[Olsr-dev] Dynamic adding of interfaces

Markus Kittenberger (spam-protected)
Thu Apr 12 11:15:52 CEST 2012

hmm a stupid workaround

is to define many interfaces in olsrd.conf that do not exist,.. (-;

e.g. put a interface list of e.g. tap0 .. tap100 into olsrd.conf

as long as u do not need more than 100 tunnel interfaces, you can add,
remove, change, update tunnels without having to restart olsrd.

so the only prerequisite you need to know is how many tunnels you roughly

but in general it might be interesting to know, how efficient olsrd (and
the kernel) is in handling thousands of interfaces:
 as olsrd regularily polls them for changes (btw. pollinginterval could be
increased in configfile))
 furthermore olsrd needs to check the netlink events he listens too,
against its list of interfaces, and i am quite sure there is no search tree
for interface names, just a list.
  (btw the netlink listener could in theory replace the interface polling
completely, currently olsrd uses both, the netlink events for low latency,
and the polling for "safety" and compatibility with really old linux

furthermore even the linux kernel seems to get slow on too many
e.g. i once creates 10k l2tp tunnels, and the creation of interfaces
noticeable slowed down during this, as likely the kernel seems to iterate
over all existing interfaces, when it creates a new one. (as maybe it needs
to check if the interface name is unique against a interface list)

operation (or routing traffic between them) instead works fine with so many
interfaces, it just creating/deleting them which seems to scale badly,..

so maybe the olsrd interface polling will slow down quadratically, as olsrd
has an interface list, and the kernel too. (and uses it for for name to ID
translations of interfaces)


On Thu, Apr 12, 2012 at 1:41 AM, Mitar <(spam-protected)> wrote:

> Hi!
> Is it possible to add dynamically interfaces while OLSR is running? We
> would like to try to use L2TP tunnels between nodes and servers and
> the problem is that on the server then there will be many many tunnels
> added as nodes connect. How it would be possible to inform OLSR of
> this new tunnels, without restarting it?
> Mitar
> --
> Olsr-dev mailing list
> (spam-protected)
> https://lists.olsr.org/mailman/listinfo/olsr-dev
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