Re: VRFs and the scalability of namespaces
From: Ben Greear <hidden>
Date: 2014-09-29 16:45:25
On 09/29/2014 06:06 AM, David Ahern wrote:
The features of note: - resource efficiency -- not having to create a proces/thread/socket per VRF to have a "presence" in all VRFs. e.g., a VRF any context that allows 1 socket to work across VRFs (L3 raw socket, TCP listen socket, unconnected UDP socket). Daemons run a 'vrf any' context; connected clients run a specific vrf context. For non-connected sockets VRF context can be passed via cmsg. - same IP address on different interfaces in different vrfs. i.e., VRF specific routing and neighbor tables - cross VRF routing. ability to receive message on 1 vrf and send it on another. Can be handled by the process itself (e.g., L3 vpns).
We have implemented support for at least most of this (excepting duplicate IPs) using routing tables, rules, and (optionally, xorp as the router). It works ok for our purposes (network simulator), but peformance is not great because you end up with a large number of ip rules and they are effectively evaluated linearly it seems. A quick way to improve performance in our scenario would be to bind rules to specific interfaces, so that packets process a smaller number of rules when they enter an interface, I think...but I have not looked into it closely. It is hard to show you an example of this without you installing our software to visualize what we are trying to do, but it our software will work on standard kernels, and we auto-generate a perl script that sets up all of the rules and such. You could compare the network diagram in our GUI with the perl script and I think understand the basics of what we are doing fairly quickly. If you want to take a detailed look, let me know and I'll set you up with a demo license. Thanks, Ben
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-- Ben Greear [off-list ref] Candela Technologies Inc http://www.candelatech.com