draft-ietf-tsvwg-gre-in-udp-encap-09.txt   draft-ietf-tsvwg-gre-in-udp-encap-10.txt 
Network Working Group E. Crabbe Network Working Group E. Crabbe
Internet-Draft Internet-Draft
Intended status: Standard Track L. Yong Intended status: Standard Track L. Yong
Huawei USA Huawei USA
X. Xu X. Xu
Huawei Technologies Huawei Technologies
T. Herbert T. Herbert
Google Facebook
Expires: July 2016 January 26, 2016 Expires: September 2016 March 1, 2016
GRE-in-UDP Encapsulation GRE-in-UDP Encapsulation
draft-ietf-tsvwg-gre-in-udp-encap-09 draft-ietf-tsvwg-gre-in-udp-encap-10
Abstract Abstract
This document describes a method of encapsulating network protocol This document describes a method of encapsulating network protocol
packets within GRE and UDP headers. In this encapsulation, the packets within GRE and UDP headers. In this encapsulation method,
source UDP port can be used as an entropy field for purposes of load the source UDP port can be used as an entropy field for purposes of
balancing, while the protocol of the encapsulated packet in the GRE load balancing, while the protocol of the encapsulated packet in the
payload is identified by the GRE Protocol Type. This document GRE payload is identified by the GRE Protocol Type. This document
specifies requirements for two applicability scenarios for this specifies requirements for two applicability scenarios for the
encapsulation: (1) General Internet and (2) well-managed operator encapsulation: (1) General Internet; (2) Controlled Environment,
networks; less restrictive requirements apply to the latter scenario e.g. well-managed operator networks. The controlled environment has
by comparison to the former. less restrictive requirements than the general Internet.
Status of This Document Status of This Document
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six Internet-Drafts are draft documents valid for a maximum of six
months and may be updated, replaced, or obsoleted by other documents months and may be updated, replaced, or obsoleted by other documents
at any time. It is inappropriate to use Internet-Drafts as reference at any time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on July 26,2016. This Internet-Draft will expire on September 1,2016.
Copyright Notice Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with carefully, as they describe your rights and restrictions with
respect to this document. Code Components extracted from this respect to this document. Code Components extracted from this
document must include Simplified BSD License text as described in document must include Simplified BSD License text as described in
Section 4.e of the Trust Legal Provisions and are provided without Section 4.e of the Trust Legal Provisions and are provided without
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4. Encapsulation Process Procedures..............................11 4. Encapsulation Process Procedures..............................11
4.1. MTU and Fragmentation....................................11 4.1. MTU and Fragmentation....................................11
4.2. Middlebox Considerations.................................12 4.2. Middlebox Considerations.................................12
4.3. Differentiated Services and ECN Marking..................12 4.3. Differentiated Services and ECN Marking..................12
5. UDP Checksum Handling.........................................13 5. UDP Checksum Handling.........................................13
5.1. UDP Checksum with IPv4...................................13 5.1. UDP Checksum with IPv4...................................13
5.2. UDP Checksum with IPv6...................................13 5.2. UDP Checksum with IPv6...................................13
5.2.1. Middlebox Considerations............................16 5.2.1. Middlebox Considerations............................16
6. Congestion Considerations.....................................17 6. Congestion Considerations.....................................17
7. Backward Compatibility........................................18 7. Backward Compatibility........................................18
8. IANA Considerations...........................................19 8. IANA Considerations...........................................18
9. Security Considerations.......................................19 9. Security Considerations.......................................19
10. Acknowledgements.............................................20 10. Acknowledgements.............................................20
11. Contributors.................................................21 11. Contributors.................................................21
12. References...................................................22 12. References...................................................22
12.1. Normative References....................................22 12.1. Normative References....................................22
12.2. Informative References..................................23 12.2. Informative References..................................23
13. Authors' Addresses...........................................24 13. Authors' Addresses...........................................24
1. Introduction 1. Introduction
Load balancing, or more specifically statistical multiplexing of Load balancing, or more specifically statistical multiplexing of
traffic using Equal Cost Multi-Path (ECMP) and/or Link Aggregation traffic using Equal Cost Multi-Path (ECMP) and/or Link Aggregation
Groups (LAGs) in IP networks is a widely used technique for creating Groups (LAGs) in IP networks, is a widely used technique for
higher capacity networks out of lower capacity links. Most existing creating higher capacity networks out of lower capacity links. Most
routers in IP networks are already capable of distributing IP existing routers in IP networks are already capable of distributing
traffic flows over ECMP paths and/or LAGs on the basis of a hash IP traffic flows over ECMP paths and/or LAGs on the basis of a hash
function performed on flow invariant fields in IP packet headers and function performed on flow invariant fields in IP packet headers and
their payload protocol headers. Specifically, when the IP payload is their payload protocol headers. Specifically, when the IP payload is
a User Datagram Protocol (UDP)[RFC768] or Transmission Control a User Datagram Protocol (UDP)[RFC768] or Transmission Control
Protocol (TCP) [RFC793] packet, router hash functions frequently Protocol (TCP) [RFC793] packet, router hash functions frequently
operate on the five-tuple of source IP address, destination IP operate on the five-tuple of source IP address, destination IP
address, source port, destination port, and protocol/next-header address, source port, destination port, and protocol/next-header
GRE encapsulation has been widely used for many applications. For GRE encapsulation has been widely used for many applications. For
example, to redirect IP traffic to traverse a different path instead example, to redirect IP traffic to traverse a different path instead
of the default path in an operator network, to tunnel private of the default path in an operator network, to tunnel private
network traffic over a public network by use of public IP network network traffic over a public network by use of public IP network
addresses, to tunnel IPv6 traffic over an IPv4 network, tunnel addresses, to tunnel IPv6 traffic over an IPv4 network, tunnel
Ethernet traffic over IP networks [RFC7637], etc. Unfortunately, use Ethernet traffic over IP networks [RFC7637], etc. Unfortunately,
of common GRE endpoints may reduce the entropy available for use in using GRE encapsulated within IP may reduce the entropy available
load balancing, especially in environments where the GRE Key field for use in load balancing compared to TCP/IP or UDP/IP, especially
[RFC2890] is not readily available for use as entropy in forwarding in cases where the GRE Key field [RFC2890] is not used for entropy
decisions. purpose, i.e., the Key field is used for security authentication.
This document defines a generic GRE-in-UDP encapsulation for This document defines a generic GRE-in-UDP encapsulation for
tunneling network protocol packets across an IP network. The GRE tunneling network protocol packets across an IP network. The GRE
header provides payload protocol type as an EtherType in the header provides payload protocol type as an EtherType in the
protocol type field [RFC2784][GREIPV6], and the UDP header provides protocol type field [RFC2784][RFC7676], and the UDP header provides
additional entropy by way of its source port. GRE-in-UDP offers the additional entropy by way of its source port. GRE-in-UDP offers the
additional possibility of using GRE across networks that might additional possibility of using GRE across networks that might
otherwise disallow it; for instance GRE-in-UDP may be used to bridge otherwise disallow it; for instance GRE-in-UDP may be used to bridge
two islands where GRE is not used natively across the Internet. two islands where GRE is not used natively across the Internet.
This encapsulation method requires no changes to the transit IP This encapsulation method requires no changes to the transit IP
network. Hash functions in most existing IP routers may utilize and network. Hash functions in most existing IP routers may utilize and
benefit from the use of a GRE-in-UDP tunnel without needing any benefit from the use of a GRE-in-UDP tunnel without needing any
change or upgrade to their ECMP implementation. The encapsulation change or upgrade to their ECMP implementation. The encapsulation
mechanism is applicable to a variety of IP networks including Data mechanism is applicable to a variety of IP networks including Data
Center and wide area networks. Center and wide area networks.
GRE-in-UDP encapsulation may be used to encapsulate already tunneled GRE-in-UDP encapsulation may be used to encapsulate already tunneled
traffic, i.e. tunnel-in-tunnel. The tunneled traffic may use GRE-in- traffic, i.e. tunnel-in-tunnel. In this case, GRE-in-UDP tunnel
UDP or other tunnel encapsulation. In this case, GRE-in-UDP tunnel
endpoints treat other tunnel endpoints as of the end hosts for the endpoints treat other tunnel endpoints as of the end hosts for the
traffic and do not differentiate such end hosts from other end traffic and do not differentiate such end hosts from other end
hosts. hosts.
1.1. Applicability Statement 1.1. Applicability Statement
GRE-in-UDP encapsulation applies to IPv4 and IPv6 networks including GRE-in-UDP encapsulation applies to IPv4 and IPv6 networks including
the Internet. When using GRE-in-UDP encapsulation, encapsulated the Internet. When using GRE-in-UDP encapsulation, encapsulated
traffic will be treated as a UDP application in an IP network. As traffic will be treated as a UDP application in an IP delivery
such, GRE-in-UDP tunnel needs to meet UDP requirements specified in network. As such, GRE-in-UDP tunnel needs to meet UDP requirements
[RFC5405bis], which imposes limits on GRE-in-UDP tunnel usage. These specified in [RFC5405bis], which imposes limits on GRE-in-UDP tunnel
limits may depend on both the network and the nature of the usage. These limits may depend on both the network and the nature of
encapsulated traffic. For example, the GRE-in-UDP tunnel protocol the encapsulated traffic. For example, the GRE-in-UDP tunnel
does not provide any congestion control functionality beyond that of protocol does not provide any congestion control functionality
the encapsulated traffic. Therefore, GRE-in-UDP MUST be used only beyond that of the encapsulated traffic. Therefore, GRE-in-UDP MUST
with congestion controlled traffic (e.g., IP traffic) and/or within be used only with congestion controlled traffic (e.g., IP traffic)
a network that has the congestion management. and/or within a network that has the congestion management.
[RFC5405bis] considers two types of applicability where IETF [RFC5405bis] considers two types of applicability where IETF
applications utilize UDP: 1) General Internet and 2) Controlled applications utilize UDP: 1) General Internet and 2) Controlled
Environment. The controlled environment means within a single Environment. The controlled environment means within a single
administrative domain or bilaterally agreed connection between administrative domain or bilaterally agreed connection between
domains. A network under controlled environment can be domains. A network under controlled environment can be
managed/operated to meet certain condition(s), which the general managed/operated to meet certain conditions while the general
Internet can't. Tunnel protocol requirements under controlled Internet cannot be. Tunnel protocol requirements under controlled
environment can be less restrictive than the requirements in the environment can be less restrictive than the requirements in the
general Internet. This document specifies GRE-in-UDP tunnel usage in general Internet. This document specifies GRE-in-UDP tunnel usage in
the general Internet and GRE-in-UDP tunnel usage in the well-managed the general Internet and GRE-in-UDP tunnel usage in the well-managed
operator network that is an example of controlled environment. operator network that is an example of controlled environment.
For the purpose of this document, a well-managed operator network is For the purpose of this document, a well-managed operator network is
defined as an IP network that is traffic-engineered and/or otherwise defined as an IP network that is traffic-engineered and/or otherwise
managed (e.g., via use of traffic rate limiters) to avoid managed (e.g., via use of traffic rate limiters) to avoid
congestion. congestion.
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Internet as Default GRE-in-UDP Tunnel; the GRE-in-UDP tunnel usage Internet as Default GRE-in-UDP Tunnel; the GRE-in-UDP tunnel usage
in a well-managed operator network as WMON GRE-in-UDP Tunnel. in a well-managed operator network as WMON GRE-in-UDP Tunnel.
1.2. GRE-in-UDP Tunnel Usage Requirements 1.2. GRE-in-UDP Tunnel Usage Requirements
The section summarizes GRE-in-UDP tunnel requirements. The The section summarizes GRE-in-UDP tunnel requirements. The
requirements for Default GRE-in-UDP tunnel are listed in Section requirements for Default GRE-in-UDP tunnel are listed in Section
1.2.1, which applies to a GRE-in-UDP tunnel over the general 1.2.1, which applies to a GRE-in-UDP tunnel over the general
Internet; the relaxed requirements for WMON GRE-in-UDP Tunnel are Internet; the relaxed requirements for WMON GRE-in-UDP Tunnel are
listed in Section 1.2.2, which applies to a GRE-in-UDP tunnel within listed in Section 1.2.2, which applies to a GRE-in-UDP tunnel within
a well-managed operator network. These networks can be IPv4 or IPv6. a well-managed operator network. These networks can use IPv4 or IPv6.
1.2.1. Requirements for Default GRE-in-UDP Tunnel 1.2.1. Requirements for Default GRE-in-UDP Tunnel
The following is a summary of the GRE-in-UDP requirements for use The following is a summary of the GRE-in-UDP requirements for use
over the general Internet: over the general Internet:
1. UDP checksum SHOULD be used when encapsulating in IPv4. 1. UDP checksum SHOULD be used when encapsulating in IPv4.
2. UDP checksum MUST be used when encapsulating in IPv6. 2. UDP checksum MUST be used when encapsulating in IPv6.
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that does not use congestion control. that does not use congestion control.
4. UDP source port that is used for flow entropy SHOULD be set to a 4. UDP source port that is used for flow entropy SHOULD be set to a
UDP ephemeral port (49152-65535). UDP ephemeral port (49152-65535).
5. UDP source port usage MUST be configurable so that a single value 5. UDP source port usage MUST be configurable so that a single value
is used for all traffic in the tunnel (this disables use of the UDP is used for all traffic in the tunnel (this disables use of the UDP
source port to provide flow entropy). source port to provide flow entropy).
6. For IPv6 delivery networks, the flow entropy SHOULD also be 6. For IPv6 delivery networks, the flow entropy SHOULD also be
placed in the flow label field. placed in the flow label field for ECMP per [RFC6438].
7. At the tunnel ingress, any fragmentation of the incoming packet 7. At the tunnel ingress, any fragmentation of the incoming packet
(e.g., because the tunnel has an MTU that is smaller than the packet (e.g., because the tunnel has an MTU that is smaller than the packet
SHOULD be performed before encapsulation [RFC7588]. In addition, the SHOULD be performed before encapsulation [RFC7588]. In addition, the
tunnel ingress MUST apply the UDP checksum to all encapsulated tunnel ingress MUST apply the UDP checksum to all encapsulated
fragments so that the tunnel egress can validate reassembly of the fragments so that the tunnel egress can validate reassembly of the
fragments, and SHOULD use the same source UDP port for all packet fragments, and SHOULD use the same source UDP port for all packet
fragments to ensure the packet fragments traversing on the same path. fragments to ensure the packet fragments traversing on the same path.
1.2.2. Requirements Changes for WMON GRE-in-UDP Tunnel 1.2.2. Requirements Changes for WMON GRE-in-UDP Tunnel
The following lists the changed requirements for WMON GRE-in-UDP The following lists the changed requirements for WMON GRE-in-UDP
Tunnel that is used in a well-managed operator network; they replace Tunnel that is used in a well-managed operator network; they replace
requirements 1-3 listed in section 1.2.1. The requirements 4-8 in requirements 1-3 listed in section 1.2.1. The requirements 4-7 in
that section are unchanged for WMON GRE-in-UDP Tunnel. that section are unchanged for WMON GRE-in-UDP Tunnel.
1. UDP checksum MAY be used when encapsulating in IPv4. 1. UDP checksum MAY be used when encapsulating in IPv4.
2. Use of UDP checksum MUST be the default when encapsulating in 2. Use of UDP checksum MUST be the default when encapsulating in
IPv6. This default MAY be overridden via configuration of UDP zero- IPv6. This default MAY be overridden via configuration of UDP zero-
checksum mode. All usage of UDP zero-checksum mode with IPv6 is checksum mode. All usage of UDP zero-checksum mode with IPv6 is
subject to the additional requirements specified in Section 5.2. subject to the additional requirements specified in Section 5.2.
3. GRE-in-UDP tunnel MAY encapsulate traffic that is not congestion 3. GRE-in-UDP tunnel MAY encapsulate traffic that is not congestion
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3.2.1. Source Port 3.2.1. Source Port
The UDP source port contains a 16-bit entropy value that is The UDP source port contains a 16-bit entropy value that is
generated by the encapsulator to identify a flow for the generated by the encapsulator to identify a flow for the
encapsulated packet. The port value SHOULD be within the ephemeral encapsulated packet. The port value SHOULD be within the ephemeral
port range, i.e., 49152 to 65535, where the high order two bits of port range, i.e., 49152 to 65535, where the high order two bits of
the port are set to one. This provides fourteen bits of entropy for the port are set to one. This provides fourteen bits of entropy for
the inner flow identifier. In the case that an encapsulator is the inner flow identifier. In the case that an encapsulator is
unable to derive flow entropy from the payload header or the entropy unable to derive flow entropy from the payload header or the entropy
usage has to be disabled for a purpose (see section 4.2), it SHOULD usage has to be disabled to meet operational requirements (see
set a randomly selected constant value for UDP source port to avoid section 4.2), it SHOULD set a randomly selected constant value for
payload packet flow reordering, e.g., use of the system time to UDP source port to avoid payload packet flow reordering, e.g., the
yield a value that is the range of entropy values. port can be chosen as a hash of the tunnel ingress and egress IP
address.
The source port value for a flow set by an encapsulator MAY change The source port value for a flow set by an encapsulator MAY change
over the lifetime of the encapsulated flow. For instance, an over the lifetime of the encapsulated flow. For instance, an
encapsulator may change the assignment for Denial of Service (DOS) encapsulator may change the assignment for Denial of Service (DOS)
mitigation or as a means to effect routing through the ECMP network. mitigation or as a means to effect routing through the ECMP network.
An encapsulator SHOULD NOT change the source port selected for a An encapsulator SHOULD NOT change the source port selected for a
flow more than once every thirty seconds. flow more than once every thirty seconds.
For IPv6 delivery network, if IPv6 flow label load balancing is For IPv6 delivery network, if IPv6 flow label load balancing is
supported [RFC6438], the flow entropy SHOULD also be placed in the supported [RFC6438], the flow entropy SHOULD also be placed in the
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An encapsulator may set the GRE Key Present, Sequence Number Present, An encapsulator may set the GRE Key Present, Sequence Number Present,
and Checksum Present bits and associated fields in the GRE header as and Checksum Present bits and associated fields in the GRE header as
defined by [RFC2784] and [RFC2890]. The reserved bits, i.e., defined by [RFC2784] and [RFC2890]. The reserved bits, i.e.,
Reserved0, SHOULD be set zero. Reserved0, SHOULD be set zero.
The GRE checksum MAY be enabled to protect the GRE header and The GRE checksum MAY be enabled to protect the GRE header and
payload. An encapsulator SHOULD NOT enable both the GRE checksum and payload. An encapsulator SHOULD NOT enable both the GRE checksum and
UDP checksum simultaneously as this would be mostly redundant. Since UDP checksum simultaneously as this would be mostly redundant. Since
the UDP checksum covers more of the packet including the GRE header the UDP checksum covers more of the packet including the GRE header
and payload, the UDP checksum SHOULD have preference to using GRE and payload, the UDP checksum SHOULD have preference to using GRE
checksum. The GRE checksum SHOULD be used for the payload integrity checksum. The GRE checksum MAY be used for the payload integrity
check when use of UDP zero-checksum. check when use of UDP zero-checksum.
An implementation MAY use the GRE keyid to authenticate the An implementation MAY use the GRE keyid to authenticate the
encapsulator. (See Security Section) In this model, a shared value encapsulator. (See Security Section) In this model, a shared value
is either configured or negotiated between an encapsulator and is either configured or negotiated between an encapsulator and
decapsulator. When a decapsulator determines a presented keyid is decapsulator. When a decapsulator determines a presented keyid is
not valid for the source, the packet MUST be dropped. not valid for the source, the packet MUST be dropped.
Although GRE-in-UDP encapsulation protocol uses both UDP header and Although GRE-in-UDP encapsulation protocol uses both UDP header and
GRE header, it is one tunnel encapsulation protocol. GRE and UDP GRE header, it is one tunnel encapsulation protocol. GRE and UDP
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The GRE-in-UDP encapsulation allows encapsulated packets to be The GRE-in-UDP encapsulation allows encapsulated packets to be
forwarded through "GRE-in-UDP tunnels". When performing GRE-in-UDP forwarded through "GRE-in-UDP tunnels". When performing GRE-in-UDP
encapsulation by the encapsulator, the entropy value is generated by encapsulation by the encapsulator, the entropy value is generated by
the encapsulator and then be filled in the Source Port field of the the encapsulator and then be filled in the Source Port field of the
UDP header. The Destination Port field is set to a value (TBD) to UDP header. The Destination Port field is set to a value (TBD) to
indicate that the UDP tunnel payload is a GRE packet. The Protocol indicate that the UDP tunnel payload is a GRE packet. The Protocol
Type header field in GRE header is set to the EtherType value Type header field in GRE header is set to the EtherType value
corresponding to the protocol of the encapsulated packet. corresponding to the protocol of the encapsulated packet.
Intermediate routers, upon receiving these UDP encapsulated packets, Intermediate routers, upon receiving these UDP encapsulated packets,
could balance these packets based on the hash of the five-tuple of could load balance these packets based on the hash of the five-tuple
UDP packets. of UDP packets.
Upon receiving these UDP encapsulated packets, the decapsulator Upon receiving these UDP encapsulated packets, the decapsulator
decapsulates them by removing the UDP and GRE headers and then decapsulates them by removing the UDP and GRE headers and then
processes them accordingly. processes them accordingly.
GRE-in-UDP allows encapsulation of unicast, broadcast, or multicast GRE-in-UDP allows encapsulation of unicast, broadcast, or multicast
traffic. Entropy may be generated from the header of encapsulated traffic. Entropy may be generated from the header of encapsulated
unicast or broadcast/multicast packets at an encapsulator. The unicast or broadcast/multicast packets at an encapsulator. The
mapping mechanism between the encapsulated multicast traffic and the mapping mechanism between the encapsulated multicast traffic and the
multicast capability in the IP network is transparent and multicast capability in the IP network is transparent and
independent to the encapsulation and is otherwise outside the scope independent to the encapsulation and is otherwise outside the scope
of this document. of this document.
To provide entropy for ECMP, GRE-in-UDP does not rely on GRE keep- To provide entropy for ECMP, GRE-in-UDP does not rely on GRE keep-
alive. It is RECOMMENED no use of GRE keep-alive in the GRE-in-UDP alive. It is RECOMMENED not to use GRE keep-alive in the GRE-in-UDP
tunnel. This aligns with middlebox traversal guidelines in Section tunnel. This aligns with middlebox traversal guidelines in Section
3.5 of [RFC5405bis]. 3.5 of [RFC5405bis].
4.1. MTU and Fragmentation 4.1. MTU and Fragmentation
Regarding packet fragmentation, an encapsulator/decapsulator SHOULD Regarding packet fragmentation, an encapsulator/decapsulator SHOULD
be compliant with [RFC7588] and the encapsulator MUST fragment the be compliant with [RFC7588] and perform fragmentation before the
packet before the encapsulation. For this case, the MTU for the encapsulation. The size of fragments SHOULD be less or equal to the
payload SHOULD be less or equal to the PMTU associated with the path PMTU associated with the path between the GRE ingress and the GRE
between the GRE ingress and the GRE egress nodes minus the GRE and egress nodes minus the GRE and UDP overhead, assuming the egress
UDP overhead, assuming the egress resemble MTU is larger than PMTU. resemble MTU is larger than PMTU. When applying payload fragment,
When applying payload fragment, the UDP checksum MUST be used so the UDP checksum MUST be used so that the receiving endpoint can
that the receiving endpoint can validate reassembly of the fragments; validate reassembly of the fragments; the same src UDP port SHOULD
the same src UDP port SHOULD be used for all packet fragments to be used for all packet fragments to ensure the transit routers will
ensure the transit routers will forward the fragments on the same forward the fragments on the same path.
path.
If a tunnel operator is able to control the payload MTU size, the If a tunnel operator is able to control the payload MTU size, the
tunnel operator SHOULD factor in the additional bytes of tunnel tunnel operator SHOULD factor in the additional bytes of tunnel
overhead when considering the MTU size to avoid the likelihood of overhead when considering the MTU size to avoid the likelihood of
fragmentation. fragmentation.
4.2. Middlebox Considerations 4.2. Middlebox Considerations
The Source Port number of the UDP header is pertinent to the The Source Port number of the UDP header is pertinent to the
middlebox behavior. Network Address/Port Translator (NAPT) is the middlebox behavior. Network Address/Port Translator (NAPT) is the
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in GRE-in-UDP tunnel. in GRE-in-UDP tunnel.
Each UDP tunnel is unidirectional, as GRE-in-UDP traffic is sent to Each UDP tunnel is unidirectional, as GRE-in-UDP traffic is sent to
the GRE-in-UDP Destination Port (TBD), and in particular, is never the GRE-in-UDP Destination Port (TBD), and in particular, is never
sent back to any port used as a UDP Source Port (which serves solely sent back to any port used as a UDP Source Port (which serves solely
as a source of entropy). It is common that a middlebox (e.g., as a source of entropy). It is common that a middlebox (e.g.,
firewall) assume that bidirectional traffic uses a common pair of firewall) assume that bidirectional traffic uses a common pair of
UDP ports. This assumption also conflicts with the use of the UDP UDP ports. This assumption also conflicts with the use of the UDP
source port number as entropy. source port number as entropy.
Hence, use UDP src port for entropy may impact middlebox behavior. Hence, use of the UDP src port for entropy may impact middlebox
If a GRE-in-UDP tunnel is expected to pass a middlebox, to avoid the behavior. If a GRE-in-UDP tunnel is expected to pass a middlebox, to
impact, the operator either disable UDP source port for entropy or avoid the impact, the operator either disable UDP source port for
configure the middlebox to deal with the UDP source port variation. entropy or configure the middlebox to deal with the UDP source port
variation.
4.3. Differentiated Services and ECN Marking 4.3. Differentiated Services and ECN Marking
To ensure that tunneled traffic gets the same treatment over the IP To ensure that tunneled traffic gets the same treatment over the IP
network, prior to the encapsulation process, an encapsulator should network, prior to the encapsulation process, an encapsulator should
process the payload to get the proper parameters to fill into the IP process the payload to get the proper parameters to fill into the IP
header such as DiffServ [RFC2983]. Encapsulation end points that header such as DiffServ [RFC2983]. Encapsulation end points that
support Explicit Congestion Notification (ECN) must use the method support Explicit Congestion Notification (ECN) must use the method
described in [RFC6040] for ECN marking propagation. The congestion described in [RFC6040] for ECN marking propagation. The congestion
control process is outside of the scope of this document. control process is outside of the scope of this document.
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5.2. UDP Checksum with IPv6 5.2. UDP Checksum with IPv6
For UDP in IPv6, the UDP checksum MUST be processed as specified in For UDP in IPv6, the UDP checksum MUST be processed as specified in
[RFC768] and [RFC2460] for both transmit and receive. [RFC768] and [RFC2460] for both transmit and receive.
When UDP is used over IPv6, the UDP checksum is relied upon to When UDP is used over IPv6, the UDP checksum is relied upon to
protect both the IPv6 and UDP headers from corruption. As such, protect both the IPv6 and UDP headers from corruption. As such,
Default GRE-in-UDP Tunnel MUST perform UDP checksum; WMON GRE-in-UDP Default GRE-in-UDP Tunnel MUST perform UDP checksum; WMON GRE-in-UDP
Tunnel MAY be configured with the UDP zero-checksum mode if the Tunnel MAY be configured with the UDP zero-checksum mode if the
well-managed operator network meets at least one of following well-managed operator network or a set of closely cooperating well-
conditions and/or within a set of closely cooperating well-managed managed operator networks (such as by network operators who have
operator network administrations (such as network operators who have
agreed to work together in order to jointly provide specific agreed to work together in order to jointly provide specific
services). services) meet at least one of following conditions:
a. Under single administrative control where it is known (perhaps a. It is known (perhaps through knowledge of equipment types and
through knowledge of equipment types and lower layer checks) that lower layer checks) that packet corruption is exceptionally
packet corruption is exceptionally unlikely and where the unlikely and where the operator is willing to take the risk of
operator is willing to take the risk of undetected packet undetected packet corruption.
corruption.
b. Under single administrative control (such as within a single b. It is judged through observational measurements (perhaps of
operator's network) where it is judged through observational historic or current traffic flows that use a non-zero checksum)
measurements (perhaps of historic or current traffic flows that that the level of packet corruption is tolerably low and where
use a non-zero checksum) that the level of packet corruption is the operator is willing to take the risk of undetected packet
tolerably low and where the operator is willing to take the risk corruption.
of undetected packet corruption.
c. Carrying applications that are tolerant of mis-delivered or c. Carrying applications that are tolerant of mis-delivered or
corrupted packets (perhaps through higher layer checksum, corrupted packets (perhaps through higher layer checksum,
validation, and retransmission or transmission redundancy) where validation, and retransmission or transmission redundancy) where
the operator is willing to rely on the applications using the the operator is willing to rely on the applications using the
tunnel to survive any corrupt packets. tunnel to survive any corrupt packets.
As such, Default GRE-in-UDP tunnel MUST perform UDP checksum; WMON The following requirements apply to WMON GRE-in-UDP Tunnel that use
GRE-in-UDP Tunnel MUST perform UDP checksum by default, this default UDP zero-checksum mode:
MAY be overridden via configuration of UDP zero-checksum mode
subject to the additional requirements specified below.
The following additional requirements apply to WMON GRE-in-UDP
Tunnel that use UDP zero-checksum mode:
a. Use of the UDP checksum with IPv6 MUST be the default a. Use of the UDP checksum with IPv6 MUST be the default
configuration of all GRE-in-UDP tunnels. configuration of all GRE-in-UDP tunnels.
b. The GRE-in-UDP tunnel implementation MUST comply with all b. The GRE-in-UDP tunnel implementation MUST comply with all
requirements specified in Section 4 of [RFC6936] and with requirements specified in Section 4 of [RFC6936] and with
requirement 1 specified in Section 5 of [RFC6936]. requirement 1 specified in Section 5 of [RFC6936].
c. The tunnel decapsulator SHOULD only allow the use of UDP zero- c. The tunnel decapsulator SHOULD only allow the use of UDP zero-
checksum mode for IPv6 on a single received UDP Destination checksum mode for IPv6 on a single received UDP Destination
skipping to change at page 15, line 21 skipping to change at page 15, line 14
e. The tunnel encapsulator SHOULD use different IPv6 addresses for e. The tunnel encapsulator SHOULD use different IPv6 addresses for
each GRE-in-UDP tunnel that uses UDP zero-checksum mode each GRE-in-UDP tunnel that uses UDP zero-checksum mode
regardless of the decapsulator in order to strengthen the regardless of the decapsulator in order to strengthen the
decapsulator's check of the IPv6 source address (i.e., the same decapsulator's check of the IPv6 source address (i.e., the same
IPv6 source address SHOULD NOT be used with more than one IPv6 IPv6 source address SHOULD NOT be used with more than one IPv6
destination address, independent of whether that destination destination address, independent of whether that destination
address is a unicast or multicast address). When this is not address is a unicast or multicast address). When this is not
possible, it is RECOMMENDED to use each source IPv6 address for possible, it is RECOMMENDED to use each source IPv6 address for
as few UDP zero-checksum mode GRE-in-UDP tunnels as is feasible. as few UDP zero-checksum mode GRE-in-UDP tunnels as is feasible.
Note that if UDP checksum is used, such restriction is not
necessary.
f. When any middlebox exists on the path of GRE-in-UDP tunnel, it f. When any middlebox exists on the path of a GRE-in-UDP tunnel,
is RECOMMENDED to use the default mode, i.e. use UDP checksum, it is RECOMMENDED to use the default mode, i.e. use UDP
to reduce the chance that the encapsulated packets to be checksum, to reduce the chance that the encapsulated packets to
dropped. be dropped.
g. Any middlebox for UDP zero-checksum mode for IPv6 MUST comply g. Any middlebox that allows UDP zero-checksum mode for IPv6 MUST
with requirement 1 and 8-10 in Section 5 of [RFC6936]. comply with requirement 1 and 8-10 in Section 5 of [RFC6936].
h. Measures SHOULD be taken to prevent IPv6 traffic with zero UDP h. Measures SHOULD be taken to prevent IPv6 traffic with zero UDP
checksums from "escaping" to the general Internet; see Section checksums from "escaping" to the general Internet; see Section
6 for examples of such measures. 6 for examples of such measures.
i. IPv6 traffic with zero UDP checksums MUST be actively monitored i. IPv6 traffic with zero UDP checksums MUST be actively monitored
for errors by the network operator. For example, the operator for errors by the network operator. For example, the operator
may monitor Ethernet layer packet error rates. may monitor Ethernet layer packet error rates.
j. If a packet with a non-zero checksum is received, the checksum j. If a packet with a non-zero checksum is received, the checksum
skipping to change at page 16, line 5 skipping to change at page 15, line 44
have been configured with UDP zero-checksum mode. have been configured with UDP zero-checksum mode.
The above requirements do not change either the requirements The above requirements do not change either the requirements
specified in [RFC2460] as modified by [RFC6935] or the requirements specified in [RFC2460] as modified by [RFC6935] or the requirements
specified in [RFC6936]. specified in [RFC6936].
The requirement to check the source IPv6 address in addition to the The requirement to check the source IPv6 address in addition to the
destination IPv6 address, plus the strong recommendation against destination IPv6 address, plus the strong recommendation against
reuse of source IPv6 addresses among GRE-in-UDP tunnels collectively reuse of source IPv6 addresses among GRE-in-UDP tunnels collectively
provide some mitigation for the absence of UDP checksum coverage of provide some mitigation for the absence of UDP checksum coverage of
the IPv6 header. Additional assurance is provided by the well- the IPv6 header. A well-managed operator network that satisfies at
managed operator network that satisfies at least one of three least one of three conditions listed above in this section provides
conditions listed in this section (beginning). additional assurance.
Hence GRE-in-UDP is suitable for transmission over lower layers in GRE-in-UDP is suitable for transmission over lower layers in the
the well-managed operator networks that are allowed by the well-managed operator networks that are allowed by the exceptions
exceptions stated above and the rate of corruption of the inner IP stated above and the rate of corruption of the inner IP packet on
packet on such networks is not expected to increase by comparison to such networks is not expected to increase by comparison to GRE
GRE traffic that is not encapsulated in UDP. For these reasons, traffic that is not encapsulated in UDP. For these reasons, GRE-in-
GRE-in-UDP does not provide an additional integrity check except UDP does not provide an additional integrity check except when GRE
when GRE checksum is used when UDP zero-checksum mode is used with checksum is used when UDP zero-checksum mode is used with IPv6, and
IPv6, and this design is in accordance with requirements 2, 3 and 5 this design is in accordance with requirements 2, 3 and 5 specified
specified in Section 5 of [RFC6936]. in Section 5 of [RFC6936].
GRE does not accumulate incorrect state as a consequence of GRE GRE does not accumulate incorrect state as a consequence of GRE
header corruption. A corrupt GRE packet may result in either packet header corruption. A corrupt GRE packet may result in either packet
discard or forwarding of the packet without accumulation of GRE discard or forwarding of the packet without accumulation of GRE
state. Active monitoring of GRE-in-UDP traffic for errors is state. Active monitoring of GRE-in-UDP traffic for errors is
REQUIRED as occurrence of errors will result in some accumulation of REQUIRED as occurrence of errors will result in some accumulation of
error information outside the protocol for operational and error information outside the protocol for operational and
management purposes. This design is in accordance with requirement 4 management purposes. This design is in accordance with requirement 4
specified in Section 5 of [RFC6936]. specified in Section 5 of [RFC6936].
The remaining requirements specified in Section 5 of [RFC6936] are The remaining requirements specified in Section 5 of [RFC6936] are
inapplicable to GRE-in-UDP. Requirements 6 and 7 do not apply not applicable to GRE-in-UDP. Requirements 6 and 7 do not apply
because GRE does not have a GRE-generic control feedback mechanism. because GRE does not include a control feedback mechanism.
Requirements 8-10 are middlebox requirements that do not apply to Requirements 8-10 are middlebox requirements that do not apply to
GRE-in-UDP tunnel endpoints, but see Section 5.2.1 for further GRE-in-UDP tunnel endpoints (see Section 5.2.1 for further middle
middle box discussion. box discussion).
It is worth mentioning that the use of a zero UDP checksum should It is worth mentioning that the use of a zero UDP checksum should
present the equivalent risk of undetected packet corruption when present the equivalent risk of undetected packet corruption when
sending similar packet using GRE-in-IPv6 without UDP [GREIPV6] and sending similar packet using GRE-in-IPv6 without UDP [RFC7676] and
without GRE checksums. without GRE checksums.
In summary, WMON GRE-in-UDP Tunnel is allowed to use UDP-zero- In summary, WMON GRE-in-UDP Tunnel is allowed to use UDP-zero-
checksum mode for IPv6, when additional requirements stated above checksum mode for IPv6 when the conditions and requirements stated
are provided. Otherwise the UDP checksum MUST be used for IPv6 as above are met. Otherwise the UDP checksum MUST be used for IPv6 as
specified in [RFC768] and [RFC2460]. Use of GRE checksum favors when specified in [RFC768] and [RFC2460]. Use of GRE checksum is
the UDP checksum is not used. recommended when the UDP checksum is not used.
5.2.1. Middlebox Considerations 5.2.1. Middlebox Considerations
IPv6 datagrams with a zero UDP checksum will not be passed by any IPv6 datagrams with a zero UDP checksum will not be passed by any
middlebox that validates the checksum based on [RFC2460] or that middlebox that validates the checksum based on [RFC2460] or that
updates the UDP checksum field, such as NATs or firewalls. Changing updates the UDP checksum field, such as NATs or firewalls. Changing
this behavior would require such middleboxes to be updated to this behavior would require such middleboxes to be updated to
correctly handle datagrams with zero UDP checksums. The GRE-in-UDP correctly handle datagrams with zero UDP checksums. The GRE-in-UDP
encapsulation does not provide a mechanism to safely fall back to encapsulation does not provide a mechanism to safely fall back to
using a checksum when a path change occurs redirecting a tunnel over using a checksum when a path change occurs redirecting a tunnel over
skipping to change at page 17, line 20 skipping to change at page 17, line 13
holed by that middlebox. holed by that middlebox.
As such, when any middlebox exists on the path of GRE-in-UDP tunnel, As such, when any middlebox exists on the path of GRE-in-UDP tunnel,
it is RECOMMENDED to use the UDP checksum to reduce the chance that it is RECOMMENDED to use the UDP checksum to reduce the chance that
the encapsulated packets to be dropped. Recommended changes to allow the encapsulated packets to be dropped. Recommended changes to allow
firewalls, NATs and other middleboxes to support use of an IPv6 zero firewalls, NATs and other middleboxes to support use of an IPv6 zero
UDP checksum are described in Section 5 of [RFC6936]. UDP checksum are described in Section 5 of [RFC6936].
6. Congestion Considerations 6. Congestion Considerations
Section 3.1.3 of [RFC5405] discussed the congestion implications of Section 3.1.9 of [RFC5405bis] discussed the congestion implications
UDP tunnels. As discussed in [RFC5405], because other flows can of UDP tunnels. As discussed in [RFC5405bis], because other flows
share the path with one or more UDP tunnels, congestion control can share the path with one or more UDP tunnels, congestion control
[RFC2914] needs to be considered. [RFC2914] needs to be considered.
The impact of congestion must be considered both in terms of the The impact of congestion must be considered both in terms of the
effect on the rest of the network of a UDP tunnel that is consuming effect on the rest of the network containing a UDP, and in terms of
excessive capacity, and in terms of the effect on the flows using the effect on the flows using the UDP tunnels. The potential impact
the UDP tunnels. The potential impact of congestion from a UDP of congestion from a UDP tunnel depends upon what sort of traffic is
tunnel depends upon what sort of traffic is carried over the tunnel, carried over the tunnel, as well as the path of the tunnel.
as well as the path of the tunnel.
In many cases, GRE-in-UDP is used to carry IP traffic. IP traffic is In many cases, GRE-in-UDP is used to carry IP traffic. IP traffic is
generally assumed to be congestion controlled, and thus a tunnel generally assumed to be congestion controlled, and thus a tunnel
carrying general IP traffic generally does not need additional carrying general IP traffic generally does not need additional
congestion control mechanisms. congestion control mechanisms.
However, GRE-in-UDP tunnel can be used in some cases to carry GRE-in-UDP tunnel can be used in some cases to carry traffic that is
traffic that is not necessarily congestion controlled. For example, not necessarily congestion controlled. For example, GRE-in-UDP may
GRE-in-UDP may be used to carry MPLS that carries pseudowire or VPN be used to carry MPLS that carries pseudowire or VPN traffic where
traffic where specific bandwidth guarantees are provided to each specific bandwidth guarantees are provided to each pseudowire or to
pseudowire or to each VPN. In such cases, network operators may each VPN. In such cases, network operators may avoid congestion by
avoid congestion by careful provisioning of their networks, by rate careful provisioning of their networks, by rate limiting of user
limiting of user data traffic, and traffic engineer according to data traffic, and traffic engineering according to path capacity.
path capacity. For this reason, GRE-in-UDP tunnel MUST be used For this reason, GRE-in-UDP tunnel MUST be used within a single
within a single operator's network that utilizes careful operator's network that utilizes careful provisioning (e.g., rate
provisioning (e.g., rate limiting at the entries of the network limiting at the entries of the network while over-provisioning
while over-provisioning network capacity) to ensure against network capacity) to ensure against congestion, or within a limited
congestion, or within a limited number of networks whose operators number of networks whose operators closely cooperate in order to
closely cooperate in order to jointly provide this same careful jointly provide this same careful provisioning.
provisioning.
The default GRE-in-UDP tunnel can be used to carry IP traffic that The default GRE-in-UDP tunnel can be used to carry IP traffic that
is known to be congestion controlled on the Internet. Internet IP is known to be congestion controlled on the Internet. Internet IP
traffic is generally assumed to be congestion-controlled. The traffic is generally assumed to be congestion-controlled. The
default GRE-in-UDP tunnel MUST NOT be used over the general Internet, default GRE-in-UDP tunnel MUST NOT be used over the general Internet,
or over non-cooperating network operators, to carry traffic that is or over non-cooperating network operators, to carry traffic that is
not congestion-controlled. not congestion-controlled.
WMON GRE-in-UDP Tunnel is used within a well-managed operator WMON GRE-in-UDP Tunnel is used within a well-managed operator
network so that it can carry the traffic that is not necessary network so that it can carry the traffic that is not necessarily
congestion controlled. Measures SHOULD be taken to prevent non- congestion controlled. Measures SHOULD be taken to prevent non-
congestion-controlled GRE-in-UDP traffic from "escaping" to the congestion-controlled GRE-in-UDP traffic from "escaping" to the
general Internet, e.g.: general Internet, e.g.:
o Physical or logical isolation of the links carrying GRE-in-UDP o Physical or logical isolation of the links carrying GRE-in-UDP
from the general Internet. from the general Internet.
o Deployment of packet filters that block the UDP ports assigned o Deployment of packet filters that block the UDP ports assigned
for GRE-in-UDP. for GRE-in-UDP.
o Imposition of restrictions on GRE-in-UDP traffic by software o Imposition of restrictions on GRE-in-UDP traffic by software
tools used to set up GRE-in-UDP tunnels between specific end tools used to set up GRE-in-UDP tunnels between specific end
systems (as might be used within a single data center). For systems (as might be used within a single data center). For
examples, a GRE-in-UDP tunnel only carries IP traffic or a GRE- examples, a GRE-in-UDP tunnel only carries IP traffic or a GRE-
in-UDP tunnel supports NVEGRE encapsulation only (Although the in-UDP tunnel supports NVGRE encapsulation [RFC7637] only
payload type is Ethernet in NVGRE, NVGRE protocol mandates that (Although the payload type is Ethernet in NVGRE, NVGRE protocol
the payload of Ethernet is IP). mandates that the payload of Ethernet is IP).
o Use of a "Circuit Breaker" for the tunneled traffic as described o Use of a "Circuit Breaker" for the tunneled traffic as described
in [CB]. in [CB].
7. Backward Compatibility 7. Backward Compatibility
In general, tunnel ingress routers have to be upgraded in order to In general, tunnel ingress routers have to be upgraded in order to
support the encapsulations described in this document. support the encapsulations described in this document.
No change is required at transit routers to support forwarding of No change is required at transit routers to support forwarding of
the encapsulation described in this document. the encapsulation described in this document.
If a router that is intended for use as a decapsulator does not If a router that is intended for use as a decapsulator does not
support or enable GRE-in-UDP encapsulation described in this support or enable GRE-in-UDP encapsulation described in this
document, it will not be listening on the destination port (TBD). document, it should not be listening on the destination port (TBD).
In these cases, the router will conform to normal UDP processing and In these cases, the router will conform to normal UDP processing and
respond to an encapsulator with an ICMP message indicating "port respond to an encapsulator with an ICMP message indicating "port
unreachable" according to [RFC792]. Upon receiving this ICMP unreachable" according to [RFC792]. Upon receiving this ICMP
message, the node MUST NOT continue to use GRE-in-UDP encapsulation message, the node MUST NOT continue to use GRE-in-UDP encapsulation
toward this peer without management intervention. toward this peer without management intervention.
8. IANA Considerations 8. IANA Considerations
IANA is requested to make the following allocations: IANA is requested to make the following allocations:
skipping to change at page 20, line 23 skipping to change at page 20, line 14
decapsulators (although different source and/or destination IP decapsulators (although different source and/or destination IP
addresses may be involved -see Section 5.2 for discussion of one addresses may be involved -see Section 5.2 for discussion of one
situation where use of different source IP addresses is important). situation where use of different source IP addresses is important).
In the case that UDP source port for entropy usage is disabled, a In the case that UDP source port for entropy usage is disabled, a
random port SHOULD be selected in order to minimize the random port SHOULD be selected in order to minimize the
vulnerability to off-path attacks.[RFC6056] The random port may also vulnerability to off-path attacks.[RFC6056] The random port may also
be periodically changed to mitigate certain denial of service be periodically changed to mitigate certain denial of service
attacks as mentioned in Section 3.2. attacks as mentioned in Section 3.2.
Using one standardized value in UDP destination port for an Using one standardized value as the UDP destination port for an
encapsulation indication may increase the vulnerability of off-path encapsulation indication may increase the vulnerability of off-path
attack. To overcome this, an alternate port may be agreed upon to attack. To overcome this, an alternate port may be agreed upon to
use between an encapsulator and decapsulator [RFC6056]. How the use between an encapsulator and decapsulator [RFC6056]. How the
encapsulator end points communicate the value is outside scope of encapsulator end points communicate the value is outside scope of
this document. this document.
This document does not require that decapsulator validates the IP This document does not require that a decapsulator validates the IP
source address of the tunneled packets (with the exception that the source address of the tunneled packets (with the exception that the
IPv6 source address MUST be validated when UDP zero-checksum mode is IPv6 source address MUST be validated when UDP zero-checksum mode is
used with IPv6), but it should be understood that failure to do so used with IPv6), but it should be understood that failure to do so
presupposes that there is effective destination-based (or a presupposes that there is effective destination-based (or a
combination of source-based and destination-based) filtering at the combination of source-based and destination-based) filtering at the
boundaries. boundaries.
Corruption of GRE header can cause a privacy and security concern Corruption of GRE header can cause a privacy and security concern
for some applications that rely on the key field for traffic for some applications that rely on the key field for traffic
segregation. When GRE key field is used for privacy and security, segregation. When GRE key field is used for privacy and security,
skipping to change at page 23, line 39 skipping to change at page 23, line 29
[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, December 1998. (IPv6) Specification", RFC 2460, December 1998.
[RFC2914] Floyd, S.,"Congestion Control Principles", RFC2914, [RFC2914] Floyd, S.,"Congestion Control Principles", RFC2914,
September 2000. September 2000.
[RFC2983] Black, D., "Differentiated Services and Tunnels", RFC2983, [RFC2983] Black, D., "Differentiated Services and Tunnels", RFC2983,
October 2000. October 2000.
[RFC3931] Lau, J., Townsley, M., and I. Goyret, "Layer Two Tunneling [RFC4787] Audet, F., et al, "network Address Translation (NAT)
Protocol - Version 3 (L2TPv3)", RFC 3931, March 2005. Behavioral Requirements for Unicast UDP", RFC4787, January
2007.
[RFC4023] Worster, T., Rekhter, Y., and E. Rosen, "Encapsulating
MPLS in IP or Generic Routing Encapsulation (GRE)", RFC
4023, March 2005.
[RFC6056] Larsen, M. and Gont, F., "Recommendations for Transport- [RFC6056] Larsen, M. and Gont, F., "Recommendations for Transport-
Protocol Port Randomization", RFC6056, January 2011. Protocol Port Randomization", RFC6056, January 2011.
[RFC6438] Carpenter, B., Amante, S., "Using the Ipv6 Flow Label for [RFC6438] Carpenter, B., Amante, S., "Using the Ipv6 Flow Label for
Equal Cost Multipath Routing and Link Aggreation in Equal Cost Multipath Routing and Link Aggreation in
Tunnels", RFC6438, November 2011. Tunnels", RFC6438, November 2011.
[RFC7588] Bonica, R., "A Fragmentation Strategy for Generic Routing [RFC7588] Bonica, R., "A Fragmentation Strategy for Generic Routing
Encapsulation (GRE)", RFC7588, July 2015. Encapsulation (GRE)", RFC7588, July 2015.
[RFC7637] Garg, P. and Wang, Y., "NVGRE: Network Virtualization [RFC7637] Garg, P. and Wang, Y., "NVGRE: Network Virtualization
Using Generic Routing Encapsulation", RFC7637, September Using Generic Routing Encapsulation", RFC7637, September
2015. 2015.
[CB] Fairhurst, G., "Network Transport Circuit Breakers", [RFC7676] Pignataro, C., Bonica, R., Krishnan, S., "IPv6 Support for
draft-ietf-tsvwg-circuit-breaker-04, work in progress. Generic Routing Encapsulation (GRE)", RFC7676, October
2015.
[GREIPV6] Pignataro, C., Bonica, R., Krishnan, S., "IPv6 Support for
Generic Routing Encapsulation (GRE)", draft-ietf-intarea-
gre-ipv6, work in progress.
[TUNNEL] Touch, J. and Townsley, M., "IP Tunnels in the Internet [CB] Fairhurst, G., "Network Transport Circuit Breakers",
Architecture", draft-ietf-intarea-tunnels-01.txt, work in draft-ietf-tsvwg-circuit-breaker-13, work in progress.
progress.
13. Authors' Addresses 13. Authors' Addresses
Edward Crabbe Edward Crabbe
Email: edward.crabbe@gmail.com Email: edward.crabbe@gmail.com
Lucy Yong Lucy Yong
Huawei Technologies, USA Huawei Technologies, USA
Email: lucy.yong@huawei.com Email: lucy.yong@huawei.com
Xiaohu Xu Xiaohu Xu
Huawei Technologies, Huawei Technologies,
Beijing, China Beijing, China
Email: xuxiaohu@huawei.com Email: xuxiaohu@huawei.com
Tom Herbert Tom Herbert
Google Facebook
1600 Amphitheatre Parkway 1 Hacker Way
Mountain View, CA Menlo Park, CA
Email : tom@herbertland.com Email : tom@herbertland.com
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