[quagga-users 11311] Re: very newbish question regarding netwok discovery

Christopher Barry christopher.barry at rackwareinc.com
Mon Jan 11 14:46:04 GMT 2010


On Mon, 2010-01-11 at 11:48 +0100, Peter J. Holzer wrote:
> On 2010-01-10 17:26:14 -0500, Christopher Barry wrote:
> > Can anyone speak to the behavior of OSPF as a potential discovery
> > protocol for the above scenario?
> 
> To speak OSPF you need an IP address, but you should be able to listen
> to it without:
> 
> # tcpdump -e -vv -n proto ospf
> 11:41:14.360321 00:13:72:3b:e3:8e > 01:00:5e:00:00:05, ethertype IPv4 (0x0800), length 78: (tos 0xc0, ttl   1, id 59875, offset 0, flags [none], proto: OSPF (89), length: 64) 143.130.50.15 > 224.0.0.5: OSPFv2, Hello, length: 44
>         Router-ID: 143.130.18.3, Area 0.0.0.1, Authentication Type: none (0)
>         Options: [External]
>           Hello Timer: 10s, Dead Timer 40s, Mask: 255.255.240.0, Priority: 1
>           Designated Router 143.130.50.15
> 
> So here you have a router 143.130.50.15/255.255.240.0, which means the
> network is 143.130.48.0/20.
> 
> I'm not sure whether all hosts can receive all multicasts, though. You
> may have to do something special to receive them.
> 
>         hp
> 

Peter,

Thanks much for both of your suggestions. It seems like OSPF hello
broadcasts appear on the net an average of every 10 seconds, so this
solution can probably work well as primary mode for my situation,
falling back to your prior suggestion as secondary.


Appreciate all of your help,
-Christopher




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