wdiff draft-ietf-6man-udpchecksums-05.txt draft-ietf-6man-udpchecksums-06.txt

Network Working Group M. Eubanks
Internet-Draft AmericaFree.TV LLC
Updates: 2460 (if approved) P. Chimento
Intended status: Standards Track Johns Hopkins University Applied
Expires: April 25, June 14, 2013 Physics Laboratory
M. Westerlund
Ericsson
October 22,
December 11, 2012

IPv6 and UDP Checksums for Tunneled Packets
draft-ietf-6man-udpchecksums-05
draft-ietf-6man-udpchecksums-06

Abstract

This document provides an update of the Internet Protocol version 6
(IPv6) specification (RFC2460) to improve the performance of IPv6 in the use
case when a tunnel protocol uses UDP with IPv6 to tunnel packets.
The performance improvement is obtained by relaxing the IPv6 UDP
checksum requirement for suitable tunneling protocol where header
information is protected on the "inner" packet being carried. This
relaxation removes the overhead associated with the computation of
UDP checksums on IPv6 packets used to carry tunnel protocols and
thereby improves the efficiency of the traversal of firewalls and
other network middleboxes by such protocols. We describe The
specification describes how the IPv6 UDP checksum requirement can be
relaxed in for the situation where the encapsulated packet itself
contains a checksum, the checksum. The limitations and risks of this approach, approach are
described, and define restrictions specified on the use of
this relaxation to mitigate these risks. the method.

Status of this Memo

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provisions of BCP 78 and BCP 79.

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Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Some Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
3. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 4
4. Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4.1. Analysis of Corruption in Tunnel Context . . . . . . . . . 5
4.2. Limitation to Tunnel Protocols . . . . . . . . . . . . . . 7
4.3. Middleboxes . . . . . . . . . . . . . . . . . . . . . . . 8
5. The Zero-Checksum Update . . . . . . . . . . . . . . . . . . . 7 8
6. Additional Observations . . . . . . . . . . . . . . . . . . . 8 9
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 10
8. Security Considerations . . . . . . . . . . . . . . . . . . . 9 10
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9 10
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9 11
10.1. Normative References . . . . . . . . . . . . . . . . . . . 9 11
10.2. Informative References . . . . . . . . . . . . . . . . . . 9 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10 11

1. Introduction

This work constitutes an update of the Internet Protocol Version 6
(IPv6) Specification [RFC2460], in the use case when a tunnel
protocol uses UDP with IPv6 to tunnel packets. With the rapid growth
of the Internet, tunneling protocols have become increasingly
important to enable the deployment of new protocols. Tunneled
protocols can be deployed rapidly, while the time to upgrade and
deploy a critical mass of routers, switches middleboxes and end hosts on the
global Internet for a new protocol is now measured in decades. At
the same time, the increasing use of firewalls and other security security-
related middleboxes means that truly new tunnel protocols, with new
protocol numbers, are also unlikely to be deployable in a reasonable
time frame, which has resulted in an increasing interest in and use
of UDP-based tunneling protocols. In such protocols, there is an
encapsulated "inner" packet, and the "outer" packet carrying the
tunneled inner packet is a UDP packet, which can pass through
firewalls and other middleboxes that perform filtering that is a fact
of life on the current Internet.

Tunnel endpoints may be routers or middleboxes aggregating traffic
from a large number of tunnel users, therefore the computation of an
additional checksum on the outer UDP packet, may be seen as an
unwarranted burden on nodes that implement a tunneling protocol,
especially if the inner packet(s) are already protected by a
checksum. In IPv4, there is a checksum on over the IP packet itself, header,
and the checksum on the outer UDP packet can may be set to zero. However
in IPv6 there is not a no checksum on in the IP packet header and RFC 2460 [RFC2460]
explicitly states that IPv6 receivers MUST discard UDP packets with a
zero checksum. So, while sending a UDP packet datagram with a zero checksum
is permitted in IPv4 packets, it is explicitly forbidden in IPv6
packets. To improve support for IPv6 UDP tunnels, this document
updates RFC 2460 to allow tunnel endpoints to use a zero UDP checksum under
constrained situations (IPv6 (primarily IPv6 tunnel transports that carry
checksum-protected packets), following the considerations applicability statements
and constraints in [I-D.ietf-6man-udpzero].

Unicast UDP Usage Guidelines for Application Designers [RFC5405]
should be consulted when reading this specification. It discusses
both UDP tunnels (Section 3.1.3) and the usage of Checksums checksums (Section
3.4).

While the origin of this specification is the problem raised by the
draft titled "Automatic IP Multicast Without Explicit Tunnels", also
known as "AMT," [I-D.ietf-mboned-auto-multicast] we expect it to have
wide applicability. Since the first version of this document, the
need for an efficient UDP tunneling mechanism has increased. Other
IETF Working Groups, notably LISP [I-D.ietf-lisp] and Softwires

[RFC5619] have expressed a need to update the UDP checksum processing
in RFC 2460. We therefore expect this update to be applicable in
future to other tunneling protocols specified by these and other IETF
Working Groups.

2. Some Terminology

For the remainder of this document, we discuss

This document discusses only IPv6, since this problem does not exist
for IPv4. Therefore all reference to 'IP' should be understood as a
reference to IPv6.

The document uses the terms "tunneling" and "tunneled" as adjectives
when describing packets. When we refer to 'tunneling packets' we
refer to the outer packet header that provides the tunneling
function. When we refer to 'tunneled packets' we refer to the inner
packet, i.e., the packet being carried in the tunnel.

2.1. 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 RFC 2119 [RFC2119].

3. Problem Statement

This document provides an update for the case where a

When using tunnel protocol
transports tunneled packets that already have a transport header with
a checksum. There is protocols based on UDP, there can be both a benefit
and a cost to computing and checking the UDP checksum of the outer
(encapsulating) UDP transport header. In certain cases, where
reducing the forwarding cost is important, such as for systems nodes that
perform the check checksum in software, where the cost may outweigh the benefit; this
benefit. This document describes a means to
avoid that cost. In the case where there is provides an inner header update for usage of the UDP
checksum with IPv6. The update is specified for use by a tunnel
protocol that transports packets that are themselves protected by a
checksum.

4. Discussion

Applicability Statement for the use of IPv6 UDP Checksum Considerations Datagrams with Zero
Checksums [I-D.ietf-6man-udpzero] describes
the issues related to
allowing UDP over IPv6 to have a valid checksum
of zero UDP checksum and is not repeated here. the
starting point for this discussion. Section 5 4 and 6 5 of
[I-D.ietf-6man-udpzero], identifies respectively identify node implementation
and inner
protocol usage requirements respectively that for datagrams sent and received with a zero
UDP checksum. These introduce constraints on the usage of a zero
checksum for UDP over IPv6. This document is
intended to satisfy these requirements.

[I-D.ietf-6man-udpzero] and mailing list discussions have noted there
is still the possibility The remainder of deep-inspection firewall devices or other
middleboxes checking this section analyses
the UDP checksum field use of the outer packet general tunnels and
thereby discarding the tunneling packets. This would be an issue
also for any legacy IPv6 system that has not implemented this update motivates why tunnel protocols are
being permitted to use the IPv6 specification. In method described in this case, update. Issues
with middleboxes are also discussed.

4.1. Analysis of Corruption in Tunnel Context

This section analyzes the impact of the different corruption modes in
the system (according context of a tunnel protocol. It indicates what needs to
RFC 2460) will discard be
considered by the zero-checksum UDP packets, designer and should log
this as an error.

The points below discuss how path errors can user of a tunnel protocol to be detected and handled
in an
robust. It also summarizes why use of a zero UDP tunneling protocol when the checksum protection is
disabled. Note that other (non-tunneling) protocols may have
different approaches, but these are not the topic of this update. We
propose the following approach to handle this problem: thought
safe for deployment.

o Context (i.e. tunneling state) should be established via by exchanging
application Protocol Data Units (PDUs) that are carried in checksummed UDP packets. That is, any control packets flowing
between the tunnel endpoints should be protected
datagrams or by UDP checksums.
The other protocols with integrity protection against
corruption. These control packets can should also contain carry any
negotiation required to enable the endpoint/adapters tunnel endpoint to accept UDP packets
datagrams with a zero
checksum. The control packets may also carry any negotiation
required to enable the endpoint/adapters to checksum and identify the set of ports that need
are used. It is important that the control traffic is robust
against corruption because undetected errors can lead to enable reception of UDP long-
lived and significant failures that affect not only the single
packet that was corrupted.

o Keep-alive datagrams with a zero
checksum.

o A system never sets the UDP checksum to zero in packets that do
not contain tunneled packets.

o UDP keep-alive packets with checksum zero can be sent should be sent to
validate
paths, given that paths the network path, because the path between tunnel
endpoints can change and so therefore the set of middleboxes in along
the path may vary change during the life of the an association. Paths with
middleboxes that are intolerant of drop datagrams with a zero UDP checksum of zero will drop
these keep-alives. To enable the keep-alives and the tunnel endpoints will to discover that. Note that and
react to this need only be done per tunnel
endpoint pair, not per tunnel context. Keep-alive behavior in a timely way, the keep-alive traffic can
should include both packets datagrams with tunnel checksums both a non-zero checksum and packets ones
with
checksums equal to a zero to enable the remote end to distinguish
between path failures and the blockage of packets with checksum
equal to zero. checksum.

o Corruption of the address information in an encapsulating packets,
i.e. IPv6 source address, destination address and/or the UDP
source port, and destination port fields :
If the restrictions in [I-D.ietf-6man-udpzero] are followed, fields. A robust tunnel
protocol should track tunnel context based on the
inner packets (tunneled packets) will be protected and run 5-tuple, i.e.
the
usual (presumably small) risk of having undetected corruption(s).
If tunneling protocol contexts contain (at a minimum) source and
destination IP addresses both the address and port for both the source and destination ports, there
are 16 possible corruption outcomes. We note
destination. A corrupted datagram that these outcomes
are not equally likely. The possible corruption outcomes may be:

* Half of the 16 possible corruption combinations have arrives at a
corrupted destination address.
may be filtered based on this check.

* If the incorrect destination is
reached and datagram header matches the node doesn't have an application for 5-tuple with a zero checksum
enabled, the
destination port, payload is matched to the wrong context. The
tunneled packet will then be dropped. If decapsulated and forwarded by the
application at
tunnel egress.

* If a corrupted datagram matches a different 5-tuple with a zero
checksum enabled, the incorrect destination payload is matched to the same tunneling
protocol wrong context,
and may be processed by the wrong tunneling protocol, if it has
passes the verification of that protocol.

* If a matching context (which can be assumed
to be corrupted datagram matches a very low probability event) the inner packet 5-tuple that does not have a
zero checksum enabled, it will be
decapsulated and forwarded. Application developers can verify discarded.

When only the context of source information is corrupted, the packets they receive using UDP, as described
in [RFC5405]. Applications that verify the context of a datagram are expected to have a high probability of discarding
corrupted data. [I-D.ietf-6man-udpzero] presents examples of
cases where corruption can inadvertently impact application
state.

* Half of could
arrive at the 8 possible corruption combinations with a correct
destination address have a corrupted source address. intended applications/protocol which will process it
and try to match it against an existing tunnel context. If the
tunnel contexts contain all elements of
protocol restricts processing to only the address-port
4-tuple, then source addresses with
established contexts the likelihood is that this corruption will be
detected. It may in fact be discarded on route due to source
address validation techniques, such as Unicast Reverse Path
Forwarding [RFC2827].

* Of the remaining 4 possibilities, with a corrupted packet enters
a valid context is reduced. When both source and destination IPv6 addresses, one has all 4
fields valid, are corrupted, this increases the
other three have one or both ports corrupted. Again, if likelihood of failing to
match a context, with the
tunneling endpoint context contains sufficient information,
these exception of errors should be detected replacing one packet
header with high probability. another one. In this case it is possible that both
are tunnels and thus the corrupted packet can match a previously
defined context.

o Corruption of source-fragmented encapsulating packets: In this
case, a tunneling protocol may reassemble fragments associated
with the wrong context at the right tunnel endpoint, or it may
reassemble fragments associated may
reassemble fragments associated with a context at the wrong tunnel
endpoint, or corrupted fragments may be reassembled at the right
context at the right tunnel endpoint. In each of these cases, the
IPv6 length of the encapsulating header may be checked (though
[I-D.ietf-6man-udpzero] points out the weakness in this check).
In addition, if the encapsulated packet is protected by a
transport (or other) checksum, these errors can be detected (with
some probability).

o Tunnel protocols using UDP have some advantages that reduce the
risk for a corrupted tunnel packet reaching a destination that
will receive it, compared to other applications. This results
from processing by the network of the inner (tunneled) packet
after being forwarded from the tunnel egress using a wrong
context:

* A tunneled packet may be forwarded to the wrong address domain,
for example a private address domain where the inner packet's
address is not routable, or may fail a source address check,
such as Unicast Reverse Path Forwarding [RFC2827], resulting in
the packet being dropped.

* The destination address of a tunneled packet may not at all be
reachable from the delivered domain. For example an Ethernet
packet where the destination MAC address is not present on the
LAN segment that was reached.

* The type of the tunneled packet may prevent delivery for
example if an IP packet payload was attempted to be interpreted
as an Ethernet packet. This is likely to result in the packet
being dropped as invalid.

* The tunneled packet checksum or integrity mechanism may detect
corruption of the inner packet caused at the same time as
corruption to the outer packet header. The resulting packet
would likely be dropped as invalid.

These different examples each help to significantly reduce the
likelihood that a corrupted inner tunneled packet is finally
delivered to a protocol listener that can be affected by the packet.
While the methods do not guarantee correctness, they can reduce the
risk of relaxing the UDP checksum requirement for a tunnel
application using IPv6.

4.2. Limitation to Tunnel Protocols

This document describes the applicability of using a zero UDP
checksum to support tunnel protocols. There are good motivations
behind this and the arguments are provided here.

o Tunnels carry inner packets that have their own semantics that
makes any corruption less likely to reach the indicated
destination and be accepted as a valid packet. This is true for
IP packets with the addition of verification that can be made by
the tunnel protocol, the networks' processing of the inner packet
headers as discussed above, and verification of the inner packet
checksums. Also non-IP inner packets are likely to be subject to
similar effects that reduce the likelihood that an mis-delivered
packet are delivered.

o Protocols that directly consume the payload must have sufficient
robustness against mis-delivered packets from any context,
including the ones that are corrupted in tunnels and any other
usage of the zero checksum. This will require an integrity
mechanism. Using a standard UDP checksum reduces the
computational load in the receiver to verify this mechanism.

o Stateful protocols or protocols where corruption causes cascade
effects need to be extra careful. In tunnel usage each
encapsulating packet provides only a transport mechanism from
tunnel ingress to tunnel egress. A corruption will commonly only
effect the single packet, not established protocol state. One
common effect is that the inner packet flow will only see a
corruption and mis-delivery of the outer packet as a lost packet.

o Some non-tunnel protocols operate with general servers that do not
know from where they will receive a packet. In such applications,
the usage of a zero UDP checksum is especially unsuitable because
there is a need to provide the first level of verification that
the packet was intended for the server. This verification
prevents the server from processing the datagram payload and spend
any significant amount of resources on it, including sending
replies or error messages.

Tunnel protocols encapsulating IP this will generally be safe, since
all IPv4 and IPv6 packets include at least one checksum at either the
network or transport layer and the network delivery of the inner
packet will further reduce the effects of corruption. Tunnel
protocols carrying non-IP packets may provide equivalent protection
due to the non-IP networks reducing the risk of delivery to
applications. However, there is need for further analysis to
understand the implications of mis-delievery of corrupted packets for
that each non-IP protocol. The analysis above suggests that non-
tunnel protocols can be expected to have significantly more cases
where a zero checksum would result in mis-delivery or negative side-
effects.

One unfortunate side-effect of increased use of a zero-checksum is
that it also increases the likelihood of acceptance when a datagram
with a context at the wrong zero UDP checksum is mis-delivered. This requires all tunnel
endpoint, or corrupted fragments may
protocols using this method to be reassembled at the right
context at designed to be robust to mis-
delivery.

4.3. Middleboxes

Applicability Statement for the right tunnel endpoint. In each use of these cases, the IPv6 length of the encapsulating header may be checked (though UDP Datagrams with Zero
Checksums [I-D.ietf-6man-udpzero] points out the weakness in notes that middlebox devices that
conform to RFC 2460 will discard datagrams with a zero UDP checksum
and should log this check).
In addition, if the encapsulated packet is protected by as an error. Thus tunnel protocols intending to
use a
transport (or other) checksum, these errors can be detected (with
some probability).

While zero UDP checksum needs to ensure that they do not guarantee correctness, these mechanism can reduce have defined a
method for handling cases when a middlebox prevents the risks of relaxing path between
the tunnel ingress and egress from supporting transmission of
datagrams with a zero UDP checksum requirement for IPv6. checksum.

5. The Zero-Checksum Update

This specification updates IPv6 to allow a zero UDP checksum of zero for in the
outer encapsulating packet datagram of a tunneling protocol. UDP endpoints
that implement this update MUST change their behavior for
any destination port explicitly configured for zero checksum and MUST
NOT discard UDP packets received with a checksum value of zero on follow the
outer packet. When this is done, it requires node requirements
"Applicability Statement for the constraints in
Section 5 and 6 use of IPv6 UDP Datagrams with Zero
Checksums" [I-D.ietf-6man-udpzero].

Specifically, the

The following text in [RFC2460] Section 8.1, 4th bullet is
updated. We refer to the following text: should be
deleted:

"Unlike IPv4, when UDP packets are originated by an IPv6 node, the
UDP checksum is not optional. That is, whenever originating a UDP
packet, an IPv6 node must compute a UDP checksum over the packet and
the pseudo-header, and, if that computation yields a result of zero,
it must be changed to hex FFFF for placement in the UDP header. IPv6
receivers must discard UDP packets containing a zero checksum, and
should log the error."

This item should be taken out of the bullet list zero checksum, and
should log the error."

This text should be replaced by:

Whenever originating a UDP packet, packet in the default mode, an IPv6
node SHOULD MUST compute a UDP checksum over the packet and the pseudo-header, pseudo-
header, and, if that computation yields a result of zero, it must MUST
be changed to hex FFFF for placement in the UDP header. IPv6
receivers SHOULD MUST by default discard UDP packets containing a zero
checksum, and SHOULD log the error. However, As an alternative usage for
some protocols, such as tunneling protocols that use UDP as a tunnel
encapsulation, MAY omit computing enable the UDP
checksum zero-checksum mode for specific sets
of ports. Any node implementing the encapsulating UDP header and set it to zero,
subject to zero-checksum mode MUST
follow the constraints described node requirements specified in Section 4 of
Applicability Statement for the use of IPv6 UDP Datagrams with
Zero Checksums [I-D.ietf-6man-udpzero]. In cases where the encapsulating

Any protocol uses a zero checksum for UDP, using the receiver of packets
sent to a port enabled to receive zero-checksum packets mode MUST NOT
discard packets solely for having a UDP checksum of zero. Note
that these constraints apply only to encapsulating protocols that
omit calculating the UDP checksum and set it to zero. An
encapsulating protocol can always choose to compute the UDP
checksum, in which case, its behavior is not updated and uses follow the
method usage
requirements specified in Section 8.1 of RFC2460.

Middleboxes MUST allow IPv6 packets with UDP checksum equal to
zero to pass. Implementations of middleboxes MAY allow
configuration 5 of specific port ranges Applicability Statement for which a zero UDP
checksum is valid and may drop IPv6 UDP packets outside those
ranges.

The path between tunnel endpoints can change, thus also the
middleboxes in the path may vary during the life of
the
association. Paths with middleboxes that are intolerant use of a IPv6 UDP
checksum of zero will drop any keep-alives sent to validate the
path using checksum zero and the endpoints will discover that.
Therefore keep-alive traffic SHOULD include both packets with
tunnel checksums and packets Datagrams with checksums equal to zero to
enable Zero Checksums
[I-D.ietf-6man-udpzero].

Middleboxes supporting IPv6 MUST follow the remote end to distinguish between path failures requirements 9, 10 and the
blockage
11 of packets with checksum equal to zero. Note that path
validation need only be done per tunnel endpoint pair, not per
tunnel context. the usage requirements specified in Section 5 of
Applicability Statement for the use of IPv6 UDP Datagrams with
Zero Checksums [I-D.ietf-6man-udpzero].

6. Additional Observations

The

This update was motivated by the existence of this issue among a significant number of protocols
being developed in the IETF motivates this specified change. The
authors would also like that are expected to make benefit from the
change. The following observations: observations are made:

o An empirically-based analysis of the probabilities of packet
corruptions (with or without checksums) has not (to our knowledge)
been conducted since about 2000. It At the time of publication, it
is now 2012. We strongly suggest that an a new empirical study is in order, study, along
with an extensive analysis of IPv6 header the corruption probabilities. probabilities of the
IPv6 header.

o A key cause to motivation for the increased usage increase in use of UDP in tunneling is the a
lack of protocol support in middleboxes. Specifically, new
protocols, such as LISP [I-D.ietf-lisp], may prefer to use UDP
tunnels to traverse an end-to-end path successfully and avoid
having their packets dropped by middleboxes. If this middleboxes were not the case, the
use
updated to support UDP-Lite [RFC3828], this would provide better
protection than offered by this update. This may be suited to a
variety of UDP-lite [RFC3828] might become more viable applications and would be expected to be preferred over
this method for some (but
not necessarily all) tunneling many tunnel protocols.

o Another issue is that the UDP checksum is overloaded with the task
of protecting the IPv6 header for UDP flows (as is the TCP
checksum for TCP flows). Protocols that do not use a pseudo-
header approach to computing a checksum or CRC have essentially no
protection from mis-delivered packets.

7. IANA Considerations

This document makes no request of IANA.

Note to RFC Editor: this section may be removed on publication as an
RFC.

8. Security Considerations

It requires less

Less work is required required to generate zero-checksum an attack packets using a zero UDP
checksum than
ones with one using a standard full UDP checksums. checksum. However, this
does not lead to any significant new vulnerabilities as because checksums
are not a security measure and can be easily generated by any
attacker. Properly configured tunnels should check the validity of
the inner packet and perform any needed security checks, regardless of the checksum
status. Most attacks are generated from compromised hosts which
automatically create checksummed packets (in other words, it would
generally be more, not less, effort for most attackers to generate
zero UDP checksums on the host). checks.

9. Acknowledgements

We would like to thank Brian Haberman Haberman, Dan Wing, Joel Halpern and Gorry Fairhurst the
IESG of 2012 for discussions and reviews. Gorry Fairhurst has been
very diligent in reviewing and help ensuring alignment between this
document and [I-D.ietf-6man-udpzero].

10. References
10.1. Normative References

[I-D.ietf-6man-udpzero]
Fairhurst, G. and M. Westerlund, "Applicability Statement
for the use of IPv6 UDP Datagrams with Zero Checksums",
draft-ietf-6man-udpzero-07 (work in progress),
October 2012.

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.

[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, December 1998.

[RFC3828] Larzon, L-A., Degermark, M., Pink, S., Jonsson, L-E., and
G. Fairhurst, "The Lightweight User Datagram Protocol
(UDP-Lite)", RFC 3828, July 2004.

[RFC5619] Yamamoto, S., Williams, C., Yokota, H., and F. Parent,
"Softwire Security Analysis and Requirements", RFC 5619,
August 2009.

10.2. Informative References

[I-D.ietf-lisp]
Farinacci, D., Fuller, V., Meyer, D., and D. Lewis,
"Locator/ID Separation Protocol (LISP)",
draft-ietf-lisp-23
draft-ietf-lisp-24 (work in progress), May November 2012.

[I-D.ietf-mboned-auto-multicast]
Bumgardner, G., "Automatic Multicast Tunneling",
draft-ietf-mboned-auto-multicast-14 (work in progress),
June 2012.

[RFC2827] Ferguson, P. and D. Senie, "Network Ingress Filtering:
Defeating Denial of Service Attacks which employ IP Source
Address Spoofing", BCP 38, RFC 2827, May 2000.

[RFC3828] Larzon, L-A., Degermark, M., Pink, S., Jonsson, L-E., and
G. Fairhurst, "The Lightweight User Datagram Protocol
(UDP-Lite)", RFC 3828, July 2004.

[RFC5405] Eggert, L. and G. Fairhurst, "Unicast UDP Usage Guidelines
for Application Designers", BCP 145, RFC 5405,
November 2008.

[RFC5619] Yamamoto, S., Williams, C., Yokota, H., and F. Parent,
"Softwire Security Analysis and Requirements", RFC 5619,
August 2009.

Authors' Addresses

Marshall Eubanks
AmericaFree.TV LLC
P.O. Box 141
Clifton, Virginia 20124
USA

Phone: +1-703-501-4376
Fax:
Email: marshall.eubanks@gmail.com

P.F. Chimento
Johns Hopkins University Applied Physics Laboratory
11100 Johns Hopkins Road
Laurel, MD 20723
USA

Phone: +1-443-778-1743
Email: Philip.Chimento@jhuapl.edu

Magnus Westerlund
Ericsson
Farogatan 6
SE-164 80 Kista
Sweden

Phone: +46 10 714 82 87
Email: magnus.westerlund@ericsson.com