Six/one-router

Six/one-router

An (unfinished) article can be found here: https://github.com/jav/six-one-router/blob/master/article/main.pdf?raw=true

Note	All features described in the article are not implemented in the prototype (yet)

Note	This prototype was developed and tested on FreeBSD 6.2

Browsing the code _~~~~~~~ To get to the call-flow:

main() calls start_sixone()  ->
for each in-interface, start_interface() is started  ->
start_interface() registers a BPFilter, on a match got_packet() is called  ->
All the cool processing is done in/from got_packet() (no more function pointers, just a straight call-path)

A technical overview

The amount of entries in the global routing tables grows exponentially. One way of addressing this problem, is to divide the address name-space into two.

• One name-space for the Internet core

  • Globally addressable

  • Administratively assigned

  • Each core-router is addressed

• One name-space for the edge networks

  • Locally managed addresses

  • An edge network has one prefix, independently of how it is connected upstream

This way, if a host in an edge network wants to reach another host, in a different edge network it only needs to address that host by it’s known IP. When the packet reaches the border router, the router does a look up "which way do I take to reach edge network XYZ?" and sends the packet in that direction. Upon reception, the address are restored. This greatly improves our ability to aggregate addresses (as opposed to the address-block fragmentation we are facing today).

We achieve:

• End to end addressing

• Routing scalability (multi-homed network does not need to spam the Internet with multiple routes)

• The possibility for an entire edge-network to multi-home and/or to be mobile

We divide IP-addresses (IPv6) into two halves, the routing prefix and the host-identity. (8 + 8 bytes).

To maintain checksum integrity, we use two bytes for checksum compensation. An address is parsed as follows

bytes  0  1  2  3  4  5  6  7  8  9  0  1  2  3  4  5
       Routing  prefix |      |    Host identifier
                       checksum
                     compensation

e.g.

ABC::1

is equivalent to

1000:0:0:F9BB::1
........