[quagga-dev 4631] Re: OSPF on parallel Unnumbered PPP links

Andrew J. Schorr aschorr at telemetry-investments.com
Fri Mar 16 13:31:11 GMT 2007


On Fri, Mar 16, 2007 at 07:35:09AM +0000, Daniel Ng wrote:
> There are at least 2 solutions:
> 
> 1) Have OSPF enabled on *both* PPP links simultaneously. Because the 2 PPP 
> links will share the same IP addresses, make any necessary changes to zebra and 
> ospfd so that they will be able to distinguish between interfaces given an IP 
> address *as well as* the interface name (ie. perhaps the 'ifindex'?).
> 
> -OR-
> 
> 2) Somehow have OSPF enabled on ppp3 as soon as ppp2 is cut. Quagga knows they 
> both go to the same remote node because they have been allocated the same IP 
> address.
> 
> 
> What do you think? Which would be easier to implement? Which would be better to 
> implement?

I'm still curious -- why can't you assign a unique private RFC 1918 /30
subnet to each of the 2 PPP links, thereby making them distinguishable
to zebra and ospfd?   For example:

   PtP link 1:  192.168.1.1/30  <--->  192.168.1.2/30
   PtP link 2:  192.168.1.5/30  <--->  192.168.1.6/30

If you did that, everything would work as is, with no patching
required.  I presume that this is how most people 
handle this problem, and I guess that's why quagga has never been
patched to support this config.  Is there something about your
network that makes this impossible?

Regards,
Andy



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