[Olsr-users] Documentation / Use-case on SrcIpRoutes setting, IP addressing in OLSRd MANET network

Aaron Daubman (spam-protected)
Thu Jun 23 18:57:59 CEST 2011


Greetings,

I've been looking over the config and am trying to determine when
SrcIpRoutes would be used (scenario / use-case)?
I know that this "tells OLSRd to set the Src flag of host routes to
the originator-ip", however, I'm wondering when this is useful /
necessary?

Alternately / in addition, do you know of documentation on rtnetlink
regarding how RTA_SRC is used? Looking at the olsrd code, it seems
this is the only change in the route table entry that SrcIpRoutes
makes (whether RTA_SRC is set), so understanding what netlink does
with this would be helpful in understanding the use case.

I know olsrd will also create a loopback with the main ip address set
if SrcIpRoutes is enabled... this didn't really help me put together a
scenario where this would be useful, though...

Related to the above, are there any addressing guides /
recommendations available for olsr (a set of best common practices)?
I'm coming from a traditional/wired background (one subnet per router
interface) and so I'm trying to understand best-practices for MANET
network addressing and how MANET routing is performed...

...trying to answer such questions as:
- "should hosts still have a /24 subnet assigned to each interface or
should it be a /30 (or a /32 even)?"
- "if I have a /24 that all OLSRd MANET devices are addressed in, how
does the link's route entry get overridden - e.g. if I'm
192.168.1.10/24 trying to reach 192.168.1.12/24 via intermediate node
192.168.1.11/24 (no direct connectivity between 10 and 12), won't I
just ARP out for the MAC of 192.168.1.12 and try and send directly to
it, rather than even look at the route table (since I will have a
broadcast interface route for 192.168.1.0/24 already)? What causes the
host to realize that the packet must be routed?

If these are 'newb' questions I would be happy to be pointed toward an
OLSRd/MANET guide that answers them - I just haven't found one that
does yet...

Thanks again,
     Aaron




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