Re: BFD confusion

Yes, its unicast and must have different sessions in shared media.

Well..what i can comment on the C-plane and D-plane is, it depends on the
architecture ;)
In newer distributed architecure and implementations BFD utilizes
the D-plane.

Best Regards,
Tharak Abraham Luke

On Fri, Jul 1, 2011 at 4:06 PM, HEMANTH RAJ <hemanthrj_at_gmail.com> wrote:

> Hey Abraham
>
> So in a broadcast multi access networks, the neighbour should send four
> separate unicast packets to the nieghbors to set up a BFD session. Because
> BFD uses unicast session with all its neighbours , So it should send a
> unicast packet to every one in a broadcast multi aces snetowrk
> Am i right ?
>
> Yes i got the Discriminator logic in BFD.
>
> So BFD echoes the BFD data packets with its neighbors. So whether BFD is a
> control palne protocol or a dat aplane protocol
>
> As per the RFC , BFD has the tendency to work on both control plane and
> data palce.
>
> In which cases it works in Data plane and in which case it is a control
> plane protocol.
>
>
> Cheers mate
>
>
>
> On Fri, Jul 1, 2011 at 4:00 PM, Abraham, Tharak <tharakabraham_at_gmail.com>wrote:
>
>> 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
>>>>>
>>>>>
>>>>> Blogs and organic groups at http://www.ccie.net
>>>>>
>>>>> _______________________________________________________________________
>>>>> Subscription information may be found at:
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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
>>>
>>>
>>
>
>
> --
> 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
Received on Fri Jul 01 2011 - 16:48:39 ART