Re: BFD confusion

Thanks a lot Abraham

Thank you for educating me :)

Cheers mate!!!

On Fri, Jul 1, 2011 at 4:48 PM, Abraham, Tharak <tharakabraham_at_gmail.com>wrote:

> 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
>>>>>>
>>>>>>
>>>>>> _______________________________________________________________________
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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
>>
>>
>

-- 
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