Internet DRAFT - draft-decraene-spring-srv6-vlsid
draft-decraene-spring-srv6-vlsid
Network Working Group B. Decraene
Internet-Draft Orange
Intended status: Standards Track R. Raszuk
Expires: 8 September 2022 NTT Network Innovations
Z. Li
C. Li
Huawei Technologies
7 March 2022
SRv6 vSID: Network Programming extension for variable length SIDs
draft-decraene-spring-srv6-vlsid-07
Abstract
This document proposes an extension to Segment Routing IPv6 (SRv6)
Network Programming to allow for SRv6 Segment Identifier (SID) of
smaller variable length. The use of smaller SRv6 SID reduces the
size the SRv6 Header (SRH). This reduces the overhead for both the
traffic volume and the network processor. It is a straightforward
extension to the SRv6 Network Programming model and its SRH
encapsulation.
Status of This Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on 8 September 2022.
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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.
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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. SRv6 Variable Length SIDs . . . . . . . . . . . . . . . . . . 4
3.1. Encoding vSIDs in the SRH . . . . . . . . . . . . . . . . 5
3.2. SRv6 vSIDs Network Programming . . . . . . . . . . . . . 7
4. Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . 7
5. Illustrations . . . . . . . . . . . . . . . . . . . . . . . . 8
5.1. Global vSIDs . . . . . . . . . . . . . . . . . . . . . . 8
5.2. Local vSIDs . . . . . . . . . . . . . . . . . . . . . . . 9
6. Optional extensions . . . . . . . . . . . . . . . . . . . . . 10
6.1. A node requiring a larger vSIDs length. . . . . . . . . . 10
6.2. Inter Routing Domains with the End.XvPS behavior . . . . 12
6.3. NSIDs flavor . . . . . . . . . . . . . . . . . . . . . . 13
7. Security Considerations . . . . . . . . . . . . . . . . . . . 14
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 14
9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 14
10. Changes / Authors Notes . . . . . . . . . . . . . . . . . . . 14
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 15
11.1. Normative References . . . . . . . . . . . . . . . . . . 15
11.2. Informative References . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17
1. Introduction
The Segment Routing (SR) architecture is defined RFC 8402 [RFC8402].
IPv6 Segment Routing Header (SRH) is defined RFC 8754 [RFC8754].
SRv6 Network Programming is defined RFC 8986 [RFC8986].
The reader is expected to be familiar with the three above documents
which define Segment Routing over the IPv6 data-plane (SRv6).
SRv6 is flexible and powerful, but in some uses cases, when a large
number of SIDs are required, the size of the SRH/SID may be seen as
too large both for some dataplane processors and traffic overhead.
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The goal of this document is to propose a solution which reduces the
size of the SRv6 header when a high number of SIDs is required with
minimal changes to the SRv6 architecture, signaling, SRH and data
plane processing.
This document extends SRH and SRv6 Network Programming to allow for
SIDs of variable length, from 1 up to 128 bits. In a way, this is a
generalization of SRv6 for any (v)SID length, where 128-bits SIDs is
a special case.
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 RFC 2119 [RFC2119] RFC 8174 [RFC8174] when, and only when, they
appear in all capitals, as shown here.
2. Overview
In a nutshell, SRv6 variable length SIDs (SRv6 vSIDs) proposes to:
* define one SRv6 SIDs prefix dedicated to SRv6 vSIDs and called
SRv6 vSIDs prefix;
* define the vSID as the SRv6 SID minus the vSIDs prefix: SRv6 SID:=
SRv6 vSIDs prefix + SRv6 vSID;
* encode, in the Segment List of the SRH, only the vSIDs.
In other words, 128-bits SRv6 SIDs are kept unchanged for signaling,
configuration and SR policies. In the data plane, this proposal
compresses the encoding of SRv6 SIDs in the SRH by not encoding the
SRv6 vSIDs prefixes which are redundant across vSIDs.
The use of the destination address in the IPv6 header is unchanged.
The IPv6 destination address still contains the current/next 128-bits
SRv6 SID. As a consequence, the IPv6 destination address already
indicates the SRv6 vSID prefix and there is no extend the SRH to
carry it.
In a way, this is similar to SR-MPLS RFC 8660 [RFC8660]:
* For SR-MPLS: SR-MPLS Label:= SRGB + Index
* For SRv6 vSID: SRv6 SID := SRv6 vSID prefix + SRv6 vSID
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One difference compared to SR-MPLS is that lowest bits of the SRv6
vSID prefix are zero which allows for an easier operation in the data
plane. Indeed,the addition of the vSID may be replaced by a copy of
the vSID bits. Another difference is that the motivation to offset
to a zero base index/vSID is different.
Except for the Segment List using (shorter) vSIDs, the format of the
SRH is unchanged. The length of the vSIDs is defined to be 128 bits
minus the length of the vSIDs prefix. It is variable but its length
does not need to be encoded in the SRH header. Indeed the vSIDs
length only needs to be known by the SR Segment Endpoint Node
processing it. As per section 4.3 of RFC 8754 [RFC8754], the SR node
identifies its local SID by performing a longest-prefix-match lookup
on the packet IPv6 destination address. This identifies the SID and
its properties, such as the SR endpoint behavior but also the length
of the vSIDs.
3. SRv6 Variable Length SIDs
An SRv6 vSID deployment choose one length 'L' of vSIDs and an
associated SRv6 vSIDs prefix.
0 (bits) vSIDs 128
Length
+--------------------------------------------------------------+
| SRv6 SID |
+--------------------------------------------------------------+
+--------------------------------------------------------------+
| SRv6 vSIDs prefix | vSID |
+--------------------------------------------------------------+
Figure 1: SRv6 SID:= SRv6 vSIDs prefix + SRv6 vSID
An SRv6 vSID deployment may use multiple SRv6 vSIDs prefixes. Each
prefix may have its own vSIDs length.
As per section 3.1 of RFC 8986 [RFC8986], an SRv6 SID can be
represented as 'B:N:FUNCT:ARG'. Where 'B' is the SRv6 SID prefix, N
is the identifier of the parent node N, FUNCT is the function of the
SID of length 128-S.
For SRv6 vSIDs, the SRv6 prefix is 'B' of length LB as advertised in
the SRv6 SID Structure Sub-Sub-TLV defined in
[I-D.ietf-lsr-isis-srv6-extensions]. The vSID length for vSIDs of
this block is computed as 128 - LB. The vSID includes 'N:FUNCT:ARG'.
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In order to simplify implementations, the length of the vSIDs MUST be
a multiple of 8-bits, up to 128 bits included, in order to provide
octet alignment in the SRH Segment List. However this specifications
is written to work for any bit granularity from 1 to 128 bits. This
allows for a future document to define a new profile with a higher
granularity (e.g. 1 bit, 4 bits, 16 bits, or an integer fraction
128-bits) depending on hardware capabilities and flexibility
requirements. To allow some implementations to be further
simplified, a specific profile 'Profile-32' is created restricting
the vSID length to be 32-bits.
3.1. Encoding vSIDs in the SRH
As per section 2 of RFC 8754 [RFC8754], the Segment Routing Header
(SRH) is defined as follows:
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Last Entry | Flags | Tag |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Segment List[0] (128 bits IPv6 address) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| |
...
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Segment List[n] (128 bits IPv6 address) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// //
// Optional Type Length Value objects (variable) //
// //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: SRH with 128-bits SRv6 SID
When vSIDs are used, there are encoded in the Segment List of the
Segment Routing Header (SRH).
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vSIDs are encoded back to back using their native length. There is
no padding between SIDs and there is no specific alignment of the
SID.
In a SRH, all vSIDs MUST have the same vSIDs length 'L' and the same
SRv6 vSIDs prefix.
If the Segment List[n] does not end on a octet boundary, then padding
bits MUST be added up to the next octet boundary. Those padding bits
MUST be set to 0 when sent and ignored on receipt.
TLVs starts on next octet boundary.
As defined in RFC 8754 [RFC8754], padding TLVs are used to pad the
SRH to a multiple of 8 octets. As vSIDs may be of any size, not
necessarily a multiple of 8 octets, the support of padding TLVs are
REQUIRED.
The fields 'Segments Left' and 'Last Entry" keep their meaning but
refers to vSIDs of length L.
The following diagram illustrates an example of SRH with vSIDs of
sixteen bits:
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Last Entry | Flags | Tag |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment List[0] | Segment List[1] |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ..... ..... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment List[n] |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// //
// Optional Type Length Value objects (variable) //
// //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: SRH with SRv6 vSIDs with 16-bits vSIDs
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3.2. SRv6 vSIDs Network Programming
This section defines a flavor for Endpoint behaviors. It defined
below using the "End" Endpoint behavior but is applicable to all SID
behaviors.
The processing takes as an argument the length L of the vSIDs. This
length L is a property of the vSID and is given as a result of the
lookup on the IPv6 destination address which identifies the SRv6 SID
and its properties. The properties include the Endpoint behavior and
the length L of the vSIDs.
When N receives a packet whose IPv6 DA is S and S is a local vSID of
length L, the lines S08 and S14 of the End processing which were, as
per section 4.1 of RFC 8986 [RFC8986]:
S08. max_LE = (Hdr Ext Len / 2) - 1
[...]
S14. Update IPv6 DA with Segment List[Segments Left]
are replaced by the following:
S08. max_LE = (Hdr Ext Len * 64 / L) - 1
[...]
S14. Copy Segment List[Segments Left] from the SRH to the L lowest
order bits of the destination address of the IPv6 header.
Note: S14. Taking into consideration that the Segment List is a list
of vSIDs of length L bits
4. Benefits
SRv6 vSID is believed to have the following benefits:
* Aligned with SRv6: SR architecture, SRv6 Network Programming.
* Reduced SID hence reduced header length.
* Flexible SID length, to accommodate for various deployment models,
network sizes, SRv6 usages.
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- A typical vSIDs length could be 32 bits. Compared to SR-MPLS
(which has a 20 bits SID) it is larger and more scalable.
Compared to SRv6 (which has a 128 bits SID) it's four times
more compact.
- Other SID length are possible: 16 bits would be 8 times more
compact than SRv6 SID and 2 times more compact the SR-MPLS shim
header and large enough for most deployments; 8 bits would be
16 (respectively 4) more compact than SRv6 SID (respectively
SR-MPLS shim header) and could fit some specific deployments
(e.g. local adjacency SID only).
* Using SRv6 header (SRH) with no additional fields.
* No requirement for additional IPv6 addressing space: a /64 per
router is more than enough. A /96 per router is the typical
requirement.
5. Illustrations
This section illustrates the usage of SRv6 vSIDs through two
examples. The first example uses global segments with a vSIDs
locator been globally routable. The second example uses local
segments only with a vSIDs locator commom to all SR end nodes hence
not been able to locate a specific SR end node. Global and local
segments are defined as per RFC 8402 [RFC8402] section 2.
5.1. Global vSIDs
In this example vSIDs are used for global SIDs and are used alone
without 128-bits SRv6 SIDs.
The SR domain has the following characteristics:
* 1 000 SR endpoints nodes;
* network diameter is 10;
* vSIDs are chosen to be 32-bits long;
* each SRv6 node is allocated a /108 to allocate its vSIDs from.
This allows for 4 096 (2^^12) locators 1 million (2^^20) local
functions on each SR node;
* the SR domain and the SRv6 vSIDs prefix is allocated:
2001:DB8::/96;
* node N is allocated 2001:DB8:0:0:0:0:N/108;
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Some metrics of this SR domain:
* An SR policy encoding a strictly routed path using only Adjacency
SIDs would need ten 32-bits vSIDs resulting in a total of 40
octets in the SRH. In contrast the use of 128-bits SRv6 SIDs
would require 160 octets;
* An SR policy using strictly routed path using four (node) SIDs
would need four 32-bits vSIDs resulting in a total of 16 octets in
the SRH. In contrast the use of 128-bits SRv6 SIDs would require
64 octets and the use of 20-bits SR-MPLS SID would require 16
octets;
* The IGP advertises 1 000 SRv6 locators to be installed in the IPv6
FIB of all IGP nodes (as per regular SRv6 and SR-MPLS);
* The IPv6 address space is one /108 per SR node for a total of one
/96 for the whole SR domain.
5.2. Local vSIDs
If SRv6 vSIDs only identifies local segments, with no needs for
global segments, there is no need for a global route toward a node
hence the 'N' may have a size of zero. This may be interesting for a
deployment using both 128-bits SRv6 SIDs and very short SRv6 vSIDs.
Such SRv6 vSIDs could be used when a strictly routed path is needed
and encoded as a list of adjacency SIDs. Given that the number of
local adjacency SIDs is independent of the size of the SR domain, and
typically below 255, one could use 8-bits vSIDs which would allow
encoding 16 vSIDs within a single 128-bits SRv6 SID hence provides a
very effective SRH compression.
In this example vSIDs are used only for local SIDs, such as adjacency
SIDs. vSIDs are used in complement with 128-bits SRv6 SIDs.
The SR domain has the following caracteristics:
* 10 000 SR endpoints nodes;
* network diameter is 30;
* SRv6 SIDs:
- each SRv6 node is allocated a /64 to allocate its 128-bits SIDs
from;
- SRv6 prefix: 2001:DB8::/48 (i.e., 65535 /64, allowing for
growth or multiple SR routing algorithms);
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- node N is allocated 2001:DB8:0:N/64;
* SRv6 vSIDs
- local vSIDs are chosen to be 8-bits in length. They are used
for adjacency SIDs hence allow for 255 Adjacency SIDs per node;
- SRv6 vSIDs prefix is allocated 2001:DB8:0:FFFF::/120;
Some metrics of this SR domain:
* An SR policy encoding a strictly routed path using only adjacency
SIDs would need thirty 8-bits vSIDs resulting in a total of 32
octets in the SRH. In contrast the use of 128-bits SRv6 SIDs
would require 480 octets and the use of 20-bits SR-MPLS SID would
require 120 octets;
* The IGP advertises 10 000 SRv6 locators to be installed in the
IPv6 FIB of all IGP nodes (as per regular SRv6 or SR-MPLS);
* The IPv6 address space is one /64 per SR node for a total of one
/48 for the whole SR domain.
6. Optional extensions
6.1. A node requiring a larger vSIDs length.
One SR Endpoint node may need a larger vSIDs space. This may
especially be the case when at the same time:
* the vSIDs Length is chosen to be small in order to optimize for
the size of the SRH header. Indeed, for topological/routing
instructions, the number of SIDs in the SRH may be high in some
use cases, up to the network diameter, calling for small vSIDs.
* one vSID is a service instruction and the number of service SIDs
may be high, requiring a SID longer than a vSIDs Length.
This section defines two solutions to increase the vSIDs length on a
node requiring a vSIDs space larger than other nodes.
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6.1.1. Allocating a shorter locator to a node.
In order to increase the vSIDs length on a node, a simple option is
to allocate multiple locators of a larger locator to this node,
within the SRv6 vSIDs prefix. As per RFC 8986 [RFC8986], a locator
may be represented as B:N where B is the SRv6 SID block (IPv6 subnet
allocated for SRv6 SIDs by the operator) and N is the identifier of
the parent node instantiating the SID. Following this format,
multiple node identifiers Ns may be allocated to a node. Allocating
'k' identifiers increase the vSIDs space of that node by 'k'.
6.1.2. Combining k vSIDs to identify a behavior.
When an SR Endpoint node needs more SIDs than allowed by the vSIDs
Length, it MAY combine two (resp. N) vSIDs of length L to
effectively benefit from a vSID of length 2*L (resp. N*L). This is
a local choice of this SR Endpoint. Nothing specific is required in
the SRH which only contains those 2 (resp. N) SIDs instead of a
single one.
Note that when two vSIDs are combined, the first vSID may be seen as
having the role of a "Context SID" identifying a context specific SID
space/table, with the second SID been looked up in this context
specific table. This is similar to the Context-Specific Label space
defined in the section 3 of RFC 5331 [RFC5331].
This section defines the extension to SRv6 Network Programming
allowing for a SID behavior "End.DT6" to be encoded with 'k' vSID.
This is equally applicable to others SID behaviors.
The processing takes as an argument the vSIDs length 'L', and the
number of vSIDs 'k'. 'L' and 'k' are a property of the vSID and are
given as a result of the lookup of the IPv6 destination address which
identifies the SRv6 SID and its properties. The properties include
the Endpoint behavior, the length L of the vSIDs and the number 'k'
of vSIDs used to encode this behavior in the SRH.
When N receives a packet destined to S and S is a local End.DT6 SID
encoded with 'k' vSIDs, N does the following processing:
When N receives a packet whose IPv6 DA is S and S is a local End.DT6
vSID of length L and encoded with 'k' vSIDs the line S02 of the
End.DT6 processing which was, as per section 4.6 of RFC 8986
[RFC8986]:
S02. If (Segments Left != 0) {
is replaced by the following:
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S02. If (Segments Left != k - 1) {
When processing the Upper-layer header of a packet, the lines S04-S05
which were:
S04. Remove the outer IPv6 Header with all its extension headers
S05. Set the packet's associated FIB table to T
are replaced by the following:
S04a. Read the k-1 next vSIDs
S04b. Remove the outer IPv6 Header with all its extension headers
S05. Set the packet's associated FIB table to the one identified by
the concatenation of the k-1 next vSIDs
6.2. Inter Routing Domains with the End.XvPS behavior
Some SRv6 traffic may need to cross multiple routing domains, such as
differents Autonomous Systems (ASes) or different routing areas.
Different routing domains may use different addressing schema making
it difficult to find a common SRv6 vSIDs prefix.
This section defines an optional solution and SID behavior allowing
for the use of different SRv6 vSIDs prefixes between routing domains.
The solution requires a new SID behavior, called "Endpoint with
cross-connect to an array of layer-3 adjacencies and SRv6 vSIDs
Prefix Swap" (End.XvPS for short) allowing for this transition of
SRv6 vSIDs prefix between two routing domains.
End.XvPS is a variant of End.X, performing both "End.X Layer-3 Cross-
Connect" and the translation of the SRv6 vSIDs prefix between the two
routing domains.
The processing takes as an argument the vSIDs length L and the prefix
P2 of the SRv6 vSIDs prefix in the second domain. Those two
parameters are a property of the (received) vSID and are given as a
result of the lookup on the IPv6 destination address which identifies
the SRv6 SID and its properties.
When N receives a packet whose IPv6 DA is S and S is a End.XvPS SID
behavior, with a local vSID length L, and a remote/next SRv6 vSIDs
prefix P2, the line S14 of the End processing which was, as per
section 4.1 of RFC 8986 [RFC8986]:
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S14. Update IPv6 DA with Segment List[Segments Left]
is replaced by the following:
S14. Copy Segment List[Segments Left] from the SRH to the L lowest
order bits of the destination address of the IPv6 header and copy the
SRv6 vSIDs prefix P2 to the 128-L highest order bits of the
destination address.
Note: the way the SRv6 vSIDs prefix P2 of the next routing domain is
known is out of scope of this document. As examples, they could be
learnt via configuration or using a signaling protocol either with
the peer domain of with a central controler (e.g. PCE).
When End.XvPS SID behavior is used, the restriction on the SRH is
relaxed and becomes: in a SRH, all vSID MUST have the same vSID
length 'L' and within a routing domain, the same SRv6 vSID
prefix.Between routing domaines, separated with the End.XvPS
behavior, SRv6 vSID prefixes may be different.
6.3. NSIDs flavor
The NSIDs flavors is a variant of the End, End.X and End.XvPS
behaviors.
The NSIDs flavors copy N vVSID from the SRH to the IPv6 destination
address.
When N receives a packet whose IPv6 DA is S and S is a NSIDs flavor,
with a local vSID length L, and a local paramater N, the lines S09,
S13 and S14 of the End processing which was, as per section 4.1 of
RFC 8986 [RFC8986]:
S09. If ((Last Entry > max_LE) or (Segments Left > Last Entry+1)) {
S13. Decrement Segments Left by 1
S14. Update IPv6 DA with Segment List[Segments Left]
are replaced by the following:
S09. If ((Last Entry > max_LE) or (Segments Left > Last Entry+1)) or
(Segments Left < = N){
S13. Decrement Segments Left by N
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S14. Copy N Segments List[Segments Left+N-1]...List[Segments Left]
from the SRH to the N*L lowest order bits of the destination address
of the IPv6 header.
Note that if N=128/L, a complete IPv6 address is copied. This is
useful when the next SR node is an SRv6 PE requiring its 128-bits
SIDs in the IPv6 destination address. This is also useful for inter
domain scenarios where both domains use unrelated address spaces and
hence use two different SRv6 vSIDs prefixes.
7. Security Considerations
This document does not change the security considerations of SRv6.
Please refers to RFC 8402 [RFC8402], RFC 8754 [RFC8754] and RFC 8986
[RFC8986] for existing security consideration.
8. Acknowledgements
This document has been inspired by the work of the SPRING WG and in
particular the work done in
[I-D.filsfils-spring-net-pgm-extension-srv6-usid] and
[I-D.li-spring-compressed-srv6-np]. The authors would like to
acknowledge the authors of these two documents.
The authors would like to thank Joel Halpern and Francois Clad for
their review and comments.
9. Contributors
Daniel Voyer
Bell Canada
Canada
Email: daniel.voyer@bell.ca
10. Changes / Authors Notes
[RFC Editor: Please remove this section before publication]
00: Initial version.
01:
* Removal of the vSID Size TLV; addition of the IS-IS extension;
addition of the SR header length check in the pseudo code.
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* Addition of the IS-IS extension;
* Addition of the SR header length check in the pseudo code.
02:
* Change of terminology (VLSID changed to vSID);
* Swapping the two examples in section 'Illustrations'.;
* Addition of two solutions to provide more vSID space to some nodes
in section 'Node requiring a larger vSID length';
* Addition of a solution for crossing routing domains using
different SRv6 vSID prefixes and/or different vSID length;
03:
* Minor updates in section 'Inter Routing Domains'
04:
* Creating of a profile only supporting vSID of length 32-bits.
* Addition of the NSIDs flavor.
05:
* Editorial changes.
* Removal of the IGP signaling extension. The size of the SRv6
block is advertised in the existing SRv6 SID Structure Sub-Sub-
TLV.
06-07: refresh.
11. References
11.1. Normative References
[I-D.ietf-lsr-isis-srv6-extensions]
Psenak, P., Filsfils, C., Bashandy, A., Decraene, B., and
Z. Hu, "IS-IS Extensions to Support Segment Routing over
IPv6 Dataplane", Work in Progress, Internet-Draft, draft-
ietf-lsr-isis-srv6-extensions-18, 20 October 2021,
<https://www.ietf.org/archive/id/draft-ietf-lsr-isis-srv6-
extensions-18.txt>.
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[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>.
[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>.
[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/info/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/info/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/info/rfc8986>.
11.2. Informative References
[I-D.filsfils-spring-net-pgm-extension-srv6-usid]
Filsfils, C., Garvia, P. C., Cai, D., Voyer, D., Meilik,
I., Patel, K., Henderickx, W., Jonnalagadda, P., Melman,
D., Liu, Y., and J. Guichard, "Network Programming
extension: SRv6 uSID instruction", Work in Progress,
Internet-Draft, draft-filsfils-spring-net-pgm-extension-
srv6-usid-12, 13 December 2021,
<https://www.ietf.org/archive/id/draft-filsfils-spring-
net-pgm-extension-srv6-usid-12.txt>.
[I-D.li-spring-compressed-srv6-np]
Li, Z., Li, C., Xie, C., LEE, K., Tian, H., Zhao, F.,
Guichard, J. N., Li, C., and S. Peng, "Compressed SRv6
Network Programming", Work in Progress, Internet-Draft,
draft-li-spring-compressed-srv6-np-02, 25 February 2020,
<https://www.ietf.org/archive/id/draft-li-spring-
compressed-srv6-np-02.txt>.
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[RFC5331] Aggarwal, R., Rekhter, Y., and E. Rosen, "MPLS Upstream
Label Assignment and Context-Specific Label Space",
RFC 5331, DOI 10.17487/RFC5331, August 2008,
<https://www.rfc-editor.org/info/rfc5331>.
[RFC8660] Bashandy, A., Ed., Filsfils, C., Ed., Previdi, S.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing with the MPLS Data Plane", RFC 8660,
DOI 10.17487/RFC8660, December 2019,
<https://www.rfc-editor.org/info/rfc8660>.
Authors' Addresses
Bruno Decraene
Orange
Email: bruno.decraene@orange.com
Robert Raszuk
NTT Network Innovations
940 Stewart Dr
Sunnyvale, CA 94085
United States of America
Email: robert@raszuk.net
Zhenbin Li
Huawei Technologies
Email: lizhenbin@huawei.com
Cheng Li
Huawei Technologies
Email: chengli13@huawei.com
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