Arg.Index to (128/LNFL - 1).
R18. }
R19. Decrement IPv6 Hop Limit by 1.
R20. Write Segment List[Segments Left][DA.Arg.Index] into the bits
[LBL..LBL+LNFL-1] of the Destination Address of the IPv6
header.
P01. Copy the IPv6 Destination Address in a CACHE entry associated
with the interface IFACE-IN.
P02. Copy Segment List[0] from the SRH to the Destination Address
of the IPv6 header.
P03. Submit the packet to the IPv6 module for transmission on
interface IFACE-OUT via NH-ADDR.
S16. }
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A.14. REPLACE-CSID Flavor for SRv6 De-masquerading Proxy
When processing an IPv6 packet received on the interface IFACE-IN and
with a destination address that does not match any address of IFACE-
IN:
S01. When an SRH is processed {
S02. If (IPv6 Hop Limit <= 1) {
S03. Send an ICMP Time Exceeded message to the Source Address,
Code 0 (hop limit exceeded in transit),
Interrupt packet processing and discard the packet.
S04. }
S05. If (Segments Left != 0) {
S06. max_last_entry = (Hdr Ext Len / 2) - 1
S07. If ((Last Entry > max_last_entry) or
(Segments Left > Last Entry)) {
S08. Send an ICMP Parameter Problem message to the Source Address,
Code 0 (Erroneous header field encountered),
Pointer set to the Segments Left field,
Interrupt packet processing and discard the packet.
S09. }
D01. Retrieve the CACHE entry associated with IFACE-IN.
D02. If the CACHE entry is not empty {
D03. Destination Address of the IPv6 header is set to CACHE.
D04. }
S11. }
S12. Decrement Hop Limit by 1.
S13. Submit the packet to the IPv6 module for transmission to the
next destination.
S14. }
A.15. NEXT-CSID Flavor for SRv6 Masquerading Proxy
When processing an IPv6 packet that matches a FIB entry locally
instantiated as an SRv6 masquerading proxy SID with the NEXT-CSID
flavor:
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N01. If (DA.Argument != 0) {
N02. If (IPv6 Hop Limit <= 1) {
N03. Send an ICMP Time Exceeded message to the Source Address
with Code 0 (Hop limit exceeded in transit),
interrupt packet processing, and discard the packet.
N04. }
N05. Copy the value of DA.Argument into the bits [LBL..(LBL+AL-1)]
of the Destination Address.
N06. Set the bits [(LBL+AL)..127] of the Destination Address to
zero.
N07. Decrement IPv6 Hop Limit by 1.
Q01. Copy the IPv6 Destination Address in a CACHE entry associated
with the interface IFACE-IN.
Q02. Copy Segment List[0] from the SRH to the Destination Address
of the IPv6 header.
Q03. Submit the packet to the IPv6 module for transmission on
interface IFACE-OUT via NH-ADDR.
N09. }
S02. If (Segments Left == 0) {
S03. Stop processing the SRH, and proceed to process the next
header in the packet, whose type is identified by
the Next Header field in the routing header.
S04. }
S05. If (IPv6 Hop Limit <= 1) {
S06. Send an ICMP Time Exceeded message to the Source Address
with Code 0 (Hop limit exceeded in transit),
interrupt packet processing, and discard the packet.
S07. }
S08. max_LE = (Hdr Ext Len / 2) - 1
S09. If ((Last Entry > max_LE) or (Segments Left > Last Entry+1)) {
S10. Send an ICMP Parameter Problem to the Source Address
with Code 0 (Erroneous header field encountered)
and Pointer set to the Segments Left field,
interrupt packet processing, and discard the packet.
S11. }
S12. Decrement IPv6 Hop Limit by 1.
S13. Decrement Segments Left by 1.
S14. Update IPv6 DA with Segment List[Segments Left].
Q01. Copy the IPv6 Destination Address in a CACHE entry associated
with the interface IFACE-IN.
Q02. Copy Segment List[0] from the SRH to the Destination Address
of the IPv6 header.
Q03. Submit the packet to the IPv6 module for transmission on
interface IFACE-OUT via NH-ADDR.
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A.16. NEXT-CSID Flavor for SRv6 De-masquerading Proxy
When processing an IPv6 packet received on the interface IFACE-IN and
with a destination address that does not match any address of IFACE-
IN:
S01. When an SRH is processed {
S02. If (IPv6 Hop Limit <= 1) {
S03. Send an ICMP Time Exceeded message to the Source Address,
Code 0 (hop limit exceeded in transit),
Interrupt packet processing and discard the packet.
S04. }
S05. If (Segments Left != 0) {
S06. max_last_entry = (Hdr Ext Len / 2) - 1
S07. If ((Last Entry > max_last_entry) or
(Segments Left > Last Entry)) {
S08. Send an ICMP Parameter Problem message to the Source Address,
Code 0 (Erroneous header field encountered),
Pointer set to the Segments Left field,
Interrupt packet processing and discard the packet.
S09. }
E01. Retrieve the CACHE entry associated with IFACE-IN.
E02. If the CACHE entry is not empty {
E03. Destination Address of the IPv6 header is set to CACHE.
E04. }
S11. }
S12. Decrement Hop Limit by 1.
S13. Submit the packet to the IPv6 module for transmission to the
next destination.
S14. }
A.17. REPLACE-CSID Flavor for Destination NAT Flavor
The Destination NAT flavor of the SRv6 masquerading proxy with the
REPLACE-CSID is executed:
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S01. When an SRH is processed {
S02. If (IPv6 Hop Limit <= 1) {
S03. Send an ICMP Time Exceeded message to the Source Address,
Code 0 (hop limit exceeded in transit),
Interrupt packet processing and discard the packet.
S04. }
S05. If (Segments Left != 0) {
S06. max_last_entry = (Hdr Ext Len / 2) - 1
S07. If ((Last Entry > max_last_entry) or
(Segments Left > Last Entry)) {
S08. Send an ICMP Parameter Problem message to the Source Address,
Code 0 (Erroneous header field encountered),
Pointer set to the Segments Left field,
Interrupt packet processing and discard the packet.
S09. }
P01. Copy the Destination Address of the IPv6 header to the
Segment List[0] entry of the SRH.
P02. Retrieve the CACHE entry associated with IFACE-IN.
P03. If the CACHE entry is not empty {
P04. Destination Address of the IPv6 header is set to CACHE.
P05. }
S11. }
S12. Decrement Hop Limit by 1.
S13. Submit the packet to the IPv6 module for transmission to the
next destination.
S14. }
A.18. NEXT-CSID Flavor for Destination NAT Flavor
The Destination NAT flavor of the SRv6 masquerading proxy with the
NEXT-CSID is executed:
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S01. When an SRH is processed {
S02. If (IPv6 Hop Limit <= 1) {
S03. Send an ICMP Time Exceeded message to the Source Address,
Code 0 (hop limit exceeded in transit),
Interrupt packet processing and discard the packet.
S04. }
S05. If (Segments Left != 0) {
S06. max_last_entry = (Hdr Ext Len / 2) - 1
S07. If ((Last Entry > max_last_entry) or
(Segments Left > Last Entry)) {
S08. Send an ICMP Parameter Problem message to the Source Address,
Code 0 (Erroneous header field encountered),
Pointer set to the Segments Left field,
Interrupt packet processing and discard the packet.
S09. }
Q01. Copy the Destination Address of the IPv6 header to the
Segment List[0] entry of the SRH.
Q02. Retrieve the CACHE entry associated with IFACE-IN.
Q03. If the CACHE entry is not empty {
Q04. Destination Address of the IPv6 header is set to CACHE.
Q05. }
S11. }
S12. Decrement Hop Limit by 1.
S13. Submit the packet to the IPv6 module for transmission to the
next destination.
S14. }
Acknowledgements
TBD.
Authors' Addresses
Cheng Li (editor)
Huawei
China
Email: c.l@huawei.com
Weiqiang Cheng
China Mobile
China
Email: chengweiqiang@chinamobile.com
Hongyi Huang (editor)
Huawei
China
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Email: hongyi.huang@huawei.com
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