Network Working Group J. Wu
Internet-Draft J. Bi
Intended status: Experimental Tsinghua University
Expires: August 29, 2007 M. Williams
Juniper Networks
Feb 25, 2007
SAVA Testbed and Experiences to Date
draft-wu-sava-testbed-experience-00
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Copyright Notice
Copyright (C) The IETF Trust (2007).
Abstract
This draft describes the testbed installed at Tsinghua University and
other Universities in China attached to the CERNET-II IPv6 backbone,
some SAVA testing that has been carried out on that network and some
preliminary results of that testing.
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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].
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. SAVA Testbed . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. CERNET2 . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.2. SAVA Testbed on CERNET2 Infrastructure . . . . . . . . . . 3
3. SAVA Solutions Tested and Experiences . . . . . . . . . . . . 5
3.1. Inter-ISP Case (Neighbouring AS) . . . . . . . . . . . . . 5
3.2. Inter-ISP Case (Intervening AS) . . . . . . . . . . . . . 8
3.3. Intra-ISP (Access Network) Case . . . . . . . . . . . . . 9
4. Test Experience . . . . . . . . . . . . . . . . . . . . . . . 10
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
6. Security Considerations . . . . . . . . . . . . . . . . . . . 10
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
8.1. Normative References . . . . . . . . . . . . . . . . . . . 10
8.2. Informative References . . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11
Intellectual Property and Copyright Statements . . . . . . . . . . 13
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1. Introduction
The problem addressed in the Source Address Validation Architecture
activity is outlined in [I-D.wu-sava-problem-statement] and a
proposed solution framework for discussion is outlined in
[I-D.wu-sava-framework].
Some potential procedures that could be used as solution elements in
the framework have been devised and one is introduced and discussed
in [I-D.wu-sava-solution-e2e-ipv6]. It should be stressed that at
this early stage, the solutions proposed in the solution document are
not intended to pre-empt work carried out by the IETF in the solution
space. Indeed, consensus must be reached on a framework before
solution work can be fully undertaken. The shape of the "holes"
needs to be established before the "pegs" can be carved.
Furthermore, it is envisaged that more than one solution could be
devised and deployed for each of the proposed solution elements
required under the framework, in keeping with the requirement for a
loosely-coupled architecture and, as far as possible, a plug-and-play
framework. The intention of the solutions documents is to provide
some solution ideas which can be implemented on the testbed described
in this document.
This document describes the testbed and the solutions implemented and
tested on it to date.
2. SAVA Testbed
2.1. CERNET2
CERNET2 is one of the China Next Generation Internet (CNGI)
backbones. CERNET2 connects 25 core nodes distributed in 20 cities
in China at speeds of 2.5-10 Gb/s. The CERNET2 backbone is an IPv6-
only network.
2.2. SAVA Testbed on CERNET2 Infrastructure
It is intended that eventually the SAVA testbed will be implemented
directly on the CERNET2 backbone, but in the early stages the testbed
has been implemented as an overlay structure on top of CERNET2. This
is because first, some of the algorithms need to be implemented in
the testbed routers themselves and to date they have not been
implemented on any of the commercial routers forming the CERNET2
backbone. Second, since CERNET2 is a production backbone, any new
protocols and networking techniques need to be tested in a non-
disruptive way.
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---------------
| Transit AS |
---------------
| |
------ ------
|ASBR| |ASBR|
------ ------
| |
| | Inter-ISP
| | layer
........|...........|.................
------ ------
|ASBR| |ASBR|
------ ------
| |
----- -----
|AS1| |AS2|
----- -----
| | Intra-ISP
| | layer
........|...........|.................
| |
----- -----
|ASw| |ASw| Access
----- ----- layer
| |
---------- ----------
| access | | access |
| net | | net |
---------- ----------
| |
----- -----
| H1| |H2 |
----- -----
Figure 1: SAVA Framework Layers
Notwithstanding the aforementioned restrictions on the early testbed,
the testbed is fully capable of functional testing of solutions for
all parts of the SAVA solution framework. Namely, it is possible to
test procedures for ensuring the validity of IPv6 source addresses in
the access network and in packets sent from the access network to an
IPv6 service provider, packets sent within one service provider's
network, packets sent between neighboring service providers and
packets sent between service providers separated by an intervening
transit network.
The testbed is distributed across 7 universities connected to
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CERNET2, namely Tsinghua University, Beijing University, Beijing
University of Post and Telecommunications, Shanghai Jiaotong
University, Wuhan Polytechnic University, Southeast University in
Nanjing, and South China Polytechnic University in Guangzhou.
Each of the university installations is connected to the CERNET2
backbone through a set of inter-ISP filtering and monitoring
equipment. (Inter-ISP Layer).
Of the installations, the installation at Tsinghua University is the
most fully-featured, with inter-ISP, Intra-ISP and access layer
validation all able to be tested. In addition, a suite of
applications that could be subject to spoofing attacks or which can
be subverted to carry out spoofing attacks are installed on a variety
of servers. The Tsingua testbed consists of three separate
Autonomous systems joined by MBGP speakers.
to be added
Figure 2: CERNET2 Overlay SAVA Test Environment
to be added
Figure 3: Tsinghua University Trustable Internet Test Network
to be added
Figure 4: Tsinghua University Network AS100 detail
to be added
Figure 5: Tsinghua University Test Network AS200 Detail
to be added
Figure 6: Tsinghua University Test Network AS300 Detail
3. SAVA Solutions Tested and Experiences
3.1. Inter-ISP Case (Neighbouring AS)
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---------
| AIMS |
------|-
|
-------------- -----------|-----
| AS-4 |----- ------| AS-1 | |-----
| |ASBR |----->|ASBR | ------|- |ASBR |---> Global IPv6
| |----- ------| | VRGE | |----- Network
--------------- | -------- |
----- -----------------
|ASBR| |ASBR|
------ ------
/ |
/ |
/ |
/ |
---------- -----
|ASBR, VE| |ASBR|
--------------- -------------
| AS-2 | | AS-3 |
| | | |
| | | |
| | | |
--------------- -------------
Key: AIMS == AS-IPv6 prefix Mapping Server, VRGE == Validation Rule
Generating Engine, VE == Validating Engine
Figure 7: Inter-ISP (Neighboring AS) Setup
In the solution implemented on the testbed, the solution for the
validation of IPv6 prefixes is separated into three functional
modules: The Validation Rule Generating Engine (VRGE), the Validation
Engine (VE) and the the AS-IPv6 prefix Mapping Server. (AIMS).
Validation rules (VR) that are generated by the VRGE are expressed as
IPv6 address prefixes.
The VRGE generates validation rules, and each AS has one. In the
testbed, these are implemented on a LINUX server. The VE loads
validation rules generated by VRGE to filter packets passed between
ASs (In the case of Figure 7, from neighbouring ASs into AS-1. In
the SAVA testbed, the VE is implemented as a simulated L2 device on a
Linux-based machine inserted into the data path just outside each
ASBR interface that faces a neigbouring AS, but in a real-world
implementation it would probably be implemented as a packet filter
set on the ASBR. The AS-IPv6 prefix mapping server is also
implemented on a Linux machine and derives a mapping between IPv6
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prefix and the AS of that prefix's "entry" into the region of
validated IPv6 prefixed by processing AS-Path information. The rules
are derived according to the table below, as described in [Gao].
---------------------------------------------------------------------------
| \Export| Own | Customer's| Sibling's | Providor's | Peer's |
|To \ | Address | Address | Address | Address | Address |
|-----\-------------------------------------------------------------------|
| Providor | Y | Y | Y | | |
|-------------------------------------------------------------------------|
| Customer | Y | Y | Y | Y | Y |
|-------------------------------------------------------------------------|
| Peer | Y | Y | Y | | |
|-------------------------------------------------------------------------|
| Sibling | Y | Y | Y | Y | Y |
---------------------------------------------------------------------------
Figure 8: AS-Relation Based Inter-AS Filtering
Different ASes exchange and transmit VR information using the AS-
relation-based export rules in the VR generation server. As per
Figure 8, an AS exports the address prefixes of its own , its
customers, its providers, it siblings and its peers to its customers
and siblings as valid prefixes, while it only exports the address
prefixes of its own, its customers and its siblings to its providers
and peers as valid prefixes. With the support of AS Number to IPv6
Address Mapping service, only AS numbers of valid address prefixes
are transferred between ASes and the AS number is mapped to address
prefixes at the VRGE. Only changes of AS relation and changes of IP
address prefixes belonging to an AS require the generation of VR
updates.
The procedure's principle steps are as folows (as seen by AS-1 in
Figure 7):
1. When the VRG has initialised, it reads the AS neighbour table and
establishes TCP connections to all the VEs in its own AS.
2. The VRGE initiates a VR renewal. According to its export table,
it sends its own originated IPv6 prefixes to neighbouring ASs
VRGEs. Rules are expressed as AS numbers.
3. When a VRGE receives the new rules from its neighbour, it then
uses its own export table to decide whether it should accept the
rules and, if it accepts a rule, whether or not it should re-
export the rule to other neighbouring ASs.
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4. If the VRGE accepts a rule, it used the AIMS to transform AS-
expressed rules into IPv6 refix-expressed rules.
5. The VRGE then pushes the thus-generated rules to all the VEs in
its AS. The VEs then use these prefix-based rules to filter
incoming packets.
3.2. Inter-ISP Case (Intervening AS)
In the case where two ASs do not exchange packets directly, it s not
possibe to deploy a solution like that in the previous section.
However, it is highly desirable for non-neighbouring ISPs to be able
to form a trust alliance such that packets leaving one AS will be
recognised by the other and inherit the validation status they
possessed on leaving the first AS. There is more than one way to do
this. For the SAVA experiments to date, the signature method
detailed in [I-D.wu-sava-solution-e2e-ipv6] has been used. This
particular method uses a weak signature.
+-----+
| REG |
+-----+
,-------------- ,--------------
,' ` `. ,' ` `.
/ \ / \
/ \ / \
; +-----+ +----+ +----+ +-----+ ;
| | ASC | |AER | |AER | | ASC | |
: +-----+ +----+` +----+ +-----+ :
\ / \ /
\ / \ /
`. ,' `. ,'
'-------------' '-------------'
AS-1 AS-2
KEY: REG == Registration Server, ASC == AS Control Server, AER == AS
Edge Router.
Figure 9: Validation Setup Between non-Neighbouring ASs
There are three major components in the system: the Registration
Server(REG), the AS Control Server(ASC), and the AS Edge Router(AER).
The Registration Server is the "center" of the trust alliance (TA) .
It maintains a member list for the TA. It performs two major
functions:
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o Processes requests from the AS Control Server, to get the member
list for the TA.
o When the member list is changed, notifiy each AS Control Server.
Each AS deploying the method should have an AS Control Server. The
AS Control Server has three major functions:
o Communicate with the Registration Server, to get the up-to-date
member list of TA.
o Communicate with the AS Control Server in other member AS in the
TA, to exchange updates of prefix ownership information, and to
exchange signatures.
o Communicate with all edge routers of the local AS, to configure the
processing component on the edge routers.
The AS Edge Router does the work of adding signature to the packet at
the sending AS, and the work of verifying and removing the signature
at the destination AS.
In the design of this system, in order to decrease the burden on the
REG, most of the control traffic happens between ASCs.
3.3. Intra-ISP (Access Network) Case
Assuming an ISP has implemented source address validation on its
connection to peers and transit providers, the intra-ISP case reverts
to access validation. There are many options for access validation,
including BCP38 filtering, depending on the strength of validation
required. The solution tested in the SAVA testbed takes the
strongest requirement for validation in the access network. That is,
any IPv6 address should have a unique association with an entity that
is specifically authorised to use that IPv6 address. (BCP38
filtering, on the other hand typically only requires that the source
address of a packet entering the provider network belong to a prefix
that is allocated to or has transit through the attached access
network.)
An Extended Access Control Protocol is used in order to distribute
authorised IPv6 addreses to end-users and to ensure a record of the
authorised user and the corresponding IPv6 address and MAC address
for each port of the access switch. As a result it is possible for
the access switch to filter any packets sent by the user (or sokmeone
pretending to be the user) that do not carry the authorised IPv6
source address and the corresponding MAC address. The SAVA extendes
access control used for this proof of concept follows the following 4
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steps:
1. End user sends an identity verification supplication, and the
access switch sends a RADIUS request to the SAVA access
validation server.
2. On successful establishment of identity, the SAVA access
validation server issues an authorised IPv6 address for the user.
3. The access switch, on receiving the RADIUS authentication success
message combines the embedded IPv6 address, the end-user
identity, end-user MAC address and the switch port number into a
binding relationship. In addition, it sends the issued address
to the end-user host.
4. The access switch begins to filter packets sent from the end-user
host. Packets which do not conform to an authorised (MAC SA,
IPv6 SA, Switch Port) tuple are discarded.
4. Test Experience
The solutions outlined above have been implemented on the testbed
described above. Successful testing of all solutions has been
carried out. A more detailed discussion will be forthcoming in the
next version of this draft.
5. IANA Considerations
This document makes no request of IANA.
Note to RFC Editor: this section may be removed on publication as an
RFC.
6. Security Considerations
7. Acknowledgements
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
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8.2. Informative References
[Gao] Gao, L., "On Inferring Autonomous System Relationships in
the Internet", Infocom 2001, December 2001.
[I-D.wu-sava-framework]
Wu, J., "Source Address Validation Architecture (SAVA)
Framework", draft-wu-sava-framework-00 (work in progress),
February 2007.
[I-D.wu-sava-problem-statement]
Wu, J., Bonica, R., Bi, J., Li, X., Ren, G., and M I.
Williams, "Source Address Validation Architecture (SAVA)
Problem Statement", February 2007.
[I-D.wu-sava-solution-e2e-ipv6]
Wu, J., "An End-to-end Source Address Validation Solution
for IPv6", draft-wu-sava-solution-e2e-ipv6-00 (work in
progress), February 2007.
Authors' Addresses
Jianping Wu
Tsinghua University
Phone:
Fax:
Email: jianping@cernet.edu.cn
URI:
Jun Bi
Tsinghua University
Phone:
Fax:
Email: junbi@tsinghua.edu.cn
URI:
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Mark Williams
Juniper Networks
Phone:
Fax:
Email: miw@juniper.net
URI:
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