| Internet-Draft | Abbreviated-Title | March 2022 |
| Li, et al. | Expires 6 September 2022 | [Page] |
- Workgroup:
- Network Working Group
- Internet-Draft:
- draft-li-idr-link-bandwidth-ext-01
- Published:
- Intended Status:
- Standards Track
- Expires:
Extension of Link Bandwidth Extended Community
Abstract
[I-D.ietf-idr-link-bandwidth] defines a BGP link bandwidth extended community attribute, which can enable devices to implement unequal-cost load-balancing. However, the bandwidth value encapsulated by the extended community attribute is of the floating-point type, which is inconvenient to use. In this document, a set of new types of link bandwidth extended community are introduced to facilitate the configuration and calculation of link bandwidth.¶
Requirements Language
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 RFC 2119 [RFC2119].¶
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/.¶
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This Internet-Draft will expire on 6 September 2022.¶
Copyright Notice
Copyright (c) 2022 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 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 Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License.¶
1. Introduction
In [I-D.ietf-idr-link-bandwidth], the link bandwidth extended community attribute is added to implement unequal-cost load balancing based on the bandwidth on a path. As defined in the draft, the bandwidth of a link is expressed in 4-octets in IEEE floating-point format.¶
In practice, the use of this floating-point format may result errors in configuration and computation. When an operator needs to manually specify the bandwidth, you also need to consider the conversion from the bandwidth value to the floating-point number. This mode is not user-friendly, especially when the routing policy is used for bandwidth matching.¶
This document introduce a more intuitive expression of link bandwidth in BGP. It uses an unsigned long integer value to describe the link bandwidth value. This is easier for operators to use and understand, and can avoid configuration and computation errors.¶
2. Link Bandwidth Extended Community
The type of Link Bandwidth Extended Community is 0x40, and the subtype is 0x04. In the attribute value, the global administrator subfield is set to the AS number of the route to which the Link Bandwidth attribute is added. In the local administrator subfield, the link bandwidth value [I-D.ietf-idr-link-bandwidth] is set to the IEEE floating-point type.¶
A new type of IPv6 Address Specific Extended Community[RFC5701] is added in this document. The ASN field of this attribute is set to the AS number of the route to which the link bandwidth attribute is added. The Link Bandwidth value field (8 bytes) is set to the link bandwidth. The following extended contents are added:¶
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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 0x03 or 0x43 | Sub-Type | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 8 bytes Link Bandwidth value (cont.) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 8 bytes Link Bandwidth value (cont.) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 4 bytes ASN | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+¶
- The value of the high-order octet of the extended Type, refer to [RFC4360], It is recommended that 0x03 and 0x43 be used.¶
- New Link Bandwidth, subtype is TBD. The value of the Link Bandwidth subfield is an unsigned long integer, in bytes per second.¶
The subtypes defined here can be used for both optional transitive and non-transitive extended community attributes.¶
3. Deployment Considerations
The extended link bandwidth extended community attribute in this document should not be used together with the standard link bandwidth extended community attribute. If a route carries both the standard link bandwidth extended community attribute and the unit link bandwidth extended community attribute, the standard link bandwidth extended community attribute is ignored.¶
In actual deployment, if a routing policy is used to match link bandwidth attributes, you can directly perform exact value matching.¶
4. IANA Considerations
This document defines a specific application of the two-octet AS specific extended community. IANA is requested to assign new sub-types for both non-transitive and transitive extended communities.¶
SubType Description ------- ------------------------------- TBD Link Bandwidth EC in bytes per second¶
5. Security Considerations
There are no additional security risks introduced by this design.¶
7. References
7.1. Normative References
- [RFC2119]
- Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <https://www.rfc-editor.org/info/rfc2119>.
7.2. References
- [I-D.ietf-idr-link-bandwidth]
- Mohapatra, P. and R. Fernando, "BGP Link Bandwidth Extended Community", Work in Progress, Internet-Draft, draft-ietf-idr-link-bandwidth-07, , <https://www.ietf.org/archive/id/draft-ietf-idr-link-bandwidth-07.txt>.
- [RFC4360]
- Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended Communities Attribute", RFC 4360, DOI 10.17487/RFC4360, , <https://www.rfc-editor.org/info/rfc4360>.
- [RFC5701]
- Rekhter, Y., "IPv6 Address Specific BGP Extended Community Attribute", RFC 5701, DOI 10.17487/RFC5701, , <https://www.rfc-editor.org/info/rfc5701>.