BGP Extensions to Support Packet Network Slicing in SR Policy

Internet-Draft	BGP for NS in SR Policy	October 2020
Liu & Peng	Expires 18 April 2021	[Page]

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 document defines extensions to BGP in order to advertise AII in SR policies.¶

Status of This Memo

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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 creteria.¶

[I-D.ietf-spring-segment-routing-policy] details the concepts of SR Policy and steering into an SR Policy.[I-D.ietf-idr-segment-routing-te-policy] specifies the way to use BGP to distribute one or more of the candidate paths of an SR Policy to the headend of that policy.¶

This document defines extensions to BGP in order to advertise AII in SR-TE policies.¶

2. SR policy with AII

To distinguish forwarding behavior of different virtual networks, each segment lists in SR policy need to be computed within the scope of TN-slice identified by AII. As AII has global significance, all segments of the same segment list can share a single AII. This document defines a new AII sub-TLV in Segment List Sub-TLV to indicate which slice this segment list belongs to,¶

    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=TBD1   |   Length      |     Flags     |   RESERVED    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                              AII                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 1: Figure 1: AII sub-TLV in Segment List Sub-TLV

where:¶

o Type: TBD1¶

o Length: 6¶

o Flags: 1 octet of flags. None are defined at this stage. Flags SHOULD be set to zero on transmission and MUST be ignored on receipt.¶

o RESERVED: 1 octet of reserved bits. SHOULD be set to zero on transmission and MUST be ignored on receipt.¶

o AII: Identifies the TN-slice (AII) information corresponding to the segment list.¶

3. Operations

The operations about advertisement and reception of SR policy can refer to [I-D.ietf-idr-segment-routing-te-policy]. Typically, a controller or a PCE can compute SR path taking acount of AII criteria, so that the SR path can be limited in the scope of TN-slice identified by AII. The AII information contained in Segment List Sub-TLV can help the headend to translate the segment to AII related SID, if the Segment Sub-TLV has not provided optional SID information.¶

Even if Segment Sub-TLV has provided valid SID information, it is also beneficial for the headend to know which slice this path belongs to, according to the AII information contained in Segment List Sub-TLV.¶

6. References

6.1. Normative References

[I-D.ietf-idr-segment-routing-te-policy]: Previdi, S., Filsfils, C., Talaulikar, K., Mattes, P., Rosen, E., Jain, D., and S. Lin, "Advertising Segment Routing Policies in BGP", Work in Progress, Internet-Draft, draft-ietf-idr-segment-routing-te-policy-09, 28 May 2020, <http://www.ietf.org/internet-drafts/draft-ietf-idr-segment-routing-te-policy-09.txt>.
[I-D.ietf-spring-segment-routing-policy]: Filsfils, C., Talaulikar, K., Voyer, D., Bogdanov, A., and P. Mattes, "Segment Routing Policy Architecture", Work in Progress, Internet-Draft, draft-ietf-spring-segment-routing-policy-08, 8 July 2020, <http://www.ietf.org/internet-drafts/draft-ietf-spring-segment-routing-policy-08.txt>.
[I-D.peng-teas-network-slicing]: Peng, S., Chen, R., Mirsky, G., and F. Qin, "Packet Network Slicing using Segment Routing", Work in Progress, Internet-Draft, draft-peng-teas-network-slicing-03, 19 February 2020, <http://www.ietf.org/internet-drafts/draft-peng-teas-network-slicing-03.txt>.

6.2. Informative References

[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", Work in Progress, Internet-Draft, draft-zch-lsr-isis-network-slicing-06, 4 September 2020, <http://www.ietf.org/internet-drafts/draft-zch-lsr-isis-network-slicing-06.txt>.