John: Hi!
I should have pointed to the current version of rfc7810bis [1], which now reads: Available Bandwidth: This field carries the available bandwidth on a link, forwarding adjacency, or bundled link in IEEE floating-point format with units of bytes per second. For a link or forwarding adjacency, available bandwidth is defined to be residual bandwidth (see Section 4.5 <https://tools.ietf.org/html/draft-ietf-lsr-isis-rfc7810bis-02#section-4.5>) minus the measured bandwidth used for the actual forwarding of non-RSVP-TE label switched path packets. For a bundled link, available bandwidth is defined to be the sum of the component link residual bandwidths (see Section 4.5 <https://tools.ietf.org/html/draft-ietf-lsr-isis-rfc7810bis-02#section-4.5>) minus the sum of the measured bandwidth used for the actual forwarding of non-RSVP-TE label switched path packets on all component links. This version gets rid of the duplication and uses “residual”. Because it’s been through WGLC I am assuming it is correct. If not, please let me know *now*, as I am about to start the IETF LC. Thanks! Alvaro. [1] https://tools.ietf.org/html/draft-ietf-lsr-isis-rfc7810bis-02 On November 28, 2018 at 4:33:54 PM, John Scudder ([email protected]) wrote: +lsr to the cc Hi Alvaro, On Nov 28, 2018, at 4:01 PM, Alvaro Retana <[email protected]> wrote: [major] AFAICT, Available Bandwidth is the only definition that is different between rfc7810/draft-ietf-lsr-isis-rfc7810bis and rfc7471. The difference comes from the correction made to address this report [1]. Instead of trying to fix the definition here, I think that a similar report should be filed against rfc7471. Please submit it and I will approve. [1] https://www.rfc-editor.org/errata/eid5486 <https://urldefense.proofpoint.com/v2/url?u=https-3A__www.rfc-2Deditor.org_errata_eid5486&d=DwMFaQ&c=HAkYuh63rsuhr6Scbfh0UjBXeMK-ndb3voDTXcWzoCI&r=hLt5iDJpw7ukqICc0hoT7A&m=pNTkxj6RjNdyIYjBZKCUjdk9QWVKbBBhnnfj9xq2jjU&s=QvXYEMqBgaIkuM7plcuybtDVxI3JTI-4EndPcX0ier8&e=> Maybe I'm missing something but isn't that erratum all wrong? Here is why I think so. I agree that there is a problem with the RFC 7810 paragraph in question: Available Bandwidth: This field carries the available bandwidth on a link, forwarding adjacency, or bundled link in IEEE floating-point format with units of bytes per second. For a link or forwarding adjacency, available bandwidth is defined to be residual bandwidth (see Section 4.5) minus the measured bandwidth used for the actual forwarding of non-RSVP-TE label switched path packets. *For a bundled link, available bandwidth is defined to be the sum of the component link available bandwidths minus the measured bandwidth used for the actual forwarding of non-RSVP-TE label switched path packets. For a bundled link, available bandwidth is defined to be the sum of the component link available bandwidths.* It seems obvious that there was a cut-and-paste problem or similar, since the same sentence is duplicated with minor changes. But the erratum leaves the duplication! The erratum wants it to be: Available Bandwidth: This field carries the available bandwidth on a link, forwarding adjacency, or bundled link in IEEE floating-point format with units of bytes per second. For a link or forwarding adjacency, available bandwidth is defined to be residual bandwidth (see Section 4.5) minus the measured bandwidth used for the actual forwarding of non-RSVP-TE label switched path packets. *For a bundled link, available bandwidth is defined to be the sum of the component link (residual) bandwidths minus the measured bandwidth used for the actual forwarding of non-RSVP-TE label switched path packets.For a bundled link, available bandwidth is defined to be the sum of the component link available bandwidths. * So the proposed "fix" is to leave the sentence duplicated, but change "available" to "(residual)" in the first copy? I don't think that could possibly be right. Just eyeballing it, it seems to me as though the correct fix would be to change the paragraph to be: Available Bandwidth: This field carries the available bandwidth on a link, forwarding adjacency, or bundled link in IEEE floating-point format with units of bytes per second. For a link or forwarding adjacency, available bandwidth is defined to be residual bandwidth (see Section 4.5) minus the measured bandwidth used for the actual forwarding of non-RSVP-TE label switched path packets. For a bundled link, available bandwidth is defined to be the sum of the component link available bandwidths minus the measured bandwidth used for the actual forwarding of non-RSVP-TE label switched path packets. For a bundled link, available bandwidth is defined to be the sum of the component link available bandwidths. in which case it would match RFC 7471. Or possibly: Available Bandwidth: This field carries the available bandwidth on a link, forwarding adjacency, or bundled link in IEEE floating-point format with units of bytes per second. For a link or forwarding adjacency, available bandwidth is defined to be residual bandwidth (see Section 4.5) minus the measured bandwidth used for the actual forwarding of non-RSVP-TE label switched path packets. For a bundled link, available bandwidth is defined to be the sum of the component link available *residual* bandwidths minus the measured bandwidth used for the actual forwarding of non-RSVP-TE label switched path packets. For a bundled link, available bandwidth is defined to be the sum of the component link available bandwidths. I have no idea which of these is right, but the erratum can't be right. Naively, they look algebraically the same, it's just a matter of where in the equation you subtract the measured bandwidth. Maybe they truly are exactly equivalent or maybe there is some subtlety that makes one right and one wrong. If the first option above is right, then RFC 7471 looks to be correct as written. If the first option is wrong, then RFC 7471 would need its own erratum as you suggest, I guess. $0.02, --John P.S.: I see the defect remains in draft-ginsberg-lsr-isis-rfc7810bis-00.
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