IPv6 Source Routing for ultralow Latency
Routing Area Working Group A. Foglar, InnoRoute
INTERNET-DRAFT M. Parker, Uni Essex
Intended status: EXPERIMENTAL T. Rokkas, Incites
Expires: January 13, 2021 July 24, 2020
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
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Revision Note for Version 02
Reference to experimental verification of the concept is added in the
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.
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
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
hierarchy level, branch 4 of the first hierarchy and branch 12
of the second hierarchy.
The behavior of each forwarding node is depending on the
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