Network Working Group B. Liu
Internet Draft Huawei Technologies Co., Ltd
Intended status: Proposed Standard October 21, 2013
Expires: April 24, 2014
ISIS Auto-Configuration
draft-liu-isis-auto-conf-00.txt
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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
potentially benefit from the self-configuring mechanisms.
Table of Contents
1. Introduction ................................................. 3
2. IS-IS Default Configuration .................................. 3
3. IS-IS NET Generation.......................................... 4
4. IS-IS NET Duplication Detection and Resolution ............... 4
4.1. Router-Hardware-Fingerprint TLV ......................... 4
4.2. NET Duplication Detection and Resolution ................ 5
5. Security Considerations ...................................... 5
6. IANA Considerations .......................................... 5
7. Acknowledgments .............................................. 5
8. References ................................................... 6
8.1. Normative References .................................... 6
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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.
The auto-configuring mechanisms are designed based on IPv6-only
environment. Some IPv4 environments might also applicable, but they
are not specifically considered.
The following aspects of IS-IS auto-configuration are described:
1. IS-IS Default Configuration
2. IS-IS NET self-generation
3. IS-IS Adjacency Formation
However, this draft does not provide a completely configuration-free
alternative to the IS-IS protocol, since some plan work by human so
far is very difficult to be achieved through algorithm. 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.
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.
2. IS-IS Default Configuration
o IS-IS SHOULD be enabled on all interfaces in a router 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.
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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.
3. 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 the following three parts:
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, tt must be set to "00".
4. 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
would need to be changed. IS-IS auto-configuring does not consider
this situation.
For the non-neighbor NET duplication detection within an area, this
document utilizes a TLV as following to do it.
4.1. 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
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TBD | >32 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Router Hardware Fingerprint |
o
o
o
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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. Note that, since the TLV is to detect MAC address
based NET duplication, the TLV content MUST NOT use MAC address only
again. Implementations SHOULD use other information exclude MAC
address.
4.2. NET Duplication Detection and Resolution
The Router-Hardware-Fingerprint TLV MUST be included in the first
originated level-1 LSP by every auto-configuring routers. An IS-IS
auto-configuring router MUST compare a received self-originated LSP's
Router-Hardware-Fingerprint TLV against its own one. If the they are
not equal, there is a NET duplication and the Router with the
numerically smaller router hardware fingerprint MUST generate a new
NET.
After selecting a new NET, the LSP with the prior duplicate NET MUST
be purged. And any IS-IS neighbor adjacencies MUST be reestablished.
5. Security Considerations
TBD.
6. IANA Considerations
The Router Hardware Fingerprint TLV type code needs an assignment.
7. Acknowledgments
Many useful comments and contributions were made by Sheng Jiang.
This document was inspired by [OSPFv3AC].
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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.
[RFC5308] Hopps, C., "Routing IPv6 with IS-IS", RFC 5308, October
2008.
[OSPFv3AC] Lindem, A., and J. Arkko, "OSPFv3 Auto-Configuration",
Work in Progress, October 2013
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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