Return-Path: X-Original-To: bess@ietfa.amsl.com Delivered-To: bess@ietfa.amsl.com Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id D71F1128DFD; Tue, 23 Oct 2018 07:47:54 -0700 (PDT) X-Virus-Scanned: amavisd-new at amsl.com X-Spam-Flag: NO X-Spam-Score: -2.599 X-Spam-Level: X-Spam-Status: No, score=-2.599 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, HTML_MESSAGE=0.001, RCVD_IN_DNSWL_LOW=-0.7, SPF_PASS=-0.001, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no 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 rLBwuxn5AOL2; Tue, 23 Oct 2018 07:47:51 -0700 (PDT) Received: from huawei.com (lhrrgout.huawei.com [185.176.76.210]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id C3B8F128BCC; Tue, 23 Oct 2018 07:47:50 -0700 (PDT) Received: from lhreml706-cah.china.huawei.com (unknown [172.18.7.107]) by Forcepoint Email with ESMTP id C8BAC4B374D35; Tue, 23 Oct 2018 15:47:45 +0100 (IST) Received: from LHREML523-MBX.china.huawei.com ([169.254.7.239]) by lhreml706-cah.china.huawei.com ([10.201.108.47]) with mapi id 14.03.0415.000; Tue, 23 Oct 2018 15:47:39 +0100 From: "Yutianpeng (Tim)" To: Alexander Vainshtein , "Wanghaibo (Rainsword)" CC: "draft-wang-bess-evpn-control-word.authors@ietf.org" , "bess@ietf.org" Thread-Topic: A question regarding draft-wang-bess-evepn-control-word Thread-Index: AdRqrNk+JB1I7psBRa+73/QNemWcWQAALOQwAAKSsZAAAlraMAAC/Q+QAAK3uvA= Date: Tue, 23 Oct 2018 14:47:38 +0000 Message-ID: <35FF0D51C8DAB54B95B0426331F984FF5208500A@lhreml523-mbx.china.huawei.com> References: <1E61161D6E31D849BEA887261DB609348C770DEE@nkgeml514-mbx.china.huawei.com> <1E61161D6E31D849BEA887261DB609348C770F2F@nkgeml514-mbx.china.huawei.com> In-Reply-To: Accept-Language: zh-CN, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.203.126.98] Content-Type: multipart/alternative; boundary="_000_35FF0D51C8DAB54B95B0426331F984FF5208500Alhreml523mbxchi_" MIME-Version: 1.0 X-CFilter-Loop: Reflected Archived-At: Subject: Re: [bess] A question regarding draft-wang-bess-evepn-control-word X-BeenThere: bess@ietf.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: BGP-Enabled ServiceS working group discussion list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 23 Oct 2018 14:47:55 -0000 --_000_35FF0D51C8DAB54B95B0426331F984FF5208500Alhreml523mbxchi_ Content-Type: text/plain; charset="gb2312" Content-Transfer-Encoding: base64 SGkgU2FzaGEsDQpJIGFtIGFsc28gdGhpbmtpbmcgb2YgdGhpcyByZWNlbnRseSBidXQgaGF2ZW6h r3QgdGFsa2VkIHdpdGggYXV0aG9yIHlldC4NCldoYXQgd2FzIGluIG15IG1pbmQgdGhlIHNvbHV0 aW9uIGlzIGFjdHVhbGx5IHNpbXBsZTogZGlyZWN0bHkgdGVhciBkb3duIChwYXJ0IG9mKSB0aGUg 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Hi Sasha,

I am also thinking of = this recently but haven=A1=AFt talked with author yet.

What was in my mind th= e solution is actually simple: directly tear down (part of) the mac-VRF or = EVI directly if CW capabilities not consistent, considering behavior in one= EVI should keep consistent (personally believe).  

I might tend to the me= chanism as below:

If router A has CW cap= abilities and receive type 1 or type 2 routes without CW, then A should dro= p these routes and report an alarm.

If router A does not h= as CW capabilities and receive type 1 or type 2 routes with CW, then A shou= ld drop these routes and report an alarm.

I believe the behavior= within EVI or Mac-VRF should keep consistent, otherwise, more questions wi= ll pop out.

Considering if a servi= ce is sensitive to packet misordering and it is ELAN, I tend to keep behavi= or within this ELAN consistent.

There could also be ot= her problems with this approach, just share an idea so far open the discuss= ion.

Regards, and lots of thanks in advance,

Tim

 

From: BESS [mailto:bess-bounces@ietf.org] = On Behalf Of Alexander Vainshtein
Sent: 23 October 2018 14:42
To: Wanghaibo (Rainsword) <rainsword.wang@huawei.com>
Cc: draft-wang-bess-evpn-control-word.authors@ietf.org; bess@ietf.or= g
Subject: Re: [bess] A question regarding draft-wang-bess-evepn-contr= ol-word

 

Dear Haibo,

Again,

Lots of thanks for a prompt response.

 

My reading of your response is as following:

1.       All egress PEs can receive EVPN-encapsulated packets without the CW

2.       All ingress PEs can sent EVPN-encapsulated packets without the CW

3.       An egress PE that can receive EVPN-encapsulated packets with t= he CW in the EVPN encapsulation,  must add the appropriate NH Capabili= ty attribute that indicates the CW-indicating label value (explicitly or implicitly) to all relevant EVPN routes.  = This includes:

a.       Per-EVI Ethernet A-D route (EVPN Route Type 1). In this case t= he CWI label would follow the label advertised in the NLRI of this route

b.      MAC/IP Advertisement route (EVPN Type 2 route). In this case t= he CWI label would follow the label advertised in the NLRI as Label1, it wo= uld not be relevant for packets that are encapsulated using Label2 (used with the Symmetric EVPN IRB).

4.       An ingress PE that has received an EVPN route with the CW capa= bility attribute wand that can support usage of CW in the EVPN encapsulatio= n, will insert both the CWI advertised in the CW capability attribute, and the CW in the EVPN packets it sends to= the corresponding egress PE.  If it does not support usage of CW in t= he encapsulation, it will not insert this label.

 

Is this understanding correct?

 

If yes, I still have a couple of questions:

1.       Suppose that you use ingress replication (IR) to deliver BUM t= raffic across EVPN. The Ingress Replication label would be advertised in th= e PTA attribute of the Inclusive Multicast Ethernet Tag Route (EVPN Type 3 route); it will not be part of the NLRI. D= o you expect the same logic to be used with regard to CW capabilities and C= WI label advertisement applied also to these routes?

2.       Per-ES Ethernet A-D Routes are advertised with the ECI expende= d Community that carries within the so-called ESI label. This label is incl= uded the EVPN encapsulation of BUM packets sent to the PE that is attached to the same multi-homed ES from wh= ich the original ES packet has been received. Do you expect the same logic = to be used with regard to CW capabilities and CWI label advertisement appli= ed also to these routes with the CWI label following the ESI label in the EVPN encapsulation of BUM packets= ?

 

Regards, and lots of thanks in advance,

Sasha

 

Office: +972-39266302

Cell:      +972-549266302

Email:   Alexander.Vainshtein@ec= itele.com

 

From: Wanghaibo (Rainsword) [mailto:rainsword.wang@huawei.com]
Sent: Tuesday, October 23, 2018 2:34 PM
To: Alexander Vainshtein <Alexander.Vainshtein@ecitele.com>
Cc: bess@ietf.org; draft-wang-bess-evpn-control-word.authors@ietf.org
Subject: RE: A question regarding draft-wang-bess-evepn-control-word=

 

Hi Alexander,

 

The solution here is= to carry the next hop capability attribute when the route is advertised. T= he capability carried here is the control word capability.

The specific format = of the next hop capability can be referred to the draft.: <draft-ietf-idr-next-hop-capability>

     =             &nb= sp;   +------------------------------+<= /p>

     =             &nb= sp;   | Capability Code (2 octets)   |

     =             &nb= sp;   +------------------------------+<= /p>

     =             &nb= sp;   | Capability Length (2 octets) |

     =             &nb= sp;   +------------------------------+<= /p>

     =             &nb= sp;   | Capability Value (variable)  |

     =             &nb= sp;   ~         &nbs= p;            &= nbsp;       ~

     =             &nb= sp;   +------------------------------+<= /p>

For the control word= capability , it may encode as :

     =             &nb= sp;   +------------------------------+<= /p>

     =             &nb= sp;   | CW Capabality Type (TBD)     |

     =             &nb= sp;   +------------------------------+<= /p>

     =             &nb= sp;   | CW Length (0 or 3)       &n= bsp;   |

     =             &nb= sp;   +------------------------------+<= /p>

     =             &nb= sp;   | CWI Label (may not exist)    |<= /span>

     =             &nb= sp;   +------------------------------+<= /p>

CWI (Control word in= dication)

 

And the forwarding P= acket example.

     =             &nb= sp;   +------------------------------+

     =             &nb= sp;   | Tunnel Label        &n= bsp;        |

     =             &nb= sp;   +------------------------------+<= /p>

     =             &nb= sp;   | EVI Label        =            |

     =             &nb= sp;   +------------------------------+<= /p>

     =             &nb= sp;   | CW Indicate Label       &nb= sp;    |

     =             &nb= sp;   +------------------------------+<= /p>

     =             &nb= sp;   | Control word       &nb= sp;         |

     =             &nb= sp;   +------------------------------+<= /p>

 

The difference betwe= en the two methods is that which value should be use for the control word c= apability indicates label.

 

Method 1, use reserv= ed label, which should be assigned by IANA, (such as the entropy label, whi= ch is the value of 7)

If we use this metho= d, then the control word capability attribute=A1=AFs CW length use 0 is enough.

And the forwarding p= acket use the IANA specified value as the CWI (Control word indication) Lab= el .(Perhaps 8 or others)

 

Method2, use normal = value, which is assigned by router.

If we use this metho= d, then the router must assign a label used for the CWI. Perhaps label. And= the control word capability attribute=A1=AFs C= W length must be 3 and must contain the value in the update message.

The forwarding packe= t must use that value as the CWI label.

 

Regards,<= /span>

Haibo

 

 

Dear Haibo,

Lots of thanks for an extra-prompt response to my question.=

 

There may be some misunderstanding here.

 

The draft says (the important text is highlighted):<= /p>

 

      There are two methods t= o specified the control word indicator label:

 

      The first method is to apply= for a reserved label to indicate

      whether the packet contains = a control word;

 

      The second method is to apply for a new labe= l when the sending

      router advertises the contro= l word capability, which is used to

   &n= bsp;  indicate whether the control word is included in the packet.

 

My question referred just to the 2nd method, while your res= ponse seems to deal with the 1st one.

 

Did I miss something?

 

Regards,

Sasha

 

Office: +972-39266302

Cell:      +972-549266302

Email:   Alexander.Vainshtein@ec= itele.com

 

From: BESS [mailto:bess-bounces@ietf.org] On Behalf Of Wanghaibo (Rainsword)
Sent: Tuesday, October 23, 2018 12:03 PM
To: Alexander Vainshtein <Alexander.Vainshtein@ecitele.com>; draft= -wang-bess-evpn-control-word.authors@ietf.org
Cc: bess@ietf.org
Subject: [bess] = =B4=F0=B8=B4: A question regarding draft-wang-bess-evepn-control-wor= d

 

Hi Alexander,

 

The number of routes= advertised by the Sender router in our solution will not change, but only = carries a next hop capability attribute with control word capability

The Receiver router = determines whether to carry the control word when forwarding packets accord= ing to its own capabilities.

 

The following figure= is an example.:

PE1----------PE2

|-----------PE3

When PE1 advertises = a route, it carries the next hop attribute of the control word capability. = The routes received by PE2 and PE3 are the same.

 

If  PE2 do not = support the control word, it will not carry the control word when forwardin= g packets to PE1.

PE1 cannot find the = control word indication label when parsing the PE2 packet. PE1 will treat t= he packet as normal.

 

If  PE3 support= the control word, it can add a control word when forwarding the packet to = the PE1, and add the control word indication label specified by the PE1.

When the PE1 receive= s the packet and finds the control word indication label in the packet. PE1= will correctly process the control word.

 

Thanks

Haibo

 

=B7=A2=BC=FE=C8=CB= : Alexander Vainshtein [mailto:Alexander.Vainshtein@ecitele.com]
=B7=A2=CB=CD=CA=B1=BC=E4: 2018=C4=EA10=D4=C223=C8=D5 16:46
=CA=D5=BC=FE=C8=CB: draft-wang-bess-evpn-control-word.authors@ietf.org
=B3=AD=CB=CD: bess@ietf.org
=D6=F7=CC=E2: A question regarding draft= -wang-bess-evepn-control-word

 

Dear authors of draft-wang-bess-evpn-control-word,

I have doubts regarding at least one of the approach= es for negotiating the CW usage in the EVPN encapsulation between egress an= d ingress PE that is defined in the draft.

 

In the case when the egress PE can receive EVPN-enca= psulated packets both with and without CW, the draft seems to propose (as o= ne of the possibilities) advertisement of two EVPN routes for each ES or MA= C/IP pair:

-     &= nbsp;    One of these routes would use the CW Capability to = indicate that it refers to the EVPN encapsulation that uses the CW, and wou= ld carry the appropriate label in its NLRI

-     &= nbsp;    The other route would not use the CW Capability to = indicate that it refers to the EVPN encapsulation that does not use the CW,= and carry a different label in its NLRI

 

The ingress PE that accepts these routes would then = use one of them based on its own ability to use the CW (or lack thereof), a= nd use the corresponding label it its EVPN encapsulation, while  the D= P in the egress PW would infer presence or absence of the CW from the received EVPN application label.<= /p>

 

Unfortunately, I do not think that this can work bec= ause, as per RFC 7432, labels in the= labeled NLRI of EVPN routes are not part of the route key for the purpose = of the BGP route key processing, while the label is treated just as the BGP= attribute. This means that, unless some form of BGP multi-path is enabled in the ingress PE (and in all RRs o= n the way between the egress PE and ingress PE) for the L2VPN/EVPN  AF= I/SAFI, only one of these routes will be selected by the BGP selection proc= ess.

 

Did I miss something substantial here?

 

Regards, and lots of thanks in advance,

Sasha

 

Office: +972-39266302

Cell:      +972-5492663= 02

Email:   Alexander.Vainshtein@ecitele.com

 


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