Re: Query regarding number of paths for Multi-homing scenario

[Padmalochan Moharana <[e-mail]>]

Hi Michael,

Thanks for the quick answer. I have one more doubt.

In below scenario, suppose the network cable connected  to NIC having
primary IP 192.168.1.2  is unplugged. Should endpoint B send data to
endpoint A using secondary IP i.e. 192.168.1.3?

Br,
Padmalochan

On Thu, Aug 5, 2010 at 5:59 PM, Michael Tuexen
<[e-mail]> wrote:
> On Aug 5, 2010, at 2:15 PM, Padmalochan Moharana wrote:
>
>> Hi All,
>>
>> I have some doubt regarding the number path use by an sctp association
>> during multi-homing scenario.
>>
>> Suppose end point “A” is single homed (having IP 192.168.1.1) and
>> endpoint “B” is multi-home (having IP 192.168.1.2 and 192.168.1.3). As
>> per definition of path in the rfc-4960 (section 1.3.)
>>
>> Path: The route taken by the SCTP packets sent by one SCTP endpoint to
>> a specific destination transport address of its peer SCTP endpoint.
>> Sending to different destination transport addresses does not
>> necessarily guarantee getting separate paths.
>>
>> As for endpoint “A” two destination address is available then two path
>> is available to send packets to endpoint B from A.
>>
>> As for endpoint “B” only one address is available then only one path
>> is available to send data to endpoint A.
>>
>> Again as per the section
>> 6.4.1. Failover from an Inactive Destination Address
>>
>> When retransmitting data that timed out, if the endpoint is
>> multi-homed, it should consider each source-destination address pair
>> in its retransmission selection policy.  When retransmitting timed-out
>> data, the endpoint should attempt to pick the most divergent source-
>> destination pair from the original source-destination pair to which
>> the packet was transmitted.
>>
>>
>> My doubts:
>> 1-    How many paths are available for endpoint B to reach endpoint A?
> There is only one destination address available for endpoint B.
>> 2-    Should endpoint B send HEARTBEAT to endpoint A from 192.168.1.3
>> (secondary IP of B) in regular interval to test the reachablity of A
>> using that IP?
> HEARTBEATs are used to monitor idle destination addresses. So endpoint B
> supervises only the one IP address of endpoint A.
>> 3-    Can endpoint B send DATA to A (192.168.1.1) from IP 192.168.1.3
>> (secondary IP of B)?
> Sure. Endpoint A will accept all SCTP packets, no matter if they come
> from 192.168.1.2 or 192.168.1.3. However, the ports must be OK and the
> v-tag must be OK.
>> 4-    Should endpoint A discard the DATA that received from
>> 192.168.1.3(secondary IP of B)?
> No.
>
> Best regards
> Michael
>>
>> Regards,
>> Padmalochan
>>
>
>