Subject: [sidr] RFC5291 - Outbound Route Filter Capability

From: Stewart Bryant <[email-masked]>
Date: Wed, 06 Feb 2013 18:47:10 +0000

The following errata was filed, but this is beyond the scope
of an errata system to address.

I think that the right process is for the WG to decide the answer
and if necessary for someone to write up a short update to
RFC5291

I will close the errata with a pointer to this thread in the
SIDR archive.

Stewart

Errata ID: 3468

*Status: Reported
Type: Technical
*
Reported By: David Lamparter
Date Reported: 2013-01-22

Section 5 says:

5. Outbound Route Filtering Capability

    A BGP speaker that is willing to receive ORF entries from its peer,
    or a BGP speaker that would like to send ORF entries to its peer,
    advertises this to the peer by using the Outbound Route Filtering
    Capability, as described below.

    The Outbound Route Filtering Capability is a new BGP Capability
    [BGP-CAP] defined as follows:

       Capability code: 3

       Capability length: variable

       Capability value: one or more of the entries as shown in Figure 3.

          +--------------------------------------------------+
          | Address Family Identifier (2 octets)             |
          +--------------------------------------------------+
          | Reserved (1 octet)                               |
          +--------------------------------------------------+
          | Subsequent Address Family Identifier (1 octet)   |
          +--------------------------------------------------+
          | Number of ORFs (1 octet)                         |
          +--------------------------------------------------+
          | ORF Type (1 octet)                               |
          +--------------------------------------------------+
          | Send/Receive (1 octet)                           |
          +--------------------------------------------------+
          | ...                                              |
          +--------------------------------------------------+
          | ORF Type (1 octet)                               |
          +--------------------------------------------------+
          | Send/Receive (1 octet)                           |
          +--------------------------------------------------+

          Figure 3: Outbound Route Filtering Capability Encoding

Notes:

RFC5291 does not specify how the ORF capability is supposed to be used
in conjunction with multiple enabled AFI/SAFI combinations. The text
can be interpreted as either "one capability instance will be sent,
carrying multiple blocks as described in Figure 3" or as "the
capability will be supplied in more than instance".

Note also that RFC3392 [BGP-CAP] Section 4 reads:

BGP speakers MAY include more than one instance of a capability (as
identified by the Capability Code) with non-zero Capability Length
field, but with different Capability Value, and either the same or
different Capability Length. Processing of these capability
instances is specific to the Capability Code and MUST be described in
the document introducing the new capability.

Latter description of how multiple instances of the capability are to be
processed - albeit relatively obvious - is nowhere to be found in RFC5291.

Respectfully requesting a clarification,

David Lamparter

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From: Chris Morrow <[email-masked]>
Date: Wed, 06 Feb 2013 13:50:39 -0500

IDR not S-IDR ? (or I missed the tie-in to S-IDR...)

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From: Stewart Bryant <[email-masked]>
Date: Wed, 06 Feb 2013 18:52:53 +0000

I beg your pardon - I missed the "S" in the WG column.

Moving it over there

Stewart

On 06/02/2013 18:50, Chris Morrow wrote:
> .

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From: Chris Morrow <[email-masked]>
Date: Wed, 06 Feb 2013 13:54:21 -0500

> I beg your pardon - I missed the "S" in the WG column.

awesome, thanks! :) it does look like something IDR should poke at though.