Proposals to discover Provisioning
DomainsÉcole polytechniqueVannes56000Francebasile.bruneau@polytechnique.eduCisco11 Rue Camille DesmoulinsIssy-les-Moulineaux92130Franceppfister@cisco.comAppledschinazi@apple.comAppletpauly@apple.comCiscoDe Kleetlaan, 6Diegem1831Belgiumevyncke@cisco.com
Internet
intareaPVDprovisioning domainshost configurationDNSThis document describes one possible way for hosts to retrieve
additional information about their Internet access configuration. The
set of configuration items required to access the Internet is called a
Provisioning Domain (PvD) and is identified by a Fully Qualified Domain
Name.This document separates the way of getting the Provisioning Domain
identifier, the way of getting the Provisioning Domain information and
the potential information contained in the Provisioning Domain.It has become very common in modern networks that hosts have Internet
or more specific access through different networking interfaces,
tunnels, or next-hop routers. The concept of Provisioning Domain (PvD)
was defined in RFC7556 as a set of network
configuration information which can be used by hosts in order to access
the network. In this document, PvDs are associated with a Fully
Qualified Domain Name (called PvD ID) which is used within the host to
identify correlated sets of configuration data and also used to retrieve
additional information about the services that the network provides.Devices connected to the Internet through multiple interfaces would
typically be provisioned with one PvD per interface, but it is worth
noting that multiple PvDs with different PvD IDs could be provisioned on
any host interface, as well as noting that the same PvD ID could be used
on different interfaces in order to inform the host that both PvDs, on
different interfaces, ultimately provide equivalent services.This document proposes multiple methods allowing the host to to
retrieve the PvD ID associated with a set of networking discover the PvD
and retrieve the PvD information. It also explains configuration as well
as the methods and format in order to retrieve some of the parameters
that can describe a PvD.PvDA provisioning domain, usually with a set of provisioning domain
information; for more information, see .The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
RFC 2119.In this document, each provisioning domain is identified by a PvD ID.
The PvD ID is a Fully Qualified Domain Name which belongs to the network
operator to avoid conflicts among network operators. The same PvD ID can
exist in several access networks if the set of configuration information
is identical in all those networks (such as in all home networks of a
residential subscriber). Within a host, the PvD ID SHOULD be associated
to all the configuration information associated to this PvD ID; this
allows for easy update and removal of information while keeping a
consistent state.This section assumes that IPv6 Router Advertisements are used to
discover the PvD ID and explains why this technique was selected.Hosts receive implicit PvDs by the means of Router Advertisements
(RA).A router MAY add a single PvD ID Option in its RAs. The PvD ID
specified in this option is then associated with all the Prefix
Information Options (PIO) included in the RA (albeit it is expected
that only one PIO will be included in the RA). All other information
contained in the RA (notably the RDNSS and Route Information Option)
are to be associated with the PvD ID. The set of information contained
in the RA forms the bootstrap (or hint) PvD. A new RA option will be
required to convey the PvD ID.When a host receives an RA which does not include a PvD ID Option,
the set of information included in the RA (such as Recursive DNS
server, IPv6 prefix) is attached to an implicit PvD identified by the
local interface ID on which the RA is received, and by the link-local
address of the router sending the RA.In the cases where a router should provide multiple independent
PvDs to all hosts, including non-PvD aware hosts, it should send
multiple RAs, as proposed in using
different source link-local addresses (LLA); the datalink layer (MAC)
address could be the same for all the different RA. If the router is
actually a VRRP instance, then the procedure is identical except that
the virtual link-layer address is used as well as virtual link-layer
addresses.Using RA allows for an early discovery of the PvD ID as it is early
in the interface start-up. As RA is usually processed in the kernel,
this requires a host OS upgrade. The RA SHOULD contain other PvD
information as explained in section .There are other techniques to discover the PvD ID that were not
selected by the authors and reviewers, this section explains why. The
design goal was to be as reliable as possible (do not depend on
Internet connectivity) and as fast as possible.For each received RA including a RDNSS option as well as a DNS
search list option, the host MAY retrieve the PvD ID by querying the
configured DNS server for records of type PTR associated with
_pvd.<DNS search name>. If a PvD ID is configured, the DNS
recursive resolver MUST reply with the PvD ID as a PTR record.
NXDOMAIN is returned otherwise.When the RDNSS address is link-local, the host MAY retrieve the
PvD ID before configuring its global scope address(es).Relying on a valid DNS service at the interface bootstrap can
lead into delay to start the interface or starting without enough
information: for example when the RDNSS is a non local address and
there is no Internet connectivity. proposes a solution to
get the name of the PvD using a reverse DNS lookup based on the host
global address(es). It merely relies on prepending a well-known
prefix '_pvd' to the reverse lookup, for example '
_pvd....ip6.arpa.'.However, the PvD information is typically provided by the network
operator, whereas the reverse DNS zone could be delegated from the
operator to the network user, in which case it would not work.It also requires a fully functional global address to retrieve
the information which may be too late for a correct host
configuration. One advantage is that it does not require any change
in the IPv6 protocol and no change in the host kernel or even in the
CPE.TBD: should state that when end-host (IoT) cannot impletement
completely this RFC it MAY select any of the PvD or the router SHOULD
send a single unicast RA (hence a single PvD) in response to the RS or
none if it detects that it cannot offer the right set of network
services.The document describes IPv6-only PvD but there are multiple ways to
link the set of IPv4 configuration information received by
DHCPv4:correlation based on the data-link layer address of the source,
if the IPv6 RA and the DHCPv4 response have the same data-link
layer address, then the information contained in the IPv4 DHCP can
be linked to the IPv6 PvD;correlation based on the interface when there is no data-link
address on the link (such as a 3GPP link), then the information
contained in the IPv4 PDP context can be linked to the IPv6 PvD
(*** TO BE VERIFIED before going -01);correlation based on the DNS search list, if the DNS search
lists are identical between the IPv6 RDNSS and the DHCPV4
response, then the information contained in the IPv4 DHCP response
can be linked to the IPv6 PvD.The correlation could be useful for some PvD information such as
Internet reachability, use of captive portal, display name of the PvD,
...In cases where the IPv4 configuration information could not be
associated with a PvD, hosts MUST consider it as attached to an
independent implicit PvD containing no other information than what is
provided through DHCPv4.Once the PvD ID is known, it MAY be used to retrieve additional
information. PvD Information is modeled as a key-value dictionary which
keys are ASCII strings of arbitrary length, and values are either
strings (encoding can vary), ordered list of values (recursively), or a
dictionary (recursively).The PvD Information may be retrieved from multiple sources (from the
bootstrap PvD contained in the RA to the secondary/extended PvD
described in this section); the PvD ID is then used to correlate the
information from different sources. The way a host should operate when
receiving conflicting information is TBD but it SHOULD at least override
information from less authenticated sources (RA) by more authenticated
sources (via TLS).Routers MAY transmit, in addition to the PvD ID option, a PvD
Bootstrap Information option, containing a first subset of PvD
information. The additional pieces of bootstrap PvD information data
set are transmitted using the short-hand notation proposed in . This requires another RA option.As there is a size limit on the amount of information a single RA
can convey, it is likely that the PvD Bootstrap Information option may
not contain the whole set of PvD Information. The set of PvD
information included in the RA is called PvD Bootstrap
Information.The host SHOULD try to download a JSON formatted file over HTTPS in
order to get more PvD information.The host MUST perform an HTTP query to
https://<PvD-ID>/v1.json. If the HTTP status of the answer is
greater than 400 the host MUST abandon and consider that there is no
additional PvD information. If the HTTP status of the answer is
between 300 and 400 it MUST follow the redirection(s). If the HTTP
status of the answer is between 200 and 300 the host MAY get a file
containing a single JSON object.The host MUST respect the cache information in the HTTP header, if
any, and at expiration of the downloaded object, it must fetch a
fresher version if any.The JSON format allows advanced structures.It can be secured using HTTPS (and DNSSEC).It is easier to update a file on a web server than to edit DNS
records. It can be especially important if we want providers to be
able to often update the remaining phone plan of the user.It is slower than using DNS because HTTPS uses TCP and TLS and
needs more packets to be exchanged to get the file.An additional HTTPS server must be deployed and configured.This approach was not selected during the design team meeting but
has kept here for reference, it will be removed after global consensus
is reached.The host could perform a DNS query for TXT resource records (RR)
for the FQDN used as PvD ID (alternatively for _pvd.<PvD-ID>).
For each retrieved PvD ID, the DNS query MUST be sent to the DNS
server configured from the same router advertisement as the PvD ID.
Syntax of the TXT response is defined in Section
5.It requires a single round-time trip in order to retrieve the PvD
Information.It can be secured using DNSSEC.A TXT record is limited to 65535 characters in theory but large
size of TXT records could require either DNS over TCP (so loosing
the 1-RTT advantage) or fragmented UDP packets (which could be
dropped by a bad choice of security policy). Large TXT records could
also be used to mount an amplification attack.It is expected that the DNS TXT records will be sufficient for
the host to configure itself with basic networking and policy
configuration. Nevertheless, if further information is required, or
when a different security model shall be used to access the PvD
Information, a SRV Resource Record including a full URL MAY be
included as a response, expecting the host to query this URL in
order to retrieve additional PvD information.PvD information is a set of key-value pairs. Keys are ASCII character
strings. Values are either a character string, an ordered list of
values, or an embedded dictionary. Value types and default behavior with
respect to some specific keys MAY be further specified (recursively).
Some keys have a default value as described in the following sections.
When there is an expiration time in a PvD, then the information MUST be
refreshed before the expiration time. The behavior of a host when the
refresh operation is not successful is TBD.Nodes using the PvD MUST support the two encodings:JSON syntax for the complete set of PvD information;short-hand notation for the bootstrap PvD.When the PvD information is transferred as a JSON file, then the key
used is the second column of the following table. The syntax of the JSON
file is obvioulsy JSON and is richer than the short-hand notation
specified in the next paragraph.When transmitting more information than the PvD ID in the RA (or when
DNS TXT resource records are used), the shorthand notataion for PvD
information is used and consists of a string containing several
"key=value;" substrings. The "key" is the first column of the following
tables, the value is encoded as:Shorthand notation for values:integer: expressed in decimal format with a '.' (dot) used for
decimals;string: expressed as UTF-8 encoded string, delimited by single
quote character, the single quote character can be expressed by two
consecutive single quote character;boolean: expressed as '0' for false and '1' for true;IPv6 address: printed as RFC5952.PvD SHOULD have a human readable name in order to be presented on a
GUI. The name can also be localized.DNS TXT key/Bootstrap PvD keyJSON keyDescriptionTypeJSON ExamplennameUser-visible service name, SHOULD be part of the bootstrap
PvDhuman-readable UTF-8 string"Foobar Service"nl10nlocalizedNameLocalized user-visible service name, language can be selected
based on the HTTP Accept-Language header in the request.human-readable UTF-8 string"Service Blabla"The content of the bootstrap PvD (from the original RA) cannot be
trusted as it is not authenticated. But, the extended PvD can be
associated with the PvD ID (as the PvD ID is used to construct the
extended PvD URL) and trusted by the used of TLS. The extended PvD
SHOULD therefore include the following information elements and, if
they are present, the host MUST verify that the all PIO of the RA fits
into the master prefix list. If any PIO prefix from the bootstrap PvD
does not fit in the master prefix array, then all information received
by the bootstrap PvD must be invalidated. In short, the
masterIPv6Prefix received over TLS is used to authenticate the
bootstrap PvD.The values of the bootstrap PvD (RDNSS, ...) are overwritten by the
values contained in the trusted extended PvD if they are present.DNS TXT keyJSON keyDescriptionTypeJSON Examplemp6masterIpv6PrefixAll the IPv6 prefixes linked to this PvD (such as a /29 for the
ISP).Array of IPv6 prefixes["2001:db8::/32"]The following set of keys can be used to specify the set of
services for which the respective PvD should be used. If present they
MUST be honored by the client, i.e., if the PvD is marked as not
usable for Internet access (walled garden), then it MUST NOT be used
for Internet access. If the usability is limited to a certain set of
domain or address prefixes (typical VPN access), then a different PvD
MUST be used for other destinations.DNS TXT keyJSON keyDescriptionTypeJSON ExamplesnoInternetInternet inaccessiblebooleantruecpcaptivePortalPresence of a captive portalbooleanfalsezdnsZonesDNS zones accessible and searchablearray of DNS zone["foo.com","sub.bar.com"]6prefixes6IPv6-prefixes accessible via this PvDarray of IPv6 prefixes["2001:db8:a::/48","2001:db8:b:c::/64"]4prefixes4IPv4-prefixes accessiblearray of IPv4 prefixes in CIDR reachable via this PvD["192.0.2.0/24","2.3.0.0/16"]The following set of keys can be used to specify the DNS
configuration for the respective PvD. If present, they MUST be honored
and used by the client whenever it wishes to access a resource
described by the PvD.DNS TXT keyJSON keyDescriptionValueJSON ExamplerdnsServersRecursive DNS serverarray of IPv6 and IPv4 addresses["2001:db8::1","192.0.2.2"]ddnsSearchDNS search domainsarray of search domains["foo.com","sub.bar.com"]NOTE: open question to the authors/reviewers: should this document
include this section or is it useless?The following set of keys can be used to signal certain
characteristics of the connection towards the PvD.They should reflect characteristics of the overall access
technology which is not limited to the link the host is connected to,
but rather a combination of the link technology, CPE upstream
connectivity, and further quality of service considerations.DNS TXT keyJSON keyDescriptionTypeJSON ExampletpthroughputMaxMaximum achievable throughput (e.g. CPE downlink/uplink)object({down(int), up(int)}) in kb/s{"down": 10000, "up": 5000}ltlatencyMinMinimum achievable latencyobject({down(int), up(int)}) in ms{"down": 10, "up": 20}rlreliabilityMaxMaximum achievable reliabilityobject({down(int), up(int)}) in 1/1000{"down": 1000, "up": 800}cpcaptivePortalCaptive portalURL of the portal"https://example.com"natNATIPv4 NAT in placebooleantruenattoNAT Time-outThe value in seconds of the NAT time-outInteger30srhsegmentRoutingHeaderThe IPv6 Segment Routing Header to be used between the IPv6
header and any other headers when using this PvDBinary string...srhDNSsegmentRoutingHeaderDnsFQDNThe DNS FQDN which is used to retrieved the actual IPv6 Segment
Routing Header to be used between the IPv6 header and any other
headers when using this PvDAscii stringsrh.pvd-foo.example.orgcostcostCost of using the connectionobjectSee NOTE: This section is included as a request for comment on the
potential use and syntax.The billing of a connection can be done in a lot of different ways.
The user can have a global traffic threshold per month, after which
his throughput is limited, or after which he/she pays each megabyte.
He/she can also have an unlimited access to some websites, or an
unlimited access during the weekends.We propose to split the final billing in elementary billings, which
have conditions (a start date, an end date, a destination IP
address...). The global billing is an ordered list of elementary
billings. To know the cost of a transmission, the host goes through
the list, and the first elementary billing whose the conditions are
fulfilled gives the cost. If no elementary billing conditions match
the request, the host MUST make no assumption about the cost.Here are the potential conditions for an elementary billing. All
conditions MUST be fulfill.Note: the final version should use short-hand key names.KeyDescriptionTypeJSON ExamplebeginDateDate before which the billing is not validISO 8601"1977-04-22T06:00:00Z"endDateDate after which the billing is not validISO 8601"1977-04-22T06:00:00Z"domainsFQDNs whose the billing is limitedarray(string)["deezer.com","spotify.com"]prefixes4IPv4 prefixes whose the billing is limitedarray(string)["78.40.123.182/32","78.40.123.183/32"]prefixes6IPv6 prefixes whose the billing is limitedarray(string)["2a00:1450:4007:80e::200e/64"]Here are the different possibilities for the cost of an
elementary billing. A missing key means
"all/unlimited/unrestricted". If the elementary billing selected has
a trafficRemaining of 0 kb, then it means that the user has no
access to the network. Actually, if the last elementary billing has
a trafficRemaining parameter, it means that when the user will reach
the threshold, he/she will not have access to the network
anymore.KeyDescriptionTypeJSON ExamplepricePerGbThe price per Gigabitfloat (currency per Gb)2currencyThe currency usedISO 4217"EUR"throughputMaxThe maximum achievable throughputfloat (kb/s)1000trafficRemainingThe traffic remainingfloat (kb)96000000Example for a user with 20 GB per month for 40 EUR, then reach a
threshold, and with unlimited data during weekends and to
deezer:If the host tries to download data from deezer.com, the
conditions of the first elementary billing are fulfilled, so the
host takes this elementary billing, finds no cost indication in it
and so deduces that it is totally free. If the host tries to
exchange data with youtube.com and the date is 2016-07-14T19:00:00Z,
the conditions of the first, second and third elementary billing are
not fulfilled. But the conditions of the fourth are. So the host
takes this elementary billing and sees that there is a threshold, 12
GB are remaining.Another example for a user abroad, who has 3 GB per year abroad,
and then pay each MB:keys starting with "x-" are reserved for private use and can be
utilized to provide vendor-, user- or enterprise-specific information.
It is RECOMMENDED to use one of the patterns "x-FQDN-KEY" or
"x-PEN-KEY" where FQDN is a fully qualified domain name or PEN is a
private enterprise number under control of
the author of the extension to avoid collisions.TBD: 1 or 2 examples when PvD are criticalFirst example could be multihoming (very much in-line with
bowbakova draft).using PvD to reach a specific destination (such as VPN or
extranet).While the PvD ID can be forged easily, if the host retrieve the
extended PvD via TLS, then the host can trust the content of the
extended PvD and verifies that the RA prefix(es) are indeed included in
the master prefixed of the extended PvD.Many thanks to M. Stenberg and S. Barth: , and are from their document .Thanks also to Ray Bellis, Lorenzo Colitti, Marcus Keane, Erik Kline,
Jen Lenkova, Mark Townsley and James Woodyatt for useful and interesting
brainstorming sessions.Private Enterprise NumbersIANA