draft-ietf-mpls-spring-entropy-label-09.txt   draft-ietf-mpls-spring-entropy-label-10.txt 
Network Working Group S. Kini Network Working Group S. Kini
Internet-Draft Internet-Draft
Intended status: Informational K. Kompella Intended status: Informational K. Kompella
Expires: October 28, 2018 Juniper Expires: October 29, 2018 Juniper
S. Sivabalan S. Sivabalan
Cisco Cisco
S. Litkowski S. Litkowski
Orange Orange
R. Shakir R. Shakir
Google Google
J. Tantsura J. Tantsura
April 26, 2018 April 27, 2018
Entropy label for SPRING tunnels Entropy label for SPRING tunnels
draft-ietf-mpls-spring-entropy-label-09 draft-ietf-mpls-spring-entropy-label-10
Abstract Abstract
Segment Routing (SR) leverages the source routing paradigm. A node Segment Routing (SR) leverages the source routing paradigm. A node
steers a packet through an ordered list of instructions, called steers a packet through an ordered list of instructions, called
segments. Segment Routing can be applied to the Multi Protocol Label segments. Segment Routing can be applied to the Multi Protocol Label
Switching (MPLS) data plane. Entropy label (EL) is a technique used Switching (MPLS) data plane. Entropy label (EL) is a technique used
in MPLS to improve load-balancing. This document examines and in MPLS to improve load-balancing. This document examines and
describes how ELs are to be applied to Segment Routing MPLS. describes how ELs are to be applied to Segment Routing MPLS.
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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 https://datatracker.ietf.org/drafts/current/. Drafts is at https://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 October 28, 2018. This Internet-Draft will expire on October 29, 2018.
Copyright Notice Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the Copyright (c) 2018 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
(https://trustee.ietf.org/license-info) in effect on the date of (https://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
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destinated to PE2. SPRING routers along the shortest path to PE2 destinated to PE2. SPRING routers along the shortest path to PE2
will switch the traffic until it reaches P5 which will perform the will switch the traffic until it reaches P5 which will perform the
LSP stitching. P5 will swap the SPRING label 1020 to the LDP label LSP stitching. P5 will swap the SPRING label 1020 to the LDP label
20 advertised by the nexthop P6. P6 will then forward the packet 20 advertised by the nexthop P6. P6 will then forward the packet
using the LDP label towards PE2. using the LDP label towards PE2.
PE1 cannot push an ELI/EL for the binding SID without knowing that PE1 cannot push an ELI/EL for the binding SID without knowing that
the tail-end of the LSP associated with the binding (PE2) is entropy the tail-end of the LSP associated with the binding (PE2) is entropy
label capable. label capable.
To accomodate the mix of signalling protocols involved during the To accomodate the mix of signaling protocols involved during the
stitching, the entropy label capability SHOULD be propagated between stitching, the entropy label capability SHOULD be propagated between
the signalling protocols. Each binding SID SHOULD have its own the signaling domains. Each binding SID SHOULD have its own entropy
entropy label capability that MUST be inherited from the entropy label capability that MUST be inherited from the entropy label
label capability of the associated LSP. If the router advertising capability of the associated LSP. If the router advertising the
the binding SID does not know the ELC state of the target FEC, it binding SID does not know the ELC state of the target FEC, it MUST
MUST NOT set the ELC for the binding SID. An ingress node MUST NOT NOT set the ELC for the binding SID. An ingress node MUST NOT push
push an ELI/EL associated with a binding SID unless this binding SID an ELI/EL associated with a binding SID unless this binding SID has
has the entropy label capability. How the entropy label capability the entropy label capability. How the entropy label capability is
is advertised for a binding SID is outside the scope of this advertised for a binding SID is outside the scope of this document.
document.
In our example, if PE2 is LDP entropy label capable, it will add the In our example, if PE2 is LDP entropy label capable, it will add the
entropy label capability in its LDP advertisement. When P5 receives entropy label capability in its LDP advertisement. When P5 receives
the FEC/label binding for PE2, it learns about the ELC and can set the FEC/label binding for PE2, it learns about the ELC and can set
the ELC in the mapping server advertisement. Thus PE1 learns about the ELC in the mapping server advertisement. Thus PE1 learns about
the ELC of PE2 and may push an ELI/EL associated with the binding the ELC of PE2 and may push an ELI/EL associated with the binding
SID. SID.
The proposed solution only works if the SPRING router advertising the The proposed solution only works if the SPRING router advertising the
binding SID is also performing the dataplane LSP stitching. In our binding SID is also performing the dataplane LSP stitching. In our
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