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Versions: (draft-gross-geneve) 00 01 02 03 04
05 06 07
Network Working Group J. Gross, Ed.
Internet-Draft
Intended status: Standards Track I. Ganga, Ed.
Expires: January 3, 2019 Intel
T. Sridhar, Ed.
VMware
July 02, 2018
Geneve: Generic Network Virtualization Encapsulation
draft-ietf-nvo3-geneve-07
Abstract
Network virtualization involves the cooperation of devices with a
wide variety of capabilities such as software and hardware tunnel
endpoints, transit fabrics, and centralized control clusters. As a
result of their role in tying together different elements in the
system, the requirements on tunnels are influenced by all of these
components. Flexibility is therefore the most important aspect of a
tunnel protocol if it is to keep pace with the evolution of the
system. This draft describes Geneve, a protocol designed to
recognize and accommodate these changing capabilities and needs.
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 January 3, 2019.
Copyright Notice
Copyright (c) 2018 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
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(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 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 . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
2. Design Requirements . . . . . . . . . . . . . . . . . . . . . 5
2.1. Control Plane Independence . . . . . . . . . . . . . . . 6
2.2. Data Plane Extensibility . . . . . . . . . . . . . . . . 7
2.2.1. Efficient Implementation . . . . . . . . . . . . . . 7
2.3. Use of Standard IP Fabrics . . . . . . . . . . . . . . . 8
3. Geneve Encapsulation Details . . . . . . . . . . . . . . . . 9
3.1. Geneve Packet Format Over IPv4 . . . . . . . . . . . . . 9
3.2. Geneve Packet Format Over IPv6 . . . . . . . . . . . . . 10
3.3. UDP Header . . . . . . . . . . . . . . . . . . . . . . . 12
3.4. Tunnel Header Fields . . . . . . . . . . . . . . . . . . 13
3.5. Tunnel Options . . . . . . . . . . . . . . . . . . . . . 14
3.5.1. Options Processing . . . . . . . . . . . . . . . . . 16
4. Implementation and Deployment Considerations . . . . . . . . 17
4.1. Encapsulation of Geneve in IP . . . . . . . . . . . . . . 17
4.1.1. IP Fragmentation . . . . . . . . . . . . . . . . . . 17
4.1.2. DSCP and ECN . . . . . . . . . . . . . . . . . . . . 17
4.1.3. Broadcast and Multicast . . . . . . . . . . . . . . . 18
4.1.4. Unidirectional Tunnels . . . . . . . . . . . . . . . 18
4.2. Constraints on Protocol Features . . . . . . . . . . . . 19
4.2.1. Constraints on Options . . . . . . . . . . . . . . . 19
4.3. NIC Offloads . . . . . . . . . . . . . . . . . . . . . . 19
4.4. Inner VLAN Handling . . . . . . . . . . . . . . . . . . . 20
5. Interoperability Issues . . . . . . . . . . . . . . . . . . . 20
6. Security Considerations . . . . . . . . . . . . . . . . . . . 21
6.1. Data Confidentiality . . . . . . . . . . . . . . . . . . 21
6.1.1. Inter-data center traffic . . . . . . . . . . . . . . 22
6.2. Data Integrity . . . . . . . . . . . . . . . . . . . . . 22
6.3. Authentication of NVE peers . . . . . . . . . . . . . . . 23
6.4. Multicast/Broadcast . . . . . . . . . . . . . . . . . . . 23
6.5. Control plane communications . . . . . . . . . . . . . . 24
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24
8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 25
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 26
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 26
10.1. Normative References . . . . . . . . . . . . . . . . . . 26
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10.2. Informative References . . . . . . . . . . . . . . . . . 27
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 29
1. Introduction
Networking has long featured a variety of tunneling, tagging, and
other encapsulation mechanisms. However, the advent of network
virtualization has caused a surge of renewed interest and a
corresponding increase in the introduction of new protocols. The
large number of protocols in this space, ranging all the way from
VLANs [IEEE.802.1Q_2014] and MPLS [RFC3031] through the more recent
VXLAN [RFC7348], NVGRE [RFC7637], often leads to questions about the
need for new encapsulation formats and what it is about network
virtualization in particular that leads to their proliferation.
While many encapsulation protocols seek to simply partition the
underlay network or bridge between two domains, network
virtualization views the transit network as providing connectivity
between multiple components of a distributed system. In many ways
this system is similar to a chassis switch with the IP underlay
network playing the role of the backplane and tunnel endpoints on the
edge as line cards. When viewed in this light, the requirements
placed on the tunnel protocol are significantly different in terms of
the quantity of metadata necessary and the role of transit nodes.
Current work such as VL2 [VL2] and the NVO3 working group
[I-D.ietf-nvo3-dataplane-requirements] have described some of the
properties that the data plane must have to support network
virtualization. However, one additional defining requirement is the
need to carry system state along with the packet data. The use of
some metadata is certainly not a foreign concept - nearly all
protocols used for virtualization have at least 24 bits of identifier
space as a way to partition between tenants. This is often described
as overcoming the limits of 12-bit VLANs, and when seen in that
context, or any context where it is a true tenant identifier, 16
million possible entries is a large number. However, the reality is
that the metadata is not exclusively used to identify tenants and
encoding other information quickly starts to crowd the space. In
fact, when compared to the tags used to exchange metadata between
line cards on a chassis switch, 24-bit identifiers start to look
quite small. There are nearly endless uses for this metadata,
ranging from storing input ports for simple security policies to
service based context for interposing advanced middleboxes.
Existing tunnel protocols have each attempted to solve different
aspects of these new requirements, only to be quickly rendered out of
date by changing control plane implementations and advancements.
Furthermore, software and hardware components and controllers all
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have different advantages and rates of evolution - a fact that should
be viewed as a benefit, not a liability or limitation. This draft
describes Geneve, a protocol which seeks to avoid these problems by
providing a framework for tunneling for network virtualization rather
than being prescriptive about the entire system.
1.1. 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 [RFC2119].
In this document, these words will appear with that interpretation
only when in ALL CAPS. Lower case uses of these words are not to be
interpreted as carrying RFC-2119 significance.
1.2. Terminology
The NVO3 framework [RFC7365] defines many of the concepts commonly
used in network virtualization. In addition, the following terms are
specifically meaningful in this document:
Checksum offload. An optimization implemented by many NICs which
enables computation and verification of upper layer protocol
checksums in hardware on transmit and receive, respectively. This
typically includes IP and TCP/UDP checksums which would otherwise be
computed by the protocol stack in software.
Clos network. A technique for composing network fabrics larger than
a single switch while maintaining non-blocking bandwidth across
connection points. ECMP is used to divide traffic across the
multiple links and switches that constitute the fabric. Sometimes
termed "leaf and spine" or "fat tree" topologies.
ECMP. Equal Cost Multipath. A routing mechanism for selecting from
among multiple best next hop paths by hashing packet headers in order
to better utilize network bandwidth while avoiding reordering a
single stream.
Geneve. Generic Network Virtualization Encapsulation. The tunnel
protocol described in this draft.
LRO. Large Receive Offload. The receive-side equivalent function of
LSO, in which multiple protocol segments (primarily TCP) are
coalesced into larger data units.
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NIC. Network Interface Card. A NIC could be part of a tunnel
endpoint or transit device and can either process Geneve packets or
aid in the processing of Geneve packets.
OAM. Operations, Administration, and Management. A suite of tools
used to monitor and troubleshoot network problems.
Transit device. A forwarding element along the path of the tunnel
making up part of the Underlay Network. A transit device MAY be
capable of understanding the Geneve packet format but does not
originate or terminate Geneve packets.
LSO. Large Segmentation Offload. A function provided by many
commercial NICs that allows data units larger than the MTU to be
passed to the NIC to improve performance, the NIC being responsible
for creating smaller segments of size less than or equal to the MTU
with correct protocol headers. When referring specifically to TCP/
IP, this feature is often known as TSO (TCP Segmentation Offload).
Tunnel endpoint. A component performing encapsulation and
decapsulation of packets, such as Ethernet frames or IP datagrams, in
Geneve headers. As the ultimate consumer of any tunnel metadata,
endpoints have the highest level of requirements for parsing and
interpreting tunnel headers. Tunnel endpoints may consist of either
software or hardware implementations or a combination of the two.
Endpoints are frequently a component of an NVE but may also be found
in middleboxes or other elements making up an NVO3 Network.
VM. Virtual Machine.
2. Design Requirements
Geneve is designed to support network virtualization use cases, where
tunnels are typically established to act as a backplane between the
virtual switches residing in hypervisors, physical switches, or
middleboxes or other appliances. An arbitrary IP network can be used
as an underlay although Clos networks composed using ECMP links are a
common choice to provide consistent bisectional bandwidth across all
connection points. Figure 1 shows an example of a hypervisor, top of
rack switch for connectivity to physical servers, and a WAN uplink
connected using Geneve tunnels over a simplified Clos network. These
tunnels are used to encapsulate and forward frames from the attached
components such as VMs or physical links.
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+---------------------+ +-------+ +------+
| +--+ +-------+---+ | |Transit|--|Top of|==Physical
| |VM|--| | | | +------+ /|Router | | Rack |==Servers
| +--+ |Virtual|NIC|---|Top of|/ +-------+\/+------+
| +--+ |Switch | | | | Rack |\ +-------+/\+------+
| |VM|--| | | | +------+ \|Transit| |Uplink| WAN
| +--+ +-------+---+ | |Router |--| |=========>
+---------------------+ +-------+ +------+
Hypervisor
()===================================()
Switch-Switch Geneve Tunnels
Figure 1: Sample Geneve Deployment
To support the needs of network virtualization, the tunnel protocol
should be able to take advantage of the differing (and evolving)
capabilities of each type of device in both the underlay and overlay
networks. This results in the following requirements being placed on
the data plane tunneling protocol:
o The data plane is generic and extensible enough to support current
and future control planes.
o Tunnel components are efficiently implementable in both hardware
and software without restricting capabilities to the lowest common
denominator.
o High performance over existing IP fabrics.
These requirements are described further in the following
subsections.
2.1. Control Plane Independence
Although some protocols for network virtualization have included a
control plane as part of the tunnel format specification (most
notably, the original VXLAN spec prescribed a multicast learning-
based control plane), these specifications have largely been treated
as describing only the data format. The VXLAN packet format has
actually seen a wide variety of control planes built on top of it.
There is a clear advantage in settling on a data format: most of the
protocols are only superficially different and there is little
advantage in duplicating effort. However, the same cannot be said of
control planes, which are diverse in very fundamental ways. The case
for standardization is also less clear given the wide variety in
requirements, goals, and deployment scenarios.
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As a result of this reality, Geneve aims to be a pure tunnel format
specification that is capable of fulfilling the needs of many control
planes by explicitly not selecting any one of them. This
simultaneously promotes a shared data format and increases the
chances that it will not be obsoleted by future control plane
enhancements.
2.2. Data Plane Extensibility
Achieving the level of flexibility needed to support current and
future control planes effectively requires an options infrastructure
to allow new metadata types to be defined, deployed, and either
finalized or retired. Options also allow for differentiation of
products by encouraging independent development in each vendor's core
specialty, leading to an overall faster pace of advancement. By far
the most common mechanism for implementing options is Type-Length-
Value (TLV) format.
It should be noted that while options can be used to support non-
wirespeed control packets, they are equally important on data packets
as well to segregate and direct forwarding (for instance, the
examples given before of input port based security policies and
service interposition both require tags to be placed on data
packets). Therefore, while it would be desirable to limit the
extensibility to only control packets for the purposes of simplifying
the datapath, that would not satisfy the design requirements.
2.2.1. Efficient Implementation
There is often a conflict between software flexibility and hardware
performance that is difficult to resolve. For a given set of
functionality, it is obviously desirable to maximize performance.
However, that does not mean new features that cannot be run at that
speed today should be disallowed. Therefore, for a protocol to be
efficiently implementable means that a set of common capabilities can
be reasonably handled across platforms along with a graceful
mechanism to handle more advanced features in the appropriate
situations.
The use of a variable length header and options in a protocol often
raises questions about whether it is truly efficiently implementable
in hardware. To answer this question in the context of Geneve, it is
important to first divide "hardware" into two categories: tunnel
endpoints and transit devices.
Endpoints must be able to parse the variable header, including any
options, and take action. Since these devices are actively
participating in the protocol, they are the most affected by Geneve.
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However, as endpoints are the ultimate consumers of the data,
transmitters can tailor their output to the capabilities of the
recipient. As new functionality becomes sufficiently well defined to
add to endpoints, supporting options can be designed using ordering
restrictions and other techniques to ease parsing.
Transit devices MAY be able to interpret the options, however, as
non-terminating devices, transit devices do not originate or
terminate the Geneve packet, hence MUST NOT insert or delete options,
which is the responsibility of Geneve endpoints. The participation
of transit devices in interpreting options is OPTIONAL.
Further, either tunnel endpoints or transit devices MAY use offload
capabilities of NICs such as checksum offload to improve the
performance of Geneve packet processing. The presence of a Geneve
variable length header SHOULD NOT prevent the tunnel endpoints and
transit devices from using such offload capabilities.
2.3. Use of Standard IP Fabrics
IP has clearly cemented its place as the dominant transport mechanism
and many techniques have evolved over time to make it robust,
efficient, and inexpensive. As a result, it is natural to use IP
fabrics as a transit network for Geneve. Fortunately, the use of IP
encapsulation and addressing is enough to achieve the primary goal of
delivering packets to the correct point in the network through
standard switching and routing.
In addition, nearly all underlay fabrics are designed to exploit
parallelism in traffic to spread load across multiple links without
introducing reordering in individual flows. These equal cost
multipathing (ECMP) techniques typically involve parsing and hashing
the addresses and port numbers from the packet to select an outgoing
link. However, the use of tunnels often results in poor ECMP
performance without additional knowledge of the protocol as the
encapsulated traffic is hidden from the fabric by design and only
endpoint addresses are available for hashing.
Since it is desirable for Geneve to perform well on these existing
fabrics, it is necessary for entropy from encapsulated packets to be
exposed in the tunnel header. The most common technique for this is
to use the UDP source port, which is discussed further in
Section 3.3.
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3. Geneve Encapsulation Details
The Geneve packet format consists of a compact tunnel header
encapsulated in UDP over either IPv4 or IPv6. A small fixed tunnel
header provides control information plus a base level of
functionality and interoperability with a focus on simplicity. This
header is then followed by a set of variable options to allow for
future innovation. Finally, the payload consists of a protocol data
unit of the indicated type, such as an Ethernet frame. Section 3.1
and Section 3.2 illustrate the Geneve packet format transported (for
example) over Ethernet along with an Ethernet payload.
3.1. Geneve Packet Format Over IPv4
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 Destination MAC Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Outer Destination MAC Address | Outer Source MAC Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Outer Source MAC Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Optional Ethertype=C-Tag 802.1Q| Outer VLAN Tag Information |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ethertype=0x0800 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Outer IPv4 Header:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Version| IHL |Type of Service| Total Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identification |Flags| Fragment Offset |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Time to Live |Protocol=17 UDP| Header Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Outer Source IPv4 Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Outer Destination IPv4 Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Outer UDP Header:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Port = xxxx | Dest Port = 6081 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| UDP Length | UDP Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Geneve Header:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Ver| Opt Len |O|C| Rsvd. | Protocol Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Virtual Network Identifier (VNI) | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Variable Length Options |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Inner Ethernet Header (example payload):
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Inner Destination MAC Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Inner Destination MAC Address | Inner Source MAC Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Inner Source MAC Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Optional Ethertype=C-Tag 802.1Q| Inner VLAN Tag Information |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Payload:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ethertype of Original Payload | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| Original Ethernet Payload |
| |
| (Note that the original Ethernet Frame's FCS is not included) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Frame Check Sequence:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| New FCS (Frame Check Sequence) for Outer Ethernet Frame |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.2. Geneve Packet Format Over IPv6
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 Destination MAC Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Outer Destination MAC Address | Outer Source MAC Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Outer Source MAC Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Optional Ethertype=C-Tag 802.1Q| Outer VLAN Tag Information |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| Ethertype=0x86DD |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Outer IPv6 Header:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Version| Traffic Class | Flow Label |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Payload Length | NxtHdr=17 UDP | Hop Limit |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ Outer Source IPv6 Address +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ Outer Destination IPv6 Address +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Outer UDP Header:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Port = xxxx | Dest Port = 6081 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| UDP Length | UDP Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Geneve Header:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Ver| Opt Len |O|C| Rsvd. | Protocol Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Virtual Network Identifier (VNI) | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Variable Length Options |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Inner Ethernet Header (example payload):
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Inner Destination MAC Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Inner Destination MAC Address | Inner Source MAC Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| Inner Source MAC Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Optional Ethertype=C-Tag 802.1Q| Inner VLAN Tag Information |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Payload:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ethertype of Original Payload | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| Original Ethernet Payload |
| |
| (Note that the original Ethernet Frame's FCS is not included) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Frame Check Sequence:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| New FCS (Frame Check Sequence) for Outer Ethernet Frame |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.3. UDP Header
The use of an encapsulating UDP [RFC0768] header follows the
connectionless semantics of Ethernet and IP in addition to providing
entropy to routers performing ECMP. The header fields are therefore
interpreted as follows:
Source port: A source port selected by the originating tunnel
endpoint. This source port SHOULD be the same for all packets
belonging to a single encapsulated flow to prevent reordering due
to the use of different paths. To encourage an even distribution
of flows across multiple links, the source port SHOULD be
calculated using a hash of the encapsulated packet headers using,
for example, a traditional 5-tuple. Since the port represents a
flow identifier rather than a true UDP connection, the entire
16-bit range MAY be used to maximize entropy.
Dest port: IANA has assigned port 6081 as the fixed well-known
destination port for Geneve. Although the well-known value should
be used by default, it is RECOMMENDED that implementations make
this configurable. The chosen port is used for identification of
Geneve packets and MUST NOT be reversed for different ends of a
connection as is done with TCP.
UDP length: The length of the UDP packet including the UDP header.
UDP checksum: The checksum MAY be set to zero on transmit for
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packets encapsulated in both IPv4 and IPv6 [RFC6935]. When a
packet is received with a UDP checksum of zero it MUST be accepted
and decapsulated. If the originating tunnel endpoint optionally
encapsulates a packet with a non-zero checksum, it MUST be a
correctly computed UDP checksum. Upon receiving such a packet,
the egress endpoint MUST validate the checksum. If the checksum
is not correct, the packet MUST be dropped, otherwise the packet
MUST be accepted for decapsulation. It is RECOMMENDED that the
UDP checksum be computed to protect the Geneve header and options
in situations where the network reliability is not high and the
packet is not protected by another checksum or CRC.
3.4. Tunnel Header Fields
Ver (2 bits): The current version number is 0. Packets received by
an endpoint with an unknown version MUST be dropped. Non-
terminating devices processing Geneve packets with an unknown
version number MUST treat them as UDP packets with an unknown
payload.
Opt Len (6 bits): The length of the options fields, expressed in
four byte multiples, not including the eight byte fixed tunnel
header. This results in a minimum total Geneve header size of 8
bytes and a maximum of 260 bytes. The start of the payload
headers can be found using this offset from the end of the base
Geneve header.
O (1 bit): OAM packet. This packet contains a control message
instead of a data payload. Control messages are sent between
Geneve endpoints. Endpoints MUST NOT forward the payload and
transit devices MUST NOT attempt to interpret or process it.
Since these are infrequent control messages, it is RECOMMENDED
that endpoints direct these packets to a high priority control
queue (for example, to direct the packet to a general purpose CPU
from a forwarding ASIC or to separate out control traffic on a
NIC). Transit devices MUST NOT alter forwarding behavior on the
basis of this bit, such as ECMP link selection.
C (1 bit): Critical options present. One or more options has the
critical bit set (see Section 3.5). If this bit is set then
tunnel endpoints MUST parse the options list to interpret any
critical options. On endpoints where option parsing is not
supported the packet MUST be dropped on the basis of the 'C' bit
in the base header. If the bit is not set tunnel endpoints MAY
strip all options using 'Opt Len' and forward the decapsulated
packet. Transit devices MUST NOT drop packets on the basis of
this bit.
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The critical bit allows hardware implementations the flexibility
to handle options processing in the hardware fastpath or in the
exception (slow) path without the need to process all the options.
For example, a critical option such as secure hash to provide
Geneve header integrity check must be processed by tunnel
endpoints and typically processed in the hardware fastpath.
Rsvd. (6 bits): Reserved field which MUST be zero on transmission
and ignored on receipt.
Protocol Type (16 bits): The type of the protocol data unit
appearing after the Geneve header. This follows the EtherType
[ETYPES] convention with Ethernet itself being represented by the
value 0x6558.
Virtual Network Identifier (VNI) (24 bits): An identifier for a
unique element of a virtual network. In many situations this may
represent an L2 segment, however, the control plane defines the
forwarding semantics of decapsulated packets. The VNI MAY be used
as part of ECMP forwarding decisions or MAY be used as a mechanism
to distinguish between overlapping address spaces contained in the
encapsulated packet when load balancing across CPUs.
Reserved (8 bits): Reserved field which MUST be zero on transmission
and ignored on receipt.
Transit devices MUST maintain consistent forwarding behavior
irrespective of the value of 'Opt Len', including ECMP link
selection. These devices SHOULD be able to forward packets
containing options without resorting to a slow path.
3.5. Tunnel Options
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option Class | Type |R|R|R| Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Variable Option Data |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Geneve Option
The base Geneve header is followed by zero or more options in Type-
Length-Value format. Each option consists of a four byte option
header and a variable amount of option data interpreted according to
the type.
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Option Class (16 bits): Namespace for the 'Type' field. IANA will
be requested to create a "Geneve Option Class" registry to
allocate identifiers for organizations, technologies, and vendors
that have an interest in creating types for options. Each
organization may allocate types independently to allow
experimentation and rapid innovation. It is expected that over
time certain options will become well known and a given
implementation may use option types from a variety of sources. In
addition, IANA will be requested to reserve specific ranges for
standardized and experimental options.
Type (8 bits): Type indicating the format of the data contained in
this option. Options are primarily designed to encourage future
extensibility and innovation and so standardized forms of these
options will be defined in a separate document.
The high order bit of the option type indicates that this is a
critical option. If the receiving endpoint does not recognize
this option and this bit is set then the packet MUST be dropped.
If the critical bit is set in any option then the 'C' bit in the
Geneve base header MUST also be set. Transit devices MUST NOT
drop packets on the basis of this bit. The following figure shows
the location of the 'C' bit in the 'Type' field:
0 1 2 3 4 5 6 7 8
+-+-+-+-+-+-+-+-+
|C| Type |
+-+-+-+-+-+-+-+-+
The requirement to drop a packet with an unknown critical option
applies to the entire tunnel endpoint system and not a particular
component of the implementation. For example, in a system
comprised of a forwarding ASIC and a general purpose CPU, this
does not mean that the packet must be dropped in the ASIC. An
implementation may send the packet to the CPU using a rate-limited
control channel for slow-path exception handling.
R (3 bits): Option control flags reserved for future use. MUST be
zero on transmission and ignored on receipt.
Length (5 bits): Length of the option, expressed in four byte
multiples excluding the option header. The total length of each
option may be between 4 and 128 bytes. A value of 0 in the Length
field implies an option with only the option header without the
variable option data. Packets in which the total length of all
options is not equal to the 'Opt Len' in the base header are
invalid and MUST be silently dropped if received by an endpoint.
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Variable Option Data: Option data interpreted according to 'Type'.
3.5.1. Options Processing
Geneve options are intended to be originated and processed by tunnel
endpoints. However, options MAY be interpreted by transit devices
along the tunnel path. Transit devices not processing Geneve headers
SHOULD process Geneve packets as any other UDP packet and maintain
consistent forwarding behavior.
In tunnel endpoints, the generation and interpretation of options is
determined by the control plane, which is out of the scope of this
document. However, to ensure interoperability between heterogeneous
devices some requirements are imposed on options and the devices that
process them:
o Receiving endpoints MUST drop packets containing unknown options
with the 'C' bit set in the option type. Conversely, transit
devices MUST NOT drop packets as a result of encountering unknown
options, including those with the 'C' bit set.
o Some options may be defined in such a way that the position in the
option list is significant. Options or their ordering, MUST NOT
be changed by transit devices.
o An option MUST NOT affect the parsing or interpretation of any
other option.
When designing a Geneve option, it is important to consider how the
option will evolve in the future. Once an option is defined it is
reasonable to expect that implementations may come to depend on a
specific behavior. As a result, the scope of any future changes must
be carefully described upfront.
Unexpectedly significant interoperability issues may result from
changing the length of an option that was defined to be a certain
size. A particular option is specified to have either a fixed
length, which is constant, or a variable length, which may change
over time or for different use cases. This property is part of the
definition of the option and conveyed by the 'Type'. For fixed
length options, some implementations may choose to ignore the length
field in the option header and instead parse based on the well known
length associated with the type. In this case, redefining the length
will impact not only parsing of the option in question but also any
options that follow. Therefore, options that are defined to be fixed
length in size MUST NOT be redefined to a different length. Instead,
a new 'Type' should be allocated.
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4. Implementation and Deployment Considerations
4.1. Encapsulation of Geneve in IP
As an IP-based tunnel protocol, Geneve shares many properties and
techniques with existing protocols. The application of some of these
are described in further detail, although in general most concepts
applicable to the IP layer or to IP tunnels generally also function
in the context of Geneve.
4.1.1. IP Fragmentation
To prevent fragmentation and maximize performance, the best practice
when using Geneve is to ensure that the MTU of the physical network
is greater than or equal to the MTU of the encapsulated network plus
tunnel headers. Manual or upper layer (such as TCP MSS clamping)
configuration can be used to ensure that fragmentation never takes
place, however, in some situations this may not be feasible.
It is strongly RECOMMENDED that Path MTU Discovery ([RFC1191],
[RFC1981]) be used by setting the DF bit in the IP header when Geneve
packets are transmitted over IPv4 (this is the default with IPv6).
The use of Path MTU Discovery on the transit network provides the
encapsulating endpoint with soft-state about the link that it may use
to prevent or minimize fragmentation depending on its role in the
virtualized network. For example, recommendations/guidance for
handling fragmenation in similar overlay encapsulation services like
PWE3 are provided in section 5.3 of [RFC3985].
Note that some implementations may not be capable of supporting
fragmentation or other less common features of the IP header, such as
options and extension headers.
4.1.2. DSCP and ECN
When encapsulating IP (including over Ethernet) packets in Geneve,
there are several considerations for propagating DSCP and ECN bits
from the inner header to the tunnel on transmission and the reverse
on reception.
[RFC2983] provides guidance for mapping DSCP between inner and outer
IP headers. Network virtualization is typically more closely aligned
with the Pipe model described, where the DSCP value on the tunnel
header is set based on a policy (which may be a fixed value, one
based on the inner traffic class, or some other mechanism for
grouping traffic). Aspects of the Uniform model (which treats the
inner and outer DSCP value as a single field by copying on ingress
and egress) may also apply, such as the ability to remark the inner
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header on tunnel egress based on transit marking. However, the
Uniform model is not conceptually consistent with network
virtualization, which seeks to provide strong isolation between
encapsulated traffic and the physical network.
[RFC6040] describes the mechanism for exposing ECN capabilities on IP
tunnels and propagating congestion markers to the inner packets.
This behavior MUST be followed for IP packets encapsulated in Geneve.
4.1.3. Broadcast and Multicast
Geneve tunnels may either be point-to-point unicast between two
endpoints or may utilize broadcast or multicast addressing. It is
not required that inner and outer addressing match in this respect.
For example, in physical networks that do not support multicast,
encapsulated multicast traffic may be replicated into multiple
unicast tunnels or forwarded by policy to a unicast location
(possibly to be replicated there).
With physical networks that do support multicast it may be desirable
to use this capability to take advantage of hardware replication for
encapsulated packets. In this case, multicast addresses may be
allocated in the physical network corresponding to tenants,
encapsulated multicast groups, or some other factor. The allocation
of these groups is a component of the control plane and therefore
outside of the scope of this document. When physical multicast is in
use, the 'C' bit in the Geneve header may be used with groups of
devices with heterogeneous capabilities as each device can interpret
only the options that are significant to it if they are not critical.
4.1.4. Unidirectional Tunnels
Generally speaking, a Geneve tunnel is a unidirectional concept. IP
is not a connection oriented protocol and it is possible for two
endpoints to communicate with each other using different paths or to
have one side not transmit anything at all. As Geneve is an IP-based
protocol, the tunnel layer inherits these same characteristics.
It is possible for a tunnel to encapsulate a protocol, such as TCP,
which is connection oriented and maintains session state at that
layer. In addition, implementations MAY model Geneve tunnels as
connected, bidirectional links, such as to provide the abstraction of
a virtual port. In both of these cases, bidirectionality of the
tunnel is handled at a higher layer and does not affect the operation
of Geneve itself.
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4.2. Constraints on Protocol Features
Geneve is intended to be flexible to a wide range of current and
future applications. As a result, certain constraints may be placed
on the use of metadata or other aspects of the protocol in order to
optimize for a particular use case. For example, some applications
may limit the types of options which are supported or enforce a
maximum number or length of options. Other applications may only
handle certain encapsulated payload types, such as Ethernet or IP.
This could be either globally throughout the system or, for example,
restricted to certain classes of devices or network paths.
These constraints may be communicated to tunnel endpoints either
explicitly through a control plane or implicitly by the nature of the
application. As Geneve is defined as a data plane protocol that is
control plane agnostic, the exact mechanism is not defined in this
document.
4.2.1. Constraints on Options
While Geneve options are more flexible, a control plane may restrict
the number of option TLVs as well as the order and size of the TLVs,
between tunnel endpoints, to make it simpler for a data plane
implementation in software or hardware to handle
[I-D.ietf-nvo3-encap]. For example, there may be some critical
information such as a secure hash that must be processed in a certain
order to provide lowest latency.
A control plane may negotiate a subset of option TLVs and certain TLV
ordering, as well may limit the total number of option TLVs present
in the packet, for example, to accommodate hardware capable of
processing fewer options [I-D.ietf-nvo3-encap]. Hence, a control
plane needs to have the ability to describe the supported TLVs subset
and their order to the tunnel end points. In the absence of a
control plane, alternative configuration mechanisms may be used for
this purpose. The exact mechanism is not defined in this document.
4.3. NIC Offloads
Modern NICs currently provide a variety of offloads to enable the
efficient processing of packets. The implementation of many of these
offloads requires only that the encapsulated packet be easily parsed
(for example, checksum offload). However, optimizations such as LSO
and LRO involve some processing of the options themselves since they
must be replicated/merged across multiple packets. In these
situations, it is desirable to not require changes to the offload
logic to handle the introduction of new options. To enable this,
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some constraints are placed on the definitions of options to allow
for simple processing rules:
o When performing LSO, a NIC MUST replicate the entire Geneve header
and all options, including those unknown to the device, onto each
resulting segment. However, a given option definition may
override this rule and specify different behavior in supporting
devices. Conversely, when performing LRO, a NIC MAY assume that a
binary comparison of the options (including unknown options) is
sufficient to ensure equality and MAY merge packets with equal
Geneve headers.
o Options MUST NOT be reordered during the course of offload
processing, including when merging packets for the purpose of LRO.
o NICs performing offloads MUST NOT drop packets with unknown
options, including those marked as critical.
There is no requirement that a given implementation of Geneve employ
the offloads listed as examples above. However, as these offloads
are currently widely deployed in commercially available NICs, the
rules described here are intended to enable efficient handling of
current and future options across a variety of devices.
4.4. Inner VLAN Handling
Geneve is capable of encapsulating a wide range of protocols and
therefore a given implementation is likely to support only a small
subset of the possibilities. However, as Ethernet is expected to be
widely deployed, it is useful to describe the behavior of VLANs
inside encapsulated Ethernet frames.
As with any protocol, support for inner VLAN headers is OPTIONAL. In
many cases, the use of encapsulated VLANs may be disallowed due to
security or implementation considerations. However, in other cases
trunking of VLAN frames across a Geneve tunnel can prove useful. As
a result, the processing of inner VLAN tags upon ingress or egress
from a tunnel endpoint is based upon the configuration of the
endpoint and/or control plane and not explicitly defined as part of
the data format.
5. Interoperability Issues
Viewed exclusively from the data plane, Geneve does not introduce any
interoperability issues as it appears to most devices as UDP packets.
However, as there are already a number of tunnel protocols deployed
in network virtualization environments, there is a practical question
of transition and coexistence.
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Since Geneve is a superset of the functionality of the most common
protocols used for network virtualization (VXLAN, NVGRE ) it should
be straightforward to port an existing control plane to run on top of
it with minimal effort. With both the old and new packet formats
supporting the same set of capabilities, there is no need for a hard
transition - endpoints directly communicating with each other use any
common protocol, which may be different even within a single overall
system. As transit devices are primarily forwarding packets on the
basis of the IP header, all protocols appear similar and these
devices do not introduce additional interoperability concerns.
To assist with this transition, it is strongly suggested that
implementations support simultaneous operation of both Geneve and
existing tunnel protocols as it is expected to be common for a single
node to communicate with a mixture of other nodes. Eventually, older
protocols may be phased out as they are no longer in use.
6. Security Considerations
As encapsulated within an UDP/IP packet, Geneve does not have any
inherent security mechanisms. As a result, an attacker with access
to the underlay network transporting the IP packets has the ability
to snoop or inject packets. Legitimate but malicious tunnel
endpoints may also spoof identifiers in the tunnel header to gain
access to networks owned by other tenants.
Within a particular security domain, such as a data center operated
by a single service provider, the most common and highest performing
security mechanism is isolation of trusted components. Tunnel
traffic can be carried over a separate VLAN and filtered at any
untrusted boundaries. In addition, tunnel endpoints should only be
operated in environments controlled by the service provider, such as
the hypervisor itself rather than within a customer VM.
When crossing an untrusted link, such as the public Internet, IPsec
[RFC4301] may be used to provide authentication and/or encryption of
the IP packets formed as part of Geneve encapsulation.
Geneve does not otherwise affect the security of the encapsulated
packets. As per the guidelines of BCP72 [RFC3552], the following
sections describe potential security risks that may be applicable to
Geneve deployments and approaches to mitigate such risks.
6.1. Data Confidentiality
Geneve is a network virtualization overlay encapsulation protocol
designed to establish tunnels between network virtualization end
points (NVE) over an existing IP network. It can be used to deploy
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multi-tenant overlay networks over an existing IP underlay network in
a public or private data center. The overlay service is typically
provided by a service provider, for example a cloud services provider
or a private data center operator. Due to the nature of multi-
tenancy in such environments, a tenant system may expect data
confidentiality to ensure its packet data is not tampered with
(active attack) in transit or a target of unauthorized monitoring
(passive attack). A tenant may expect the overlay service provider
to provide data confidentiality as part of the service or a tenant
may bring its own data confidentiality mechanisms like IPsec or TLS
to protect the data end to end between its tenant systems.
An NVE, used in multi-tenant environments, MUST have the capability
to encrypt the tenant data end to end between the NVEs. The NVEs may
use existing well established encryption mechanisms such as IPsec,
DTLs, etc., The NVEs SHOULD have a configurable option to disable the
encryption if, for example, the packet data is already encrypted by
the tenant system.
6.1.1. Inter-data center traffic
A tenant system in a customer premises (private data center) may want
to connect to tenant systems on their tenant overlay network in a
public cloud data center or a tenant may want to have its tenant
systems located in multiple geographically separated data centers for
high availability. Geneve data traffic between tenant systems across
such separated networks should be protected from threats when
traversing public networks. Any Geneve overlay data leaving the data
center network, beyond the operators security domain, for example
over a public Internet SHOULD be secured by encryption mechanisms
such as IPsec or other VPN mechanisms to protect the communications
between the NVEs when they are geographically separated over
untrusted network links. Implementation of specific data protection
mechanisms employed between data centers is beyond the scope of this
document.
6.2. Data Integrity
Geneve encapsulation is used between NVEs to establish overlay
tunnels over an existing IP underlay network. In a multi-tenant data
center, a rogue or compromised tenant system may try to launch a
passive attack such as monitoring the traffic of other tenants, or an
active attack such as spoofing or trying to inject unauthorized
Geneve encapsulated traffic into the network. To prevent such
attacks, an NVE MUST not propagate Geneve packets beyond the NVE to
tenant systems and SHOULD employ packet filtering mechanisms so as
not to forward unauthorized traffic between TSs in different tenant
networks.
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A compromised network node or a transit device within a data center
may launch an active attack trying to tamper with the Geneve packet
data between NVEs. Malicious tampering of Geneve header fields may
cause the packet from one tenant to be forwarded to a different
tenant network. If an operator determines the possibility of such
threat in their environment, the operator may choose to employ data
integrity mechanisms between NVEs. In order to prevent such risks, a
Geneve NVE MUST have the capability to protect the integrity of
Geneve packets including packet headers, options and payload on
communications between NVE pairs. A cryptographic data protection
mechanism such as IPsec may be used to provide data integrity
protection. The NVE SHOULD have a configuration option to enable or
disable the data integrity protection, based on the presence of
threats in their environment. A data center operator may choose to
deploy any other data integrity mechanisms as applicable and
supported in their underlay networks.
Geneve supports Geneve Options, so an operator may choose to use a
Geneve option TLV to provide a cryptographic data protection
mechanism, to verify the data integrity of the Geneve header, Geneve
options or the entire Geneve packet including the payload.
Implementation of such a mechanism is beyond the scope of this
document.
6.3. Authentication of NVE peers
A rogue network device or a compromised NVE in a data center
environment might be able to spoof Geneve packets as if it came from
a legitimate NVE. In order to mitigate such a risk, a Geneve NVE
MUST support an Authentication mechanism, such as IPsec AH, to ensure
that the Geneve packet originated from the intended NVE peer, in
environments where spoofing or rogue devices is a potential threat.
Other simpler source checks such as ingress filtering for VLAN/MAC/IP
address, reverse path forwarding checks, etc., may be used in certain
trusted environments to ensure Geneve packets originated from the
intended NVE peer.
6.4. Multicast/Broadcast
In typical data center networks where IP multicasting is not
supported in the underlay network, multicasting can be supported
using multiple unicast tunnels. The same security requirements as
described in the above sections can be used to protect Geneve
communications between NVE peers. If IP multicasting is supported in
the underlay network and the operator chooses to use it for multicast
traffic among Geneve endpoints, then Geneve NVEs used in such
environments SHOULD support data protection mechanisms such as IPsec
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with Multicast extensions [RFC5374] to protect multicast traffic
among Geneve NVE groups.
6.5. Control plane communications
A Network Virtualization Authority (NVA) as outlined in [RFC8014] may
be used as a control plane for configuring and managing the Geneve
NVEs. The data center operator is expected to use security
mechanisms to protect the communications between the NVA to NVEs and
use authentication mechanisms to detect any rogue or compromised NVEs
within their administrative domain. Data protection mechanisms for
control plane communication or authentication mechanisms between the
NVA and the NVEs is beyond the scope of this document.
7. IANA Considerations
IANA has allocated UDP port 6081 as the well-known destination port
for Geneve. Upon publication, the registry should be updated to cite
this document. The original request was:
Service Name: geneve
Transport Protocol(s): UDP
Assignee: Jesse Gross <jgross@vmware.com>
Contact: Jesse Gross <jgross@vmware.com>
Description: Generic Network Virtualization Encapsulation (Geneve)
Reference: This document
Port Number: 6081
In addition, IANA is requested to create a "Geneve Option Class"
registry to allocate Option Classes. This shall be a registry of
16-bit hexadecimal values along with descriptive strings. The
identifiers 0x0-0xFF are to be reserved for standardized options for
allocation by IETF Review [RFC5226] and 0xFFF0-0xFFFF for
Experimental Use. Otherwise, identifiers are to be assigned to any
organization with an interest in creating Geneve options on a First
Come First Served basis. The registry is to be populated with the
following initial values:
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+----------------+--------------------------------------+
| Option Class | Description |
+----------------+--------------------------------------+
| 0x0000..0x00FF | Unassigned - IETF Review |
| 0x0100 | Linux |
| 0x0101 | Open vSwitch |
| 0x0102 | Open Virtual Networking (OVN) |
| 0x0103 | In-band Network Telemetry (INT) |
| 0x0104 | VMware |
| 0x0105 | Amazon |
| 0x0106 | Cisco |
| 0x0107..0xFFEF | Unassigned - First Come First Served |
| 0xFFF0..FFFF | Experimental |
+----------------+--------------------------------------+
8. Contributors
The following individuals were authors of an earlier version of this
document and made significant contributions:
Pankaj Garg
Microsoft Corporation
1 Microsoft Way
Redmond, WA 98052
USA
Email: pankajg@microsoft.com
Chris Wright
Red Hat Inc.
1801 Varsity Drive
Raleigh, NC 27606
USA
Email: chrisw@redhat.com
Puneet Agarwal
Innovium, Inc.
6001 America Center Drive
San Jose, CA 95002
USA
Email: puneet@innovium.com
Kenneth Duda
Arista Networks
5453 Great America Parkway
Santa Clara, CA 95054
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USA
Email: kduda@arista.com
Dinesh G. Dutt
Cumulus Networks
140C S. Whisman Road
Mountain View, CA 94041
USA
Email: ddutt@cumulusnetworks.com
Jon Hudson
Independent
Email: jon.hudson@gmail.com
Ariel Hendel
Facebook, Inc.
1 Hacker Way
Menlo Park, CA 94025
USA
Email: ahendel@fb.com
9. Acknowledgements
The authors wish to thank Martin Casado, Bruce Davie and Dave Thaler
for their input, feedback, and helpful suggestions.
10. References
10.1. Normative References
[RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768,
DOI 10.17487/RFC0768, August 1980,
<https://www.rfc-editor.org/info/rfc768>.
[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>.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", RFC 5226,
DOI 10.17487/RFC5226, May 2008,
<https://www.rfc-editor.org/info/rfc5226>.
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10.2. Informative References
[ETYPES] The IEEE Registration Authority, "IEEE 802 Numbers", 2013,
<http://www.iana.org/assignments/ieee-802-numbers/
ieee-802-numbers.xml>.
[I-D.ietf-nvo3-dataplane-requirements]
Bitar, N., Lasserre, M., Balus, F., Morin, T., Jin, L.,
and B. Khasnabish, "NVO3 Data Plane Requirements", draft-
ietf-nvo3-dataplane-requirements-03 (work in progress),
April 2014.
[I-D.ietf-nvo3-encap]
Boutros, S., Ganga, I., Garg, P., Manur, R., Mizrahi, T.,
Mozes, D., Nordmark, E., Smith, M., Aldrin, S., and I.
Bagdonas, "NVO3 Encapsulation Considerations", draft-ietf-
nvo3-encap-01 (work in progress), October 2017.
[IEEE.802.1Q_2014]
IEEE, "IEEE Standard for Local and metropolitan area
networks--Bridges and Bridged Networks", IEEE 802.1Q-2014,
DOI 10.1109/ieeestd.2014.6991462, December 2014,
<http://ieeexplore.ieee.org/servlet/
opac?punumber=6991460>.
[RFC1191] Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191,
DOI 10.17487/RFC1191, November 1990,
<https://www.rfc-editor.org/info/rfc1191>.
[RFC1981] McCann, J., Deering, S., and J. Mogul, "Path MTU Discovery
for IP version 6", RFC 1981, DOI 10.17487/RFC1981, August
1996, <https://www.rfc-editor.org/info/rfc1981>.
[RFC2983] Black, D., "Differentiated Services and Tunnels",
RFC 2983, DOI 10.17487/RFC2983, October 2000,
<https://www.rfc-editor.org/info/rfc2983>.
[RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol
Label Switching Architecture", RFC 3031,
DOI 10.17487/RFC3031, January 2001,
<https://www.rfc-editor.org/info/rfc3031>.
[RFC3552] Rescorla, E. and B. Korver, "Guidelines for Writing RFC
Text on Security Considerations", BCP 72, RFC 3552,
DOI 10.17487/RFC3552, July 2003,
<https://www.rfc-editor.org/info/rfc3552>.
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[RFC3985] Bryant, S., Ed. and P. Pate, Ed., "Pseudo Wire Emulation
Edge-to-Edge (PWE3) Architecture", RFC 3985,
DOI 10.17487/RFC3985, March 2005,
<https://www.rfc-editor.org/info/rfc3985>.
[RFC4301] Kent, S. and K. Seo, "Security Architecture for the
Internet Protocol", RFC 4301, DOI 10.17487/RFC4301,
December 2005, <https://www.rfc-editor.org/info/rfc4301>.
[RFC5374] Weis, B., Gross, G., and D. Ignjatic, "Multicast
Extensions to the Security Architecture for the Internet
Protocol", RFC 5374, DOI 10.17487/RFC5374, November 2008,
<https://www.rfc-editor.org/info/rfc5374>.
[RFC6040] Briscoe, B., "Tunnelling of Explicit Congestion
Notification", RFC 6040, DOI 10.17487/RFC6040, November
2010, <https://www.rfc-editor.org/info/rfc6040>.
[RFC6935] Eubanks, M., Chimento, P., and M. Westerlund, "IPv6 and
UDP Checksums for Tunneled Packets", RFC 6935,
DOI 10.17487/RFC6935, April 2013,
<https://www.rfc-editor.org/info/rfc6935>.
[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,
<https://www.rfc-editor.org/info/rfc7348>.
[RFC7365] Lasserre, M., Balus, F., Morin, T., Bitar, N., and Y.
Rekhter, "Framework for Data Center (DC) Network
Virtualization", RFC 7365, DOI 10.17487/RFC7365, October
2014, <https://www.rfc-editor.org/info/rfc7365>.
[RFC7637] Garg, P., Ed. and Y. Wang, Ed., "NVGRE: Network
Virtualization Using Generic Routing Encapsulation",
RFC 7637, DOI 10.17487/RFC7637, September 2015,
<https://www.rfc-editor.org/info/rfc7637>.
[RFC8014] Black, D., Hudson, J., Kreeger, L., Lasserre, M., and T.
Narten, "An Architecture for Data-Center Network
Virtualization over Layer 3 (NVO3)", RFC 8014,
DOI 10.17487/RFC8014, December 2016,
<https://www.rfc-editor.org/info/rfc8014>.
Gross, et al. Expires January 3, 2019 [Page 28]
Internet-Draft Geneve Protocol July 2018
[VL2] Greenberg, A., et al., "VL2: A Scalable and Flexible Data
Center Network", ACM SIGCOMM Computer Communication
Review, DOI 10.1145/1594977.1592576, 2009,
<http://www.sigcomm.org/sites/default/files/ccr/
papers/2009/October/1594977-1592576.pdf>.
Authors' Addresses
Jesse Gross (editor)
Email: jesse@kernel.org
Ilango Ganga (editor)
Intel Corporation
2200 Mission College Blvd.
Santa Clara, CA 95054
USA
Email: ilango.s.ganga@intel.com
T. Sridhar (editor)
VMware, Inc.
3401 Hillview Ave.
Palo Alto, CA 94304
USA
Email: tsridhar@vmware.com
Gross, et al. Expires January 3, 2019 [Page 29]
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