Re: BFD confusion

1. If its application specific anything above 1024 is accepted.
But numbers available in drafts are 3784/3785 (single hop and multihop again
should vary)

2. Unicast

3. Correct. Two fields named "My Discriminator" and "Your Discriminator"
works in such a way that the local discriminator is sent in the My
Discriminator field in the BFD Control packet, and is echoed back in the
Your Discriminator field of packets sent from the remote end. Discriminator
value identifies each session, and must be unique among all BFD sessions on
the system.

Best Regards,
Tharak Abraham Luke

On Fri, Jul 1, 2011 at 3:38 PM, HEMANTH RAJ <hemanthrj_at_gmail.com> wrote:

> 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 ?
>>>
>>>
>>>
>>> --
>>> 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
>>>
>>>
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>>>
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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

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Received on Fri Jul 01 2011 - 16:00:12 ART