Internet DRAFT - draft-cp-lsr-fa-aware-te
draft-cp-lsr-fa-aware-te
Networking Working Group R. Chen
Internet-Draft S. Peng
Intended status: Standards Track ZTE Corporation
Expires: October 20, 2021 April 18, 2021
IGP Extensions to Support Flex-Algorithm Aware Traffic Engineering
draft-cp-lsr-fa-aware-te-00
Abstract
[I-D.ietf-lsr-flex-algo]proposes a solution that allows IGPs
themselves to compute constraint based paths over the network, and it
also specifies a way of using Segment Routing (SR) Prefix-SIDs and
SRv6 locators to steer packets along the constraint-based paths.
[RFC8570] describes IS-IS extensions to distribute network-
performance information (such as residual bandwidth, and available
bandwidth).
This draft describes the IGP extensions to advertise the
corresponding network-performance information of the Flex-Algorithm.
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 October 20, 2021.
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
Chen & Peng Expires October 20, 2021 [Page 1]
Internet-Draft IGP Ext for flex-algo Aware TE April 2021
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components 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. Conventions used in this document . . . . . . . . . . . . . . 3
3. IS-IS Extensins for FA-TE . . . . . . . . . . . . . . . . . . 3
3.1. Maximum Reservable Link Bandwidth per Algorithm Sub-TLV . 3
3.2. Available Link Bandwidth per Algorithm Sub-TLV . . . . . 4
3.3. Utilized Link Bandwidth per Algorithm Sub-TLV . . . . . . 5
4. OSPF Extensins for FA-TE . . . . . . . . . . . . . . . . . . 6
5. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
7. Security Considerations . . . . . . . . . . . . . . . . . . . 8
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8
9. Normative References . . . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
[I-D.ietf-lsr-flex-algo]proposes a solution that allows IGPs
themselves to compute constraint based paths over the network, and it
also specifies a way of using Segment Routing (SR) Prefix-SIDs and
SRv6 locators to steer packets along the constraint-based paths.
[RFC8570] describes IS-IS extensions to distribute network-
performance information (such as link delay, delay variation, packet
loss, residual bandwidth, and available bandwidth).
The current Flex-Algorithm technology may support the implementation
of different QoS (Quality of Service QoS) policies of different
algorithms (algorithm) at the forwarding plane. It includes
different bandwidth, traffic class of service, queue scheduling
policies (such as low-delay queue, Priority Queuing priority queue)
and discard policies (such as tail discard and random discard). This
is actually the local behavior of the forwarding plane inside a node.
However, it's not enough. In order to comprehensively optimize the
service traffic running in each Flex-Algorithm and avoid unnecessary
traffic congestion, the relevant path control technology needs to be
implemented in the control plane. That is, to manage and maintain
the bandwidth resource reservation and consumption information for
each Flex-algo plane, and use the information for path calculation
and orchestration of the Flex-Algorithm.
Chen & Peng Expires October 20, 2021 [Page 2]
Internet-Draft IGP Ext for flex-algo Aware TE April 2021
This draft describes the IGP extensions to advertise the
corresponding network-performance information of the Flex-Algorithm.
2. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC2119.
3. IS-IS Extensins for FA-TE
This document registers new IS-IS FA-TE sub-TLVs in the "Sub-TLVs for
TLVs 22, 23, 141, 222, and 223" registry. These new sub-TLVs provide
ways to distribute network-performance information of the Flex-
Algorithm.
This document registers several sub-TLVs:
Type Description
----------------------------------------------------
TBD Maximum Reservable Link Bandwidth per Algorithm
TBD Available Bandwidth per Algorithm
TBD Utilized Bandwidth per Algorithm
3.1. Maximum Reservable Link Bandwidth per Algorithm Sub-TLV
This sub-TLV advertises maximum reservable link bandwidth attributes
on a particular link for a Flex-Algorithm.
The Maximum Reservable Link Bandwidth per Algorithm Sub-TLV has the
following format:
Chen & Peng Expires October 20, 2021 [Page 3]
Internet-Draft IGP Ext for flex-algo Aware TE April 2021
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 | Algorithm |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Maximum Reservable Link Bandwidth |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1
Type: TBD1 (Suggested value to be assigned by IANA)
Length: 1 octets.
Algorithm: 1 octets. Flex-Algorithm number,the value between 128 and
255 inclusive,the same as the definition of Flex-Algorithm in
[I-D.ietf-lsr-flex-algo]. Indicates that the value in the Maximum
Reserved Link Bandwidth field is for a specific Flex-algo plane.
Maximum Reserved Link Bandwidth: 4 octets.Indicates the maximum link
bandwidth that can be reserved for a specific FA-algorithm.
Note that the maximum reserved link bandwidth irrelevant to Flex-algo
can be classified as MRLB-FA corresponding to algorithm 0.
Therefore, the Sub-TLV (set the Algorithm field to 0) or the Maximum
Reservable Link Bandwidth Sub-TLV defined by [RFC5305] can be used.If
a node receives two types of notifications at the same time, the
bandwidth value carried in the conventional known Sub-TLV is
preferred.
3.2. Available Link Bandwidth per Algorithm Sub-TLV
This Sub-TLV advertises the available bandwidth on a particular link
for a specific Flex-Algorithm.
The Available Link Bandwidth per Algorithm Sub-TLV has the following
format:
Chen & Peng Expires October 20, 2021 [Page 4]
Internet-Draft IGP Ext for flex-algo Aware TE April 2021
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 | Algorithm |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Available Link Bandwidth |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3
Type: TBD3 (Suggested value to be assigned by IANA)
Length: 1 octets.
Algorithm: 1 octets. Flex-Algorithm number,the value between 128 and
255 inclusive,the same as the definition of Flex-Algorithm in
[I-D.ietf-lsr-flex-algo]. Indicates that the value in the Available
Link Bandwidth field is for a specific Flex-algo plane.
Available Link Bandwidth: 4 octets. Indicates the available link
bandwidth that can be reserved for a specific FA-algorithm.
Note that the available link bandwidth irrelevant to Flex-algo can be
classified as ARLB-FA corresponding to algorithm 0. Therefore, the
Sub-TLV (set the Algorithm field to 0) or the Unidirectional
Available Bandwidth Sub-TLV defined by [RFC8570] can be used.If a
node receives two types of notifications at the same time, the
bandwidth value carried in the conventional known Sub-TLV is
preferred.
3.3. Utilized Link Bandwidth per Algorithm Sub-TLV
This Sub-TLV advertises the utilized bandwidth on a particular link
for a specific Flex-Algorithm.
The Utilized Link Bandwidth per Algorithm Sub-TLV has the following
format:
Chen & Peng Expires October 20, 2021 [Page 5]
Internet-Draft IGP Ext for flex-algo Aware TE April 2021
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 | Algorithm |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Utilized Link Bandwidth |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4
Type: TBD4 (Suggested value to be assigned by IANA)
Length: 1 octets.
Algorithm: 1 octets. Flex-Algorithm number,the value between 128 and
255 inclusive,the same as the definition of Flex-Algorithm in
[I-D.ietf-lsr-flex-algo]. Indicates that the value in the Utilized
Link Bandwidth field is for a specific Flex-Algorithm plane.
Utilized Link Bandwidth: 4 octets. Indicates the Utilized link
bandwidth that can be reserved for a specific Flex-Algorithm.
Note that the Utilized link bandwidth irrelevant to Flex-algo can be
classified as ULB-FA corresponding to algorithm 0. Therefore, the
Sub-TLV (set the Algorithm field to 0) or the Unidirectional Utilized
Bandwidth Sub-TLV defined by [RFC8570] can be used.If a node receives
two types of notifications at the same time, the bandwidth value
carried in the conventional known Sub-TLV is preferred.
4. OSPF Extensins for FA-TE
OSPF extensions for FA-TE will be defined in next version.
5. Examples
Assume two Flex-Algorithm, FA128 and FA129, with the following
configuration parameters:
Per TE link resource allocation:
Max-BW(interface): 100G (derived from the physical interface BW)
Max-resv-BW(interface): 100G (default: equal to Max-BW)
Flex-Algorithm:
Max-resv-link-BW(FA128): 10G
Max-resv-link-BW(FA129): 20G
Chen & Peng Expires October 20, 2021 [Page 6]
Internet-Draft IGP Ext for flex-algo Aware TE April 2021
Time0: no LSPs
When the controller is used for path calculation, the controller first collects the network
topology information through the BGP-LS, which contains the MRLB-FA/ULB-FA/ALB-FA information
of each link. Static bandwidth reservation information maintained by the controller:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TE link | Flex-Algorithm | Bandwidth |
|-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
| | FA0 | MRLB-FA = 70G | ULB-A = 0 | ALB-A = 70G |
| |-+-+-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
| Link 1 | FA128 | MRLB-FA = 10G | ULB-A = 0 | ALB-A = 10G |
| |-+-+-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
| | FA129 | MRLB-FA = 20G | ULB-A = 0 | ALB-A = 20G |
+-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
Time1: Create a new TE path1 in FA 128 with reserved bandwidth of 5G
The controller updates the reserved static bandwidth information:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TE link | Flex-Algorithm | Bandwidth |
|-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
| | FA0 | MRLB-FA = 70G | ULB-FA = 0| ALB-FA = 70G |
| |-+-+-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
| Link 1 | FA128 | MRLB-FA = 10G | ULB-FA = 0| ALB-FA = 10G |
| | | (TE path1 statically | | |
| | |reserve 5G, remaining 5G}| | |
| |-+-+-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-+-+-+-+-|-+-+-+-+-+-|-+-+-+-+-+-+-+-+-|
| | FA129 | MRLB-FA = 20G | ULB-FA = 0| ALB-FA = 20G |
+-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Time3: After the TE path1 starts to carry traffic, suppose the service traffic on the TE path1
runs at full load.The controller updates the reserved static bandwidth information:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TE link | Flex-Algorithm | Bandwidth |
|-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
| | FA0 | MRLB-FA = 70G | ULB-FA = 0 | ALB-FA = 70G |
| |-+-+-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
| Link 1 | FA128 | MRLB-FA = 10G | ULB-FA = 5G | ALB-FA = 5G |
| | | (TE path1 statically | | |
| | |reserve 5G, remaining 5G}| | |
| |-+-+-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-+-+-+-+-|-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-|
| | FA129 | MRLB-FA = 20G | ULB-FA = 0 | ALB-FA = 20G |
+-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Now suppose to continue to create another TE path2 in the Flex-algo 128.
This TE path needs to reserve 6G bandwidth. When the controller is used for path computation,
path computation will fail, Beacuse there is no link resource that meets the bandwidth requirement.
Chen & Peng Expires October 20, 2021 [Page 7]
Internet-Draft IGP Ext for flex-algo Aware TE April 2021
6. IANA Considerations
IANA maintains the registry for the sub-TLVs. IANA has registered
the following sub-TLVs in the "Sub-TLVs for TLVs 22, 23, 141, 222,
and 223" registry:
Type Description
----------------------------------------------------
TBD Maximum Reservable Link Bandwidth per Algorithm
TBD Residual Bandwidth per Algorithm
TBD Available Bandwidth per Algorithm
TBD Utilized Bandwidth per Algorithm
7. Security Considerations
TBD.
8. Acknowledgements
TBD.
9. Normative References
[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-13 (work in progress), October 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>.
[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>.
[RFC8570] Ginsberg, L., Ed., Previdi, S., Ed., Giacalone, S., Ward,
D., Drake, J., and Q. Wu, "IS-IS Traffic Engineering (TE)
Metric Extensions", RFC 8570, DOI 10.17487/RFC8570, March
2019, <https://www.rfc-editor.org/info/rfc8570>.
Chen & Peng Expires October 20, 2021 [Page 8]
Internet-Draft IGP Ext for flex-algo Aware TE April 2021
Authors' Addresses
Ran Chen
ZTE Corporation
Email: chen.ran@zte.com.cn
Shaofu Peng
ZTE Corporation
Email: peng.shaofu@zte.com.cn
Chen & Peng Expires October 20, 2021 [Page 9]
