Internet DRAFT - draft-sun-softwire-lightweigh-4over6-deployment
draft-sun-softwire-lightweigh-4over6-deployment
Network Working Group Q. Sun
Internet-Draft C. Xie
Intended status: Standards Track China Telecom
Expires: January 15, 2014 Y. Lee
Comcast
M. Chen
FreeBit
July 14, 2013
Deployment Considerations for Lightweight 4over6
draft-sun-softwire-lightweigh-4over6-deployment-04
Abstract
Lightweight 4over6 is a mechanism which moves the translation
function from tunnel lwAFTR (AFTR) to lwB4s (B4s), and hence reduces
the mapping scale on the lwAFTR to per-customer level. This document
discusses various deployment models of Lightweight 4over6. It also
describes the deployment considerations and applicability of the
Lightweight 4over6 architecture.
Status of this Memo
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This Internet-Draft will expire on January 15, 2014.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 4
3. Deployment Model . . . . . . . . . . . . . . . . . . . . . . . 5
4. Overall Deployment Considerations . . . . . . . . . . . . . . 7
4.1. Addressing and Routing . . . . . . . . . . . . . . . . . . 7
4.2. Port-set Management . . . . . . . . . . . . . . . . . . . 7
4.3. lwAFTR Discovery . . . . . . . . . . . . . . . . . . . . . 8
4.4. Impacts on Accouting . . . . . . . . . . . . . . . . . . . 8
5. lwAFTR Deployment Consideration . . . . . . . . . . . . . . . 9
5.1. Logging at the lwAFTR . . . . . . . . . . . . . . . . . . 9
5.2. MTU and Fragmentation Considerations . . . . . . . . . . . 9
5.3. Reliability Considerations of lwAFTR . . . . . . . . . . . 9
5.4. Placement of AFTR . . . . . . . . . . . . . . . . . . . . 10
5.5. Port set algorithm consideration . . . . . . . . . . . . . 10
5.6. Path Consistency Consideration . . . . . . . . . . . . . . 10
6. lwB4 Deployment Consideration . . . . . . . . . . . . . . . . 12
6.1. NAT traversal issue . . . . . . . . . . . . . . . . . . . 12
6.2. Static Port Forwarding Configuration . . . . . . . . . . . 12
7. DS-Lite Compatibility Consideration . . . . . . . . . . . . . 13
7.1. Case 1: Integrated Network Element with Lightweight
4over6 and DS-Lite AFTR Scenario . . . . . . . . . . . . . 13
7.2. Case 2: DS-Lite Coexistent scenario with Separated AFTR . 14
8. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 15
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Appendix 1. Appendix:Experimental Result . . . . . . . . . . . . 19
1.1. Experimental environment . . . . . . . . . . . . . . . . . 19
1.2. Experimental results . . . . . . . . . . . . . . . . . . . 20
1.3. Conclusions . . . . . . . . . . . . . . . . . . . . . . . 21
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 22
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1. Introduction
Lightweight 4over6 [I-D.ietf-softwire-lw4over6] is an extension to
DS-Lite which simplifies the AFTR module [RFC6333] with distributed
NAT function among B4 elements. The lwB4 in Lightweight 4over6 is
provisioned with an IPv6 address, an IPv4 address and a port-set. It
performs NAPT on end user's packets with the provisioned IPv4 address
and port-set. IPv4 packets are forwarded between the lwB4 and the
lwAFTR over a Softwire using IPv4-in-IPv6 encapsulation. The lwAFTR
maintains one mapping entry per subscriber with the IPv6 address,
IPv4 address and port-set. Therefore, this extension removes the
NAT44 module from the AFTR and replaces the session-based NAT table
to a per-subscriber based mapping table. This should relax the
requirement to create dynamic session-based log entries. This
mechanism preserves the dynamic feature of IPv4/IPv6 address binding
as in DS-Lite, so it has no coupling between IPv6 address and IPv4
address/port-set as any full stateless solution ([RFC6052] or
[I-D.ietf-softwire-map]) requires. This document discusses
deployment models of Lightweight 4over6. It also describes the
deployment considerations and applicability of the Lightweight 4over6
architecture.
Terminology of this document follows the definitions and
abbreviations of [I-D.ietf-softwire-lw4over6].
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2. 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].
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3. Deployment Model
Lightweight 4over6 is suitable for operators who would like to free
any correlation of the IPv6 address with IPv4 address and port-set
(or port-range). In comparison to full stateless solutions like MAP
[I-D.ietf-softwire-map] and 4rd [I-D.ietf-softwire-4rd], Lightweight
4over6 frees address planning of IPv6 delegation for CPE from mapping
rule administration and management in the network. Thus, IPv6
addressing is completely flexible to fit other deployment
requirements, e.g., auto-configuration, service classification, user
management, QoS support, etc. The philosophy here is that bits of
IPv6 address should be left for IPv6 usage first.
Lightweight 4over6 can be deployed in a residential network (depicted
in Figure1). In this scenario, a lwB4 would acquire an IPv4 address
and a port-set after a successful user authentication process and
IPv6 provisioning process. Then, it establishes an IPv4-in-IPv6
softwire using the IPv6 address to deliver IPv4 services to its
connected host via the lwAFTR in the network. The lwB4 can act as a
CPE, or software located in the host. The lwAFTR supports
Lightweight 4over6 which keeps the mapping between lwB4's IPv6
address and its allocated IPv4 address + port set. The supporting
system may keep the binding information as well for logging and user
management.
+---------------+
| Supporting |
| System |
+-------+-------+
|
+---------------+--------------|
| | |
+---------+ +------+---+ +--+--+ |
| Host | | lwB4 | | | |
| |--| | ======-| BNG | === +---------+ +-----------+
+---------+ +----------+ +--|--+ | | | IPv4 |
| lwAFTR |---| Internet |
+---------+ +------+---+ +--+--+ | | | |
| Host |--| lwB4 | =======| | ====+---------+ +-----------+
| | | | | BNG | |
+---------+ +----------+ +--|--+ |
+ | |
+---------------+--------------+
Figure 1 Deployment Model
There are two deployment models in practice: one is called bottom-up
and the other is top-down. In bottom-up model, after port-restricted
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IPv4 address is allocated to a given subscriber, the lwAFTR will
report mapping records to the supporting system on creating a binding
for traffic logging if necessary. Operators may use
[I-D.ietf-behave-syslog-nat-logging] or
[I-D.ietf-behave-ipfix-nat-logging] to report the port set allocated
by lwAFTR. In this way, the lwAFTR can determine the binding by its
own and there is little impact on existing network architecture. In
top-down model, the Supporting system should firstly determine the
binding information for each subscriber and then synchronize it with
the lwAFTR. With this method, one binding record can be easily
synchronized with multiple lwAFTRs and stateless failover can be
achieved. However, new mechanism (e.g.
[I-D.zhou-dime-4over6-provisioning]) needs to be introduced to notify
each individual binding record between the Supporting system and the
lwAFTR.
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4. Overall Deployment Considerations
4.1. Addressing and Routing
In Lightweight 4over6, there is no inter-dependency between IPv4 and
IPv6 addressing schemes. IPv4 address pools are configured
centralized in lwAFTR for IPv6 subscribers. These IPv4 prefix must
advertise to IPv4 Internet accordingly.
For IPv6 addressing and routing, there are no additional addressing
and routing requirements. The existing IPv6 address assignment and
routing announcement should not be affected. For example, in PPPoE
scenario, a CPE could obtain a prefix via prefix delegation
procedure, and the hosts behind CPE would get its own IPv6 addresses
within the prefix through SLAAC or DHCPv6 statefully. This IPv6
address assignment procedure has nothing to do with restricted IPv4
address allocation.
4.2. Port-set Management
In Lightweight 4over6, each lwB4 will get its restricted IPv4 address
and a port-set after successful user authentication process and IPv6
provisioning process. This port-set assignment can been achieved by
DHCPv4-over-DHCPv6 [I-D.ietf-dhc-dhcpv4-over-dhcpv6] and PCP
[I-D.ietf-pcp-port-set].
Operator may use DHCPv4 to provision IPv4 address to the lwB4. In a
typical deployment, the DHCP server is a centralized DHCP server and
lwAFTR is the DHCP relay agent to relay the dhcp messages to the
server over unicast. Rarely DHCP server will collocate with the
lwAFTR to provision IPv4 resources to the lwB4.
Operator may also use PCP Port-set Option to provision IPv4 address
and port-set to the lwB4. In a typical deployment, PCP server will
collocate with lwAFTR, and the subscriber's binding can be determined
by lwAFTR. The PCP request should be sent to the lwAFTR's tunnel
end-point address. It is not common that PCP server will be
centralized deployed in which the lwAFTR is the PCP proxy to relay
PCP requests.
It is also possible that subscriber's binding is determined in AAA
server. In this case, the BNGs will embed with a DHCPv4-over-DHCPv6
server function which allows them to locally handle any DHCPv4-over-
DHCPv6 requests initiated by hosts. The AAA server will pass the
subscriber's binding to a BNG using the AAA attribute in [I-D.sun-
softwire-lw4over6-radext] and in turn populates the mapping of the
lwB4.
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Some operators may offer different service level agreements (SLA) to
users that some users may require more ports then others. In this
deployment scenario, the operator can implement differentiated
policies in provisioning system specified to a user's lwB4 or a group
of lwB4s to allocate a certain range of port-set. The lwAFTR may
also run multiple instances with different port-set sizes to build
the mapping table.
4.3. lwAFTR Discovery
A Lightweight 4over6 lwB4 must discover the lwAFTR's IPv6 address
before offering any IPv4 services. This IPv6 address can be learned
through an out-of-band channel, static configuration, or dynamic
configuration. In practice, Lightweight 4over6 lwB4 can use the same
DHCPv6 option [RFC6334]to discover the FQDN of the lwAFTR.
When Lightweight 4over6 is deployed in the same place with DS-Lite,
either different FQDNs can be configured for Lightweight 4over6 and
DS-Lite separately or different DHCPv6 options can be used for
Lightweight 4over6 [I-D.sun-softwire-lw4over6-dhcpv6] and DS-Lite.
More detailed considerations on DS-Lite compatibility will be
discussed in Section6.
4.4. Impacts on Accouting
In Lightweight 4over6, the accounting impact due to the tunneling
protocol is the same with DS-Lite (see section 6.2 of [RFC6908]).
However, since in Lightweight 4over6, the IPv4 service is only
available after port-set allocation, if operators will regard IPv4
service as a on-demand value-added service, e.g. IPv6 connectivity
is offered by default, while IPv4 connectivity will be offered untill
a subscriber requires, etc., IPv4 service accounting should start
after port-set allocation has completely.
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5. lwAFTR Deployment Consideration
As Lightweight 4over6 is an extension to DS-Lite, both technologies
share similar deployment considerations. For example: Interface
consideration, Lawful Intercept Considerations, Blacklisting a shared
IPv4 Address, AFTR's Policies, AFTR Impacts on Accounting Process,
etc., in [RFC6908] can also be applied here. This document only
discusses new considerations specific to Lightweight 4over6.
5.1. Logging at the lwAFTR
In Lightweight 4over6, operators only log one entry per subscriber.
The log should include subscriber's IPv6 address used for the
softwire, the public IPv4 address and the port-set. The port set
algorithm implemented in Lightweight 4over6 lwAFTR should be
synchronized with the one implemented in logging system. For
example, if contiguous port set algorithm is adopted in the lwAFTR,
the same algorithm should also been applied to the logging system.
Since the mapping in lwAFTR does not contain destination-specific
information, operator should be aware that they will not be able to
have destination-specific log.
5.2. MTU and Fragmentation Considerations
As Lightweight 4over6 is also a tunneling protocol, the same
consideration regarding to the fragmentation and reassembly in DS-
Lite [RFC6908] can also be applied. The only difference is that NAT
functionality has been removed to lwB4 from lwAFTR in Lightweight
4over6. Therefore, on receiving an IPv4 fragmented packet after
decapsulation in the lwB4, the lwB4 should further re-assemble the
packets before doing NAT since the transport protocol information is
only available in the first fragment.
5.3. Reliability Considerations of lwAFTR
Operators may deploy multiple lwAFTRs for robustness, reliability,
and load balancing. In Lightweight 4over6, subscriber to IPv4 and
port-set mapping must be pre-provisioned in the lwAFTR before
providing IPv4 serives. For redundancy, the backup lwAFTR must
either have the subscriber mapping already provisioned or notify the
lwB4 to create a new mapping in the backup lwAFTR. The first option
can be considered as Hot Standby mode, which requires state
syncronization between multiple lwAFTRs. In Hot Standby mode, the
bindings are replicated on-the-fly from the Primary lwAFTR to the
Backup lwAFTR. When the Primary lwAFTR fails, the Backup lwAFTR will
take over all the existing established sessions. In this mode, the
internal hosts are not required to re-initiate the bindings with the
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external hosts. In Lightweight 4over6, since the number of mapping
states has been greatly reduced compared to DS-Lite, it is reasonable
to adopt Hot Standby mode when there are only two lwAFTRs (one for
Primary lwAFTR and one for Backup lwAFTR). However, if the number of
lwAFTRs is larger than two, it is not scalable to deploy Hot Standby
mode since each two of the lwAFTRs should to syncronize the binding
states.
The second option is to use Cold Standby mode which does not require
a Backup Standby lwAFTR to synchronize binding states. In failover,
the lwAFTR has to notify the lwB4 to create a new binding, or fetch
the binding by itself. [I-D.lee-softwire-lw4over6-failover]
describes these two approaches for simple Cold Standby mode. For
most deployment scenarios, we believe that Cold Standby mode should
be sufficient enough and is thus recommended.
5.4. Placement of AFTR
The lwAFTR can be deployed in a "centralized model" or a "distributed
model".
In the "centralized model", the lwAFTR could be located at the higher
place, e.g. at the exit of MAN, etc. Since the lwAFTR has good
scalability and can handle numerous concurrent sessions, we recommend
to adopt the "centralized model" for Lightweight 4over6 as it is
cost-effective and easy to manage.
In the "distributed model", lwAFTR is usually integrated with the
BRAS/SR. Since newly emerging customers might be distributed in the
whole Metro area, we have to deploy lwAFTR on all BRAS/SRs. This
will cost a lot in the initial phase of the IPv6 transition period.
5.5. Port set algorithm consideration
If each lwB4 is given a set of ports, port randomization algorithm
can only select port in the given port-set. This may introduce
security risk because hackers can make a more predictable guess of
what port a subscriber may use. Therefore, non-continuous port set
algorithms (e.g. as defined in [I-D.ietf-softwire-map]) can be used
to improve security.
5.6. Path Consistency Consideration
In Lightweight 4over6, if the binding state is not syncronized among
multiple lwAFTRs, the lwAFTR in which the subscriber's binding state
is stored should be exactly the one to service the subscriber.
Otherwise, there will be no match in lwAFTR. This requires the
provionsion packets (either using DHCPv4-over-DHCPv6 or PCP Port-set)
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should arrive at the same lwAFTR as the subsquent IP-in-IP traffic.
If multiple lwAFTRs are using the same Tunnel End Point address and
there are intermediate routers between lwB4 and lwAFTR, there might
be a problem when intermediate routers perform ECMP based on L4 hash
for the plain provionsion packets while doing L3 hash for subsequent
IP-in-IP traffic. In this case, it is recommended that the
privioning packet is sent over IPv6 tunnel so that intermediate
routers can only process ECMP using L3 hash.
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6. lwB4 Deployment Consideration
For lwB4 consideration, the DNS Deployment Considerations and B4
Remote Management in [RFC6908] can also be applied here. In this
section, we only describe the considerations sepcific to Lightweight
4over6.
6.1. NAT traversal issue
In Lightweight 4over6, since the subscriber's source port will be
restricted to the port-set allocated from the provisioning system,
this will have impact on some NAT traversal mechanisms. For example,
in UPnP 1.0, the external port number which can be used by remote
peer is selected by UPnP client in end host. If the client randomly
selects a port number which is not in that valid port-set, the UPnP
process will fail. This is likely to happen because end-host does
not know the port-set in lwB4. More detailed experimental results
can be found in [I-D.deng-aplusp-experiment-results]. This problem
will not exist in UPnP 2.0 because the UPnP client in the end-host
will negotiate the external port number with the server. Another way
is to implement a mechanism (e.g. [I-D.ietf-pcp-port-set], etc.) in
end host to fetch the port-set from lwB4. The UPnP client can then
select the port number within the port-set.
6.2. Static Port Forwarding Configuration
Currently, some external initiated applications rely on manual port
configuration to reserve a port in the CPE. The restricted port-set
in lwB4 will also have impacts on manual port forwarding
configuration. It is recommended that the port-set allocated from
the provioning system should be shown explicitly in the lwB4, which
can be used as a hint for subscribers to add port forwarding mapping.
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7. DS-Lite Compatibility Consideration
Lightweight 4over6 can be either deployed all alone, or combined with
DS-Lite [RFC6333]. Since Lightweight 4over6 does not any have extra
requirement on IPv6 addressing, it can use use the same addressing
scheme with DS-Lite, together with routing policy, user management
policy, etc. Besides, the bottom-up model has quite similar
requirement and workflow on the supporting system with DS-Lite.
Therefore, it is suitable for operators to deploy incrementally in
existing DS-Lite network
7.1. Case 1: Integrated Network Element with Lightweight 4over6 and DS-
Lite AFTR Scenario
In this case, DS-Lite has been deployed in the network. Later in the
deployment schedule, the operator decided to implement Lightweight
4over6 lwAFTR function in the same network element(depicted in
Figure2). Therefore, the same network element needs to support both
transition mechanisms.
There are two options to distinguish the traffic from two transition
mechanisms.
The first one is to distinguish using the client's source IPv4
address. The IPv4 address from Lightweight 4over6 is public address
as NAT has been done in the lwB4, and IPv4 address for DS-lite is
private address as NAT will be done on AFTR. When the network
element receives an encapsulated packet, it would de-capsulate packet
and apply the transition mechanism based on the IPv4 source address
in the packet. This requires the network element to examine every
packet and may introduce significant extra load to the network
element. However, both the B4 element and Lightweight 4over6 lwB4
can use the same DHCPv6 option [RFC6334] with the same FQDN of the
AFTR and lwAFTR.
The second one is to distinguish using the destination's tunnel IPv6
address. One network element can run separated instances for
Lightweight 4over6 and DS-Lite with different tunnel addresses. Then
B4 element and Lightweight 4over6 lwB4 can use the same DHCPv6 option
[RFC6334] with different FQDNs pointing to corresponding tunnel
addresses. This requires the supporting system should distinguish
different types of users when assigning the FQDNs in DHCPv6 process.
Another option is to use a new DHCPv6 option
[I-D.sun-softwire-lw4over6-dhcpv6] to discover lwAFTR's FQDN.
+---------------+--------------|
+ | |
+---------+ +------+---+ +--+--+ |
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| Host | | LW 4over6| | | |
| |--| lwB4| ======-| BNG | === +-------------+ +-----------+
+---------+ +----------+ +--|--+ |LW 4over6 | | IPv4 |
|lwAFTR/|---| Internet |
+---------+ +------+---+ +--+--+ |DS-Lite AFTR | | |
| Host |--| DS-Lite | =======| | ====+-------------+ +-----------+
| | | B4 | | BNG | |
+---------+ +----------+ +--|--+ |
+ | |
+---------------+--------------+
Figure 2 DS-Lite Coexistence scenario with Integrated AFTR
7.2. Case 2: DS-Lite Coexistent scenario with Separated AFTR
This is similar to Case 1. The difference is the lwAFTR and AFTR
functions won't be co-located in the same network element (depicted
in Figure3). This use case decouples the functions to allow more
flexible deployment. For example, an operator may deploy AFTR closer
to the edge and lwAFTR closer to the core. Moreover, it does not
require the network element to pre-configure with the CPE's IPv6
addresses. An operator can deploy more AFTR and lwAFTR at needed.
However, this requires the B4 and lwB4 to discover the corresponding
network element. In this case, B4 element and Lightweight 4over6
lwB4 can still use [RFC6334] with different FQDNs pointing to
corresponding tunnel end-point addresses, and the supporting system
should distinguish different types of users.
+---+---------------+-----------------|
+ | |
+---------+ +------+---+ +------+-----+ |
| Host | | LW 4over6| | BNG | |
| |--| lwB4| ======-|DS-Lite AFTR| === +------------+ +-----------+
+---------+ +----------+ +------+-----+ |LW 4over6 | | IPv4 |
|lwAFTR|---| Internet |
+---------+ +------+---+ +------+-----+ | | | |
| Host |--| DS-Lite | =======| BNG | ====+------------+ +-----------+
| | | B4 | |DS-Lite AFTR| |
+---------+ +----------+ +------+-----+ |
+ | |
+-------------------+-----------------+
Figure 3 DS-Lite Coexistence scenario with Seperated AFTR
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8. Acknowledgement
TBD
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9. References
[I-D.bajko-pripaddrassign]
Bajko, G., Savolainen, T., Boucadair, M., and P. Levis,
"Port Restricted IP Address Assignment",
draft-bajko-pripaddrassign-04 (work in progress),
April 2012.
[I-D.cui-softwire-b4-translated-ds-lite]
Cui, Y., Sun, Q., Boucadair, M., Tsou, T., Lee, Y., and I.
Farrer, "Lightweight 4over6: An Extension to the DS-Lite
Architecture", draft-cui-softwire-b4-translated-ds-lite-11
(work in progress), February 2013.
[I-D.deng-aplusp-experiment-results]
Deng, X., Boucadair, M., and F. Telecom, "Implementing A+P
in the provider's IPv6-only network",
draft-deng-aplusp-experiment-results-00 (work in
progress), March 2011.
[I-D.ietf-behave-ipfix-nat-logging]
Sivakumar, S. and R. Penno, "IPFIX Information Elements
for logging NAT Events",
draft-ietf-behave-ipfix-nat-logging-00 (work in progress),
March 2013.
[I-D.ietf-behave-syslog-nat-logging]
Chen, Z., Zhou, C., Tsou, T., and T. Taylor, "Syslog
Format for NAT Logging",
draft-ietf-behave-syslog-nat-logging-01 (work in
progress), May 2013.
[I-D.ietf-dhc-dhcpv4-over-ipv6]
Cui, Y., Wu, P., Wu, J., and T. Lemon, "DHCPv4 over IPv6
Transport", draft-ietf-dhc-dhcpv4-over-ipv6-06 (work in
progress), March 2013.
[I-D.ietf-pcp-base]
Wing, D., Cheshire, S., Boucadair, M., Penno, R., and P.
Selkirk, "Port Control Protocol (PCP)",
draft-ietf-pcp-base-29 (work in progress), November 2012.
[I-D.ietf-pcp-port-set]
Sun, Q., Boucadair, M., Sivakumar, S., Zhou, C., Tsou, T.,
and S. Perreault, "Port Control Protocol (PCP) Extension
for Port Set Allocation", draft-ietf-pcp-port-set-01 (work
in progress), May 2013.
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[I-D.ietf-softwire-4rd]
Despres, R., Jiang, S., Penno, R., Lee, Y., Chen, G., and
M. Chen, "IPv4 Residual Deployment via IPv6 - a Stateless
Solution (4rd)", draft-ietf-softwire-4rd-06 (work in
progress), July 2013.
[I-D.ietf-softwire-dslite-deployment]
Lee, Y., Maglione, R., Williams, C., Jacquenet, C., and M.
Boucadair, "Deployment Considerations for Dual-Stack
Lite", draft-ietf-softwire-dslite-deployment-08 (work in
progress), January 2013.
[I-D.ietf-softwire-lw4over6]
Cui, Y., Sun, Q., Boucadair, M., Tsou, T., Lee, Y., and I.
Farrer, "Lightweight 4over6: An Extension to the DS-Lite
Architecture", draft-ietf-softwire-lw4over6-00 (work in
progress), April 2013.
[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-07
(work in progress), May 2013.
[I-D.lee-softwire-lw4over6-failover]
Lee, Y., Sun, Q., and C. Liu, "Simple Failover Mechanism
for Lightweight 4over6",
draft-lee-softwire-lw4over6-failover-00 (work in
progress), July 2013.
[I-D.sun-softwire-lw4over6-dhcpv6]
Xie, C., Sun, Q., Lee, Y., Tsou, T., and P. Wu, "Dynamic
Host Configuration Protocol for IPv6 (DHCPv6) Option for
Lightweight 4over6", draft-sun-softwire-lw4over6-dhcpv6-00
(work in progress), July 2013.
[I-D.zhou-dime-4over6-provisioning]
Zhou, C. and T. Taylor, "Attribute-Value Pairs For
Provisioning Customer Equipment Supporting IPv4-Over-IPv6
Transitional Solutions",
draft-zhou-dime-4over6-provisioning-00 (work in progress),
March 2013.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC6052] Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X.
Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052,
Sun, et al. Expires January 15, 2014 [Page 17]
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October 2010.
[RFC6333] Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual-
Stack Lite Broadband Deployments Following IPv4
Exhaustion", RFC 6333, August 2011.
[RFC6334] Hankins, D. and T. Mrugalski, "Dynamic Host Configuration
Protocol for IPv6 (DHCPv6) Option for Dual-Stack Lite",
RFC 6334, August 2011.
[RFC6431] Boucadair, M., Levis, P., Bajko, G., Savolainen, T., and
T. Tsou, "Huawei Port Range Configuration Options for PPP
IP Control Protocol (IPCP)", RFC 6431, November 2011.
[RFC6908] Lee, Y., Maglione, R., Williams, C., Jacquenet, C., and M.
Boucadair, "Deployment Considerations for Dual-Stack
Lite", RFC 6908, March 2013.
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1. Appendix:Experimental Result
We have deployed Lightweight 4over6 in our operational network of
HuNan province, China. It is designed for broadband access network,
and different versions of lwB4 have been implemented including a
linksys box, a software client for windows XP, vista and Windows 7.
It can be integrated with existing dial-up mechanisms such as PPPoE,
etc. The major objectives listed below aimed to verify the
functionality and performance of Lightweight 4over6:
o Verify how to deploy Lightweight 4over6 in a practical network.
o Verify the impact of applications with Lightweight 4over6.
o Verify the performance of Lightweight 4over6.
1.1. Experimental environment
The network topology for this experiment is depicted in Figure 2.
+--------+
+-----+ +---------+ | Syslog |
|Host1+--+lwB4|--+ | Server | --------
+-----+ +---------+ | +---+----+ /// \\\
| /------\ | // \\
| // \\ +---+----+ | |
+-----+ +---------+ +-+--+ | IPv6 | | | | IPv4 Internet |
|Host2+--|lwB4|--+BRAS+--| Network |---| Concen-+-+ |
+-----+ +---------+ +-+--+ \\ // | trator | \\ //
| \---+--/ +--------+ \\\ ///
| | ---------
+-----+ +---------+ | |
|Host3+--+lwB4+---+ |
+-----+ +---------+ | --------
| // \\
| / \
+---------------------+IPv6 Internet +
| |
\ /
\\ //
-------
Figure 2 Lightweight 4over6 experiment topology
In this deployment model, lwAFTR is co-located with a extended PCP
server to assign restricted IPv4 address and port set for lwB4. It
also triggers subscriber-based logging event to a centrilized syslog
server. IPv6 address pools for subscribers have been distributed to
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BRASs for configuration, while the public available IPv4 address
pools are configured by the centralized lwAFTR with a default address
sharing ratio. It is rather flexible for IPv6 addressing and
routing, and there is little impact on existing IPv6 architecture.
In our experiment, lwB4 will firstly get its IPv6 address and
delegated prefix through PPPoE, and then initiate a PCP-extended
request to get public IPv4 address and its valid port set. The
lwAFTR will thus create a subscriber-based state accordingly, and
notify syslog server with {IPv6 address, IPv4 address, port set,
timestamp}.
1.2. Experimental results
In our trial, we mainly focused on application test and performance
test. The applications have widely include web, email, Instant
Message, ftp, telnet, SSH, video, Video Camera, P2P, online game,
voip and so on. For performance test, we have measured the
parameters of concurrent session numbers and throughput performance.
The experimental results are listed as follows:
+--------------------+----------------------+-----------------------+
| Application Type | Test Result |Port Number Occupation |
+--------------------+----------------------+-----------------------+
| Web | ok | normal websites: 10~20|
| | IE, Firefox, Chrome | Ajex Flash webs: 30~40|
+--------------------+----------------------+-----------------------+
| Video | ok, web based or | 30~40 |
| | client based | |
+--------------------+----------------------+-----------------------+
| Instant Message | ok | |
| | QQ, MSN, gtalk, skype| 8~20 |
+--------------------+----------------------+-----------------------+
| P2P | ok | lower speed: 20~600 |
| |utorrent,emule,xunlei | (per seed) |
| | | higher speed: 150~300 |
+--------------------+----------------------+-----------------------+
| FTP | need ALG for active | 2 |
| | mode, flashxp | |
+--------------------+----------------------+-----------------------+
| SSH, TELNET | ok |1 for SSH, 3 for telnet|
+--------------------+----------------------+-----------------------+
| online game | ok for QQ, flash game| 20~40 |
+--------------------+----------------------+-----------------------+
Figure 3 Lightweight 4over6 experimental result
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The performance test for lwAFTR is taken on a normal PC. Due to
limitations of the PC hardware, the overall throughput is limited to
around 800 Mbps. However, it can still support more than one hundred
million concurrent sessions.
1.3. Conclusions
From the experiment, we can have the following conclusions:
o Lightweight 4over6 has good scalability. As it is a lightweight
solution which only maintains per-subscription state information,
it can easily support a large amount of concurrent subscribers.
o Lightweight 4over6 can be deployed rapidly. There is no
modification to existing addressing and routing system in our
operational network. And it is simple to achieve traffic logging.
o Lightweight 4over6 can support a majority of current IPv4
applications.
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Authors' Addresses
Qiong Sun
China Telecom
Room 708, No.118, Xizhimennei Street
Beijing 100035
P.R.China
Phone: +86-10-58552936>
Email: sunqiong@ctbri.com.cn
Chongfeng Xie
China Telecom
Room 708, No.118, Xizhimennei Street
Beijing 100035
P.R.China
Phone: +86-10-58552116>
Email: xiechf@ctbri.com.cn
Yiu L. Lee
Comcast
One Comcast Center
Philadelphia, PA 19103
USA
Email: yiu_lee@cable.comcast.com
Maoke Chen
FreeBit Co., Ltd.
13F E-space Tower, Maruyama-cho 3-6
Shibuya-ku, Tokyo 150-0044
Japan
Email: fibrib@gmail.com
Sun, et al. Expires January 15, 2014 [Page 22]
