| Internet-Draft | BFD for Geneve | May 2022 |
| Min, et al. | Expires 16 November 2022 | [Page] |
This document describes the use of the Bidirectional Forwarding Detection (BFD) protocol in point-to-point Generic Network Virtualization Encapsulation (Geneve) tunnels used to make up an overlay network.¶
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 16 November 2022.¶
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.¶
"Generic Network Virtualization Encapsulation" (Geneve) [RFC8926] provides an encapsulation scheme that allows building an overlay network by decoupling the address space of the attached virtual hosts from that of the network.¶
This document describes the use of Bidirectional Forwarding Detection (BFD) protocol [RFC5880] to enable monitoring continuity of the path between two Geneve tunnel endpoints, which may be NVE (Network Virtualization Edge) or other device acting as a Geneve tunnel endpoint. Specifically, the asynchronous mode of BFD, as defined in [RFC5880], is used to monitor a p2p Geneve tunnel, and support for BFD Echo function is outside the scope of this document. For simplicity, in this document, NVE is used to represent Geneve tunnel endpoint, TS (Tenant System) is used to represent the physical or virtual device attached to a Geneve tunnel endpoint from the outside. VAP (Virtual Access Point) is the NVE side of the interface between the NVE and the TS, and a VAP is a logical network port (virtual or physical) into a specific virtual network. For detailed definitions and descriptions of NVE, TS and VAP, please refer to [RFC7365] and [RFC8014].¶
The use cases and the deployment of BFD for Geneve are consistent with what's described in Section 1 and 3 of [RFC8971] ("Bidirectional Forwarding Detection (BFD) for Virtual eXtensible Local Area Network (VXLAN)"), except for the usage of Management VNI, which in the case of Geneve is described in [I-D.ietf-nvo3-geneve-oam], and outside the scope of this document. The major difference between Geneve and VXLAN [RFC7348] is that Geneve supports multi-protocol payload and variable length options.¶
BFD: Bidirectional Forwarding Detection¶
Geneve: Generic Network Virtualization Encapsulation¶
NVE: Network Virtualization Edge¶
TS: Tenant System¶
VAP: Virtual Access Point¶
VNI: Virtual Network Identifier¶
VXLAN: Virtual eXtensible Local Area Network¶
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.¶
Concerning whether the Geneve data packets include an Ethernet frame or an IP packet, this document defines two formats of BFD packet encapsulation in Geneve. BFD session is originated and terminated at VAP of an NVE, selection of the BFD packet encapsulation is based on how the VAP encapsulates the data packets.¶
If the VAP that originates the BFD packets is used to encapsulate Ethernet data frames, then BFD packets are encapsulated in Geneve as described below. The Geneve packet formats over IPv4 and IPv6 are defined in Section 3.1 and 3.2 of [RFC8926] respectively. The Outer IP/UDP and Geneve headers MUST be encoded by the sender as defined in [RFC8926]. Note that the outer IP header and the inner IP header may not be of the same address family, in other words, outer IPv6 header accompanied with inner IPv4 header and outer IPv4 header accompanied with inner IPv6 header are both possible.¶
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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | ~ Outer Ethernet Header ~ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | ~ Outer IPvX Header ~ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | ~ Outer UDP Header ~ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | ~ Geneve Header ~ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | ~ Inner Ethernet Header ~ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | ~ Inner IPvX Header ~ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | ~ Inner UDP Header ~ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | ~ BFD Control Packet ~ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Outer Ethernet FCS | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The BFD packet MUST be carried inside the inner Ethernet frame of the Geneve packet. The inner Ethernet frame carrying the BFD Control packet has the following format:¶
Ethernet Header:¶
IP Header:¶
When the BFD packets are encapsulated in Geneve in this way, the Geneve header defined in [RFC8926] follows the value set below.¶
If the VAP that originates the BFD packets is used to encapsulate IP data packets, then BFD packets are encapsulated in Geneve as described below. The Geneve packet formats over IPv4 and IPv6 are defined in Section 3.1 and 3.2 of [RFC8926] respectively. The Outer IP/UDP and Geneve headers MUST be encoded by the sender as defined in [RFC8926]. Note that the outer IP header and the inner IP header may not be of the same address family, in other words, outer IPv6 header accompanied with inner IPv4 header and outer IPv4 header accompanied with inner IPv6 header are both possible.¶
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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | ~ Ethernet Header ~ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | ~ Outer IPvX Header ~ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | ~ Outer UDP Header ~ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | ~ Geneve Header ~ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | ~ Inner IPvX Header ~ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | ~ Inner UDP Header ~ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | ~ BFD Control Packet ~ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | FCS | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The BFD packet MUST be carried inside the inner IP packet of the Geneve packet. The inner IP packet carrying the BFD Control packet has the following format:¶
IP header:¶
When the BFD packets are encapsulated in Geneve in this way, the Geneve header defined in [RFC8926] follows the value set below.¶
Once a packet is received, the NVE MUST validate the packet as described in [RFC8926].¶
In BFD over Geneve, a BFD session is originated and terminated at VAP, usually one NVE owns multiple VAPs, so multiple BFD sessions may be running between two NVEs, there needs to be a mechanism for demultiplexing received BFD packets to the proper session. Furthermore, due to the fact that [RFC8014] allows for N-to-1 mapping between VAP and VNI at one NVE, multiple BFD sessions between two NVEs for the same VNI are allowed. Also note that a BFD session can only be established between two VAPs that are mapped to the same VNI and use the same way to encapsulate data packets.¶
If the BFD packet is received with Your Discriminator equals to 0, for different BFD encapsulation, the procedure for demultiplexing the received BFD packets is different.¶
If the BFD packet is received with non-zero Your Discriminator, then the BFD session MUST be demultiplexed only with Your Discriminator as the key.¶
Security issues discussed in [RFC5880], [RFC5881], and [RFC8926] apply to this document.¶
This document supports establishing multiple BFD sessions between the same pair of NVEs, each BFD session over a pair of VAPs residing in the same pair of NVEs, there SHOULD be a mechanism to control the maximum number of such sessions that can be active at the same time.¶
This document has no IANA action requested.¶
The authors would like to acknowledge Reshad Rahman, Jeffrey Haas and Matthew Bocci for their guidance on this work.¶
The authors would like to acknowledge David Black for his explanation on the mapping relation between VAP and VNI.¶