Re: OSPF network type and BFD

Hi,
This is because Sw2 is the DR and sees itself as the one in charge of
announcing routes. DR listen to LSA on multicast address 224.0.0.6 and then
it announces it to 224.0.0.5 i.e all ospf routers.
It will not accept routes on multicast address 224.0.0.5
Sw1 on the other hand doesnt believe in DR so it will send directly its
routes to 224.0.0.5
Of course Sw2 will ignore it.

HTH,
Abdullah
29703
On Oct 8, 2011 11:26 AM, "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
>
> _______________________________________________________________________
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html

Blogs and organic groups at http://www.ccie.net
Received on Sat Oct 08 2011 - 21:55:54 ART