The IPv6 Compact Routing Header (CRH)
draft-bonica-6man-comp-rtg-hdr-27
6man R. Bonica
Internet-Draft Juniper Networks
Intended status: Standards Track Y. Kamite
Expires: 16 May 2022 NTT Communications Corporation
A. Alston
D. Henriques
Liquid Telecom
L. Jalil
Verizon
12 November 2021
The IPv6 Compact Routing Header (CRH)
draft-bonica-6man-comp-rtg-hdr-27
Abstract
This document defines two new Routing header types. Collectively,
they are called the Compact Routing Headers (CRH). Individually,
they are called CRH-16 and CRH-32.
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 16 May 2022.
Copyright Notice
Copyright (c) 2021 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
Bonica, et al. Expires 16 May 2022 [Page 1]
Internet-Draft IPv6 Compressed Routing Header November 2021
extracted from this document must include Simplified BSD License text
as described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
3. The Compressed Routing Headers (CRH) . . . . . . . . . . . . 3
4. The CRH Forwarding Information Base (CRH-FIB) . . . . . . . . 4
5. Processing Rules . . . . . . . . . . . . . . . . . . . . . . 6
5.1. Computing Minimum CRH Length . . . . . . . . . . . . . . 7
5.2. CRH Removal Procedure . . . . . . . . . . . . . . . . . . 8
6. Mutability . . . . . . . . . . . . . . . . . . . . . . . . . 8
7. Applications And SIDs . . . . . . . . . . . . . . . . . . . . 8
8. Management Considerations . . . . . . . . . . . . . . . . . . 9
9. Security Considerations . . . . . . . . . . . . . . . . . . . 9
10. Implementation and Deployment Status . . . . . . . . . . . . 9
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10
13. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 10
14. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
14.1. Normative References . . . . . . . . . . . . . . . . . . 11
14.2. Informative References . . . . . . . . . . . . . . . . . 11
Appendix A. CRH Processing Examples . . . . . . . . . . . . . . 12
A.1. The SID List Contains One Entry For Each Segment In The
Path . . . . . . . . . . . . . . . . . . . . . . . . . . 13
A.2. The SID List Omits The First Entry In The Path . . . . . 14
Appendix B. A Packet Recycling Use-Case . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15
1. Introduction
IPv6 [RFC8200] source nodes use Routing headers to specify the path
that a packet takes to its destination. The IETF has defined several
Routing header types [IANA-RH]. This document defines two new
Routing header types. Collectively, they are called the Compact
Routing Headers (CRH). Individually, they are called CRH-16 and CRH-
32.
The CRH allows IPv6 source nodes to specify the path that a packet
takes to its destination. The CRH:
* Can be encoded in relatively few bytes.
* Is designed to operate within a network domain. (See Section 9).
Bonica, et al. Expires 16 May 2022 [Page 2]
Internet-Draft IPv6 Compressed Routing Header November 2021
The following are reasons for encoding the CRH in as few bytes as
possible:
* Many ASIC-based forwarders copy headers from buffer memory to on-
chip memory. As header sizes increase, so does the cost of this
copy.
* Because Path MTU Discovery (PMTUD) [RFC8201] is not entirely
reliable, many IPv6 hosts refrain from sending packets larger than
the IPv6 minimum link MTU (i.e., 1280 bytes). When packets are
small, the overhead imposed by large Routing Headers is excessive.
2. 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.
3. The Compressed Routing Headers (CRH)
Both CRH versions (i.e., CRH-16 and CRH-32) contain the following
fields:
* Next Header - Defined in [RFC8200].
* Hdr Ext Len - Defined in [RFC8200].
* Routing Type - Defined in [RFC8200]. Value TBD by IANA. (For
CRH-16, the suggested value is 5. For CRH-32, the suggested value
is 6.)
* Segments Left - Defined in [RFC8200].
* Type-specific Data - Described in [RFC8200].
In the CRH, the Type-specific data field contains a list of Segment
Identifiers (SIDs). Each SID represents both of the following:
* A segment of the path that the packet takes to its destination.
* An entry in the CRH Forwarding Information Base (CRH-FIB)
(Section 4).
Bonica, et al. Expires 16 May 2022 [Page 3]
Internet-Draft IPv6 Compressed Routing Header November 2021
SIDs are listed in reverse order. So, the first SID in the list
represents the final segment in the path. Because segments are
listed in reverse order, the Segments Left field can be used as an
index into the SID list. In this document, the "current SID" is the
SID list entry referenced by the Segments Left field.
The first segment in the path can be omitted from the list. See
Appendix A for examples.
In the CRH-16 (Figure 1), each SID is encoded in 16-bits. In the
CRH-32 (Figure 2), each SID is encoded in 32-bits.
In all cases, the CRH MUST end on a 64-bit boundary. So, the Type-
specific data field MUST be padded with zeros if the CRH would
otherwise not end on a 64-bit boundary.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header | Hdr Ext Len | Routing Type | Segments Left |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SID[0] | SID[1] |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
| .........
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
Figure 1: CRH-16
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header | Hdr Ext Len | Routing Type | Segments Left |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ SID[0] +
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ SID[1] +
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ SID[n] +
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: CRH-32
4. The CRH Forwarding Information Base (CRH-FIB)
Each SID identifies a CRH-FIB entry.
Bonica, et al. Expires 16 May 2022 [Page 4]
Internet-Draft IPv6 Compressed Routing Header November 2021
Each CRH-FIB entry contains:
* An IPv6 address (optional).
* A topological function.
* Arguments for the topological function (optional).
* Flags.
* A service function (optional).
* Arguments for the service function (optional).
The IPv6 address can represent either:
* An interface on the next segment endpoint.
* An SRv6 SID [RFC8986], instantiated on the next segment endpoint.
The first ten bits of the IPv6 address MUST NOT be fe00. That prefix
is reserved for link-local [RFC6890] addresses.
The topological function specifies how the processing node forwards
the packet to the next segment endpoint. The following are examples:
* Forward the packet through the least-cost path to the next segment
endpoint.
* Forward the packet through a specified interface.
* Encapsulate the packet in another IPv6 header of any type (e.g.,
MPLS, IPv6) and forward either through the least cost path or a
specified interface.
* Recycle the packet, as if the node had forwarded to one of its own
interfaces. When recycling is complete, process the next SID.
See Appendix B for a packet recycling use-case.
Some topological functions require parameters. For example, a
topological function might require a parameter that identifies the
interface through which the packet should be forwarded.
The following flags are defined:
* The PSP flag indicates whether the penultimate segment endpoint
(i.e., the node that sets Segments Left to 0) MAY remove the CRH.
Bonica, et al. Expires 16 May 2022 [Page 5]
Internet-Draft IPv6 Compressed Routing Header November 2021
* The OAM flag indicates whether the processing node should invoke
OAM procedures for which it is configured.
The service function is optional. If present, it invokes a node
specific procedure. The following are examples of node specific
procedures:
* Emit telemetry.
* Subject the packet's payload to a firewall rule.
* Replicate the packet, forwarding one copy and retaining the other
for sampling, analysis, or other purposes.
Node specific procedures are not subject to standardization. A node
can support any number of node specific procedures and associate them
with any SIDs.
Some service functions require parameters. For example, an
instruction to emit telemetry might require an IP address to which
telemetry should be sent.
The CRH-FIB can be populated:
* By an operator, using a Command Line Interface (CLI).
* By a controller, using the Path Computation Element (PCE)
Communication Protocol (PCEP) [RFC5440] or the Network
Configuration Protocol (NETCONF) [RFC6241].
* By a distributed routing protocol [ISO10589-Second-Edition],
[RFC5340], [RFC4271].
5. Processing Rules
The following rules describe CRH processing:
* If Segments Left equals 0, skip over the CRH and process the next
header in the packet.
* If Hdr Ext Len indicates that the CRH is larger than the
implementation can process, discard the packet and send an ICMPv6
[RFC4443] Parameter Problem, Code 0, message to the Source
Address, pointing to the Hdr Ext Len field.
* Compute L, the minimum CRH length ( Section 5.1).
Bonica, et al. Expires 16 May 2022 [Page 6]
Internet-Draft IPv6 Compressed Routing Header November 2021
* If L is greater than Hdr Ext Len, discard the packet and send an
ICMPv6 Parameter Problem, Code 0, message to the Source Address,
pointing to the Segments Left field.
* Decrement Segments Left.
* Search for the current SID in the CRH-FIB. In this document, the
"current SID" is the SID list entry referenced by the Segments
Left field.
* If the search does not return a CRH-FIB entry, discard the packet
and send an ICMPv6 Parameter Problem, Code 0, message to the
Source Address, pointing to the current SID.
* If Segments Left is greater than 0 and the CRH-FIB entry contains
a multicast address, discard the packet and send an ICMPv6
Parameter Problem, Code 0, message to the Source Address, pointing
to the current SID.
* If present, copy the IPv6 address from the CRH-FIB entry to the
Destination Address field in the IPv6 header.
* Decrement the IPv6 Hop Limit.
* If the CRH-FIB entry contains a service function, execute it.
* If Segments Left is equal to zero, and the PSP flag in the CRH-FIB
entry is set, execute the CRH removal procedure ( Section 5.2).
* Submit the packet, its topological function and its parameters to
the IPv6 module. See NOTE.
NOTE: By default, the IPv6 module determines the next-hop and
forwards the packet. However, the topological function may elicit
another behavior. For example, the IPv6 module may forward the
packet through a specified interface.
5.1. Computing Minimum CRH Length
The algorithm described in this section accepts the following CRH
fields as its input parameters:
* Routing Type (i.e., CRH-16 or CRH-32).
* Segments Left.
It yields L, the minimum CRH length. The minimum CRH length is
measured in 8-octet units, not including the first 8 octets.
Bonica, et al. Expires 16 May 2022 [Page 7]
Internet-Draft IPv6 Compressed Routing Header November 2021
<CODE BEGINS>
switch(Routing Type) {
case CRH-16:
if (Segments Left <= 2)
return(0)
sidsBeyondFirstWord = Segments Left - 2;
sidPerWord = 4;
case CRH-32:
if (Segments Left <= 1)
return(0)
sidsBeyondFirstWord = Segments Left - 1;
sidsPerWord = 2;
case default:
return(0xFF);
}
words = sidsBeyondFirstWord div sidsPerWord;
if (sidsBeyondFirstWord mod sidsPerWord)
words++;
return(words)
<CODE ENDS>
5.2. CRH Removal Procedure
The processing node SHOULD execute the following procedure, if it is
capable of doing so:
* Update the Next Header field in the header preceding the CRH using
a value taken from the Next Header field in the CRH.
* Decrease the Payload Length filed in the IPv6 header by 8*(x+1),
where value of x is equal to the value of the Hdr Ext Len field in
the CRH.
* Remove the CRH from the IPv6 header chain.
6. Mutability
In the CRH, the Segments Left field is mutable. All remaining fields
are immutable.
7. Applications And SIDs
A CRH contains one or more SIDs. Each SID is processed by exactly
one node.
Bonica, et al. Expires 16 May 2022 [Page 8]
Internet-Draft IPv6 Compressed Routing Header November 2021
Therefore, a SID is not required to have domain-wide significance.
Applications can:
* Allocate SIDs so that they have domain-wide significance.
* Allocate SIDs so that they have node-local significance.
8. Management Considerations
PING and TRACEROUTE [RFC2151] both operate correctly in the presence
of the CRH.
9. Security Considerations
Networks that process the CRH MUST NOT accept packets containing the
CRH from untrusted sources. Their border routers SHOULD discard
packets that satisfy the following criteria:
* The packet contains a CRH
* The Segments Left field in the CRH has a value greater than 0
* The Destination Address field in the IPv6 header represents an
interface that resides inside of the network.
Many border routers cannot filter packets based upon the Segments
Left value. These border routers MAY discard packets that satisfy
the following criteria:
* The packet contains a CRH
* The Destination Address field in the IPv6 header represents an
interface that resides inside of the network.
10. Implementation and Deployment Status
Juniper Networks has produced experimental implementations of the CRH
on:
* A LINUX-based software platform
* The MX-series (ASIC-based) router
Liquid Telecom has deployed the CRH, on a limited basis, in their
network. Other experimental deployments are in progress.
Bonica, et al. Expires 16 May 2022 [Page 9]
Internet-Draft IPv6 Compressed Routing Header November 2021
11. IANA Considerations
This document makes the following registrations in the "Internet
Protocol Version 6 (IPv6) Parameters" "Routing Types" subregistry
maintained by IANA:
+-------+------------------------------+---------------+
| Value | Description | Reference |
+=======+==============================+===============+
| 5 | CRH-16 | This document |
+-------+------------------------------+---------------+
| 6 | CRH-32 | This document |
+-------+------------------------------+---------------+
12. Acknowledgements
Thanks to Dr. Vanessa Ameen, Fernando Gont, Naveen Kottapalli, Joel
Halpern, Tony Li, Gerald Schmidt, Nancy Shaw, Ketan Talaulikar, and
Chandra Venkatraman for their contributions to this document.
13. Contributors
Gang Chen
Baidu
No.10 Xibeiwang East Road Haidian District
Beijing 100193 P.R. China
Email: phdgang@gmail.com
Yifeng Zhou
ByteDance
Building 1, AVIC Plaza, 43 N 3rd Ring W Rd Haidian District
Beijing 100000 P.R. China
Email: yifeng.zhou@bytedance.com
Gyan Mishra
Verizon
Bonica, et al. Expires 16 May 2022 [Page 10]
Internet-Draft IPv6 Compressed Routing Header November 2021
Silver Spring, Maryland, USA
Email: hayabusagsm@gmail.com
14. References
14.1. 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/info/rfc2119>.
[RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet
Control Message Protocol (ICMPv6) for the Internet
Protocol Version 6 (IPv6) Specification", STD 89,
RFC 4443, DOI 10.17487/RFC4443, March 2006,
<https://www.rfc-editor.org/info/rfc4443>.
[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/info/rfc8174>.
[RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", STD 86, RFC 8200,
DOI 10.17487/RFC8200, July 2017,
<https://www.rfc-editor.org/info/rfc8200>.
[RFC8201] McCann, J., Deering, S., Mogul, J., and R. Hinden, Ed.,
"Path MTU Discovery for IP version 6", STD 87, RFC 8201,
DOI 10.17487/RFC8201, July 2017,
<https://www.rfc-editor.org/info/rfc8201>.
14.2. Informative References
[IANA-RH] IANA, "Routing Headers",
<https://www.iana.org/assignments/ipv6-parameters/
ipv6-parameters.xhtml#ipv6-parameters-3>.
[ISO10589-Second-Edition]
International Organization for Standardization,
""Intermediate system to Intermediate system intra-domain
routeing information exchange protocol for use in
conjunction with the protocol for providing the
connectionless-mode Network Service (ISO 8473)", ISO/IEC
10589:2002, Second Edition,", November 2001.
Bonica, et al. Expires 16 May 2022 [Page 11]
Internet-Draft IPv6 Compressed Routing Header November 2021
[RFC2151] Kessler, G. and S. Shepard, "A Primer On Internet and TCP/
IP Tools and Utilities", FYI 30, RFC 2151,
DOI 10.17487/RFC2151, June 1997,
<https://www.rfc-editor.org/info/rfc2151>.
[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Border Gateway Protocol 4 (BGP-4)", RFC 4271,
DOI 10.17487/RFC4271, January 2006,
<https://www.rfc-editor.org/info/rfc4271>.
[RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF
for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008,
<https://www.rfc-editor.org/info/rfc5340>.
[RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol (PCEP)", RFC 5440,
DOI 10.17487/RFC5440, March 2009,
<https://www.rfc-editor.org/info/rfc5440>.
[RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
and A. Bierman, Ed., "Network Configuration Protocol
(NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
<https://www.rfc-editor.org/info/rfc6241>.
[RFC6890] Cotton, M., Vegoda, L., Bonica, R., Ed., and B. Haberman,
"Special-Purpose IP Address Registries", BCP 153,
RFC 6890, DOI 10.17487/RFC6890, April 2013,
<https://www.rfc-editor.org/info/rfc6890>.
[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/info/rfc8986>.
Appendix A. CRH Processing Examples
This appendix demonstrates CRH processing in the following scenarios:
* The SID list contains one entry for each segment in the path
(Appendix A.1).
* The SID list omits the first entry in the path (Appendix A.2).
Bonica, et al. Expires 16 May 2022 [Page 12]
Internet-Draft IPv6 Compressed Routing Header November 2021
----------- ----------- -----------
|Node: S | |Node: I1 | |Node: I2 |
|Loopback: |---------------|Loopback: |---------------|Loopback: |
|2001:db8::a| |2001:db8::1| |2001:db8::2|
----------- ----------- -----------
| |
| ----------- |
| |Node: D | |
---------------------|Loopback: |---------------------
|2001:db8::b|
-----------
Figure 3: Reference Topology
Figure 3 provides a reference topology that is used in all examples.
+=====+==============+===================+
| SID | IPv6 Address | Forwarding Method |
+=====+==============+===================+
| 2 | 2001:db8::2 | Least-cost path |
+-----+--------------+-------------------+
| 11 | 2001:db8::b | Least-cost path |
+-----+--------------+-------------------+
Table 1: Node SIDs
Table 1 describes two entries that appear in each node's CRH-FIB.
A.1. The SID List Contains One Entry For Each Segment In The Path
In this example, Node S sends a packet to Node D, via I2. In this
example, I2 appears in the CRH segment list.
+=====================================+===================+
| As the packet travels from S to I2: | |
+=====================================+===================+
| Source Address = 2001:db8::a | Segments Left = 1 |
+-------------------------------------+-------------------+
| Destination Address = 2001:db8::2 | SID[0] = 11 |
+-------------------------------------+-------------------+
| | SID[1] = 2 |
+-------------------------------------+-------------------+
Table 2
Bonica, et al. Expires 16 May 2022 [Page 13]
Internet-Draft IPv6 Compressed Routing Header November 2021
+=====================================+===================+
| As the packet travels from I2 to D: | |
+=====================================+===================+
| Source Address = 2001:db8::a | Segments Left = 0 |
+-------------------------------------+-------------------+
| Destination Address = 2001:db8::b | SID[0] = 11 |
+-------------------------------------+-------------------+
| | SID[1] = 2 |
+-------------------------------------+-------------------+
Table 3
A.2. The SID List Omits The First Entry In The Path
In this example, Node S sends a packet to Node D, via I2. In this
example, I2 does not appear in the CRH segment list.
+=====================================+===================+
| As the packet travels from S to I2: | |
+=====================================+===================+
| Source Address = 2001:db8::a | Segments Left = 1 |
+-------------------------------------+-------------------+
| Destination Address = 2001:db8::2 | SID[0] = 11 |
+-------------------------------------+-------------------+
Table 4
+=====================================+===================+
| As the packet travels from I2 to D: | |
+=====================================+===================+
| Source Address = 2001:db8::a | Segments Left = 0 |
+-------------------------------------+-------------------+
| Destination Address = 2001:db8::b | SID[0] = 11 |
+-------------------------------------+-------------------+
Table 5
Appendix B. A Packet Recycling Use-Case
Bonica, et al. Expires 16 May 2022 [Page 14]
Internet-Draft IPv6 Compressed Routing Header November 2021
Network A--D1
/ \ /
/ \ /
/ \ /
S ---- P +
\ / \
\ / \
\ / \
Network B---DN
Figure 4: Packet Recycling Use-case
In Figure 4:
* The SR domain contains Node S, Node P, and a set of destination
nodes (D1 through DN)
* S is connected to P
* P is connected to Network A and to Network B. Neither of these
networks are SR-capable.
* The destination nodes connect to both Network A and Network B
S needs to reach each destination node through two SR paths. One SR
path traverses Network A while the other traverses Network B.
Uncompressed SRv6 can encode this SR Path in two segments,with one
segment instantiated on P and the other on the destination. To
support this strategy, P instantiates two END.X SIDs (one per
network).
CRH compressed SRv6 can encode this SR Path in two or three segments.
When it encodes the path in two segments, one segment instantiated on
P and the other on the destination. To support this strategy, P
instantiates 2*N SIDs (one per network per destination). When CRH
compressed SRv6 encodes the path in three segments, two segments are
instantiated on P and the other on the destination. The first
segment on P updates the IPv6 Destination address without forwarding
the packet, while the other segment on P forwards the packet without
updating the IPv6 destination address. To support this strategy, P
instantiates 2+N SIDs (one per network and one per destination).
Authors' Addresses
Ron Bonica
Juniper Networks
2251 Corporate Park Drive
Bonica, et al. Expires 16 May 2022 [Page 15]
Internet-Draft IPv6 Compressed Routing Header November 2021
Herndon, Virginia 20171
United States of America
Email: rbonica@juniper.net
Yuji Kamite
NTT Communications Corporation
3-4-1 Shibaura, Minato-ku,
108-8118
Japan
Email: y.kamite@ntt.com
Andrew Alston
Liquid Telecom
Nairobi
Kenya
Email: Andrew.Alston@liquidtelecom.com
Daniam Henriques
Liquid Telecom
Johannesburg
South Africa
Email: daniam.henriques@liquidtelecom.com
Luay Jalil
Verizon
Richardson, Texas
United States of America
Email: luay.jalil@one.verizon.com
Bonica, et al. Expires 16 May 2022 [Page 16]