Network Working Group B. Liu
Internet Draft Huawei Technologies
Intended status: Standards Track Bruno Decraene
Expires: August 18, 2014 Orange
I. Farrer
Deutsche Telekom AG
M. Abrahamsson
T-System
February 14, 2014
ISIS Auto-Configuration
draft-liu-isis-auto-conf-01.txt
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 August 18, 2014.
Copyright Notice0
Copyright (c) 2012 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
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Bing Liu Expires August 18, 2014 [Page 1]
Internet-Draft ISIS Auto-Configuration February 2014
Abstract
This document describes mechanisms for IS-IS to be self-configuring.
Such mechanisms could reduce the management burden to configure a
network. One obvious environment that could benefit from these
mechanisms is IPv6 home network where plug-and-play would be expected.
Besides home network, some simple enterprise/ISP networks might also
benefit from the self-configuring mechanisms.
Table of Contents
1. Introduction ................................................. 3
2. Design Scope ................................................. 3
3. Protocol Specification ....................................... 4
3.1. IS-IS Default Configuration ............................. 4
3.2. IS-IS NET Generation .................................... 4
3.3. IS-IS NET Duplication Detection and Resolution........... 5
3.3.1. Router-Hardware-Fingerprint TLV .................... 5
3.3.2. NET Duplication Detection and Resolution Procedures. 5
3.4. Authentication TLV ...................................... 6
3.5. Wide Metric ............................................. 7
3.6. Adjacency Formation Consideration ....................... 7
4. Co-existence with Other IGP Auto-configuration ............... 7
5. Security Considerations ...................................... 7
6. IANA Considerations .......................................... 8
7. Acknowledgments .............................................. 8
8. References ................................................... 8
8.1. Normative References .................................... 8
8.2. Informative References .................................. 8
Bing Liu Expires August 18, 2014 [Page 2]
Internet-Draft ISIS Auto-Configuration February 2014
1. Introduction
This memo describes mechanisms for IS-IS [RFC1195][RFC5308] to be
auto-configuring. Such mechanisms could reduce the management burden
to configure a network. One example is home network where plug-and-
play would be expected. Besides home network, some simple
enterprise/ISP networks might also potentially benefit from the auto-
configuring mechanisms.
In addition, this memo defines how such un-configured routers should
behave, also limits the risk on existing network using IS-IS (Setcion
3.4 & 3.5).
IS-IS auto-configuration mainly contains the following aspects:
1. IS-IS Default Configuration
2. IS-IS NET self-generation
3. NET duplication detection and resolution
4. Authentication and Wide Metric TLV
2. Design Scope
The auto-configuring mechanisms are not specifically designed based
on IPv4 or IPv6.
The auto-configuring mechanisms enabled interfaces are assumed to
have a 48-bit MAC address.
The main targeted application scenarios are supposed to be home
networks or small enterprise networks .etc. where plug-n-play is
expected and complex topology/hierarchy is not needed. Sophisticate
requirements from service provider networks are out of scope.
So this document does not provide a complete configuration-free
alternative to the IS-IS protocol. The following features of IS-IS
are NOT supported by this document:
o Auto-configuring multiple IS-IS processes. The auto-configuration
mechanisms only support configuring a single process.
o Route between multiple IS-IS areas. The auto-configuration
mechanisms only support routers that are within a single area.
Bing Liu Expires August 18, 2014 [Page 3]
Internet-Draft ISIS Auto-Configuration February 2014
o Auto-configuring multiple operation levels. The auto-configuration
mechanisms only support level-1 operation mode.
o This document does not consider interoperability with other routing
protocols.
3. Protocol Specification
3.1. IS-IS Default Configuration
o IS-IS SHOULD be enabled on all interfaces in a router that requires
the IS-IS auto-configuration as default. For some specific situations,
interface MAY be excluded if it is a clear that running IS-IS on the
interface is not required.
o IS-IS interfaces MUST be auto-configured to an interface type
corresponding to their layer-2 capability. For example, Ethernet
interfaces will be auto-configured as broadcast networks and Point-
to-Point Protocol (PPP) interfaces will be auto-configured as Point-
to-Point interfaces.
o IS-IS auto-configuration interfaces MUST be configured with level-1.
3.2. IS-IS NET Generation
In IS-IS, a router (known as an IS) is identified by an Network
Entity Title (NET) which is the address of a Network Service Access
Point (NSAP) and represented with an IS-IS specific address format.
The NSAP is a logical entity which represents an instance of the IS-
IS protocol running on an IS.
The NET consists of three parts. The auto-generation mechanisms of
each part are described as the following:
Area address: This field is 1 to 13 octets in length. In IS-IS auto-
configuring, this field MUST be 0 in 13 octets length.
System ID: This field follows the area address field, and is 6 octets
in length. As specified in IS-IS protocol, this field must be unique
among all level-1 routers in the same area when the IS operates at
Level 1. In IS-IS auto-configuring, this field SHOULD be the MAC
address of one IS-IS enabled interface.
NSEL: This field is the N-selector, and is 1 octet in length. In IS-
IS auto-configuring, it must be set to "00".
Bing Liu Expires August 18, 2014 [Page 4]
Internet-Draft ISIS Auto-Configuration February 2014
3.3. IS-IS NET Duplication Detection and Resolution
As described in Section 3, in IS-IS auto-configuring the NETs are
distinguished by the System ID field in which it is a MAC address. So
for IS-IS neighbors' NET duplication, it is equal to MAC address
duplication in a LAN, which means a serious problem that devices need
to be changed. So the NET duplication detection and resolution
mechanism is actually used between non-neighbors which are within
the same IS-IS area.
The rational of IS-IS NET duplication detection and resolution is
described as the following.
3.3.1. Router-Hardware-Fingerprint TLV
The Router-Hardware-Fingerprint TLV is defined in [OSPFv3AC]. This
document re-uses it to achieve NET duplication detection.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Router Hardware Fingerprint (Variable) |
. .
. .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1 Router-Hardware-Fingerprint TLV Format
As defined in [OSPFv3AC], the contents of the hardware fingerprint
should be some combination of CPU ID, or serial number(s) that
provides an extremely high probability of uniqueness. It MUST be
based on hardware attributes that will not change across hard and
soft restarts. The length of the Router-Hardware-Fingerprint is
variable but must be 32 octets or greater.
Note that, since the TLV is to detect MAC address based NET
duplication, the TLV content MUST NOT only use MAC address. MAC
address plus other information are also not recommended to use.
3.3.2. NET Duplication Detection and Resolution Procedures
1) Flood the Router-Hardware-Fingerprint TLVs
When an IS-IS auto-configuration router gets online, it MUST include
the Router-Hardware-Fingerprint TLV in the first originated level-1
Bing Liu Expires August 18, 2014 [Page 5]
Internet-Draft ISIS Auto-Configuration February 2014
LSP. Then all the routers in the area could receive the information
in the TLV.
2) Compare the received Router-Hardware-Fingerprint TLVs
An IS-IS auto-configuring router MUST compare a received self-
originated LSP's Router-Hardware-Fingerprint TLV against its own one.
If they are equal, it means the LSP was indeed originated by the
router itself; if they are not equal, it means some other router has
the same NET originated the LSP, thus there is a NET duplication.
3) Duplication resolution
When NET duplication occurs, the router with the numerically smaller
router hardware fingerprint MUST generate a new NET.
4) Purge the LSPs containing duplicated NET
Before flooding the new NET, the LSP with the prior duplicate NET
MUST be purged. And any IS-IS neighbor adjacencies MUST be
reestablished.
5) Re-join the network with the new NET
After purging the LSPs with the duplicated NET, the router re-join
the IS-IS auto-configuration network with the newly generated NET.
3.4. Authentication TLV
Every IS-IS auto-configuration message MUST include an authentication
TLV (TLV 10, [RFC5304]) with the Type 1 authentication mode
("Cleartext Password") in order to avoid the auto-conf router to
accidentally join an existing IS-IS network which is not intended to
be auto-configured.
This feature is necessary because a low end CPE joining an existing
IS-IS network might seriously break it or cause unnecessary
management confusion.
The cleartext password is specified as "isis-autoconf". Routers that
implement IS-IS auto-configuration MUST use this password as default,
so that different routers could authenticate each other with no human
intervene as default. And routers MUST be able to set manual password
by the users.
Bing Liu Expires August 18, 2014 [Page 6]
Internet-Draft ISIS Auto-Configuration February 2014
3.5. Wide Metric
IS-IS auto-configuration routers SHOULD support wide metric (TLV 22,
[RFC5305]). It is recommended that IS-IS auto-configuration routers
use a high metric value (e.g. 1000000) as default in order to
typically prefer the manually configured adjacencies rather than the
auto-conf ones.
3.6. Adjacency Formation Consideration
ISIS does not require strict hold timers matching to form adjacency.
But a reasonable range might be needed. Whether we need to specify a
best practice timers in ISIS-AC is an open question.[TBD].
4. Co-existence with Other IGP Auto-configuration
If a router supports multiple IGP auto-configuration mechanisms (e.g.
both IS-IS auto-configuration and OSPF auto-configuration), then in
practice it is a problem that there should be a mechanism to decide
which IGP to be used, or even both.
However, it is not proper to specify choice/interaction of multiple
IGPs in any standalone IGP auto-configuration protocols. It should be
done in the CPE level. Currently, there is some relevant work
emerging, for example, the suggestion from [HOMENET-HNCP] is to have
the proposed HNCP (Home Network Control Protocol) choose what IGP
should be used.
5. Security Considerations
Unwanted routers could easily join in an existing IS-IS auto-
configuration network by setting the authentication password as
"isis-autoconf" default value or sniff the cleartext password online.
However, this is a common security risk shared by other IS-IS
networks that don't set proper authentication mechanisms. For wired
deployment, the wired line itself could be considered as an implicit
authentication that normally unwanted routers are not able to connect
to the wire line; for wireless deployment, the authentication could
be achieve at the lower wireless link layer.
Malicious router could modify the SystemID field to cause NET
duplication detection and resolution vibrate thus cause the routing
system vibrate.
Bing Liu Expires August 18, 2014 [Page 7]
Internet-Draft ISIS Auto-Configuration February 2014
6. IANA Considerations
The Router Hardware Fingerprint TLV type code needs an assignment by
IANA.
7. Acknowledgments
Many useful comments and contributions were made by Sheng Jiang.
This document was inspired by [OSPFv3AC].
8. References
8.1. Normative References
[RFC1195] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and
dual environments", RFC 1195, December 1990.
[RFC5304] Li, T. and R. Atkinson, "IS-IS Cryptographic
Authentication", RFC 5304, October 2008.
[RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic
Engineering", RFC 5305, October 2008.
[RFC5308] Hopps, C., "Routing IPv6 with IS-IS", RFC 5308, October
2008.
8.2. Informative References
[OSPFv3AC]Lindem, A., and J. Arkko, "OSPFv3 Auto-Configuration", Work
in Progress, October 2013
[HOMENET-HNCP]
Stenberg, M., and S. Barth, "Home Networking Control
Protocol", Work in Progress, February 05
Bing Liu Expires August 18, 2014 [Page 8]
Internet-Draft ISIS Auto-Configuration February 2014
Authors' Addresses
Bing Liu
Huawei Technologies Co., Ltd
Q14, Huawei Campus
No.156 Beiqing Rd.
Hai-Dian District, Beijing 100095
P.R. China
Email: leo.liubing@huawei.com
Bruno Decraene
Orange
Issy-les-Moulineaux
FR
Email: bruno.decraene@orange.com
Ian Farrer
Deutsche Telekom AG
Bonn,
Germany
Email: ian.farrer@telekom.de
Mikael Abrahamsson
T-Systems
Stockholm,
Sweden
Email: mikael.abrahamsson@t-systems.se
Bing Liu Expires August 18, 2014 [Page 9]