Re: [mpls] draft-fang-mpls-label-forwarding-no-swap - how much does it really save?

Stewart Bryant <stbryant@cisco.com> Wed, 29 July 2015 12:52 UTC

Return-Path: <stbryant@cisco.com>
X-Original-To: mpls@ietfa.amsl.com
Delivered-To: mpls@ietfa.amsl.com
Received: from localhost (ietfa.amsl.com [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id ABA511A8A7E for <mpls@ietfa.amsl.com>; Wed, 29 Jul 2015 05:52:35 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -14.511
X-Spam-Level:
X-Spam-Status: No, score=-14.511 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, RCVD_IN_DNSWL_HI=-5, SPF_PASS=-0.001, T_RP_MATCHES_RCVD=-0.01, USER_IN_DEF_DKIM_WL=-7.5] autolearn=ham
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 4rB02Pjp6Mf7 for <mpls@ietfa.amsl.com>; Wed, 29 Jul 2015 05:52:33 -0700 (PDT)
Received: from aer-iport-4.cisco.com (aer-iport-4.cisco.com [173.38.203.54]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id DD3491A8A72 for <mpls@ietf.org>; Wed, 29 Jul 2015 05:52:32 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=cisco.com; i=@cisco.com; l=4836; q=dns/txt; s=iport; t=1438174353; x=1439383953; h=reply-to:subject:references:to:cc:from:message-id:date: mime-version:in-reply-to:content-transfer-encoding; bh=7rBjr0DttEcdPK0TA4jM/hZLIXu+z5AUmBeBtIOT3mA=; b=iU+9UgckVT92lZ7rCBIJQjHK6FT+Y8OZ9eRDPdu/GPGcmHSqGgyP+dO/ wvwQxVVEISIRYOab89PTpi3+zuZlDIuixdAjmYUD3/bB2sz5K7rl9asNd fcxJKkJCd9H/sjyg0eHZEAuVSSf7l4sSBgZxYJpOHq7l1yPcpguOMUkv1 I=;
X-IronPort-AV: E=Sophos;i="5.15,570,1432598400"; d="scan'208";a="583661779"
Received: from aer-iport-nat.cisco.com (HELO aer-core-4.cisco.com) ([173.38.203.22]) by aer-iport-4.cisco.com with ESMTP; 29 Jul 2015 12:52:31 +0000
Received: from [64.103.106.92] (dhcp-bdlk10-data-vlan300-64-103-106-92.cisco.com [64.103.106.92]) by aer-core-4.cisco.com (8.14.5/8.14.5) with ESMTP id t6TCqUkQ031600; Wed, 29 Jul 2015 12:52:31 GMT
References: <DB3PR03MB0780AE3E11BEA6B29B81FF5B9D810@DB3PR03MB0780.eurprd03.prod.outlook.com> <EA360A7AB9D90D4B9E9173B6D27C371EE3F60C0D@MTKMBS61N1.mediatek.inc> <55B64078.7030601@cisco.com> <EA360A7AB9D90D4B9E9173B6D27C371EE3F624BE@MTKMBS61N1.mediatek.inc> <55B7617A.90808@cisco.com> <EA360A7AB9D90D4B9E9173B6D27C371EE3F64252@MTKMBS61N1.mediatek.inc> <F9B5D5ED-6380-4D82-9A61-589150DFF6D4@broadcom.com> <EA360A7AB9D90D4B9E9173B6D27C371EE3F6448F@MTKMBS61N1.mediatek.inc>
To: Andrew Qu <andrew.qu@mediatek.com>, Shahram Davari <davari@broadcom.com>
From: Stewart Bryant <stbryant@cisco.com>
Message-ID: <55B8CC8F.60303@cisco.com>
Date: Wed, 29 Jul 2015 13:52:31 +0100
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:38.0) Gecko/20100101 Thunderbird/38.1.0
MIME-Version: 1.0
In-Reply-To: <EA360A7AB9D90D4B9E9173B6D27C371EE3F6448F@MTKMBS61N1.mediatek.inc>
Content-Type: text/plain; charset=windows-1252; format=flowed
Content-Transfer-Encoding: 7bit
Archived-At: <http://mailarchive.ietf.org/arch/msg/mpls/m6znhcxJntXNqAEBb_CCOWmhrRY>
Cc: "mpls@ietf.org" <mpls@ietf.org>, Robert Raszuk <robert@raszuk.net>
Subject: Re: [mpls] draft-fang-mpls-label-forwarding-no-swap - how much does it really save?
X-BeenThere: mpls@ietf.org
X-Mailman-Version: 2.1.15
Precedence: list
Reply-To: stbryant@cisco.com
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: <https://mailarchive.ietf.org/arch/browse/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: Wed, 29 Jul 2015 12:52:35 -0000

On 28/07/2015 18:55, Andrew Qu wrote:
> Hi Shahram,
>
> This is a question that must be answered,  but could you please hold the question for now?
>
> I just want to have one issue clarified before moving to another.
>
> Do we agree that _IF_ global label becomes necessary,  no-swap as primitive is necessary?
No, the primitive is not *needed*.

Stewart
>
> Understood that _IF_ will be next topic to follow.
>
> Thanks,
>
> Andrew
>
> -----Original Message-----
> From: Shahram Davari [mailto:davari@broadcom.com]
> Sent: Tuesday, July 28, 2015 9:40 AM
> To: Andrew Qu
> Cc: stbryant@cisco.com; Alexander Vainshtein; Robert Raszuk; mpls@ietf.org
> Subject: Re: [mpls] draft-fang-mpls-label-forwarding-no-swap - how much does it really save?
>
> Andrew
>
> Continue operation in segment routing and in HSDN is not global label. Global label means every router knows how to forward a global label. What is the application for a global label and how does each router know how to forward it?
>
> Regards,
> Shahram
>
>
>> On Jul 28, 2015, at 7:58 AM, Andrew Qu <andrew.qu@mediatek.com> wrote:
>>
>> Hi Stewart,
>>
>> Agreed that SWAP must be kept because MPLS fundamentals can't be broken.
>> And I agreed that _if_ there is NO such global label space idea,
>> no-swap is optimization of swap as well.
>>
>> However I don't agree no-swap become an optimization in terms of
>> network Behavior when global label idea become a needed thing.
>>
>>
>> When global Label introduced, then no_swap is the conceptually right
>> thing for the transition [even Local implementation can use swap to
>> achieve, again, per previous conversation, the popular wisdom, which I
>> agreed as well,  is that this is local implementation, we should not
>> get involved, so we must define no-swap as the new primitive at RFC
>> level]
>>
>>
>> So the question really boils down to that do we need global label?
>>
>> I believe that is the key thing here.  May be we can put swap/no-swap aside for the moment.
>>
>> Thanks,
>>
>> Andrew
>>
>>
>> -----Original Message-----
>> From: Stewart Bryant [mailto:stbryant@cisco.com]
>> Sent: Tuesday, July 28, 2015 4:03 AM
>> To: Andrew Qu; Alexander Vainshtein; Robert Raszuk; Shahram Davari
>> Cc: mpls@ietf.org
>> Subject: Re: [mpls] draft-fang-mpls-label-forwarding-no-swap - how much does it really save?
>>
>>> Adding "NO_SWAP" for new/future generation DEVICE does NOT break
>>> backward capability.
>> Andrew
>>
>> Existing devices should be assumed to have non-aligned label spaces.
>> (there is much empirical evidence to support this position)
>>
>> So if you have a no-swap only device between two existing devices you cannot be sure that you can build an LSP.
>>
>> A backwards compatible device would therefore need to support swap.
>>
>> Once you support swap then no-swap become an optimization.
>>
>> - Stewart
>>
>>
>> ************* Email Confidentiality Notice ******************** The
>> information contained in this e-mail message (including any
>> attachments) may be confidential, proprietary, privileged, or
>> otherwise exempt from disclosure under applicable laws. It is intended
>> to be conveyed only to the designated recipient(s). Any use,
>> dissemination, distribution, printing, retaining or copying of this
>> e-mail (including its
>> attachments) by unintended recipient(s) is strictly prohibited and may
>> be unlawful. If you are not an intended recipient of this e-mail, or
>> believe that you have received this e-mail in error, please notify the
>> sender immediately (by replying to this e-mail), delete any and all
>> copies of this e-mail (including any attachments) from your system,
>> and do not disclose the content of this e-mail to any other person. Thank you!
>>
> ************* Email Confidentiality Notice ********************
> The information contained in this e-mail message (including any
> attachments) may be confidential, proprietary, privileged, or otherwise
> exempt from disclosure under applicable laws. It is intended to be
> conveyed only to the designated recipient(s). Any use, dissemination,
> distribution, printing, retaining or copying of this e-mail (including its
> attachments) by unintended recipient(s) is strictly prohibited and may
> be unlawful. If you are not an intended recipient of this e-mail, or believe
> that you have received this e-mail in error, please notify the sender
> immediately (by replying to this e-mail), delete any and all copies of
> this e-mail (including any attachments) from your system, and do not
> disclose the content of this e-mail to any other person. Thank you!
>
> .
>


-- 
For corporate legal information go to:

http://www.cisco.com/web/about/doing_business/legal/cri/index.html