IETF Logo Mail Archive

[mpls] Meaning of sub-TLVs for TLV 21 in Return Path Specified

"George Swallow (swallow)" <swallow@cisco.com> Tue, 21 May 2013 16:23 UTC

Return-Path: <swallow@cisco.com>
X-Original-To: mpls@ietfa.amsl.com
Delivered-To: mpls@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id E527421F98AC for <mpls@ietfa.amsl.com>; Tue, 21 May 2013 09:23:05 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -110.598
X-Spam-Level:
X-Spam-Status: No, score=-110.598 tagged_above=-999 required=5 tests=[BAYES_00=-2.599, HTML_MESSAGE=0.001, RCVD_IN_DNSWL_HI=-8, USER_IN_WHITELIST=-100]
Received: from mail.ietf.org ([12.22.58.30]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 4OBkjBrrvmIj for <mpls@ietfa.amsl.com>; Tue, 21 May 2013 09:23:00 -0700 (PDT)
Received: from rcdn-iport-2.cisco.com (rcdn-iport-2.cisco.com [173.37.86.73]) by ietfa.amsl.com (Postfix) with ESMTP id 1D2CC21F98AB for <mpls@ietf.org>; Tue, 21 May 2013 09:22:55 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=cisco.com; i=@cisco.com; l=2884; q=dns/txt; s=iport; t=1369153375; x=1370362975; h=from:to:cc:subject:date:message-id:mime-version; bh=U2bcKxZCYJ3YpSwKzocqhDBpr/sRKMNHc3L9BXxY9A0=; b=NIDDcl76oY6onXaYwM8RltNQZDEI9sKBryGMCACFnGR+A1JGlp9SL3tL xFBjoOq52Hv5yJJi+h38GXiEd2yj3Yys2JpQiL1wDZ6c0SqwepnkOD8/S mcNkQjlv+FztSv45FPYes3E+KoLV5XustQvsnZPLThj2pHOpkALb2EXLh 4=;
X-IronPort-Anti-Spam-Filtered: true
X-IronPort-Anti-Spam-Result: AgYGACyem1GtJV2a/2dsb2JhbABPCoJERMB3gQiBCRZtB4IlAQR5EgEMAR1WJwQODYgFu1qNXoELMYJ6YQOoeIMPgiY
X-IronPort-AV: E=Sophos; i="4.87,714,1363132800"; d="scan'208,217"; a="213165207"
Received: from rcdn-core-3.cisco.com ([173.37.93.154]) by rcdn-iport-2.cisco.com with ESMTP; 21 May 2013 16:22:54 +0000
Received: from xhc-rcd-x01.cisco.com (xhc-rcd-x01.cisco.com [173.37.183.75]) by rcdn-core-3.cisco.com (8.14.5/8.14.5) with ESMTP id r4LGMonZ011501 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=FAIL); Tue, 21 May 2013 16:22:54 GMT
Received: from xmb-rcd-x10.cisco.com ([169.254.15.56]) by xhc-rcd-x01.cisco.com ([173.37.183.75]) with mapi id 14.02.0318.004; Tue, 21 May 2013 11:22:53 -0500
From: "George Swallow (swallow)" <swallow@cisco.com>
To: "draft-ietf-mpls-return-path-specified-lsp-ping.all@tools.ietf.org" <draft-ietf-mpls-return-path-specified-lsp-ping.all@tools.ietf.org>
Thread-Topic: Meaning of sub-TLVs for TLV 21 in Return Path Specified
Thread-Index: AQHOVj9xsbdxNWyKhUe07sOydMXSag==
Date: Tue, 21 May 2013 16:22:52 +0000
Message-ID: <2FE467D3673DCE409A84D67EC2F607BB0FA82512@xmb-rcd-x10.cisco.com>
Accept-Language: en-US
Content-Language: en-US
X-MS-Has-Attach:
X-MS-TNEF-Correlator:
user-agent: Microsoft-MacOutlook/14.2.5.121010
x-originating-ip: [10.98.56.166]
Content-Type: multipart/alternative; boundary="_000_2FE467D3673DCE409A84D67EC2F607BB0FA82512xmbrcdx10ciscoc_"
MIME-Version: 1.0
Cc: "mpls@ietf.org" <mpls@ietf.org>
Subject: [mpls] Meaning of sub-TLVs for TLV 21 in Return Path Specified
X-BeenThere: mpls@ietf.org
X-Mailman-Version: 2.1.12
Precedence: list
List-Id: Multi-Protocol Label Switching WG <mpls.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/mpls>, <mailto:mpls-request@ietf.org?subject=unsubscribe>
List-Archive: <http://www.ietf.org/mail-archive/web/mpls>
List-Post: <mailto:mpls@ietf.org>
List-Help: <mailto:mpls-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/mpls>, <mailto:mpls-request@ietf.org?subject=subscribe>
X-List-Received-Date: Tue, 21 May 2013 16:23:06 -0000

Mach, et al. -

In section 4.1. Sending an Echo Request, it is stated:

The Reply Path TLV includes one or several reply path sub-TLV(s) to
identify the return path(s) the egress LSR should use for its reply.

It would appear that the semantics of TLV 21 are very different than the semantics of TLV 1.  Since TLV 1 defines a FEC stack which maps to a single LSP.  Why do you want the NIL FEC which only makes sense as part of a FEC stack?

Under what circumstances would you ever use one of the multicast FECs (sub-TLVs 17, 18, 19, 20)?

What is the meaning of a return path to a VPN IPv4 prefix, or  VPN IPv6 prefix?  Note that if the prefix is multi-homed it may not even return to the originating PE!

What is the meaning of a return path to an L2 VPN endpoint?

George

v2.23.0 | Report a Bug | By Email