Re: [Idr] I-DAction:draft-ietf-idr-as4octet-extcomm-generic-subtype-02.txt

"Dhananjaya Rao (dhrao)" <dhrao@cisco.com> Tue, 27 July 2010 20:46 UTC

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Date: Tue, 27 Jul 2010 13:46:05 -0700
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From: "Dhananjaya Rao (dhrao)" <dhrao@cisco.com>
To: "Robert Raszuk (raszuk)" <raszuk@cisco.com>, idr@ietf.org
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Subject: Re: [Idr] I-DAction:draft-ietf-idr-as4octet-extcomm-generic-subtype-02.txt
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Hi Robert,

As has been discussed, this draft simply provides parity for
RFC1997 style communities for 4-byte ASes so that operators
can use it as they have been using regular communities; it doesn't
aim to add any more extensive tools.

However, your specific question does resurrect a basic question I
had about the interpretation of the extended community type. IIRC,
this had come up on the list a year or so back, but didn't result
in much discussion.

How is the non-transitive extended community type supposed to be used ?
Is it strictly applicable only within the AS where it was originated ?

I had interpreted it to be similar to the MED, in that, it could be
originated on an AS boundary and sent to an eBGP peer, which would
honor the extended community (if a matching policy was configured),
but that peer's AS would not propogate the extended community to
other ASes. This, I had thought, would be how a provider AS could use
the non-transitive generic extcomm defined in this draft to strictly
scope communities used with customer ASes.

This could just be a misinterpretation on my part, but I would
be interested in hearing your and others' views on it.

Thanks,
-Dhananjaya

>-----Original Message-----
>From: idr-bounces@ietf.org [mailto:idr-bounces@ietf.org] On 
>Behalf Of Robert Raszuk (raszuk)
>Sent: Tuesday, July 27, 2010 11:51 AM
>To: idr@ietf.org
>Subject: Re: [Idr] 
>I-DAction:draft-ietf-idr-as4octet-extcomm-generic-subtype-02.txt
>
>Hi,
>
>As it has been correctly suggested by Hannes Gredler from Juniper 
>Networks and Steve Padgett from Google it seems that it is very 
>practical to have a way to limit propagation scope of the injected BGP 
>communities even for customer assigned values only to his/her/it's 
>direct provider AS.
>
>In Wide BGP Communities that can *and will be in the next rev* 
>achieved 
>by new explicit action field flag.
>
>I would like to see how this can be achieved in the below 
>extended type 
>of extended communities encoding.
>
>The point to note is that by itself addresses many concerns of wider 
>then customer-provider propagation boundary of any BGP community 
>propagation.
>
>Many thx,
>R.
>
>
>> A New Internet-Draft is available from the on-line 
>Internet-Drafts directories.
>> This draft is a work item of the Inter-Domain Routing 
>Working Group of the IETF.
>>
>>
>> 	Title           : Generic Subtype for BGP Four-octet AS 
>specific extended community
>> 	Author(s)       : D. Rao, et al.
>> 	Filename        : 
>draft-ietf-idr-as4octet-extcomm-generic-subtype-02.txt
>> 	Pages           : 6
>> 	Date            : 2010-07-26
>>
>> Maintaining the current best practices with communities, ISPs and
>> enterprises that are assigned a 4-octet AS number may want the BGP
>> UPDATE messages they receive from their customers or peers to include
>> a 4-octet AS specific extended community.  This document defines a
>> new sub-type within the four-octet AS specific extended community to
>> facilitate this practice.
>>
>> A URL for this Internet-Draft is:
>> 
>http://www.ietf.org/internet-drafts/draft-ietf-idr-as4octet-ext
>comm-generic-subtype-02.txt
>>
>> Internet-Drafts are also available by anonymous FTP at:
>> ftp://ftp.ietf.org/internet-drafts/
>>
>> Below is the data which will enable a MIME compliant mail reader
>> implementation to automatically retrieve the ASCII version of the
>> Internet-Draft.
>>
>>
>>
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