draft-ietf-mpls-ldp-gtsm-03.txt   draft-ietf-mpls-ldp-gtsm-04.txt 
MPLS Working Group C. Pignataro MPLS Working Group C. Pignataro
Internet-Draft R. Asati Internet-Draft R. Asati
Intended status: Standards Track Cisco Systems Updates: 5036 (if approved) Cisco Systems
Expires: February 27, 2012 August 26, 2011 Intended status: Standards Track November 13, 2011
Expires: May 16, 2012
The Generalized TTL Security Mechanism (GTSM) for Label Distribution The Generalized TTL Security Mechanism (GTSM) for Label Distribution
Protocol (LDP) Protocol (LDP)
draft-ietf-mpls-ldp-gtsm-03 draft-ietf-mpls-ldp-gtsm-04
Abstract Abstract
The Generalized TTL Security Mechanism (GTSM) describes a generalized The Generalized TTL Security Mechanism (GTSM) describes a generalized
use of a packets Time to Live (TTL) (IPv4) or Hop Limit (IPv6) to use of a packets Time to Live (TTL) (IPv4) or Hop Limit (IPv6) to
verify that the packet was sourced by a node on a connected link, verify that the packet was sourced by a node on a connected link,
thereby protecting the router's IP control-plane from CPU utilization thereby protecting the router's IP control-plane from CPU utilization
based attacks. This technique improves security and is used by many based attacks. This technique improves security and is used by many
protocols. This document defines the GTSM use for Label Distribution protocols. This document defines the GTSM use for Label Distribution
Protocol (LDP). Protocol (LDP).
This specification uses a bit reserved in RFC 5036 and therefore
updates RFC 5036.
Status of this Memo Status of this Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on February 27, 2012. This Internet-Draft will expire on May 16, 2012.
Copyright Notice Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
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include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Specification of Requirements . . . . . . . . . . . . . . . 3 1.1. Specification of Requirements . . . . . . . . . . . . . . . 3
1.2. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.2. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. GTSM Procedures for LDP . . . . . . . . . . . . . . . . . . . . 4 2. GTSM Procedures for LDP . . . . . . . . . . . . . . . . . . . . 4
2.1. GTSM Flag in Common Hello Parameter TLV . . . . . . . . . . 4 2.1. GTSM Flag in Common Hello Parameter TLV . . . . . . . . . . 4
2.2. GTSM Sending and Receiving Procedures for LDP Link 2.2. GTSM Sending and Receiving Procedures for LDP Link
Hello . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Hello . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.3. GTSM Sending and Receiving Procedures for LDP 2.3. GTSM Sending and Receiving Procedures for LDP
Initialization . . . . . . . . . . . . . . . . . . . . . . 5 Initialization . . . . . . . . . . . . . . . . . . . . . . 5
3. LDP Peering Scenarios and GTSM Considerations . . . . . . . . . 6 3. LDP Peering Scenarios and GTSM Considerations . . . . . . . . . 6
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 7 5. Security Considerations . . . . . . . . . . . . . . . . . . . . 7
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 7 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 7
skipping to change at page 3, line 41 skipping to change at page 3, line 41
3. Sending and Receiving procedures for LDP Initilization message 3. Sending and Receiving procedures for LDP Initilization message
GTSM specifies that it SHOULD NOT be enabled by default in order to GTSM specifies that it SHOULD NOT be enabled by default in order to
remain backward-compatible with the unmodified protocol; this remain backward-compatible with the unmodified protocol; this
document specifies having a built-in dynamic GTSM capability document specifies having a built-in dynamic GTSM capability
negotiation for LDP to suggest the use of GTSM, provided GTSM is not negotiation for LDP to suggest the use of GTSM, provided GTSM is not
enabled unless both peers can detect each others' support for GTSM enabled unless both peers can detect each others' support for GTSM
procedures and agree on its usage as described in this document. procedures and agree on its usage as described in this document.
This specification uses a bit reserved in Section 3.5.2 of [RFC5036]
and therefore updates [RFC5036].
1.1. Specification of Requirements 1.1. Specification of Requirements
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
1.2. Scope 1.2. Scope
This document defines procedures for LDP using IPv4 routing, but not This document defines procedures for LDP using IPv4 routing, but not
for LDP using IPv6 routing, since the latter has GTSM built into the for LDP using IPv6 routing, since the latter has GTSM built into the
skipping to change at page 4, line 17 skipping to change at page 4, line 23
peering sessions, in line with Section 5.5 of [RFC5082]. peering sessions, in line with Section 5.5 of [RFC5082].
Consequently, any LDP method or feature that relies on multi-hop LDP Consequently, any LDP method or feature that relies on multi-hop LDP
peering sessions would not work with GTSM and will require peering sessions would not work with GTSM and will require
(statically or dynamically) disabling GTSM. See Section 3. (statically or dynamically) disabling GTSM. See Section 3.
2. GTSM Procedures for LDP 2. GTSM Procedures for LDP
2.1. GTSM Flag in Common Hello Parameter TLV 2.1. GTSM Flag in Common Hello Parameter TLV
A new flag in Common Hello Parameter TLV, named G flag (for GTSM), is A new flag in Common Hello Parameter TLV, named G flag (for GTSM), is
defined by this document. An LSR indicates that it is capable of defined by this document in a previously reserved bit. An LSR
applying GTSM procedures, as defined in this document, to the indicates that it is capable of applying GTSM procedures, as defined
subsequent LDP peering session, by setting the GTSM flag to 1. The in this document, to the subsequent LDP peering session, by setting
Common Hello Parameters TLV, defined in Section 3.5.2 of [RFC5036], the GTSM flag to 1. The Common Hello Parameters TLV, defined in
is updated as shown in Figure 1. Section 3.5.2 of [RFC5036], is updated as shown in Figure 1.
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|0| Common Hello Parms(0x0400)| Length | |0|0| Common Hello Parms(0x0400)| Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Hold Time |T|R|G| Reserved | | Hold Time |T|R|G| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
T, Targeted Hello T, Targeted Hello
skipping to change at page 7, line 7 skipping to change at page 7, line 12
GTSM. Otherwise, GTSM would not be enforced on the second LDP GTSM. Otherwise, GTSM would not be enforced on the second LDP
peering session corresponding to the Extended Discovery. peering session corresponding to the Extended Discovery.
This document allows for the implementation to provide an option to This document allows for the implementation to provide an option to
statically (e.g., via configuration) and/or dynamically override the statically (e.g., via configuration) and/or dynamically override the
default behavior and enable/disable GTSM on a per-peer basis. This default behavior and enable/disable GTSM on a per-peer basis. This
would address all the exceptions listed above. would address all the exceptions listed above.
4. IANA Considerations 4. IANA Considerations
IANA is requested to assign the G, GTSM bit in the Common Hello This document has no IANA actions.
Parameters TLV (see Figure 1 in Section 2.1), as per allocation
policy defined at [I-D.ietf-mpls-ldp-iana].
5. Security Considerations 5. Security Considerations
This document increases the security for LDP, making it more This document increases the security for LDP, making it more
resilient to off-link attacks. resilient to off-link attacks.
6. Acknowledgments 6. Acknowledgments
The authors of this document do not make any claims on the The authors of this document do not make any claims on the
originality of the ideas described. The concept of GTSM for LDP has originality of the ideas described. The concept of GTSM for LDP has
been proposed a number of times, and is documented in both the been proposed a number of times, and is documented in both the
Experimental and Standards Track specifications of GTSM. Among other Experimental and Standards Track specifications of GTSM. Among other
people, we would like to acknowledge Enke Chen and Albert Tian for people, we would like to acknowledge Enke Chen and Albert Tian for
their document "TTL-Based Security Option for the LDP Hello Message". their document "TTL-Based Security Option for the LDP Hello Message".
The authors would like to thank Loa Andersson, Bin Mo, Mach Chen, and The authors would like to thank Loa Andersson, Bin Mo, Mach Chen,
Vero Zheng for a thorough review and most useful comments and Vero Zheng, Adrian Farrel, and Eric Rosen for a thorough review and
suggestions. most useful comments and suggestions.
7. References 7. References
7.1. Normative References 7.1. Normative References
[I-D.ietf-mpls-ldp-iana]
Pignataro, C. and R. Asati, "Label Distribution Protocol
(LDP) Internet Assigned Numbers Authority (IANA)
Considerations Update", draft-ietf-mpls-ldp-iana-01 (work
in progress), May 2011.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5036] Andersson, L., Minei, I., and B. Thomas, "LDP [RFC5036] Andersson, L., Minei, I., and B. Thomas, "LDP
Specification", RFC 5036, October 2007. Specification", RFC 5036, October 2007.
[RFC5082] Gill, V., Heasley, J., Meyer, D., Savola, P., and C. [RFC5082] Gill, V., Heasley, J., Meyer, D., Savola, P., and C.
Pignataro, "The Generalized TTL Security Mechanism Pignataro, "The Generalized TTL Security Mechanism
(GTSM)", RFC 5082, October 2007. (GTSM)", RFC 5082, October 2007.
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