[Olsr-users] Question about listed HNA networks and "active" olsr interfaces

Teco Boot (spam-protected)
Wed Oct 12 15:38:17 CEST 2011

Responding on original mail:

The Ethernet is a normal subnet, right? And high speed, so it makes sense
to prefer it over the mesh link. So with LinkQualityAlgorithm "etx_ffeth"
and Mode "ether" olsrd knows how to handle it.

For mesh interfaces, a longest match prefix (/32, /128) is made reachable
for all nodes in the network. Each such prefix has separate routes on each
router. Some say the host prefix is to be configured on the mesh interface
(RFC5889). But this results in remote reachability problems is routing daemon
was stopped. Therefore, RFC5889 is not practical, and shorter prefix lengths
are used for configuring the interface. So we have different subnet lengths
for mesh interfaces itself and the routes to it.

For ether interfaces, we could turn off this host prefix length injection 
mechanism and send out HNA for the connected subnet. This is how routers 
usualy work.

So yes, I support a change:
  On interfaces that are up and mode for that interface is "ether": send out an
  HNA with configured prefix for that interface.


Op 12 okt 2011, om 14:28 heeft ZioPRoTo (Saverio Proto) het volgende geschreven:

> Hello,
> I did not understand the detail of your setup, however:
> 1) it is fine to have multiple nodes in the network announcing via HNA
> the same prefix, as long as these node are really connected with some
> interface to that subnet
> 2) hna is a global configuration parameter for the olsrd demon, so the
> prefix will be announced whatever is the state of the interfaces.
> However you open here a discussion about a potential new feature of
> binding a HNA prefix to a Interface status. I'll discuss this on a
> separate thread.
> Saverio
> 2011/9/27 Eric Malkowski <(spam-protected)>:
>> Hi All-
>> It's been a while since I've posted here and I'm still using OLSR 0.5.8-r6
>> (latest stable of that series before 0.6.X came out).
>> I have a basic question about listing networks as HNA in the config and the
>> "Active" interfaces one does OLSR on.
>> I usually never list a subnet in the HNA list at the beginning of the config
>> file AND list the interface that the HNA subnet is tied to for "active" OLSR
>> at the end of the file.  I have run into a situation where it would be
>> beneficial to do this.  Is it OK to do this?
>> An example could be like this -- two typical mesh + ap nodes out of range of
>> each other but connected with a simple wired interface:
>> Outdoor node:
>> ath0  AP network listed only as HNA
>> ath1  Mesh   (does active OLSR, NOT listed as HNA in config)
>> eth0  Glue network  (does active OLSR NOT listed as HNA in
>> config)
>> Other node connected by wired link:
>> eth0  Glue network (does active OLSR NOT listed as HNA in
>> config)
>> ath1  Mesh  (does active OLSR, NOT listed as HNA in config)
>> ath0  AP network listed only as HNA
>> I've found that even though the two ath1 interfaces (on same subnet) are
>> separated by the wired link, clients on each ath0 networks of either node
>> enjoy connectivity everywhere.
>> What I do is have one of the two nodes act as a convenience DHCP server on
>> eth0 so if someone plugs in a wired client, they can get an IP.  If internet
>> is available, the default route gets them internet access.  However since
>> the eth0 network is not listed as an HNA by at least ONE of the
>> two nodes, someone on eth0 w/ a DHCP address may not be able to get
>> everywhere since only host routes are listed for and
>> I'd like to simply have each node list their eth0 network as an
>> HNA in the config.  Any ideas if this will be a problem?  As I said, I
>> normally don't configure an interface for active OLSR AND to be listed as
>> HNA in the config at the same time as it didn't seem like the right thing to
>> do, but I'm thinking to keep everyone to have full connectivity everywhere
>> who might grab an IP from the networks on ath0 or eth0 of each node, it
>> would make make sense that the eth0 network is listed as HNA in
>> one of the two nodes' config files or both.  The more I think about this I
>> would think it should be fine.
>> I hope this makes sense.
>> Thanks,
>> -Eric Malkowski
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