Definition of Time to Live TLV for LSP-Ping Mechanisms
RFC 7394
Internet Engineering Task Force (IETF) S. Boutros
Request for Comments: 7394 S. Sivabalan
Category: Standards Track G. Swallow
ISSN: 2070-1721 S. Saxena
Cisco Systems
V. Manral
Ionos Networks
S. Aldrin
Huawei Technologies, Inc.
November 2014
Definition of Time to Live TLV for LSP-Ping Mechanisms
Abstract
LSP-Ping is a widely deployed Operation, Administration, and
Maintenance (OAM) mechanism in MPLS networks. However, in the
present form, this mechanism is inadequate to verify connectivity of
a segment of a Multi-Segment Pseudowire (MS-PW) and/or bidirectional
co-routed Label Switched Path (LSP) from any node on the path of the
MS-PW and/or bidirectional co-routed LSP. This document defines a
TLV to address this shortcoming.
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/rfc7394.
Boutros, et al. Standards Track [Page 1]
RFC 7394 TTL TLV for LSP-Ping Mechanisms November 2014
Copyright Notice
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Table of Contents
1. Introduction ....................................................2
2. Terminology .....................................................3
3. Time To Live TLV ................................................4
3.1. TTL TLV Format .............................................4
3.2. Usage ......................................................4
4. Operation .......................................................5
4.1. Traceroute Mode ............................................6
4.2. Error Scenario .............................................6
5. Security Considerations .........................................6
6. IANA Considerations .............................................7
7. References ......................................................7
7.1. Normative References .......................................7
Acknowledgements ...................................................7
Contributors .......................................................7
Authors' Addresses .................................................8
1. Introduction
An MS-PW may span across multiple service provider networks. In
order to allow Service Providers (SPs) to verify segments of such
MS-PWs from any node on the path of the MS-PW, any node along the
path of the MS-PW, should be able to originate an MPLS Echo Request
packet to any other node along the path of the MS-PW and receive the
corresponding MPLS Echo Reply. If the originator of the MPLS Echo
Request is at the end of a MS-PW, the receiver of the request can
send the reply back to the sender without knowing the hop-count
distance of the originator. The reply will be intercepted by the
originator regardless of the TTL value on the reply packet. But, if
the originator is not at the end of the MS-PW, the receiver of the
MPLS Echo Request may need to know how many hops away the originator
Boutros, et al. Standards Track [Page 2]
RFC 7394 TTL TLV for LSP-Ping Mechanisms November 2014
of the MPLS Echo Request is so that it can set the TTL value on the
MPLS header for the MPLS Echo Reply to be intercepted at the
originator node.
In MPLS networks, for bidirectional co-routed LSPs, if it is desired
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