Hello,
I am writing a routing daemon that is able to assign different gateways to
a destination address for different classes of service. Multiple DiffServ
Code Point values are mapped into a single class of service. I have
accomplished this by using the iptables MARK target to label each packet
with a class of service value and then using ''ip rule add
fwmark'' to have
each packet routed in the appropriate class. However, I now need to
combine this routing daemon with other programs to create a complete system
and more than one of them requires the iptables QUEUE target. There exists
an IPQ Multiplex Daemon (ipqmd), but it uses the iptables MARK target to
identify which packets are sent to which program, and I can''t use MARK
for
two different things. I have tried to use ''ip rule add tos''
to map TOS
field values into route tables directly (this works great with tc for the
queues), but I am only allowed to set the 4 TOS bits, not the full field (I
believe it is the kernel, not iproute2 that rejects the values). I have
seen some man pages that also document a ''dsfield'' option, but
I have not
found a version of iproute2 for which this is actually accepted. I have
also not seen a u32 filter for ''ip rule'' although
''tc'' has one (iptables
also has one in patch-o-matic), which would be extremely useful.
Does anyone have a suggestion on how I can get these things to work
together? There are several options, if I can get any to work:
1. Find a way to filter TOS values directly into route tables
2. Find a way to get packets that come from a certain qdisc to map into a
certain route table. (packets are already sorted into queues and queues map
directly to route tables -- there is one of each for every class of
service)
3. Find a way to pack multiple values into the iptables MARK (so more than
one app can use it)
4. (If nothing else works:) Write my own IPQ multiplex daemon that
doesn''t
use iptables MARK
5. Maybe I could abuse routing realms (thereby not allowing me to use them
for their intended purpose if I should choose to do so in the future)?
6. Other (please specify in comments :-)
I have looked through the past few months of the archives and haven''t
seen
anything relating to the inability of ''ip rule'' to handle dscp
values, and
I have tried the latest version of iproute2 and looked at source for the
latest Linux kernel release (I am running on a 2.6.9 kernel) to see if it
looked like it would handle non-TOS values (although I''m not certain
I''ve
looked at the right kernel code for that). I would prefer not to have to
write my own IPQ multiplex daemon (or try to get my company to authorize me
to "enhance" the existing GPL''ed one).
Thank you,
Ian Worden
Rockwell Collins, Inc.
