[trill] 答复: Re: Comments on draft-dunbar-trill-directory-assisted-encap

Hi, Donald

Please see my comments inline with [hfw]

(1) The remote egress RBridge could not learn the {nickname, MAC} pair by 
the data frame.
[Linda] The “nickname” is Ingress’ nickname, the MAC-SA is ingress’ 
too. So the egress RBridge should be able to learn the mapping between the 
Ingress’ nickname and its MAC. Why do you say “could not”?
(dee3) Right, its asymmetric. So the end station does the ingress but the 
egress RBridge does the usual egress process, learning the remote MAC 
address as attached to the ingress nickname in the TRILL Data frame -- but 
it does not matter that much if the egress RBridge learns anything if you 
do ingress for traffic going the other way at the end station also.
[hfw] This is one of the scenarios : local end station can do TRILL 
encapsulation, while the remote endstation only process the native frame.

(2) The transit RBridges could not pass the RPF check for 
multi-destination forwarding. 
[Linda] Why? The data frame is same as if the frame is encapsulated by the 
Ingress RBridge. 
 (dee3) The only place where there might be an RPF check problem is on 
receipt at the first edge RBridge so some care may be needed there. 
Alternatively, you could just not do the ingress at the end station for 
multi-destination frames but have them ingressed by the edge RBridge.
[hfw] Is phantom nickname golabl unique or RB unique? For global unique, 
all the edge RBridges have the same value. In this situation, the RPF does 
not pass for multi-destination.
     For RB unique, different edge RBridges have different phantom 
nicknames. In this situation, it wastes many nicknames. We can assign the 
RB1's nickname (N1, not phantom nickname) to the non-RBridge nodes.
Thanks!
Fangwei

Donald Eastlake <d3e3e3@gmail.com> 
发件人:  trill-bounces@ietf.org
2013-08-21 08:46

收件人
Linda Dunbar <linda.dunbar@huawei.com>
抄送
"trill-bounces@ietf.org" <trill-bounces@ietf.org>, "hu.fangwei@zte.com.cn" 
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主题
Re: [trill] Comments on draft-dunbar-trill-directory-assisted-encap

Hi,

See at (dee3).

On Tue, Aug 20, 2013 at 5:31 PM, Linda Dunbar <linda.dunbar@huawei.com> 
wrote:
Fang Wei, 

Answers to your comments are inserted below:

From: hu.fangwei@zte.com.cn [mailto:hu.fangwei@zte.com.cn] 
Sent: Monday, August 19, 2013 9:57 PM

To: Linda Dunbar
Cc: trill@ietf.org; trill-bounces@ietf.org
Subject: RE: [trill] Comments on 
draft-dunbar-trill-directory-assisted-encap

Hi,Linda 

I understand that R1 would keep the encapsulation frame from E1. There 
would bring two issues: 

(1) The remote egress RBridge could not learn the {nickname, MAC} pair by 
the data frame.
[Linda] The “nickname” is Ingress’ nickname, the MAC-SA is ingress’ 
too. So the egress RBridge should be able to learn the mapping between the 
Ingress’ nickname and its MAC. Why do you say “could not”?
(dee3) Right, its asymmetric. So the end station does the ingress but the 
egress RBridge does the usual egress process, learning the remote MAC 
address as attached to the ingress nickname in the TRILL Data frame -- but 
it does not matter that much if the egress RBridge learns anything if you 
do ingress for traffic going the other way at the end station also.
(2) The transit RBridges could not pass the RPF check for 
multi-destination forwarding. 
[Linda] Why? The data frame is same as if the frame is encapsulated by the 
Ingress RBridge. 
 (dee3) The only place where there might be an RPF check problem is on 
receipt at the first edge RBridge so some care may be needed there. 
Alternatively, you could just not do the ingress at the end station for 
multi-destination frames but have them ingressed by the edge RBridge.
Thanks,
Donald
=============================
 Donald E. Eastlake 3rd   +1-508-333-2270 (cell)
 155 Beaver Street, Milford, MA 01757 USA
 d3e3e3@gmail.com
Linda

Linda Dunbar <linda.dunbar@huawei.com> 
2013-08-20 10:41 

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"hu.fangwei@zte.com.cn" <hu.fangwei@zte.com.cn> 
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trill-bounces@ietf.org> 
主题
RE: [trill] Comments on draft-dunbar-trill-directory-assisted-encap

Fang Wei, 

Sorry for the late response due to lack of internet access during my 
vacation last two weeks. Answers to your questions are inserted below: 

From: hu.fangwei@zte.com.cn [mailto:hu.fangwei@zte.com.cn] 
Sent: Friday, August 09, 2013 2:59 AM
To: Linda Dunbar
Cc: trill@ietf.org; trill-bounces@ietf.org
Subject: Re: [trill] Comments on 
draft-dunbar-trill-directory-assisted-encap 

Hi,Linda 

When R1 receives a frame, it will check the MAC-SA, and find that it is 
from E1.  Will R1 re-encapsulate the ingress nickname from "phantom 
nickname" to N1(R1's nickname)? 
[Linda] R1 will not re-encapsulate the frame because the MAC-DA of the 
frame is R1.  R1 will terminate the MAC header and look into  the payload, 
which is a TRILL frame. R1 will put another MAC header with MAC-DA being 
the egress RBridge’s MAC and MAC-SA being its own MAC. 

In addition, how about the multi-destination forwarding , does the 
multi-destination forwarding support in this document? 

[Linda] For multi destination frames, the destination Nickname should be a 
root of multicast tree. 

Linda 

Best Regards. 

Linda Dunbar <linda.dunbar@huawei.com> 
发件人:  trill-bounces@ietf.org 
2013-08-03 14:39 

收件人
"hu.fangwei@zte.com.cn" <hu.fangwei@zte.com.cn>, "trill@ietf.org" <
trill@ietf.org> 
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主题
Re: [trill] Comments on draft-dunbar-trill-directory-assisted-encap

Fang Wei, 

Sorry for the delayed response. Answers to your comments are inserted 
below: 

From: trill-bounces@ietf.org [mailto:trill-bounces@ietf.org] On Behalf Of 
hu.fangwei@zte.com.cn
Sent: Wednesday, July 31, 2013 10:49 AM
To: trill@ietf.org
Subject: [trill] Comments on draft-dunbar-trill-directory-assisted-encap 

Hi, Linda 

I have several comments: 

(1) We say that E1 is the "Non-RBridge Nodes", R1 is the local edge 
RBridge. E1 will encapsulate the TRILL encapsuation with the ingress 
nickname as "Phantom nickname", and  egress nickname as the nickname of 
R1(we say it N1). The encapuslation frame will be forwarded to R1. My 
question is that, how R1 know that the trill encapuslation frame is sent 
by E1(Non-RBridge node)?   

[Linda] There is an Ethernet header in front of the RBridge header. R1 
knows that the frame from is from E1 from the MAC-SA. 

(2) The concept of  'TRILL   Encapsulating node'' or ''Simplified RBridge' 
is defined in section 3. But it never used in the document. Is it the same 
meaning with non-RBridge nodes? 

[Linda] We call a non-RBridge nodes that can encapsulate TRILL header as 
“TRILL Encapsulating node”, or “Directory reliant smart end node”. We 
can finalize the term when going through the WG adoption. 

Linda 

Fangwei 

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