Implementing IPv6 in an embedded Linux Kernel

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Implementing IPv6 in an embedded Linux Kernel
Pooja Nagpal pooja.nagpal_at_oracle.com
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Agenda

• The Context Networks Devices
• Functionality vs Resources
• The Implementation Challenge
• Choosing a kernel implementation
• Platform Support Implementation Architecture
• Coding
• Testing

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• embedded technology emerging
• smaller, smarter devices in the line
• cameras, sensors, actuators
• intelligent communication
• smarter home office environments
• require connectivity to internet

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Networking in the Embedded world

• era of standalone devices is fading
• network aware systems are in demand
• Mobility is a new dimension
• IPv6 fits the picture
• large number of nodes
• provides global addressability

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Resource Restrictions

• Low Cost Network Appliances
• limited CPU, memory
• networking solutions
• large and slow
• tremendous challenge for different
• types of networks
• target applications

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Real World Examples
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Developer Concerns

• must not bloat footprint
• Performance
• extensiveness of IPv6 protocol
• security overheads
• normal functionality of devices must not suffer

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Scaling down IPv6

• TACA project
• explores minimal functionality
• proposed the okabe internet draft
• Defines minimal features
• All features need not be supported
• routing and packet forwarding
• jumbograms
• fragmentation

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A Survey of Embedded kernels

• uLinux
• Runs only on 386
• needs 4M swap space
• Midori linux project
• large footprint
• ELKS
• Small footprint of 640K
• Network implementation simple

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the target OS

• Embeddable Linux kernel subset
• provides Unix v7 functionality approx.
• already being used
• Psion 16 bit organizers

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ELKS networking model

• IPv4 implemented as a daemon
• IPv6 also implemented as daemon
• Data link layer support -
• only slip support present
• PPP driver under development to make IPv6 usable

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kernel
Serial cable only
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Testing
packet with wrong payload
Neighbor solicitation
Tester
Target
Neighbor advertisement
ICMP Parameter Problem
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Sample Output
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For more information

• www.elks.sourceforge.net
• www.tahi.org
• www.linuxdevices.com