Re: BFD echo mode

["Vishwas Manral" <[e-mail]>]

Hi Nobo,

>> Seeing some vendor documentation it seems they use a seperate
>> port for the echo mode - as the source and the destination
>> address.
>
> I hope vendors aren't using different udp dest port for echo packets.
>
> http://tools.ietf.org/html/draft-ietf-bfd-v4v6-1hop-08 Sec4.1.
>
> BFD Echo packets MUST be transmitted in UDP packets with destination
> UDP port 3785 in an IPv4 packet.
Thankf for this.

>> Can the asusmption that the echo mode packet is a BFD packet
>> be made (so the BFD source / dest packet identifiers can be
>> used)? The base BFD spec seems to state the content of the
>> packet need not be specified as the packet is just looped back.
>
> BFD echo packets can be identified by UDP dest port 3785.
> Data beyond UDP header is not specified, and that's left up to vendors.
>
>> So I can see how we could look an IP packet in the case of
>> Single Hop (by having the MAC Destination Address of the
>> peer) but having IP address and destination the same (as of
>> the source).
>
> I don't think there's anything that specifies that dest & src addresses
> must be the same. For dest addresses tho, it maybe easier to
> demultiplex if dest address is the outgoing interface.
That is correct. I guess you mean the destination IP address in your
message above, is that right?

Thanks,
Vishwas

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