Internet DRAFT - draft-peng-lsr-isis-network-slicing-srv6
draft-peng-lsr-isis-network-slicing-srv6
LSR Shaofu. Peng
Internet-Draft Ran. Chen
Intended status: Standards Track Gregory. Mirsky
Expires: July 25, 2020 ZTE Corporation
January 22, 2020
ISIS Extension to Support Network Slicing over IPv6 Dataplane
draft-peng-lsr-isis-network-slicing-srv6-00
Abstract
[I-D.peng-teas-network-slicing] defines an unified TN-slice
identifier, i.e., AII(administrative instance identifier) and related
processing combined with Segment Routing technology, for the purpose
of unified identification of topology, computing, storage resources,
unified partition of L2 and L3 link resources, unified basis of
underlay path selection within or between domains, and unified flow
steering rule with SR policy color scheme. This document describes
the ISIS extensions required to support Packet Network Slicing over
IPv6 dataplane.
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Advertising SRv6 Capabilities and Maximum SID Depths . . . . 3
3. Advertising Participated TN-slice . . . . . . . . . . . . . . 3
4. TN-slice specific SRv6 SIDs and Reachability . . . . . . . . 3
5. Advertising Anycast Property . . . . . . . . . . . . . . . . 4
6. Advertising Locators and End SIDs for specific TN-slice . . . 4
6.1. SRv6 Locator per TN-slice TLV Format . . . . . . . . . . 4
6.2. SRv6 End SID for specific TN-slice . . . . . . . . . . . 6
7. Advertising SRv6 Adjacency SIDs for specific TN-slice . . . . 6
7.1. SRv6 End.X SID per TN-slice sub-TLV . . . . . . . . . . . 7
7.2. SRv6 LAN End.X SID per TN-slice sub-TLV . . . . . . . . . 8
8. SRv6 SID Structure Indication . . . . . . . . . . . . . . . . 10
9. Advertising Endpoint Behaviors . . . . . . . . . . . . . . . 10
10. Security Considerations . . . . . . . . . . . . . . . . . . . 10
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
12.1. SRv6 Locator per TN-slice TLV . . . . . . . . . . . . . 10
12.2. SRv6 End.X SID per TN-slice and SRv6 LAN End.X SID per
TN-slice sub-TLVs . . . . . . . . . . . . . . . . . . . 11
13. Normative References . . . . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12
1. Introduction
For a packet network, network slicing requires the underlying network
to support partitioning of the network resources to provide the
client with dedicated (private) networking, computing, and storage
resources drawn from a shared pool. [I-D.peng-teas-network-slicing]
defines an unified TN-slice identifier, i.e., AII(administrative
instance identifier) and related processing combined with Segment
Routing technology, for the purpose of unified identification of
topology, computing, storage resources, unified partition of L2 and
L3 link resources, unified basis of underlay path selection within or
between domains, and unified flow steering rule with SR policy color
scheme.
[I-D.zch-lsr-isis-network-slicing] describes the ISIS extensions
required to support Packet Network Slicing over SR-MPLS dataplane.
This document continues to describe the ISIS extensions required to
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support Packet Network Slicing over IPv6 dataplane, it will
supplement on the basis of [I-D.ietf-lsr-isis-srv6-extensions].
For SRv6 case, IPv6 address resource is directly used to represent
SID, so that different IPv6 block could be allocated to different TN-
slice. There are two possible ways to advertise TN-slice specfic
IPv6 block:
o Traditional prefix reachability, for default AII (0) specific IPv6
block.
o New SRv6 Locator per TN-slice advertisement, for nonzero TN-slice
specific IPv6 block.
2. Advertising SRv6 Capabilities and Maximum SID Depths
SRv6 capable router can advertise the SRv6 Capabilities sub-TLV and
Maximum SRv6 SID Depths (MSD) as defined in
[I-D.ietf-lsr-isis-srv6-extensions].
3. Advertising Participated TN-slice
SRv6 capable router indicates participated TN-slice by advertising
the TN-slice identifier Participation sub-TLV as defined in
[I-D.zch-lsr-isis-network-slicing].
4. TN-slice specific SRv6 SIDs and Reachability
A node is provisioned with TN-slice specific locators for each of the
TN-slice identified by AII participated by that node. Each locator
is a covering prefix for all SIDs provisioned on that node which have
the matching AII.
Locators MUST be advertised in the SRv6 Locator per TN-slice TLV (see
Section 6.1). Forwarding entries for the locators advertised in the
SRv6 Locator per TN-slice TLV MUST be installed in the forwarding
plane of receiving SRv6 capable routers when the associated AII is
supported by the receiving node.
Locators are routable and MAY also be advertised in Prefix
Reachability TLVs (236 or 237). But locators associated with non
default AII SHOULD NOT be advertised in Prefix Reachability TLVs (236
or 237).
Locators associated with default AII (0) SHOULD be advertised in a
Prefix Reachability TLV (236 or 237) so that legacy routers (i.e.,
routers which do NOT support SRv6) will install a forwarding entry
for default AII (0) SRv6 traffic.
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In cases where a locator advertisement is received in both in a
Prefix Reachability TLV and an SRv6 Locator per TN-slice TLV, the
Prefix Reachability advertisement MUST be preferred when installing
entries in the forwarding plane. This is to prevent inconsistent
forwarding entries on SRv6 capable/SRv6 incapable routers.
TN-slice specific SRv6 SIDs are advertised as sub-TLVs in the SRv6
Locator per TN-slice TLV except for TN-slice specific SRv6 End.X
SIDs/LAN End.X SIDs which are associated with a specific Neighbor/
Link and are therefore advertised as sub-TLVs in TLVs 22, 23, 222,
223, and 141.
TN-slice specific SRv6 SIDs are not directly routable and MUST NOT be
installed in the forwarding plane. Reachability to TN-slice specific
SRv6 SIDs depends upon the existence of a covering TN-slice specific
locator.
Adherence to the rules defined in this section will assure that TN-
slice specific SRv6 SIDs associated with a supported AII will be
forwarded correctly, while SRv6 SIDs associated with an unsupported
AII will be dropped. NOTE: The drop behavior depends on the absence
of a default/summary route covering a given locator.
5. Advertising Anycast Property
The same prefix/SRv6 Locator can be advertised by multiple routers.
See A-flag defined in [I-D.ietf-lsr-isis-srv6-extensions] to
advertise the anycast property.
6. Advertising Locators and End SIDs for specific TN-slice
The SRv6 Locator per TN-slice TLV is introduced to advertise SRv6
Locators and End SIDs associated with each locator for specific TN-
slice.
This new TLV shares the sub-TLV space defined for TLVs 135, 235, 236
and 237.
6.1. SRv6 Locator per TN-slice TLV Format
The SRv6 Locator per TN-slice TLV has the following format:
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
SRv6 Locator per TN-slice format
Followed by one or more locator entries of the form:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metric |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | AII ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... AII | Loc Size | Locator (variable)...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sub-tlv-len | Sub-TLVs (variable) . . . |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
SRv6 Locator entry per TN-slice format
Type: TBA1
Length: variable.
Locator entry:
Metric: 4 octets. As described in [RFC5305].
Flags: 1 octet. The following flags are defined
0
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|D| Reserved |
+-+-+-+-+-+-+-+-+
where:
D bit: When the Locator is leaked from level-2 to level-1, the D bit
MUST be set. Otherwise, this bit MUST be clear. Locators with the D
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bit set MUST NOT be leaked from level-1 to level-2. This is to
prevent looping.
The remaining bits are reserved for future use. They SHOULD be set
to zero on transmission and MUST be ignored on receipt.
AII: 4 octet. Administrative Instance Identifier, As defined in
[I-D.peng-teas-network-slicing], represented as the TN-slice
Identifier.
Loc-Size: 1 octet. Number of bits in the Locator field. (1 - 128)
Locator: 1-16 octets. This field encodes the advertised SRv6
Locator. The Locator is encoded in the minimal number of octets for
the given number of bits.
Sub-TLV-length: 1 octet. Number of octets used by sub-TLVs
Optional sub-TLVs.
6.2. SRv6 End SID for specific TN-slice
The SRv6 End SID sub-TLV defined in
[I-D.ietf-lsr-isis-srv6-extensions] can be reused in this document to
advertise TN-slice specific SRv6 Segment Identifiers (SID) with
Endpoint behaviors.
The SRv6 End SID sub-TLV is advertised in the SRv6 Locator per TN-
slice TLV defined in the previous section. SRv6 End SIDs inherit the
AII from the parent locator.
The SRv6 End SID MUST be a subnet of the associated Locator. SRv6
End SIDs which are NOT a subnet of the associated locator MUST be
ignored.
Multiple SRv6 End SIDs MAY be associated with the same locator. In
cases where the number of SRv6 End SID sub-TLVs exceeds the capacity
of a single TLV, multiple Locator per TN-slice TLVs for the same TN-
slice specific locator MAY be advertised. For a given AII/Locator
the AII value MUST be the same in all TLVs. If this restriction is
not met all TLVs for that AII/Locator MUST be ignored.
7. Advertising SRv6 Adjacency SIDs for specific TN-slice
This document defines two new sub-TLVs of TLV 22, 23, 222, 223, and
141 - namely "SRv6 End.X SID per TN-slice" and "SRv6 LAN End.X SID
per TN-slice".
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All End.X SIDs for specific TN-slice MUST be a subnet of a Locator
with matching AII which is advertised by the same node in an SRv6
Locator per TN-slice TLV. End.X SIDs which do not meet this
requirement MUST be ignored.
7.1. SRv6 End.X SID per TN-slice sub-TLV
This sub-TLV is used to advertise a TN-slice specific SRv6 SID
associated with a point to point adjacency. Multiple SRv6 End.X SID
per TN-slice sub-TLVs MAY be associated with the same adjacency.
The SRv6 End.X SID per TN-slice sub-TLV has the following format:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Flags | Weight |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AII |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Endpoint Behavior |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SID (128 bits) . . . |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SID (cont . . .) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SID (cont . . .) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SID (cont . . .) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Sub-sub-tlv-len| Sub-sub-TLVs (variable) . . . |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
SRv6 End.X SID per TN-slice format
Type: TBA2
Length: variable.
Flags: 1 octet.
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|B|S|P|Reserved |
+-+-+-+-+-+-+-+-+
where:
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B-Flag: Backup flag. If set, the End.X SID is eligible for
protection (e.g., using IPFRR) as described in [RFC8355].
S-Flag. Set flag. When set, the S-Flag indicates that the End.X SID
refers to a set of adjacencies (and therefore MAY be assigned to
other adjacencies as well).
P-Flag. Persistent flag. When set, the P-Flag indicates that the
End.X SID is persistently allocated, i.e., the End.X SID value
remains consistent across router restart and/or interface flap.
Other bits: MUST be zero when originated and ignored when received.
Weight: 1 octet. The value represents the weight of the End.X SID
for the purpose of load balancing. The use of the weight is defined
in [RFC8402].
AII: 4 octet. Administrative Instance Identifier, As defined in
[I-D.peng-teas-network-slicing], represented as TN-slice Identifier.
Endpoint Behavior: 2 octets. As defined in
[I-D.ietf-spring-srv6-network-programming]. Legal behavior values
for this sub-TLV are defined in Section 8.
SID: 16 octets. This field encodes the advertised SRv6 SID.
Sub-sub-TLV-length: 1 octet. Number of octets used by sub-sub-TLVs
Note that multiple TLVs for the same neighbor may be required in
order to advertise all of the SRv6 End.X SIDs associated with that
neighbor.
7.2. SRv6 LAN End.X SID per TN-slice sub-TLV
This sub-TLV is used to advertise a TN-slice specific SRv6 SID
associated with a LAN adjacency. Since the parent TLV is advertising
an adjacency to the Designated Intermediate System(DIS) for the LAN,
it is necessary to include the System ID of the physical neighbor on
the LAN with which the SRv6 SID is associated. Given that a large
number of neighbors may exist on a given LAN a large number of SRv6
LAN END.X SID per TN-slice sub-TLVs may be associated with the same
LAN. Note that multiple TLVs for the same DIS neighbor may be
required in order to advertise all of the TN-slice specific SRv6
End.X SIDs associated with that neighbor.
The SRv6 LAN End.X SID per TN-slice sub-TLV has the following format:
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | System ID (6 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | Weight | AII ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... AII | Endpoint Behavior |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SID (128 bits) . . . |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SID (cont . . .) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SID (cont . . .) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SID (cont . . .) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Sub-sub-tlv-len| sub-sub-TLVs (variable) . . . |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
SRv6 LAN End.X SID per TN-slice format
Type: TBA3
Length: variable.
System-ID: 6 octets of IS-IS System-ID of length "ID Length" as
defined in [ISO10589].
Flags: 1 octet.
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|B|S|P|Reserved |
+-+-+-+-+-+-+-+-+
where B,S, and P flags are as described in Section 7.1. Other bits:
MUST be zero when originated and ignored when received.
Weight: 1 octet. The value represents the weight of the End.X SID
for the purpose of load balancing. The use of the weight is defined
in [RFC8402].
AII: 4 octet. Administrative Instance Identifier, As defined in
[I-D.peng-teas-network-slicing], represented as TN-slice Identifier.
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Endpoint Behavior: 2 octets. As defined in
[I-D.ietf-spring-srv6-network-programming]. Legal behavior values
for this sub-TLV are defined in Section 8.
SID: 16 octets. This field encodes the advertised SRv6 SID.
Sub-sub-TLV-length: 1 octet. Number of octets used by sub-sub-TLVs.
8. SRv6 SID Structure Indication
The SRv6 SID Structure Sub-Sub-TLV defined in
[I-D.ietf-lsr-isis-srv6-extensions] can be reused in this document to
indicate the SRv6 SID Structure information. The SRv6 SID Structure
Sub-Sub-TLV could be an optional Sub-Sub-TLV of:
SRv6 End SID Sub-TLV (Section 6.2)
SRv6 End.X SID per TN-slice Sub-TLV (Section 7.1)
SRv6 LAN End.X SID per TN-slice Sub-TLV (Section 7.2)
9. Advertising Endpoint Behaviors
The Endpoint behaviors and their codepoints, which MAY be advertised
by IS-IS and the SID sub-TLVs in which each type MAY Appear, are
consistent with that in [I-D.ietf-lsr-isis-srv6-extensions].
10. Security Considerations
Security concerns for IS-IS are addressed in [ISO10589], [RFC5304],
and [RFC5310].
11. Acknowledgements
TBD
12. IANA Considerations
This document requests allocation for the following TLVs and sub-
TLVs in the ISIS TLV registry.
12.1. SRv6 Locator per TN-slice TLV
This document adds one new TLV to the IS-IS TLV Codepoints registry.
Value: TBA1
Name: SRv6 Locator for specific TN-slice
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12.2. SRv6 End.X SID per TN-slice and SRv6 LAN End.X SID per TN-slice
sub-TLVs
This document adds the definition of two new sub-TLVs in the "sub-
TLVs for TLV 22, 23, 25, 141, 222 and 223 registry".
Type: TBA2
Description: SRv6 End.X SID per TN-slice
Type: TBA3
Description: SRv6 LAN End.X SID per TN-slice
13. Normative References
[I-D.ietf-lsr-isis-srv6-extensions]
Psenak, P., Filsfils, C., Bashandy, A., Decraene, B., and
Z. Hu, "IS-IS Extension to Support Segment Routing over
IPv6 Dataplane", draft-ietf-lsr-isis-srv6-extensions-04
(work in progress), January 2020.
[I-D.ietf-spring-srv6-network-programming]
Filsfils, C., Camarillo, P., Leddy, J., Voyer, D.,
Matsushima, S., and Z. Li, "SRv6 Network Programming",
draft-ietf-spring-srv6-network-programming-08 (work in
progress), January 2020.
[I-D.peng-teas-network-slicing]
Peng, S., Chen, R., Mirsky, G., and F. Qin, "Packet
Network Slicing using Segment Routing", draft-peng-teas-
network-slicing-02 (work in progress), December 2019.
[I-D.zch-lsr-isis-network-slicing]
Zhu, Y., Chen, R., Peng, S., and F. Qin, "IS-IS Extensions
to Support Packet Network Slicing using Segment Routing",
draft-zch-lsr-isis-network-slicing-03 (work in progress),
December 2019.
[RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic
Engineering", RFC 5305, DOI 10.17487/RFC5305, October
2008, <https://www.rfc-editor.org/info/rfc5305>.
[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>.
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Authors' Addresses
Shaofu Peng
ZTE Corporation
Email: peng.shaofu@zte.com.cn
Ran Chen
ZTE Corporation
Email: chen.ran@zte.com.cn
Gregory Mirsky
ZTE Corporation
Email: gregimirsky@gmail.com
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