The Generalized TTL Security Mechanism (GTSM) for the Label Distribution Protocol (LDP)
RFC 6720
| Document | Type |
RFC - Proposed Standard
(August 2012; No errata)
Updated by RFC 7552
Updates RFC 5036
|
|
|---|---|---|---|
| Last updated | 2015-10-14 | ||
| Replaces | draft-asati-pignataro-mpls-ldp-gtsm | ||
| Stream | IETF | ||
| Formats | plain text pdf html bibtex | ||
| Reviews | |||
| Stream | WG state | WG Document | |
| Document shepherd | No shepherd assigned | ||
| IESG | IESG state | RFC 6720 (Proposed Standard) | |
| Consensus Boilerplate | Unknown | ||
| Telechat date | |||
| Responsible AD | Adrian Farrel | ||
| IESG note | Loa Andersson is the document shepherd (loa@pi.nu). | ||
| Send notices to | (None) | ||
Internet Engineering Task Force (IETF) C. Pignataro
Request for Comments: 6720 R. Asati
Updates: 5036 Cisco Systems
Category: Standards Track August 2012
ISSN: 2070-1721
The Generalized TTL Security Mechanism (GTSM) for
the Label Distribution Protocol (LDP)
Abstract
The Generalized TTL Security Mechanism (GTSM) describes a generalized
use of a packet's Time to Live (TTL) (IPv4) or Hop Limit (IPv6) to
verify that the packet was sourced by a node on a connected link,
thereby protecting the router's IP control plane from CPU
utilization-based attacks. This technique improves security and is
used by many protocols. This document defines the GTSM use for the
Label Distribution Protocol (LDP).
This specification uses a bit reserved in RFC 5036 and therefore
updates RFC 5036.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc6720.
Pignataro & Asati Standards Track [Page 1]
RFC 6720 GTSM for LDP August 2012
Copyright Notice
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.
Table of Contents
1. Introduction ....................................................2
1.1. Specification of Requirements ..............................3
1.2. Scope ......................................................3
2. GTSM Procedures for LDP .........................................4
2.1. GTSM Flag in the Common Hello Parameter TLV ................4
2.2. GTSM Sending and Receiving Procedures for LDP Link Hello ...5
2.3. GTSM Sending and Receiving Procedures for LDP
Initialization .............................................5
3. LDP Peering Scenarios and GTSM Considerations ...................5
4. Security Considerations .........................................6
5. Acknowledgments .................................................7
6. References ......................................................7
6.1. Normative References .......................................7
6.2. Informative References .....................................8
1. Introduction
LDP [RFC5036] specifies two peer discovery mechanisms, a Basic one
and an Extended one, both using UDP transport. The Basic Discovery
mechanism is used to discover LDP peers that are directly connected
at the link level, whereas the Extended Discovery mechanism is used
to locate Label Switching Router (LSR) neighbors that are not
directly connected at the link level. Once discovered, the LSR
neighbors can establish the LDP peering session, using the TCP
transport connection.
The Generalized TTL Security Mechanism (GTSM) [RFC5082] is a
mechanism based on IPv4 Time To Live (TTL) or IPv6 Hop Limit value
verification so as to provide a simple and reasonably robust defense
from infrastructure attacks using forged protocol packets from
outside the network. GTSM can be applied to any protocol peering
Pignataro & Asati Standards Track [Page 2]
RFC 6720 GTSM for LDP August 2012
session that is established between routers that are adjacent.
Therefore, GTSM can protect an LDP protocol peering session
established using Basic Discovery.
This document specifies LDP enhancements to accommodate GTSM. In
particular, this document specifies the enhancements in the following
areas:
1. The Common Hello Parameter TLV of LDP Link Hello message
2. Sending and Receiving procedures for LDP Link Hello message
3. Sending and Receiving procedures for LDP Initialization message
GTSM specifies that "it SHOULD NOT be enabled by default in order to
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