L R. chen
Internet-Draft Sh. Peng
Intended status: Standards Track ZTE Corporation
Expires: March 6, 2021 September 2, 2020
BGP-LS Extensions for Transport Slice
draft-chen-idr-bgp-ls-transport-slice-02
Abstract
[I-D.peng-teas-network-slicing] defines a unified TN-slice
identifier, AII(administrative instance identifier), to indicate the
topology, computing, storage resources of the dedicated virtual
network for both intra-domain and inter-domain network slicing
scenarios. This draft defines extensions to BGP-LS protocol in order
to advertise the information of the transport slice.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on March 6, 2021.
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
3. BGP-LS Extensions for transport slice . . . . . . . . . . . . 3
3.1. Node Attribute TLVs . . . . . . . . . . . . . . . . . . . 3
3.1.1. TN-slice identifier Participation TLV . . . . . . . . 3
3.2. Link Attribute TLVs . . . . . . . . . . . . . . . . . . . 4
3.2.1. TN-slice Identifier list sub-TLV . . . . . . . . . . 4
3.2.2. L2 Bundle Member TN-Slice Identifier TLV . . . . . . 5
3.2.3. Adjacency-SID for TN-slice Identifier TLV . . . . . . 5
3.2.4. LAN-Adj-SID for TN-slice Identifier TLV . . . . . . . 6
3.3. Prefix Attribute TLVs . . . . . . . . . . . . . . . . . . 7
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9
6. Normative References . . . . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
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 a unified TN-slice identifier, AII(administrative instance
identifier), to indicate the topology, computing, storage resources
of the dedicated virtual network for both intra-domain and inter-
domain network slicing scenarios, and how to compute SR-BE or SR-TE
path according to TN-slice Identifier combined with other criteria.
[I-D.zch-lsr-isis-network-slicing] defines the IS-IS extensions
required to distribute TN-slice Identifier(that is AII) information
in an AS.
In order to satisfy the need for applications that require
topological visibility across one area or Autonomous System (AS).
This document specifies extensions to the BGP Link-state address-
family in order to advertise TN-slice specific information. An
external component (e.g., a controller) then can collect TN-slice
information in the "northbound" direction.
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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. BGP-LS Extensions for transport slice
BGP-LS [RFC7752] defines the link-state NLRI that can be a Node NLRI,
a Link NLRI or a Prefix NLRI. The link-state information is mapped
to BGP link-state NLRI within the BGP-LS Attribute. In addition,
[I-D.ietf-idr-bgpls-inter-as-topology-ext] defines Stub Link NLRI
that is used to describe the inter-as link. This document adds
additional BGP-LS Attribute TLVs in order to encode TN-slice
information. It does not introduce any changes to the encoding of
the BGP-LS NLRIs.
3.1. Node Attribute TLVs
3.1.1. TN-slice identifier Participation TLV
The TN-slice identifier Participation TLV is used to advertise which
TN-slice a router wants to take part in. It is a new TLV of the
optional BGP-LS Attribute that is associated with the node NLRI.
This information is derived from TN-slice identifier Participation
sub-TLV of IS-IS (section 3 of [I-D.zch-lsr-isis-network-slicing].
The TN-slice identifier Participation 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 2
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=TBD1 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AII for virtual networks 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AII for virtual networks N |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: TN-slice identifier Participation TLV
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where:
Type: TBD1 (Suggested value to be assigned by IANA)
Length: variable.
AII for VN: allocate different TN-slice identifier (AII) for
different virtual networks. AII is used to distinguish different
virtual network resources. The node can join to multiple slices at
the same time.
3.2. Link Attribute TLVs
The following Link Attribute TLVs are defined:
+-------+---------------------------------------------+
| Type | Description |
+-------+---------------------------------------------+
| TBD2 | The TN-slice Identifier list TLV |
| TBD3 | L2 Bundle Member TN-Slice Identifier TLV |
| TBD4 | Adjacency-SID for TN-slice Identifier TLV |
| TBD5 | LAN-Adj-SID for TN-slice Identifier TLV |
+-------+---------------------------------------------+
Table 1:The new Link Attribute TLVs
These TLVs should only be added to the BGP-LS Attribute associated
with the Link NLRI or Stub Link NLRI.
3.2.1. TN-slice Identifier list sub-TLV
TN-slice Identifier can be used to color links and partition underlay
resource. This section is derived from TN-slice Identifier list sub-
TLV of IS-IS (section 4 of [I-D.zch-lsr-isis-network-slicing].)
The TN-slice Identifier list 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 2
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=TBD2 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AII for virtual networks 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AII for virtual networks N |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2
Type: TBD2 (Suggested value to be assigned by IANA)
Length: variable.
AII for VN: allocate different TN-slice identifier (AII) for
different virtual networks. AII is used to distinguish different
virtual network resources. The link can join to multiple slices at
the same time. The link can be configured to an IGP instance, or as
an inter-as link.
3.2.2. L2 Bundle Member TN-Slice Identifier TLV
This TLV is used to advertise TN-slice Identifier for L2 Bundle
Member associated with a parent L3 adjacency which is Point-to-Point.
This information is derived from TN-slice Identifier for L2 Bundle
Member sub-TLV of IS-IS (section 5 of
[I-D.zch-lsr-isis-network-slicing]). The following format is defined
for this sub-TLV:
Type: TBD3.
Length: variable
L2 Bundle Member TN-slice Identifier.There MUST be one TN-slice
Identifier(AII) for each of the L2 Bundle Members advertised under
the preceding L2 Bundle Member Attribute Descriptor. The parrent
link can be configured to an IGP instance, or as an inter-as link.
3.2.3. Adjacency-SID for TN-slice Identifier TLV
This TLV is used to distinguish forwarding behavior of different
virtual networks, Adjacency-SID need to be allocated per TN-slice
Identifier. This information is derived from TN-slice Identifier for
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Adjacency-SID for TN-slice Identifier sub-TLV of IS-IS (section 7 of
[I-D.zch-lsr-isis-network-slicing]).
The following format is defined for this sub-TLV:
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 2
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=TBD4 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | Weight | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AII |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SID/Index/Label(Variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3
where:
Type:TBD4(Suggested value to be assigned by IANA)
Length: Variable. Depending on the size of the SID.
Weight: Variable. 1 octet carrying the weight used for load-balancing
purposes. The use of weight is described in section 3.4 of
[RFC8402].
AII: Identifies the TN-slice (AII) information corresponding to the
Adjacency-SID.
The "Flags" and "SID/Index/Label" fields are the same as the
Adjacency-SID sub-TLV [RFC8667].
3.2.4. LAN-Adj-SID for TN-slice Identifier TLV
In LAN subnetworks, [RFC8667] defines the LAN-Adj-SID sub-TLV for a
router to advertise the Adj-SID of each of its neighbors.
LAN-Adj-SID for TN-slice Identifier TLV is used to distinguish
forwarding behavior of different virtual networks, Adjacency-SID need
to be allocated per TN-slice Identifier. This information is derived
from the LAN-Adj-SID for TN-slice Identifier sub-TLV of IS-IS
(section 8 of I-D. [I-D.zch-lsr-isis-network-slicing]).
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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 2
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=TBD5 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | Weight | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Neighbor System-ID (ID length octets) |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AII |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SID/Label/Index (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4
where:
Type:TBD5 (Suggested value to be assigned by IANA)
Length: Variable. Depending on the size of the SID.
The "Flags" and "SID/Index/Label" fields are the same as the
Adjacency-SID sub-TLV [RFC8667].
AII: Identifies the TN-slice (AII) information corresponding to the
Adjacency-SID.
3.3. Prefix Attribute TLVs
Prefix-SID for TN-slice Identifier TLV should only be added to the
BGP-LS Attribute associated with the Prefix NLRI describing the
prefix of the IGP node. This TLV is used to distinguish forwarding
behavior of different virtual networks.This information is derived
from TN-slice identifier Participation sub-TLV of IS-IS (section 6 of
[I-D.zch-lsr-isis-network-slicing]).
The Prefix-SID for TN-slice Identifier 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 2
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=TBD6 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flag | Algorithm | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AII |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SID/Index/Label(Variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5
where:
Type:TBD6 (Suggested value to be assigned by IANA)
Length: Variable. Depending on the size of the SID.
The "Flags" and "SID/Index/Label" fields are the same as the Prefix-
SID sub-TLV [RFC8667].
Algorithm: Accoridng to section "3.2. SR-Algorithm Sub-TLV" of
[RFC8667], two values can be set in this field.
o 0: Shortest Path First (SPF) algorithm based on link metric.
o 1: Strict Shortest Path First (SPF) algorithm based on link
metric.
Note that[I-D.ietf-lsr-flex-algo] also allows user to define other
algorithm values, i.e., FA-id within [128, 255], for the purpose of
constraint based path computation. However, an FA-id algorithm value
MUST not be set in this field, the reason is that FA-id has not
semantic local within AII.
AII: Identifies the TN-slice (AII) information corresponding to the
Prefix-SID.
4. IANA Considerations
This document does not define any new protocol or any extension to an
existing protocol.
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5. Acknowledgements
TBD
6. Normative References
[I-D.ietf-idr-bgpls-inter-as-topology-ext]
Wang, A., Chen, H., Talaulikar, K., and S. Zhuang, "BGP-LS
Extension for Inter-AS Topology Retrieval", draft-ietf-
idr-bgpls-inter-as-topology-ext-08 (work in progress),
April 2020.
[I-D.ietf-lsr-flex-algo]
Psenak, P., Hegde, S., Filsfils, C., Talaulikar, K., and
A. Gulko, "IGP Flexible Algorithm", draft-ietf-lsr-flex-
algo-10 (work in progress), August 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-03 (work in progress), February 2020.
[I-D.zch-lsr-isis-network-slicing]
Zhu, Y., Chen, R., Peng, S., and F. Qin, "IS-IS Extensions
to Support Transport Network Slices using Segment
Routing", draft-zch-lsr-isis-network-slicing-05 (work in
progress), July 2020.
[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>.
[RFC4915] Psenak, P., Mirtorabi, S., Roy, A., Nguyen, L., and P.
Pillay-Esnault, "Multi-Topology (MT) Routing in OSPF",
RFC 4915, DOI 10.17487/RFC4915, June 2007,
<https://www.rfc-editor.org/info/rfc4915>.
[RFC5120] Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi
Topology (MT) Routing in Intermediate System to
Intermediate Systems (IS-ISs)", RFC 5120,
DOI 10.17487/RFC5120, February 2008,
<https://www.rfc-editor.org/info/rfc5120>.
[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>.
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[RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and
S. Ray, "North-Bound Distribution of Link-State and
Traffic Engineering (TE) Information Using BGP", RFC 7752,
DOI 10.17487/RFC7752, March 2016,
<https://www.rfc-editor.org/info/rfc7752>.
[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>.
[RFC8667] Previdi, S., Ed., Ginsberg, L., Ed., Filsfils, C.,
Bashandy, A., Gredler, H., and B. Decraene, "IS-IS
Extensions for Segment Routing", RFC 8667,
DOI 10.17487/RFC8667, December 2019,
<https://www.rfc-editor.org/info/rfc8667>.
Authors' Addresses
Ran Chen
ZTE Corporation
No.50 Software Avenue, Yuhuatai District
Nanjing
China
Email: chen.ran@zte.com.cn
Shaofu
ZTE Corporation
No.68 Zijinghua Road, Yuhuatai District
Nanjing
China
Email: peng.shaofu@zte.com.cn
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