| NVO3 Working Group | X. Min |
| Internet-Draft | G. Mirsky |
| Intended status: Standards Track | ZTE Corp. |
| Expires: August 20, 2020 | S. Pallagatti |
| VMware | |
| February 17, 2020 |
BFD for Geneve
draft-xiao-nvo3-bfd-geneve-02
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.
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"Generic Network Virtualization Encapsulation" (Geneve) [I-D.ietf-nvo3-geneve] 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 echo BFD 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 [I-D.ietf-bfd-vxlan]. The major difference between Geneve and "Virtual eXtensible Local Area Network" (VXLAN) [RFC7348] encapsulation 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 format over IPv4 is defined in Section 3.1 of [I-D.ietf-nvo3-geneve]. The Geneve packet format over IPv6 is defined in Section 3.2 of [I-D.ietf-nvo3-geneve]. The Outer IP/UDP and Geneve headers MUST be encoded by the sender as defined in [I-D.ietf-nvo3-geneve]. 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Geneve Encapsulation of BFD Control Packet With the Inner Ethernet/IP/UDP Header
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:
When the BFD packets are encapsulated in Geneve in this way, the Geneve header defined in [I-D.ietf-nvo3-geneve] 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 format over IPv4 is defined in Section 3.1 of [I-D.ietf-nvo3-geneve]. The Geneve packet format over IPv6 is defined in Section 3.2 of [I-D.ietf-nvo3-geneve]. The Outer IP/UDP and Geneve headers MUST be encoded by the sender as defined in [I-D.ietf-nvo3-geneve]. 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Geneve Encapsulation of BFD Control Packet With the Inner IP/UDP Header
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:
When the BFD packets are encapsulated in Geneve in this way, the Geneve header defined in [I-D.ietf-nvo3-geneve] follows the value set below.
Once a packet is received, the NVE MUST validate the packet as described in [I-D.ietf-nvo3-geneve].
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.
This document does not raise any additional security issues beyond those of the specifications referred to in the list of references.
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.
| [I-D.ietf-bfd-vxlan] | Networks, J., Paragiri, S., Govindan, V., Mudigonda, M. and G. Mirsky, "BFD for VXLAN", Internet-Draft draft-ietf-bfd-vxlan-10, January 2020. |
| [RFC7348] | Mahalingam, M., Dutt, D., Duda, K., Agarwal, P., Kreeger, L., Sridhar, T., Bursell, M. and C. Wright, "Virtual eXtensible Local Area Network (VXLAN): A Framework for Overlaying Virtualized Layer 2 Networks over Layer 3 Networks", RFC 7348, DOI 10.17487/RFC7348, August 2014. |