SCTP Mulithoming Communication PATHS Query

[Sambasiva Rao Manchili <sambasiva.manchili@xxxxxxxxxxxxxxxx>]

Hallo,

 

I  have a query related to SCT Mulithoming communication paths.

Host-X: (IPpx  IPax): Multihomed Association  with Host-Y (IPpy  IPay).

 

Host-X  SCTP Client is running with SCTP stack provided by Vendor X
Host-Y  SCTP Server is running with SCTP stack provided by Vendor Y.

 

Notation.

IPpx  means IP Address of Primary  path on Host-X
IPax  means IP Address of Alternate path on Host-X

 

IPpy  means IP Address of Primary path on Host-Y
IPpy  means IP Address of Primary path on Host-Y

 

Host-X is Communicating as follows :-
-------------------------------------------------------

 

Primary IP  to Primary IP
Host-X(IPpx)--------HBEAT---------->Host-Y(IPpy)
Host-X(IPpx)<-------HBEAT-ACK------Host-Y(IPpy)

 

Alternate IP to Alternate IP
Host-X(IPax)--------HBEAT---------->Host-Y(IPay)
Host-X(IPax)<-------HBEAT-ACK------Host-Y(IPay)

 

/*
 * Host-X installed in Customer network.
 * Customer Network not configured/ not capable to deliver to destination
 * in the following two paths. I do not know if they have special requirement
 * to configure their network only primary talks to primary and alternate talks
 * to alternate, but I see disadvantage in their setup.
 * Host-X  keeps on trying to reach every Destination received in the
 * INIT_ACK message from Host-Y
 *
 */
Primary to Alternate Address
Host-X(IPpx)--------HBEAT---------->Host-Y(IPay) (DOES N0T REACH IPay)
Host-X(IPax)--------HBEAT---------->Host-Y(IPpy) (DOES NOT REACH IPpy)

 

Now Host-X was forced to configured Path Max Retransmissions and Max Init Retransmissions to value of 5, while RTO Initial and RTO MAX value is set to 1 second.
This results
1. to mark the destination endpoint IPay as NETWORK DOWN on Host-X when  it exceeds max retranmission in same path(cross) consecutively and

 

2. then sends INIT from IPpx to IPpy and also IPpx to IPay and as soon as it gets  the response from any destination(in customer nework only from IPpy) it is marked as NETWORK UP,

 

3. but soon or later we receive again NETWORK DOWN and same repeats from step 1.

 

 

Now the query is,

Is it right to tell custome Network to re-configure their network to allow
cross communication ?

 

OR

 

Is it MUST to change the Host-X stack to stop communicating Cross
i.e., IPpx trying to reach IPay.

 

Advantage that I see from Host-X Stack :
I also see an advantage with Host-X tranport addresses IPs trying to reach every destination
of the peer. The advantage is If the path between the  Host-Y(IPpy)  and its next hop is broken and
If the path between Host-X(IPax) and its next hop is broken still Multihoming makes real sense and
could cope up with such breakdown in network while Host-X(IPpx)------->Host-Y(IPay)

 

If I overlook any other disadvantage of Host-X stack, please correct me.

 

Looking forward for your suggestion from your expert knowledge. If something not clear please feel to ask me.

Thanks in advance.

 

Thanks,

samba.

 

 

 

Sambasiva Rao Manchili
Software Development Engineer
________________________________
 
NEXUS TELECOM AG
Network and Service Investigation
Muertschenstrasse 25
P.O. Box 1413
CH-8048 Zurich
Switzerland

Direct/mobile: +41 78 750 6808
Main: +41 44 355 6611
Email: sambasiva.manchili@xxxxxxxxxxxxxxxx
Website: www.nexustelecom.com

 

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