IETF Logo Mail Archive

Re: [OSPF] FW: Forwarding address set for type-5

"Acee Lindem (acee)" <acee@cisco.com> Wed, 13 July 2016 11:45 UTC

Return-Path: <acee@cisco.com>
X-Original-To: ospf@ietfa.amsl.com
Delivered-To: ospf@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 0C79E12DD4A for <ospf@ietfa.amsl.com>; Wed, 13 Jul 2016 04:45:54 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -15.807
X-Spam-Level:
X-Spam-Status: No, score=-15.807 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, HTML_MESSAGE=0.001, RCVD_IN_DNSWL_HI=-5, RCVD_IN_MSPIKE_H4=-0.01, RCVD_IN_MSPIKE_WL=-0.01, RP_MATCHES_RCVD=-1.287, SPF_PASS=-0.001, USER_IN_DEF_DKIM_WL=-7.5] autolearn=ham autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (1024-bit key) header.d=cisco.com
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id J3CwXXhqaSEK for <ospf@ietfa.amsl.com>; Wed, 13 Jul 2016 04:45:52 -0700 (PDT)
Received: from alln-iport-1.cisco.com (alln-iport-1.cisco.com [173.37.142.88]) (using TLSv1.2 with cipher DHE-RSA-SEED-SHA (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 6208012B007 for <ospf@ietf.org>; Wed, 13 Jul 2016 04:45:52 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=cisco.com; i=@cisco.com; l=11611; q=dns/txt; s=iport; t=1468410352; x=1469619952; h=from:to:subject:date:message-id:mime-version; bh=HQYd/cmBJInoGoPZQAMUyiUTtikuQwSY8+5HgJ37UOE=; b=SK8bc+2l47NKrrUvUK7SBjxeQo7SfAbOSsOPRToQMESWOBQsu4c7Ryr+ r6pW76Z71mVinSDc+Hf51vFX42gI4FfLRjg37SOtLtSpe1xiYm1OO8kiY llDXFSNMFWixOLypspbiiuEQqUYpyxwIwX97vUTihO0hINPRezJbMJAl8 k=;
X-IronPort-Anti-Spam-Filtered: true
X-IronPort-Anti-Spam-Result: A0CKBQAbKYZX/4QNJK1dgnBOVnwGs16CdYIPgXqGGB6BETkTAQEBAQEBAWUnhFwBAQUjCl4BCA4DAwECKAMCBDAUCAEKBAESiDCxS48GAQEBAQEFAQEBAQEBIYp3hB5DgmGCWgWTXoU+AYUsiSqBa4RZiGuQFgEgAzGDcW6HdER/AQEB
X-IronPort-AV: E=Sophos;i="5.28,357,1464652800"; d="scan'208,217";a="297329437"
Received: from alln-core-10.cisco.com ([173.36.13.132]) by alln-iport-1.cisco.com with ESMTP/TLS/DHE-RSA-AES256-SHA; 13 Jul 2016 11:45:51 +0000
Received: from XCH-RTP-015.cisco.com (xch-rtp-015.cisco.com [64.101.220.155]) by alln-core-10.cisco.com (8.14.5/8.14.5) with ESMTP id u6DBjpW7023182 (version=TLSv1/SSLv3 cipher=AES256-SHA bits=256 verify=FAIL); Wed, 13 Jul 2016 11:45:51 GMT
Received: from xch-rtp-015.cisco.com (64.101.220.155) by XCH-RTP-015.cisco.com (64.101.220.155) with Microsoft SMTP Server (TLS) id 15.0.1210.3; Wed, 13 Jul 2016 07:45:50 -0400
Received: from xch-rtp-015.cisco.com ([64.101.220.155]) by XCH-RTP-015.cisco.com ([64.101.220.155]) with mapi id 15.00.1210.000; Wed, 13 Jul 2016 07:45:50 -0400
From: "Acee Lindem (acee)" <acee@cisco.com>
To: Radha Danda <rdanda@Brocade.com>, "ospf@ietf.org" <ospf@ietf.org>
Thread-Topic: [OSPF] FW: Forwarding address set for type-5
Thread-Index: AQHR3PwaXm8y5VG7+EaCNXtDO1/J2w==
Date: Wed, 13 Jul 2016 11:45:50 +0000
Message-ID: <D3ABA0CA.6B844%acee@cisco.com>
Accept-Language: en-US
Content-Language: en-US
X-MS-Has-Attach:
X-MS-TNEF-Correlator:
x-ms-exchange-messagesentrepresentingtype: 1
x-ms-exchange-transport-fromentityheader: Hosted
x-originating-ip: [10.116.152.196]
Content-Type: multipart/alternative; boundary="_000_D3ABA0CA6B844aceeciscocom_"
MIME-Version: 1.0
Archived-At: <https://mailarchive.ietf.org/arch/msg/ospf/odjF0JnB-GxtiWcr8cRNzQAhnpg>
Subject: Re: [OSPF] FW: Forwarding address set for type-5
X-BeenThere: ospf@ietf.org
X-Mailman-Version: 2.1.17
Precedence: list
List-Id: The Official IETF OSPG WG Mailing List <ospf.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/ospf>, <mailto:ospf-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/ospf/>
List-Post: <mailto:ospf@ietf.org>
List-Help: <mailto:ospf-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/ospf>, <mailto:ospf-request@ietf.org?subject=subscribe>
X-List-Received-Date: Wed, 13 Jul 2016 11:45:54 -0000

Hi Radha,
The forwarding address (next-hop) for an AS-External LSA may be advertised if it is reachable via an OSPF inter-area or intra-area route. You included connected routes  in your question and this is not necessarily correct since a connected route will only be accessible to other OSPF routers in the domain if it is advertised in OSPF. For NSSA LSAs, the next-hop should be reachable via an intra-area route in the NSSA.

Some implementations limit the advertising to the case where the next-hop is on a multi-access network.

Hope this helps,
Acee



From: OSPF <ospf-bounces@ietf.org<mailto:ospf-bounces@ietf.org>> on behalf of Radha Danda <rdanda@Brocade.com<mailto:rdanda@Brocade.com>>
Date: Wednesday, July 13, 2016 at 7:15 AM
To: OSPF WG List <ospf@ietf.org<mailto:ospf@ietf.org>>
Subject: [OSPF] FW: Forwarding address set for type-5

Hi All,

I need clarification on setting the Forwarding address set for type-5 LSA. As per RFC 2328 it is not obviously mentioned anywhere that the forwarding address can be set to connected, inter-area or intra-area routers but in the section 16.4 (Calculating AS external routes) it is mentioned that the forwarding address can be set to inter-area or intra-area as well. Snippet from the RFC is provided below for quick reference. Can you please confirm if the forwarding address can be set to ospf connected, inter-area or intra-area route while generating external LSA. Thanks.

**********************************
If the forwarding address is non-zero, look up the
            forwarding address in the routing table.[24] The matching
            routing table entry must specify an intra-area or inter-area
            path; if no such path exists, do nothing with the LSA and
            consider the next in the list.
******************************

Best Regards,
Radha

v2.23.0 | Report a Bug | By Email