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Boosting Ethernet’s scalability
Malcolm Scott UNIVERSITY OF
Jon Crowcroft
CAMBRIDGE
Computer Laboratory
Project: The Intelligent Airport (TINA) One Specific Problem: Address Tables
• Airports increasingly require ubiquitous systems MAC address Port • Maintained by every switch
• Both fixed and mobile appliances 01:23:45:67:89:ab 12 • Automatically learned
• Requirement for an intelligent, adaptive wired
00:a1:b2:c3:d4:e5 16 • Table capacity ~8000 addresses
… … • Full table means broadcast
and wireless infrastructure
The project is a collaboration between the Destination location known:
University of Cambridge, UCL, Swansea
University and a few industrial partners. destination
source Frame only
transmitted on
switch correct port
Our work: Addressing and Routing
Destination location lost due to table overflow:
• Determine new algorithms for addressing and
routing able to operate seamlessly in a destination
combined wired and wireless environment source Capacity wasted on
needlessly broadcast
Which means: switch frames!
• Start with Ethernet, as it’s ubiquitous
• But Ethernet does not scale well enough
• So fix it This problem arises because the MAC address namespace is
unstructured (as far as switches are concerned).
MOOSE
Airport network topology
RoF leaf hub RoF leaf hub RoF leaf hub
Multi-layer Origin-Organised
Scalable Ethernet
RoF fibre hub RoF fibre hub RoF fibre hub
The solution: introduce structure to MAC addresses
WAP WAP
22:22:22:00:00:01
RoF hybrid hub RoF hybrid hub
WAP leaf
WAP
22:22:22:00:00:02 nodes
22:22:22:00:00:03 33:33:33:00:00:01
...
33:33:33:00:00:02
switch switch
11:11:11 22:22:22 33:33:33:00:00:03
datacentre
GSM
33:33:33:00:00:04
switch ...
...
RoF service hub 33:33:33
Frame source addresses are rewritten on entry to the network
(by the home switch, which allocates the node identifier)
Internet servers
Switches need only store the locations of other switches:
gateway Above, switch 11:11:11 only needs two address table entries!
Radio over copper
Radio over fibre
Data over fibre
Completely transparent to standard Ethernet end nodes
Internet
Email: Malcolm.Scott@cl.cam.ac.uk
