kbfd-devel

[Kbfd-devel] BFD interval command: ifindex needed

[Peter S. <pes...@gm...>]

Hi,

I have a question regarding the recently implemented BFD interval
command (BFD_SETLINK).

In order to change BFD timer intervals, one has to fill in a
bfd_nl_linkinfo structure, and send it through the netlink socket to
kbfd. How can I obtain the correct value for the ifindex field of this
structure from userspace, if I have just set up a new session with a
peer? All I know is the source and destination interface addresses
involved in this BFD session.

Thank you,
Peter

--
Peter Szilagyi
Budapest University of Technology and Economics
Project page: http://opt.tmit.bme.hu/~kbfd/

Re: [Kbfd-devel] BFD interval command: ifindex needed

[Hajime Tazaki<ta...@sf...>]

Hi Peter,

Welcom to the kbfd-devel ML!
I'm waiting for you.

At Sun, 8 Jun 2008 21:19:23 +0200,
Peter Szilagyi wrote:

>I have a question regarding the recently implemented BFD interval
>command (BFD_SETLINK).
>
>In order to change BFD timer intervals, one has to fill in a
>bfd_nl_linkinfo structure, and send it through the netlink socket to
>kbfd. How can I obtain the correct value for the ifindex field of this
>structure from userspace, if I have just set up a new session with a
>peer? All I know is the source and destination interface addresses
>involved in this BFD session.

I guess that you are talking about using bfd from BGP.
#ospfd/ospf6d can recognize ifindex when they create the new
 session.


Ah, this might be a bug.

If the session was created, and userspace didn't specify
ifindex of this session, kbfd would try to get the ifindex
value from the destination address of this session.

Like below, (from bfd_session_new() in kbfd_session.c:)

        if (ifindex == 0)
            ifindex = bfd->proto->get_oif(dst);

But if there is no route information to the destination at
this time, kbfd cannot get this ifindex value. After that,
"show bfd neighbors" command would show "unknown" interface.

This should be fixed with retrying to set the value of
ifindex when session's state would change to "BSM_Up".


And when the session of bfd has just created, and the route
to the destination isn't prepared, we cannot see which
interface would be used by this session.

Actually kbfd support only 1-hop neighbor, so this should be
done by operator at now.....

#Did you mean that?
 I hope this is your question......

regards,
hajime

Re: [Kbfd-devel] BFD interval command: ifindex needed

[Peter S. <pes...@gm...>]

On Wed, Jun 11, 2008 at 12:34 PM, Hajime Tazaki <ta...@sf...> wrote:
>
> I guess that you are talking about using bfd from BGP.
> #ospfd/ospf6d can recognize ifindex when they create the new
>  session.

Hi,

I was setting up BFD connections from my own application, not through
quagga's ospfd. Since than I've managed to figure out that I should
simply have called if_nametoindex() and fill in the bfd_nl_linkinfo
struct accordingly. It was by no means any fault of kbfd, just my
ignorance about this ifindex stuff.

Thanks for your reply,
Peter

Re: [Kbfd-devel] BFD interval command: ifindex needed

[Hajime Tazaki<ta...@sf...>]

At Wed, 11 Jun 2008 12:47:12 +0200,
Peter Szilagyi wrote:
>
>On Wed, Jun 11, 2008 at 12:34 PM, Hajime Tazaki <ta...@sf...> wrote:
>>
>> I guess that you are talking about using bfd from BGP.
>> #ospfd/ospf6d can recognize ifindex when they create the new
>>  session.
>
>Hi,
>
>I was setting up BFD connections from my own application, not through
>quagga's ospfd. Since than I've managed to figure out that I should
>simply have called if_nametoindex() and fill in the bfd_nl_linkinfo
>struct accordingly. It was by no means any fault of kbfd, just my
>ignorance about this ifindex stuff.

I see.

And you have your own application for kbfd?
Great! I'd like to see it if you don't mind. ;)

thanks,
hajime

Re: [Kbfd-devel] BFD interval command: ifindex needed

[Peter S. <pes...@gm...>]

On Wed, Jun 11, 2008 at 12:59 PM, Hajime Tazaki <ta...@sf...> wrote:
>
>
> And you have your own application for kbfd?
> Great! I'd like to see it if you don't mind. ;)

Of course. It is a research project at the university present in my
signature, aiming to provide a reasonably usable implementation of the
Not-via IP Fast Reroute algorithm (which is an IETF draft maintained
by Cicso, see http://www.ietf.org/internet-drafts/draft-ietf-rtgwg-ipfrr-notvia-addresses-02.txt).

IP Fast Reroute techniques in general try to provide QoS in IP
networks by re-routing traffic around a failed component (e.g. router
or link). They aim to be fast by utilizing two key features: there is
no global signalling of the failure (contrary to OSPF which would
originate LSAs announcing the topology change), and secondly, each
node prepares for any possible single failure in advance, before
anything actually has failed. This approach enables them to act
immediately (that is, to re-route without further computation) and
locally (routers not adjacent to the failure don't have to do
anything).

For all of this to be achieved, each router has to know when one of
its neighbours goes down, or is operational again. This task is
fulfilled by running BFD sessions between each pair of adjacent
routers, for which we use kbfd.

If you are interested in the source code, I will upload a tarball to
let you examine it. It has been written in C++ for Linux, and so far
stood the proof of a couple of live demos, so should be stable enough
for others to check out.

Regards,
Peter

-- 
Peter Szilagyi
Budapest University of Technology and Economics
Project page: http://opt.tmit.bme.hu/~kbfd/