mutli-homing behavior with primary path disabled in the network.

Anand N Ilkal <> Mon, 22 November 2010 09:58 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id 4002D28C0F3 for <>; Mon, 22 Nov 2010 01:58:45 -0800 (PST)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -2.598
X-Spam-Status: No, score=-2.598 tagged_above=-999 required=5 tests=[BAYES_00=-2.599, HTML_MESSAGE=0.001]
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id aDnc-rmfB4jp for <>; Mon, 22 Nov 2010 01:58:44 -0800 (PST)
Received: from ( []) by (Postfix) with ESMTP id 0145028C0E0 for <>; Mon, 22 Nov 2010 01:58:43 -0800 (PST)
Received: by wwa36 with SMTP id 36so6879374wwa.13 for <>; Mon, 22 Nov 2010 01:59:38 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=gamma; h=domainkey-signature:mime-version:received:received:date:message-id :subject:from:to:content-type; bh=ON4uX1AZYaxFtcVs/cY8QLnjdud5/vjjlboRC3V2lrw=; b=ho5fHCwguPBlbtqyOSDTbgg9gM6cvGLtMdyMPYGMGMKPHX+f0tBdSFkVxwveDnuF4v jaqaaSjEM3w9Kiy3GwCw1LE4l9gE7bP8FgdVDDVUXWzwTbNTa3IY00rcIfBiK4DeNcY/ +w9HOz1iGL8PLrrkUfgP1IHzhg6qGlltRa34M=
DomainKey-Signature: a=rsa-sha1; c=nofws;; s=gamma; h=mime-version:date:message-id:subject:from:to:content-type; b=S5Fi9jkf7t2onMw6x3no2tCjEFkb7hQQdA9ftvkA6juZv14TKiv0mhvPie69kHujCD XAmkYR39nG/Lwekje1SyRB55D0LDF1JPOZJE9ObMnvg2w2hHy14P3nfZv/Yfofm8/q+b qyBz7G4yxTuJyJXOvJ1xNzdU2ONdgV3v462xc=
MIME-Version: 1.0
Received: by with SMTP id n17mr2181925wbu.204.1290419978550; Mon, 22 Nov 2010 01:59:38 -0800 (PST)
Received: by with HTTP; Mon, 22 Nov 2010 01:59:38 -0800 (PST)
Message-ID: <>
Subject: mutli-homing behavior with primary path disabled in the network.
From: Anand N Ilkal <>
Content-Type: multipart/alternative; boundary="001485f777ee6ebf930495a15012"
X-Mailman-Approved-At: Thu, 09 Dec 2010 03:03:39 -0800
X-Mailman-Version: 2.1.9
Precedence: list
List-Id: Transport Area Working Group <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
Date: Mon, 22 Nov 2010 09:58:45 -0000
X-Original-Date: Mon, 22 Nov 2010 15:29:38 +0530
X-List-Received-Date: Mon, 22 Nov 2010 09:58:45 -0000


I have a multi-home association between Node A(IP1, IP2) and Node B(IP3,
IP4). IP1 and IP3 are configured as primary IP's.

A static route is configured between Node A and Node B for IP1 and IP3.
Hence it will always take this path for message exchange.
Now at the intermediate node this route is disabled. Hence no message reach
other end using IP1 and IP3.

It is observed that even HEARTBEAT's are not exchanged between IP1 and IP3.
Since secondary path is available, the messages are
exchanged between IP2 and IP4. in addition to this all message are tried on
the primary path first and then are sent on the secondary path.

1. How long SCTP tries sending message on primary path? or it tries for the
lifetime of the association?
2. How the decision of forbiding primary path is taken? is this the job of
SCTP layer or IP layer beneath it? or it wont take such decision?
3. when is the message exchange is resumed on primary path?

with regards,
Anand kumar Ilkal