IPv6 Source Routing for ultralow Latency

Document Type Active Internet-Draft (individual)
Authors Andreas Foglar  , Mike Parker  , Theodoros Rokkas 
Last updated 2021-01-22
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Routing Area Working Group                         A. Foglar, InnoRoute
INTERNET-DRAFT                                     M. Parker, Uni Essex
Intended status: EXPERIMENTAL                      T. Rokkas, Incites
Expires: January 13, 2021                          January 23, 2021 

          IPv6 Source Routing for ultralow Latency


  This Internet-Draft describes a hierarchical addressing scheme 
  for IPv6, intentionally very much simplified to allow for very 
  fast source routing experimentation using simple forwarding 
  nodes. Research groups evaluate achievable latency reduction 
  for special applications such as radio access networks, 
  industrial networks or other networks requiring very low 
Status of This Memo

  This Internet-Draft is submitted in full conformance with the
  provisions of BCP 78 and BCP 79.
  Internet-Drafts are working documents of the Internet Engineering
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  material or to cite them other than as "work in progress."

Copyright Notice

  Copyright (c) 2019 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
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  described in the Simplified BSD License.
Revision Note for Version 02

  Reference to experimental verification of the concept is added in the
  section "Acknowledgements".  

Revision Note for Version 03

  Section 6 about Security Considerations has been inserted. 
Revision Note for Version 04

  Section 7 about Redundancy has been inserted.

 Revision Note for Version 05
  Section 8 about IANA Considerations added.
Revision Note for Version 06

  Section 8 about IANA Considerations updated.
Revision Note for Version 07

  Section 6 about Security Considerations improved.

1. Introduction

  To achieve minimum latency the forwarding nodes must support 
  cut-through technology as opposed to the commonly used store-
  and-forward technology. Cut-through means, that the packet 
  header already leaves a node at the egress port while the tail 
  of the packet is still received at the ingress port. This 
  short time does not allow complex routing decisions. 

  Therefore, a very simple routing address field structure is 
  specified below. It should limit the complexity of the 
  forwarding node used in the experiments. Therefore, in this 
  text the term "forwarding node" is used instead of "router", 
  although the device is operating in OSI Layer 3 and accordingly
  executes router functions such as decrementing the hop limit field.
  Redundancy issues are not considered. 

2. IPv6 address prefix structure

  The following proposal uses the 64-bit IPv6 address prefix.
  Each forwarding node has up to 16 ports and hence needs 4 bits 
  of the address field to decide to which port a packet should 
  be forwarded. The 64-bit prefix is divided into 16 sub-fields 
  of 4 bit, defining up to 16 hierarchy levels. A forwarding 
  node is configured manually to which of the sub-fields it should
  evaluate for the forwarding decision. 
  A number n of leading 4-bit fields cannot be used for forwarding 
  decisions, but must have a special value to indicate the 
  'escape prefix' of the experimental forwarding mode. 
  The 64-bit prefix of the IPv6 address has this structure:
  | n x 4-bit escape prefix |(16-n) x 4-bit address fields |
  The first 4-bit field following the escape prefix has the 
  highest hierarchy level, the last 4-bit field has the lowest 
  hierarchy level.

3. Forwarding node behavior

  The forwarding node has up to 16 downlink ports and at least 
  one uplink port. Typically, the forwarding nodes are arranged 
  in a regular tree structure with one top node, up to 16 nodes 
  in the second hierarchy, up to 256 nodes in the third hierarchy 
  and so on for up to 16-n hierarchies.
  A forwarding node must be configured to operate at a certain 
  position in the hierarchical network. For example, at third 
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