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Signaling Entropy Label Capability and Entropy Readable Label Depth Using IS-IS

The information below is for an old version of the document.
Document Type
This is an older version of an Internet-Draft that was ultimately published as RFC 9088.
Expired & archived
Authors Xiaohu Xu , Sriganesh Kini , Siva Sivabalan , Clarence Filsfils , Stephane Litkowski
Last updated 2019-03-28 (Latest revision 2018-09-24)
Replaces draft-xu-isis-mpls-elc
RFC stream Internet Engineering Task Force (IETF)
Additional resources Mailing list discussion
Stream WG state WG Document
Document shepherd (None)
IESG IESG state Expired
Consensus boilerplate Unknown
Telechat date (None)
Responsible AD (None)
Send notices to (None)

This Internet-Draft is no longer active. A copy of the expired Internet-Draft is available in these formats:


Multiprotocol Label Switching (MPLS) has defined a mechanism to load balance traffic flows using Entropy Labels (EL). An ingress Label Switching Router (LSR) cannot insert ELs for packets going into a given tunnel unless an egress LSR has indicated via signaling that it has the capability of processing ELs, referred to as Entropy Label Capability (ELC), on that tunnel. In addition, it would be useful for ingress LSRs to know each LSR's capability of reading the maximum label stack depth and performing EL-based load-balancing, referred to as Entropy Readable Label Depth (ERLD), in the cases where stacked LSPs are used for whatever reasons. This document defines mechanisms to signal these two capabilities using IS-IS. These mechanisms are useful when the label advertisement is also done via IS-IS. In addition, this document introduces the Non-IGP Functional Capabilities Sub-TLV for advertising IS-IS router's actual non-IGP functional capabilities. ELC is one of such non-IGP functional capabilities.


Xiaohu Xu
Sriganesh Kini
Siva Sivabalan
Clarence Filsfils
Stephane Litkowski

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)