Re: (short version) Re: Last Call: <draft-faltstrom-uri-10.txt> (The Uniform Resource Identifier (URI) DNS Resource Record) to Proposed Standard
Dirk-Willem van Gulik <dirkx@webweaving.org> Mon, 23 February 2015 16:00 UTC
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Subject: Re: (short version) Re: Last Call: <draft-faltstrom-uri-10.txt> (The Uniform Resource Identifier (URI) DNS Resource Record) to Proposed Standard
From: Dirk-Willem van Gulik <dirkx@webweaving.org>
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Date: Mon, 23 Feb 2015 17:00:29 +0100
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Cc: John C Klensin <john-ietf@jck.com>
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John, On 23 Feb 2015, at 16:05, John C Klensin <john-ietf@jck.com> wrote: > experience with confusion about MX and SRV priorities to be > cautious about adding another ranking field, especially one > whose values are interpreted as "largest integer has the highest > preference" while the more traditional priority is interpreted > as "smallest integer is highest preference". Because IANA While the text is clear to ‘me’ - I have to agree I’ve more than once seen this go wrong during initial implementations (all easily fixed by a few emails with the authors though). BUT given that the confusion arises from text[1] which is very similar to the original in SRV rfc2782[2] - and given that we have (and will have) that issue for all use of SRV I am not sure if this should go into this draft. And am wondering why it would not be better to have a separate explanation RFC which deals with this; and the Order/Preference of NAPTR (3). Dw. 1: From version 10 of the draft: 4.2. Priority The priority of the target URI in this RR. Its range is 0-65535. A client MUST attempt to contact the URI with the lowest-numbered priority it can reach; URIs with the same priority SHOULD be tried in the order defined by the weight field. 4.3. Weight A server selection mechanism. The weight field specifies a relative weight for entries with the same priority. Larger weights SHOULD be given a proportionately higher probability of being selected. The range of this number is 0-65535. 2: RFC2782: Priority The priority of this target host. A client MUST attempt to contact the target host with the lowest-numbered priority it can reach; target hosts with the same priority SHOULD be tried in an order defined by the weight field. The range is 0-65535. This is a 16 bit unsigned integer in network byte order. Weight A server selection mechanism. The weight field specifies a relative weight for entries with the same priority. Larger weights SHOULD be given a proportionately higher probability of being selected. The range of this number is 0-65535. This is a 16 bit unsigned integer in network byte order. Domain administrators SHOULD use Weight 0 when there isn't any server selection to do, to make the RR easier to read for humans (less noisy). In the presence of records containing weights greater than 0, records with weight 0 should have a very small chance of being selected. In the absence of a protocol whose specification calls for the use of other weighting information, a client arranges the SRV RRs of the same Priority in the order in which target hosts, specified by the SRV RRs, will be contacted. The following algorithm SHOULD be used to order the SRV RRs of the same priority: To select a target to be contacted next, arrange all SRV RRs (that have not been ordered yet) in any order, except that all those with weight 0 are placed at the beginning of the list. Compute the sum of the weights of those RRs, and with each RR associate the running sum in the selected order. Then choose a uniform random number between 0 and the sum computed (inclusive), and select the RR whose running sum value is the first in the selected order which is greater than or equal to the random number selected. The target host specified in the selected SRV RR is the next one to be contacted by the client. Remove this SRV RR from the set of the unordered SRV RRs and apply the described algorithm to the unordered SRV RRs to select the next target host. Continue the ordering process until there are no unordered SRV RRs. This process is repeated for each Priority. 3: RFC2915 —> rfc3404. Order A 16-bit unsigned integer specifying the order in which the NAPTR records MUST be processed to ensure the correct ordering of rules. Low numbers are processed before high numbers, and once a NAPTR is found whose rule "matches" the target, the client MUST NOT consider any NAPTRs with a higher value for order (except as noted below for the Flags field). Preference A 16-bit unsigned integer that specifies the order in which NAPTR records with equal "order" values SHOULD be processed, low numbers being processed before high numbers. This is similar to the preference field in an MX record, and is used so domain administrators can direct clients towards more capable hosts or lighter weight protocols. A client MAY look at records with higher preference values if it has a good reason to do so such as not understanding the preferred protocol or service. The important difference between Order and Preference is that once a match is found the client MUST NOT consider records with a different Order but they MAY process records with the same Order but different Preferences. I.e., Preference is used to give weight to rules that are considered the same from an authority standpoint but not from a simple load balancing standpoint.
- Re: Last Call: <draft-faltstrom-uri-10.txt> (The … Mark Nottingham
- Re: Last Call: <draft-faltstrom-uri-10.txt> (The … Patrik Fältström
- Re: Last Call: <draft-faltstrom-uri-10.txt> (The … Mark Nottingham
- Re: Last Call: <draft-faltstrom-uri-10.txt> (The … Eliot Lear
- Re: Last Call: <draft-faltstrom-uri-10.txt> (The … Patrik Fältström
- Re: Last Call: <draft-faltstrom-uri-10.txt> (The … Patrik Fältström
- Re: Last Call: <draft-faltstrom-uri-10.txt> (The … Eliot Lear
- (short version) Re: Last Call: <draft-faltstrom-u… John C Klensin
- Re: (short version) Re: Last Call: <draft-faltstr… Viktor Dukhovni
- Re: (short version) Re: Last Call: <draft-faltstr… John C Klensin
- Re: (short version) Re: Last Call: <draft-faltstr… Viktor Dukhovni
- Re: (short version) Re: Last Call: <draft-faltstr… Dirk-Willem van Gulik
- Re: Last Call: <draft-faltstrom-uri-10.txt> (The … Patrik Fältström
- Re: (short version) Re: Last Call: <draft-faltstr… Viktor Dukhovni
- Re: (short version) Re: Last Call: <draft-faltstr… Sam Hartman
- Re: (short version) Re: Last Call: <draft-faltstr… Paul Hoffman
- Re: (short version) Re: Last Call: <draft-faltstr… Viktor Dukhovni
- Re: (short version) Re: Last Call: <draft-faltstr… Viktor Dukhovni
- Re: (short version) Re: Last Call: <draft-faltstr… Mark Andrews
- Re: (short version) Re: Last Call: <draft-faltstr… Patrik Fältström
- Re: (short version) Re: Last Call: <draft-faltstr… Sam Hartman
- Re: (short version) Re: Last Call: <draft-faltstr… Pete Resnick
- Re: (short version) Re: Last Call: <draft-faltstr… Patrik Fältström
- Re: (short version) Re: Last Call: <draft-faltstr… Viktor Dukhovni
- Re: (short version) Re: Last Call: <draft-faltstr… John C Klensin
- Re: (short version) Re: Last Call: <draft-faltstr… John C Klensin
- Re: (short version) Re: Last Call: <draft-faltstr… Sam Hartman
- Re: (short version) Re: Last Call: <draft-faltstr… Sam Hartman
- Re: Last Call: <draft-faltstrom-uri-10.txt> (The … Andrew Newton
- Re: (short version) Re: Last Call: <draft-faltstr… Nico Williams
- Re: (short version) Re: Last Call: <draft-faltstr… Nico Williams
- Re: (short version) Re: Last Call: <draft-faltstr… Patrik Fältström
- Re: (short version) Re: Last Call: <draft-faltstr… Nico Williams
- Re: Last Call: <draft-faltstrom-uri-10.txt> (The … Mark Nottingham
- Re: (short version) Re: Last Call: <draft-faltstr… Patrik Fältström
- Re: (short version) Re: Last Call: <draft-faltstr… Viktor Dukhovni
- Re: (short version) Re: Last Call: <draft-faltstr… Patrik Fältström
- Re: (short version) Re: Last Call: <draft-faltstr… Viktor Dukhovni
- Re: (short version) Re: Last Call: <draft-faltstr… Patrik Fältström
- Re: (short version) Re: Last Call: <draft-faltstr… Eliot Lear
- Re: (short version) Re: Last Call: <draft-faltstr… Patrik Fältström
- Re: (short version) Re: Last Call: <draft-faltstr… Eliot Lear
- Re: Last Call: <draft-faltstrom-uri-10.txt> (The … Andrew Newton
- Re: (short version) Re: Last Call: <draft-faltstr… Phillip Hallam-Baker
- Re: (short version) Re: Last Call: <draft-faltstr… Eliot Lear
- Re: Last Call: <draft-faltstrom-uri-10.txt> (The … Andrew Newton
- Re: (short version) Re: Last Call: <draft-faltstr… Eliot Lear
- Re: (short version) Re: Last Call: <draft-faltstr… Sam Hartman
- Re: (short version) Re: Last Call: <draft-faltstr… Sam Hartman
- Re: (short version) Re: Last Call: <draft-faltstr… Sam Hartman
- Re: Last Call: <draft-faltstrom-uri-10.txt> (The … Patrik Fältström
- Re: (short version) Re: Last Call: <draft-faltstr… Pete Resnick
- Re: (short version) Re: Last Call: <draft-faltstr… Nico Williams
- Re: (short version) Re: Last Call: <draft-faltstr… Viktor Dukhovni
- Re: (short version) Re: Last Call: <draft-faltstr… Nico Williams
- draft-newton-link-rr (was Re: Last Call: <draft-f… Nico Williams
- Re: draft-newton-link-rr (was Re: Last Call: <dra… Nico Williams
- Re: (short version) Re: Last Call: <draft-faltstr… Mark Andrews
- Re: (short version) Re: Last Call: <draft-faltstr… Phillip Hallam-Baker
- Re: (short version) Re: Last Call: <draft-faltstr… Viktor Dukhovni
- Re: (short version) Re: Last Call: <draft-faltstr… Mark Andrews
- Re: (short version) Re: Last Call: <draft-faltstr… Phillip Hallam-Baker
- Re: (short version) Re: Last Call: <draft-faltstr… Sam Hartman
- Re: Last Call: <draft-faltstrom-uri-10.txt> (The … Patrik Fältström
- Re: draft-newton-link-rr (was Re: Last Call: <dra… Patrik Fältström
- Re: (short version) Re: Last Call: <draft-faltstr… Viktor Dukhovni
- Re: draft-newton-link-rr (was Re: Last Call: <dra… Andrew Newton
- Re: (short version) Re: Last Call: <draft-faltstr… John C Klensin
- Re: (short version) Re: Last Call: <draft-faltstr… Viktor Dukhovni
- Re: draft-newton-link-rr (was Re: Last Call: <dra… Patrik Fältström
- Re: Last Call: <draft-faltstrom-uri-10.txt> (The … Mark Andrews
- Re: (short version) Re: Last Call: <draft-faltstr… Mark Nottingham
- Re: (short version) Re: Last Call: <draft-faltstr… Patrik Fältström
- Re: (short version) Re: Last Call: <draft-faltstr… Mark Nottingham
- Re: (short version) Re: Last Call: <draft-faltstr… Pete Resnick
- Re: (short version) Re: Last Call: <draft-faltstr… Pete Resnick
- Re: (short version) Re: Last Call: <draft-faltstr… Viktor Dukhovni
- Re: (short version) Re: Last Call: <draft-faltstr… Patrik Fältström
- Re: (short version) Re: Last Call: <draft-faltstr… Sam Hartman
- Re: (short version) Re: Last Call: <draft-faltstr… Viktor Dukhovni
- Re: (short version) Re: Last Call: <draft-faltstr… Eliot Lear
- Re: (short version) Re: Last Call: <draft-faltstr… Pete Resnick
- Re: (short version) Re: Last Call: <draft-faltstr… Viktor Dukhovni
- Re: (short version) Re: Last Call: <draft-faltstr… Sam Hartman
- Re: (short version) Re: Last Call: <draft-faltstr… Sam Hartman
- Re: (short version) Re: Last Call: <draft-faltstr… John C Klensin
- Re: (short version) Re: Last Call: <draft-faltstr… John C Klensin
- Re: (short version) Re: Last Call: <draft-faltstr… John C Klensin
- Re: (short version) Re: Last Call: <draft-faltstr… John C Klensin
- Re: (short version) Re: Last Call: <draft-faltstr… John C Klensin
- Re: (short version) Re: Last Call: <draft-faltstr… John C Klensin
- Re: (short version) Re: Last Call: <draft-faltstr… Eliot Lear
- Re: (short version) Re: Last Call: <draft-faltstr… Eliot Lear
- Re: (short version) Re: Last Call: <draft-faltstr… Nico Williams
- Re: (short version) Re: Last Call: <draft-faltstr… Patrik Fältström
- Re: (short version) Re: Last Call: <draft-faltstr… Patrik Fältström
- Re: (short version) Re: Last Call: <draft-faltstr… Patrik Fältström
- Re: (short version) Re: Last Call: <draft-faltstr… Pete Resnick
- Re: (short version) Re: Last Call: <draft-faltstr… Pete Resnick
- Where to do the work was Re: (short version) Re: … t.p.
- Re: (short version) Re: Last Call: <draft-faltstr… Patrik Fältström