(usagi-users 03489) IPV6 Multipath in AODV

[YongHan Lee <y_h_lee@xxxxxxxxx>]

I am a student and do a semester project in
networking. My subject is "ipv6 multipath AODV routing
implementation".

To achieve my goal I would like to find a way to pick
a desired route entry from several route entries to
one and same destination (but each route entry has
different next hop). The criteria to pick a route
entry is not destination address and not
pick-top-entry anymore, but destination address and
next hop address. 

For example:
Kernel IPv6 routing table
Destination    Next Hop        F M R Use Iface
fec0::10/128   fec0::1         U 0 4  1  eth1
fec0::10/128   fec0::2         U 0 4  1  eth1
fec0::10/128   fec0::3         U 0 4  1  eth1
fec0::10/128   fec0::6         U 0 4  1  eth1
fec0::10/128   fec0::9         U 0 4  1  eth1
fec0::10/128   fec0::7         U 0 4  1  eth1

When I do an ssh connection to fec0::10, I want to
take the route with next hop fec0::3, but for a http
connection to fec0::10 I want to take route with next
hop fec0::7. Decision is done by application in
userspace.

I thought to write a Kernel module for this, but since
I do not know well the kernel architecture, especially
the kernel ipv6 networking section, I do not know if
and how it is possible. 

My first idea was to use netfilter for ipv6, but I
could not add ipv6 routes to multiple routing tables
with marks. 

> echo 220 mytable.out >> /etc/iproute2/rt_tables
> ip -6 route add default via fec0::2/16 dev eth1
table mytable.out

But for ipv4 it worked without any problems. (thread
for this:
https://lists.netfilter.org/pipermail/netfilter/2005-August/062252.html


And now I try to write a Kernel module which should
retrieve all route entries from the kernel routing
table (in fib6_node, rt6_info or dst_entry struct), in
order that when an IP packet will be send, the routing
table in user space (is a seperate routing table with
more parameters) evaluates which route to destination
and send the IP packet with next hop information to my
module. My module then compares the retrieved route
entries with the destination address of the IP packet
and the appended next hop information. When it has the
desired route entry, it changes the destination
(struct dst_entry) in the sk_buff structure of this IP
packet and send out. This all should happen at POST
ROUTING hook (after kernel's "route decision").

I have started to write my kernel module, but it was
not able to retrieve route entries from the kernel
routing table, because a lot of the functions are
static.
For example I wanted to write a function in my kernel
module which gives me the route entry of the kernel
routing table with the requested next hop (and not all
entries). For this, it iterates the fib6_nodes from
the root (like fib6_lookup(&ip6_routing_table, daddr,
addr) [from ip6_fib.c]), but the kernel returns me:
Sep 13 17:31:34 m66533pp kernel: kaodv: Unknown symbol
fib6_lookup
Sep 13 17:31:34 m66533pp kernel: kaodv: Unknown symbol
ip6_routing_table
even they are defined in kallsyms and I included the
ip6_fib.h file.

I would be very glad if you could give me some helps
or advises (how it is possible or my idea is totally
impossible). Some links to architecture of kernel
routing table would be already a great help for me.

I use kernel 2.6.8.1 and mandrake linux 10.0.




		
__________________________________ 
Yahoo! Mail - PC Magazine Editors' Choice 2005 
http://mail.yahoo.com