Re: Question on HB in SCTP Multihoming

Janaka,

Regardless of RFC, if the local node is sending ICMP (port unreachable)
and ICMP (protocol unreachable) for a port for which there is an existing
SCTP assocation, then the local node is messed up: it is not only
telling the remote node that there is no association for the SCTP port
but it is telling the remote node that one of its IP addresses does not
even have SCTP support.  The remote node is correct in dropping the
association.

There is no nak for a HEARTBEAT: if the implementation receive a valid HB
(correct tag) port and IP address that is part of an existing association
from an address with which the node has an association, it MUST respond
with a HEARTBEAT ACK.

--brian

Janaka Sooriyaaratchi wrote:                 (Mon, 29 Dec 2008 16:50:25)
> 
>    Hi Experts,
>    The following question is related to SCTP multihoming with Two IP
>    addresses in each Node (Client and the Server).
>    I need to know the correct behavior of Heart beat response when one of
>    the IP addresses are not reachable.
> 
>    Pls look at the example below;
> 
>    Local Node                                                      Remote
>    Node
>    (Client, Port 2905)
>    (Server, Port 2906)
>    (Primary)   10.114.4.132  Ip Interface1(Link1)          <---------->
>    10.102.232.7
>    (Secondary) 10.114.4.140 Ip Interface2(Link2)           <---------->
>    10.102.232.39
>    SCTP is Configured as Multihomed.
> 
>    In the above configuration SCTP port address 10.114.4.140 is down, and
>    local node sends ICMP response as below;
> 
>    2008-08-12 15:09:32.666577      10.102.232.39   10.114.4.140
>    SCTP    HEARTBEAT
>    2008-08-12 15:09:32.667161      10.114.4.140    10.102.232.39
>    ICMP    Destination unreachable (Port unreachable)
>    ICMP:
>    Type: Destination Unreachable
>    Code: protocol Unreachabel
> 
>    This causes the Remote Node to react badly , that is, Remote node
>    sends SCTP abort to the primary link (10.114.4.132  ) taking down the
>    whole SCTP user.
> 
>    We donot have the full internal visibility to Remote Node as it
>    belongs to another Vendor. But what  we do know is that the  Remote
>    Node does not like the ICMP message as a response to the HB request.
> 
>    According to RFC 4960 ICMP handling is Defined in Appendix C, we may
>    argue that the Local behaves correctly in sending the ICMP message.
>    But the question remains not answered is that "can the Local node
>    sends ICMP message as a response to HB request?". Is this specifically
>    mentioned in RFC 4960. What is the equivalent NAK message to HB
>    request in SCTP?
> 
>    Other Argument we had there related to ICMP message was that Remote
>    node does not support ICMP messages, meaning follows RFC 2960 , where
>    ICMP handling is not defined.
> 
>    In this case what would be the Response to HB request? Should the
>    local Node Silently Discard the HB message?
> 
>    Pls would you discuss this issues with respect relevant RFCs.
>    Thanks in Advance.
> 
>    According to
>    Best Regards
>    Janaka Sooriyaaratchi

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-- 
Brian F. G. Bidulock
[email protected]
http://www.openss7.org/