Re: BFD confusion

Hey Abraham,

Thanks for ur explanation. I still have some more questions

1.So now BFD runs over UDP , BFD uses which port numbers to communicate.

2. In the BFD packet, the destination address is a multicast address or a
unicast address. ie I am asking about the BFD hellos.

3. In the discriminator field. FOr example if it is broadcast mulit acess
network , there are 4 four neighbors in the same interface, So it maintains
a unique discriminator for each neighbor, Am i getting it right.?? Correct
me i f i am wrong

So in point to point mode , there should be no discriminator field right?

On Fri, Jul 1, 2011 at 3:07 PM, Abraham, Tharak <tharakabraham_at_gmail.com>wrote:

> Hemanth,
>
> 1. Discriminator fields are used to uniquely identify multiple BFD sessions
> between the same pair or sessions w.r.t Multiaccess networks. I hope i
> needn't explain multiplexing and demultiplexing.
>
> 2. BFD runs on top of the [ UDP+IP+L2 ]
>
> 3. BFD is generally specified under an interface and hence will take the
> primary ip add of the interface.
> It doesn't form adjacency like the hello protocols used in ospf/eigrp but
> generally works based on echoing.The source and dest ip would be the same
> but L2 address would be of the neighbor.
>
> You may also tie the BFD process with the existing routing protocol too.
>
> Sorry if it sounds confusing but Implementation w.r.t BFD mode always
> depends ;)
>
>
> Best Regards,
> Tharak Abraham Luke
>
>
> On Fri, Jul 1, 2011 at 1:04 PM, HEMANTH RAJ <hemanthrj_at_gmail.com> wrote:
>
>> Hi guys
>> I am reading BFD RFC and i am not able to get some points in it
>>
>> 1. What is the use of Discriminator field in BFD Control ?. It says it is
>> used to demultiplex control plane packets to their neighbor . i cant
>> understand what is called as demultiplex control plane packets to the
>> neighbors
>>
>> 2. BFD works on which layer . Is it a Layer 2 encapsulation or L3
>> encapsulation . or it s a L2.5 encapsulation.
>>
>> 3. Which address that BFD uses to communicate with its neighbor? RFC says
>> it
>> is application specific and i am not getting the point exactly ?
>>
>>
>> Can some one shed some light on it ?
>>
>>
>>
>> --
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>>
>> Yours Friendly,
>> H P HEMANTH RAJ
>> CCIE#28593 (R&S)
>> Cisco Systems
>>
>>
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-- 
Problems arise because we talk,problems are not solved because we don't talk
So good or bad talk to your affectionate one's freely.
Yours Friendly,
H P HEMANTH RAJ
CCIE#28593 (R&S)
Cisco Systems
Blogs and organic groups at http://www.ccie.net