Re: OSPF network type and BFD

First part of ur question is simple ..

Whatever network type combinations that you have mentioned are "
COMPATIBLE".

Remember ; to form adjacency what all is required ? hello , dead timer match
, area same , auth same , stub flags same , MTU same .. These things are
same in your case .. hence neighbor relationship is UP .

But having neighbor relationship UP doesn't means ; that it will exchange
routes .

I remember it this way ,,,,,
There are types which elect DR/ BDR .. and these are Broadcast and
Non-Broadcast ..
As long as neighbor relationship is UP between these type ; they will
exchange routes .

i.e media that elects Dr| BDr will exchange routes with media that exchange
Dr | BDr only .

HTH
Gaurav Madan
CCIE

On Sat, Oct 8, 2011 at 1:32 PM, CCIE KID <eliteccie_at_gmail.com> wrote:

> Hi fellas,
>
> I am doing OSPF labs and found a peculiar thing . I have two 3560 switches
> connected to each other SW1---------------Sw2 back to back . the two fast
> ethernet links are running OSPF and i enable network type as point-to-point
> on SW1 and broadcast on SW2. I find it really puzzling to se that they
> formed neighborship but they r not exchanging their databases. I heard in
> one of the Brians INE ATC which says that the compatible network types are
>
> Point to point-----point to point
> Point to point ---point to multipoint
> point to mulitpoint-----point to multipoint
>
> Broadcast--Broadcast
> Broadcast---NonBroadcast
> NonBroadcast-----NonBroadcast
>
> But here i can see that a point to point network type can form neighborship
> with the broadcast network type .But they not exchanging the routes I am
> not
> able to reach SW1 loopback from SW2 even though SW1 is advertising its
> loopback in OSPF. I want to know the LOGIC behind it .? they r forming
> neighborship but they are not exchanging routes? How is this possible?
>
> And also in which OSPF packet type they will exchange the NETWORK TYPES of
> both switches and how the OSPF running switches comes to now about the
> other sides network Type.
>
>
> 2... My second questions is about BFD.. What purpose does BFD solve. I know
> that Fibre links has an inbuilt mechanism of checking whether the
> bidrectional connection is up or not by using light frequencies for every
> 50
> ms. But Ethernet has a fundamental flaw of not checking the bidirectional
> flow of traffic. It just checks the integrity of the electrical pulses of
> the interface connection to the link by using their own keepalives . My
> questions is BFD functions in only Ethernet interfaces or else what problem
> does BFD solve in this real time world?
>
>
>
>
> --
> With Warmest Regards,
>
> CCIE KID
> CCIE#29992 Security
>
>
> Blogs and organic groups at http://www.ccie.net
>
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Received on Sat Oct 08 2011 - 19:18:46 ART