Adding multiple multicast routing tables.

I am working on adding support for multiple multicast routing tables, and would welcome some feedback if anyone has comments.

It looks like there are several globals currently. I would plan to wrap those in a 'mroute_table_entry struct and have the global be a hash of these routing tables.

Inside this table, I'd add a hash of vifs (no more max limit for vifs), the mroute_socket for this table, and 32-bit vif_index (routing-table id).

In the ip_mroute_setsockopt, add a 32-bit table-id to all of the optnames. This will increase the optlen by 4 for all options, so we can know it's the new API. For MRT_INIT, could pass in something like this, for instance:

struct foo {
uint32 mrt_table_idx;
uint32 mrt_version;
}

Or, use entirely new MRT_* sockopts so there is no chance
of confusion. I plan to update xorp to support this API, so I can be flexible on the API.

User space will need a way to detect the new API. I could probably just try to INIT with a larger optlen. 2.6.25 (and probably many previous kernels)

appears to error nicely if optlen != sizeof(int), so I can trigger on that.

The mcast table ID would be associated directly with the 'regular' routing table index, so if the mcast is table-id 4444, then any routes associated with it should be added to the unicast routing table 4444. Or, it could be mapped, but I am not sure there is much benefit for that added complexity.

getsockopt and the ioctl would need similar changes to the setsockopt.

ip_mr_input looks interesting...not sure how to decide which mroute_socket it uses...maybe it doesn't matter?

And, for things like pim_rcv*, might need some sort of table lookup to map a skb->dev into a mroute table so that it can handle the reg_vif_num thing. To make this really fast, a new member could be added to struct netdev.

A netdev may belong to no more that one mcast routing table. If someone wants to share NICS, they can use something like mac-vlans to multiplex the physical device.

Suggestions are welcome.

Thanks,
Ben

Ben Greear <[email protected]> Candela Technologies Inc  http://www.candelatech.com