Internet DRAFT - draft-ietf-dhc-dynamic-shared-v4allocation
draft-ietf-dhc-dynamic-shared-v4allocation
DHC WG Y. Cui
Internet-Draft Q. Sun
Intended status: Standards Track Tsinghua University
Expires: November 29, 2015 I. Farrer
Deutsche Telekom AG
Y. Lee
Comcast
Q. Sun
China Telecom
M. Boucadair
France Telecom
May 28, 2015
Dynamic Allocation of Shared IPv4 Addresses
draft-ietf-dhc-dynamic-shared-v4allocation-09
Abstract
This memo describes the dynamic allocation of shared IPv4 addresses
to clients using DHCPv4. Address sharing allows a single IPv4
address to be allocated to multiple active clients simultaneously,
each client being differentiated by a unique set of transport layer
source port numbers. The necessary changes to existing DHCPv4 client
and server behavior are described and a new DHCPv4 option for
provisioning clients with shared IPv4 addresses is included.
Due to the nature of IP address sharing, some limitations to its
applicability are necessary. This memo describes these limitations
and recommends suitable architectures and technologies where address
sharing may be utilized.
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 http://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 November 29, 2015.
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Copyright Notice
Copyright (c) 2015 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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Applicability Statement . . . . . . . . . . . . . . . . . . . 3
3. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
4. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
5. Functional Overview . . . . . . . . . . . . . . . . . . . . . 4
6. Client-Server Interaction . . . . . . . . . . . . . . . . . . 4
7. Client Behavior . . . . . . . . . . . . . . . . . . . . . . . 5
7.1. Restrictions to Client Usage of a Shared IPv4 Address . . 6
8. Server Behavior . . . . . . . . . . . . . . . . . . . . . . . 7
8.1. Leasing Shared and Non-Shared IPv4 Addresses from a
Single DHCP 4o6 Server . . . . . . . . . . . . . . . . . 8
9. DHCPv4 Port Parameters Option . . . . . . . . . . . . . . . . 8
10. Security Considerations . . . . . . . . . . . . . . . . . . . 9
10.1. Port Randomization . . . . . . . . . . . . . . . . . . . 10
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 11
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
13.1. Normative References . . . . . . . . . . . . . . . . . . 11
13.2. Informative References . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
1. Introduction
The shortage of available public IPv4 addresses means that it is not
always possible for operators to allocate a full IPv4 address to
every connected device. This problem is particularly acute whilst an
operator is migrating from their existing, native IPv4 network to a
native IPv6 network with IPv4 provided as an overlay service. During
this phase, public IPv4 addresses are needed to provide for both
existing and transition networks.
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Two main types of solutions have emerged to address the problem (see
Appendix A of [RFC6269]):
1. Deploying Carrier Grade Network Address Translation devices
(CGNAT, [RFC6888]).
2. Distributing the same public IPv4 address to multiple clients
differentiated by non-overlapping layer 4 port sets.
This memo focuses on the second category of solutions.
[RFC7341] introduces a "DHCP 4o6 Server", which offers dynamic
leasing for IPv4 addresses to clients as in DHCPv4 [RFC2131] but
transported within a DHCPv6 message flow. This memo specifies a new
DHCPv4 option: OPTION_V4_PORTPARAMS, and describes how it can be used
for the dynamic leasing of shared IPv4 addresses.
Although DHCPv4 over DHCPv6 is used as the underlying DHCPv4
transport mechanism throughout this document, OPTION_V4_PORTPARAMS as
a DHCPv4 option may also be used in other solutions, if required.
2. Applicability Statement
The solution allows multiple hosts to be simultaneously allocated the
same IP address. As the IP address is no longer a unique identifier
for a host, this extension is only suitable for specific
architectures based on the Address plus Port model (A+P) [RFC6346].
Specifically, this document presents a solution that applies to
[I-D.ietf-softwire-lw4over6] and certain configurations of
[I-D.ietf-softwire-map] (e.g., EA-bit length set to 0).
The solution should only be used on point-to-point links, tunnels,
and/or in environments where authentication at the link layer is
performed before IP address assignment. It is not suitable for
network access over shared media, including Ethernet, WLAN, cable,
etc..
3. 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].
4. Terminology
This document makes use of the following terms:
Shared IPv4 address: An IPv4 address with a restricted layer 4 port
set.
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Port Set ID (PSID): Identifier for a range of ports assigned to a
DHCP client.
5. Functional Overview
Functionally, the dynamic allocation of shared IPv4 addresses by the
DHCP 4o6 Server is similar to the dynamic allocation process for
'full' IPv4 addresses described in [RFC2131]. The essential
difference is that the DHCP 4o6 Server can allocate the same IPv4
address to more than one DHCP 4o6 client simultaneously, providing
that each shared address allocation also includes a range of layer 4
source ports unique to that address (i.e., the combined tuple of IPv4
address and Port Set ID is to be unique for each active lease).
The DHCP 4o6 client implements OPTION_V4_PORTPARAMS (described
below), which is a DHCPv4 option containing PSID (Port Set ID)
information. The client includes this option within the Parameter
Request List option [RFC2132] in its DHCPv4 DHCPDISCOVER and
DHCPREQUEST messages, indicating its support for shared, dynamic
address leasing to the DHCP 4o6 server.
OPTION_V4_PORTPARAMS is also implemented by the server to identify
clients that support shared, dynamic address leasing. With this
option, the server can dynamically allocate PSIDs to clients and
maintain shared IPv4 address leases. The server then manages unique
client leases based the IPv4 address and PSID tuple, instead of using
only the IPv4 address.
In the event that a dynamic, shared addressing capable client
receives more than one DHCP 4o6 offer, where a received offer does
not contain OPTION_V4_PORTPARAMS (i.e., is an offer for a full IPv4
address), then the client SHOULD prefer the full IPv4 offer over the
shared IPv4 address offer(s), unless specifically configured
otherwise.
6. Client-Server Interaction
The following DHCPv4 message flow is transported within the
DHCPv4-query and DHCPv4-response messages as in DHCPv4 over DHCPv6
[RFC7341].
1. When the client constructs the DHCPv4 DHCPDISCOVER message to be
transported within the DHCPv4-query message, the DHCPDISCOVER
message MUST include the client identifier option (constructed as
per [RFC4361]) and the Parameter Request List (PRL) option with
the code of OPTION_V4_PORTPARAMS. The client MAY insert an
OPTION_V4_PORTPARAMS with preferred values in related fields as a
suggestion to the DHCP 4o6 Server.
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2. DHCP 4o6 Servers that receive the DHCPDISCOVER message and
support shared IPv4 addresses respond with a DHCPOFFER message
with the shared IPv4 address in the 'yiaddr' field and MUST add
an OPTION_V4_PORTPARAMS option containing an available restricted
port set. If the DHCPDISCOVER included an OPTION_V4_PORTPARAMS
option containing a non-zero PSID-Len field, the DHCP 4o6 Server
MAY allocate a port set of the requested size to the client
(depending on policy). The DHCPOFFER message is then
encapsulated in the DHCPv4-response message and sent to the
client.
3. The client evaluates all received DHCPOFFER messages and selects
one (e.g., based on the configuration parameters received, such
as the size of the offered port set). The client then sends a
DHCPREQUEST encapsulated in the DHCPv4-query message containing
the corresponding OPTION_V4_PORTPARAMS received in the DHCPOFFER
message.
4. The server identified in the DHCPREQUEST message creates a
binding for the client. The binding includes the client
identifier, the IPv4 address and the PSID. These parameters are
used by both the server and the client to identify a lease in any
DHCP message. The server MUST respond with a DHCPACK message
containing OPTION_V4_PORTPARAMS for the requesting client.
5. On receipt of the DHCPACK message with the configuration
parameters, the client MUST NOT perform an in-use probe on the
address, such as ARPing for a duplicate allocated address.
6. If the client chooses to relinquish its lease by sending a
DHCPRELEASE message, the client MUST include the leased network
address and OPTION_V4_PORTPARAMS (with the allocated PSID) to
identify the lease to be released.
In the case that the client has stored the previously allocated
address and restricted port set, the logic described in Section 3.2
of [RFC2131] MUST be followed on the condition that the client's
source IPv6 address for DHCP 4o6 does not change. Note, this
corresponds to the INIT-REBOOT state defined in [RFC2131]. The
client MUST include the OPTION_V4_PORTPARAMS with the requested port
set information in the message flow, which starts with a DHCPREQUEST
message. If the client's DHCP 4o6 IPv6 source address is changed for
any reason, the client MUST re-initiate the DHCP 4o6 shared-address
provisioning process by sending a DHCPDISCOVER message.
7. Client Behavior
A DHCP 4o6 client sending a DHCPDISCOVER message for a shared IPv4
address MUST include the OPTION_V4_PORTPARAMS option code in the
Parameter Request List option. If a client has been successfully
allocated an IPv4 address and PSID previously, the client's
DHCPDISCOVER message MAY include the 'requested IP address' option
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along with an OPTION_V4_PORTPARAMS to request that a specific IPv4
address and PSID be re-assigned. Alternatively, the client MAY omit
the 'requested IP address' option, but include an
OPTION_V4_PORTPARAMS with a non-zero value in only the PSID-Len
field, as a hint to the server for the preferred size of the port
set.
A client that requests OPTION_V4_PORTPARAMS, but receives DHCPOFFER
and DHCPACK messages without OPTION_V4_PORTPARAMS SHOULD proceed as
defined in [RFC7341] and configure a full IPv4 address with no
address sharing (see Section 8.1 for the server's behavior).
When receiving a DHCPACK message containing OPTION_V4_PORTPARAMS, the
client MUST use the received explicit PSID for configuring the
interface for which the DHCP 4o6 request was made.
The client MUST NOT probe a newly received IPv4 address (e.g., using
ARP) to see if it is in use by another host.
When the client renews or releases its DHCP lease, it MUST put the
values of offset, PSID length and PSID into OPTION_V4_PORTPARAMS, and
send it to the server within corresponding DHCPv4 messages that are
conveyed through DHCPv4-query message.
In the event that the client's DHCP 4o6 IPv6 source address is
changed for any reason, the client MUST re-initiate the DHCP 4o6
shared-address provisioning process by sending a DHCPDISCOVER
message.
7.1. Restrictions to Client Usage of a Shared IPv4 Address
As a single IPv4 address is being shared between a number of
different clients, the allocated shared address is only suitable for
certain uses. The client MUST implement a function to ensure that
only the allocated layer 4 ports of the shared IPv4 address are used
for sourcing new connections, or accepting inbound connections.
The client MUST apply the following rules for all traffic destined to
or originating from the shared IPv4 address:
o The client MUST use only port-aware protocols (e.g., TCP, UDP,
DCCP etc.) or ICMP implementing [RFC5508].
o All connections originating from the shared IPv4 address MUST use
a source port taken from the allocated restricted port set.
o The client MUST NOT accept inbound connections on ports outside of
the allocated restricted port set.
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In order to prevent addressing conflicts which could arise from the
allocation of the same IPv4 address, the client MUST NOT use the
received restricted IPv4 address to perform ARP operations.
The mechanism by which a client implements the above rules is out of
the scope of this document.
In the event that the DHCPv4 over DHCPv6 configuration mechanism
fails for any reason, the client MUST NOT configure an IPv4 link-
local address [RFC3927] (taken from the 169.254.0.0/16 range).
8. Server Behavior
The DHCP 4o6 Server MUST NOT reply with OPTION_V4_PORTPARAMS unless
the client has explicitly listed the option code in the Parameter
Request List (Option 55) [RFC2132].
The DHCP 4o6 Server SHOULD reply with OPTION_V4_PORTPARAMS if the
client includes OPTION_V4_PORTPARAMS in its Parameter Request List.
In order to achieve the dynamic management of shared IPv4 addresses,
the server is required to implement an address and port-set pool that
provides the same function as the address pool in a regular DHCP
server. Also, the server uses the combination of address and PSID as
the key for maintaining the state of a lease, and for searching for
an available lease for assignment. The leasing database is required
to include the IPv4 address, PSID and client identifier of the
requesting client.
When a server receives a DHCPDISCOVER message with
OPTION_V4_PORTPARAMS in the Parameter Request List option, the server
determines an IPv4 address with a PSID for the requesting client. If
an IPv4 address with a PSID is available, the server SHOULD follow
the logic below to select which specific address and PSID to
provision to the client. The logic is similar to that in
Section 4.3.1 of [RFC2131].
o The client's current address with the PSID as recorded in the
client's current lease binding, ELSE
o The client's previous address with PSID as recorded in the
client's (expired or released) binding, if that address with PSID
is in the server's pool of available addresses and PSIDs, and not
already allocated, ELSE
o The address requested in the 'Requested IP Address' option along
with the PSID parameters requested in the OPTION_V4_PORTPARAMS, if
that pair of address and PSID is valid and not already allocated,
ELSE
o A new address with a PSID allocated from the server's pool of
available addresses and PSIDs.
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Upon receipt of a DHCPRELEASE message with OPTION_V4_PORTPARAMS, the
server searches for the lease using the address in the 'ciaddr' field
and the PSID information in the OPTION_V4_PORTPARAMS, and marks the
lease as unallocated if a record (matching that PSID) is maintained
by the server for that client.
The port-set assignment MUST be coupled with the address assignment
process. Therefore the server MUST assign the address and port set
in the same DHCP message.
When defining the pools of IPv4 addresses and PSIDs which are
available to lease to clients, the server MUST implement a mechanism
to reserve some port ranges (e.g., 0-1023) from allocation to
clients. The reservation policy SHOULD be configurable.
8.1. Leasing Shared and Non-Shared IPv4 Addresses from a Single DHCP
4o6 Server
A single DHCP 4o6 server may serve clients that do not support
OPTION_V4_PORTPARAMS as well as those that do. As the rules for the
allocation of shared addresses differ from the rules for full IPv4
address assignment, the DHCP 4o6 server MUST implement a mechanism to
ensure that clients not supporting OPTION_V4_PORTPARAMS do not
receive shared addresses. For example, two separate IPv4 addressing
pools could be used, one of which allocates IPv4 addresses and PSIDs
only to clients that have requested them.
If the server is only configured with address pools for shared
address allocation, it MUST discard requests that do not contain
OPTION_V4_PORTPARAMS in the Parameter Request List option.
A server configured with non-shared address pools can be instructed
to honor received requests that contain OPTION_V4_PORTPARAMS in the
Parameter Request List option (that is ignore OPTION_V4_PORTPARAMS
and serve the requesting clients with non-shared IPv4 addresses).
9. DHCPv4 Port Parameters Option
The meaning of 'offset', 'PSID-len', and 'PSID' fields of the DHCPv4
Port Parameters Option is identical to that of 'offset', 'PSID-len',
and 'PSID' fields of the S46 Port Parameters Option (Section 4.5 of
[I-D.ietf-softwire-map-dhcp]). The use of the same encoding in both
options is meant to ensure compatibility with existing port set
implementations.
The format of OPTION_V4_PORTPARAMS is shown in Figure 1.
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0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| option-code | option-len |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| offset | PSID-len |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| PSID |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
Figure 1: DHCPv4 Port Parameters Option
o option-code: OPTION_V4_PORTPARAMS (TBA)
o option-len: 4
o offset: (PSID offset) 8 bits long field that specifies the numeric
value for the excluded port range/offset bits (A-bits), as per
section 5.1 of [I-D.ietf-softwire-map]. Allowed values are
between 0 and 15, with the default value being 6 for MAP based
implementations. This parameter is unused by a Lightweight 4over6
client and should be set to 0.
o PSID-len: Bit length value of the number of significant bits in
the PSID field (also known as 'k'). When set to 0, the PSID field
is to be ignored. After the first 'a' bits, there are k bits in
the port number representing the value of PSID. Subsequently, the
address sharing ratio would be 2^k.
o PSID: Explicit 16-bit (unsigned word) PSID value. The PSID value
algorithmically identifies a set of ports assigned to a client.
The first k-bits on the left of this 2-octets field is the PSID
value. The remaining (16-k) bits on the right are padding zeros.
[I-D.ietf-softwire-map] Section 5.1 provides a full description of
how the PSID is interpreted by the client.
In order to exclude the system ports ([RFC6335]) or ports reserved by
ISPs, the former port-sets that contain well-known ports MUST NOT be
assigned unless the operator has explicitly configured otherwise
(e.g., by allocating a full IPv4 address).
10. Security Considerations
The security considerations described in [RFC2131] and [RFC7341] are
also potentially applicable to this solution. Unauthorised DHCP 4o6
servers in the network could be used to stage an amplification attack
or to supply invalid configuration leading to service disruption.
The risks of these types of attacks can be reduced through the use of
unicast DHCP 4o6 message flows (enabled by supplying DHCP 4o6 server
unicast addresses within the OPTION_DHCP4_O_DHCP6_SERVER option).
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A malicious user could attempt a DoS attack by requesting a large
number ofIPv4 address (or fractional address) and port sets
allocations, exhausting the available addresses and port sets for
other clients. This can be mitigated through DHCP 4o6 address
allocation policy, limiting the number of simultaneously active IPv4
leases for clients whose request originate from each customer site.
The purpose of the client identifier option is to ensure that the
same client retains the same parameters over time. This interferes
with the client's privacy, as it allows the server to track the
client. Clients can manage their privacy exposure by controlling the
value of the client identifier, trading off stability of parameter
allocation for privacy. We expect that guidance on this trade-off
will be discussed in a future version of
[I-D.ietf-dhc-anonymity-profile].
Additional security considerations are discussed in Section 11 of
[I-D.ietf-softwire-map] and Section 9 of
[I-D.ietf-softwire-lw4over6].
10.1. Port Randomization
Preserving port randomization [RFC6056] may be more difficult because
the host can only randomize the ports inside a fixed port range (see
Section 13.4 of [RFC6269]).
More discussion to improve the robustness of TCP against Blind In-
Window Attacks can be found at [RFC5961]. Other means than the
(IPv4) source port randomization to provide protection against
attacks should be used (e.g., use [RFC5961] to improve the robustness
of TCP against Blind In-Window Attacks, use IPv6).
11. IANA Considerations
IANA is requested to assign the following new DHCPv4 Option Code in
the registry maintained in: http://www.iana.org/assignments/bootp-
dhcp-parameters/:
Option Name Value Data Meaning
length
-------------------- ----- ------ -----------------------------------
OPTION_V4_PORTPARAMS TBA 4 This option is used to configure a
set of ports bound to a shared IPv4
address.
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12. Acknowledgements
This document is merged from [I-D.sun-dhc-port-set-option] and
[I-D.farrer-dhc-shared-address-lease].
The authors would like to thank Peng Wu, Gabor Bajko, Teemu
Savolainen, Ted Lemon, Tina Tsou, Pierre Levis, Cong Liu, Marcin
Siodelski, and Christian Huitema for their contributions.
Many thanks to Brian Haberman for the review.
13. References
13.1. Normative References
[I-D.ietf-softwire-lw4over6]
Cui, Y., Qiong, Q., Boucadair, M., Tsou, T., Lee, Y., and
I. Farrer, "Lightweight 4over6: An Extension to the DS-
Lite Architecture", draft-ietf-softwire-lw4over6-13 (work
in progress), November 2014.
[I-D.ietf-softwire-map]
Troan, O., Dec, W., Li, X., Bao, C., Matsushima, S.,
Murakami, T., and T. Taylor, "Mapping of Address and Port
with Encapsulation (MAP)", draft-ietf-softwire-map-13
(work in progress), March 2015.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC
2131, March 1997.
[RFC2132] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor
Extensions", RFC 2132, March 1997.
[RFC4361] Lemon, T. and B. Sommerfeld, "Node-specific Client
Identifiers for Dynamic Host Configuration Protocol
Version Four (DHCPv4)", RFC 4361, February 2006.
[RFC5961] Ramaiah, A., Stewart, R., and M. Dalal, "Improving TCP's
Robustness to Blind In-Window Attacks", RFC 5961, August
2010.
[RFC6056] Larsen, M. and F. Gont, "Recommendations for Transport-
Protocol Port Randomization", BCP 156, RFC 6056, January
2011.
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[RFC7341] Sun, Q., Cui, Y., Siodelski, M., Krishnan, S., and I.
Farrer, "DHCPv4-over-DHCPv6 (DHCP 4o6) Transport", RFC
7341, August 2014.
13.2. Informative References
[I-D.farrer-dhc-shared-address-lease]
Farrer, I., "Dynamic Allocation of Shared IPv4 Addresses
using DHCPv4 over DHCPv6", draft-farrer-dhc-shared-
address-lease-00 (work in progress), June 2013.
[I-D.ietf-dhc-anonymity-profile]
Huitema, C., Mrugalski, T., and S. Krishnan, "Anonymity
profile for DHCP clients", draft-ietf-dhc-anonymity-
profile-00 (work in progress), May 2015.
[I-D.ietf-softwire-map-dhcp]
Mrugalski, T., Troan, O., Farrer, I., Perreault, S., Dec,
W., Bao, C., Yeh, L., and X. Deng, "DHCPv6 Options for
configuration of Softwire Address and Port Mapped
Clients", draft-ietf-softwire-map-dhcp-12 (work in
progress), March 2015.
[I-D.sun-dhc-port-set-option]
Qiong, Q., Lee, Y., Sun, Q., Bajko, G., and M. Boucadair,
"Dynamic Host Configuration Protocol (DHCP) Option for
Port Set Assignment", draft-sun-dhc-port-set-option-02
(work in progress), October 2013.
[RFC3927] Cheshire, S., Aboba, B., and E. Guttman, "Dynamic
Configuration of IPv4 Link-Local Addresses", RFC 3927, May
2005.
[RFC5508] Srisuresh, P., Ford, B., Sivakumar, S., and S. Guha, "NAT
Behavioral Requirements for ICMP", BCP 148, RFC 5508,
April 2009.
[RFC6269] Ford, M., Boucadair, M., Durand, A., Levis, P., and P.
Roberts, "Issues with IP Address Sharing", RFC 6269, June
2011.
[RFC6335] Cotton, M., Eggert, L., Touch, J., Westerlund, M., and S.
Cheshire, "Internet Assigned Numbers Authority (IANA)
Procedures for the Management of the Service Name and
Transport Protocol Port Number Registry", BCP 165, RFC
6335, August 2011.
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[RFC6346] Bush, R., "The Address plus Port (A+P) Approach to the
IPv4 Address Shortage", RFC 6346, August 2011.
[RFC6888] Perreault, S., Yamagata, I., Miyakawa, S., Nakagawa, A.,
and H. Ashida, "Common Requirements for Carrier-Grade NATs
(CGNs)", BCP 127, RFC 6888, April 2013.
Authors' Addresses
Yong Cui
Tsinghua University
Beijing 100084
P.R. China
Phone: +86-10-6260-3059
Email: yong@csnet1.cs.tsinghua.edu.cn
Qi Sun
Tsinghua University
Beijing 100084
P.R. China
Phone: +86-10-6278-5822
Email: sunqi@csnet1.cs.tsinghua.edu.cn
Ian Farrer
Deutsche Telekom AG
CTO-ATI, Landgrabenweg 151
Bonn, NRW 53227
Germany
Email: ian.farrer@telekom.de
Yiu L. Lee
Comcast
One Comcast Center
Philadelphia PA 19103
USA
Email: yiu_lee@cable.comcast.com
Cui, et al. Expires November 29, 2015 [Page 13]
Internet-Draft Dynamic Shared IPv4 Allocation May 2015
Qiong Sun
China Telecom
Room 708, No.118, Xizhimennei Street
Beijing 100035
P.R. China
Phone: +86-10-58552936
Email: sunqiong@ctbri.com.cn
Mohamed Boucadair
France Telecom
Rennes 35000
France
Email: mohamed.boucadair@orange.com
Cui, et al. Expires November 29, 2015 [Page 14]
