Re: [Idr] https://tools.ietf.org/html/draft-wang-idr-rd-orf-00

Aijun Wang <wangaj3@chinatelecom.cn> Thu, 16 July 2020 08:58 UTC

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From: "Aijun Wang" <wangaj3@chinatelecom.cn>
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Subject: Re: [Idr] https://tools.ietf.org/html/draft-wang-idr-rd-orf-00
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Hi, Robert:

 

When the RD is designed as per VRF per PE, the mechanism of RD based ORF can also apply-------The received router needs only extract and reflect the most influenced RDs back to upstream router(ASBR/RR),  and then to notify the source of these VPN routes to control the prefixes advertisement.

Actually, the above design will make the RD-ORF more accurate than the RT based control.

 

 

Best Regards

 

Aijun Wang

China Telecom

 

 

 

From: robert@raszuk.net [mailto:robert@raszuk.net] 
Sent: Thursday, July 16, 2020 3:06 PM
To: Aijun Wang <wangaijun@tsinghua.org.cn>
Cc: wangw36@chinatelecom.cn; Aijun Wang <wangaj3@chinatelecom.cn>cn>; idr@ietf. org <idr@ietf.org>
Subject: Re: [Idr] https://tools.ietf.org/html/draft-wang-idr-rd-orf-00

 

> It can also be used to identify the VPN customer.  

 

Sorry but no. 

 

Best practice for number of reasons is to make RD unique per VRF and not per VPN. We should not standardize something which is a pretty bad idea to start with. 

 

Kind regards,

Robert

 

 

 

 

 

On Thu, Jul 16, 2020 at 4:40 AM Aijun Wang <wangaijun@tsinghua.org.cn <mailto:wangaijun@tsinghua.org.cn> > wrote:

Hi, Robert:

 

Thanks for your reviews and comments.

As you said, RD is to make the VPN prefix unique within the VPN’s domain. It can also be used to identify the VPN customer.

The usage of RT, just as you said, is to control what routes are distributed where, that is to say, to control the customer’s VPN topology. RT can’t be used to identify one VPN customer.

 

The scenarios/problems described in this draft(https://tools.ietf.org/html/draft-wang-idr-rd-orf-00) are not for the VPN topology control, but for the VPN prefix limit management, which is signed along with the agreement with the VPN customer.

This is the reason that we select the RD-based ORF control mechanism.

 

More detail reply are inline below. Wish to get more your comments/suggestions on them.

 

Thanks in advance.

 

Best Regards

 

Aijun Wang

China Telecom 

 

From: idr-bounces@ietf.org <mailto:idr-bounces@ietf.org>  [mailto:idr-bounces@ietf.org <mailto:idr-bounces@ietf.org> ] On Behalf Of Robert Raszuk
Sent: Thursday, July 16, 2020 2:26 AM
To: wangw36@chinatelecom.cn <mailto:wangw36@chinatelecom.cn> ; Aijun Wang <wangaj3@chinatelecom.cn <mailto:wangaj3@chinatelecom.cn> >
Cc: idr@ietf. org <idr@ietf.org <mailto:idr@ietf.org> >
Subject: [Idr] https://tools.ietf.org/html/draft-wang-idr-rd-orf-00

 

Dear Aijun & Wei,

 

I have read your draft as per subject. 

 

I think there is a serious misunderstanding on what RD's role is in RFC4364. 

 

RDs MUST never be used to signal anything which would in any way influence what routes are distributed where. Their sole role is to make the VPN prefix unique across given VPN's domain. 

【WAJ】RD can be used to identify one VPN customer

 

It is RTs which are used to import routes to VRFs on PEs. What you are trying to do is exactly why we have defined some time back RTC (RFC4684). Applications from section 5.1 and 5.2 can be happily addressed with use of RTC. 

【WAJ】RT is used to control VPN topology, same as the mechanism of RTC(4684). But the application described in section 5.1 and 5.2 of this draft is not for VPN topology control, but for VPN route-limit management, which is based on customer/RD.

 

Informationally let me also point out that RFC7543 has defined extensions to ORF to signal RTs for reducing size VPN RIBs in specific Hub & Spoke topologies. 

【WAJ】RFC7543 is to pull the prefix that cover one specific host address, to get the more optimal route information from the Hub, not the same scenarios as described in the current draft.

 

Last your proposal calls for treating ORF as a transitive message without any loop protection. That is not a good idea. 

【WAJ】ORF messages are exchanged within only the directed BGP sessions. Such Messages will be regenerated when it is needed to send to another BGP peer.  Would you like to describe more for the loop scenarios? 

 

I recommend to protect your PEs from being overwhelmed by VPN routes by prefix limit instead. 

【WAJ】Prefix Limit mechanism can be used for Option –A, but not for Option B/C, as that described in the draft.

 

Kind regards,

R.

 

PS. Did we have any discussion in IDR or BESS on this proposal ?