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Eric Newberry, 06/10/2018 03:25 PM
Face Management¶
- Table of contents
- Face Management
Face Management is a module of NFD Management protocol.
It provides:
- commands to create and destroy faces
- commands to enable and disable LocalControlHeader features on a face
- a dataset of description of all active faces and their counters
- a dataset of description of all active channels
- a notification stream for face creating and destroying events
Face Management commands, datasets, and notifications are available under namespace ndn:/localhost/nfd/faces
.
FaceUri¶
A FaceUri represents the underlying protocol and address used by a Face.
Every Face has two FaceUris: one for local endpoint, and the other for remote endpoint.
UDP¶
udp[4|6]://<IP-or-host>[:<port>]
Examples:
udp4://192.0.2.1:6363
(canonical form)udp6://[2001:db8::1]:6363
(canonical form)udp6://[fe80::1068:dddb:fe26:fe3f%en0]:6363
(canonical form for link-local IPv6 addresses)udp6://[fe80::1068:dddb:fe26:fe3f%25en0]:6363
(equivalent, but not canonical, version of the above FaceUri)udp://192.0.2.1
(remote-port defaults to 6363)udp://example.net:6363
udp4://example.net:6363
(resolve hostname to IPv4 address only)udp6://example.net:6363
(resolve hostname to IPv6 address only)udp4://224.0.23.170:56363
(multicast, canonical form)
LocalUri of a NIC-associated UDP face has the form:
udp[4|6]+dev://<NIC>:<port>
This is only used in face dataset.
Examples:
udp4+dev://eth1:6363
udp6+dev://en0:6363
TCP¶
tcp[4|6]://<IP-or-host>[:<port>]
Examples:
tcp4://192.0.2.1:6363
(canonical form)tcp6://[2001:db8::1]:6363
(canonical form)tcp6://[fe80::1068:dddb:fe26:fe3f%en0]:6363
(canonical form for link-local IPv6 addresses)tcp6://[fe80::1068:dddb:fe26:fe3f%25en0]:6363
(equivalent, but not canonical, version of the above FaceUri)tcp://192.0.2.1
(remote-port defaults to 6363)tcp://example.net:6363
tcp4://example.net:6363
(resolve hostname to IPv4 address only)tcp6://example.net:6363
(resolve hostname to IPv6 address only)
UNIX stream¶
unix://<path>
Examples:
unix:///var/run/nfd.sock
(note that there are three forward-slashes after 'unix:')
File descriptor¶
fd://<file-descriptor>
Examples:
fd://6
Ethernet¶
ether://[<MAC>]
Examples:
ether://[08:00:27:01:01:01]
ether://[33:33:01:01:01:01]
(multicast)
Network device¶
dev://<interface-name>
Examples:
dev://eth0
Underlying protocol and FaceUri scheme¶
Underlying protocol | Remote FaceUri scheme | Local FaceUri scheme |
---|---|---|
IPv4 UDP unicast | udp4 | udp4 |
IPv6 UDP unicast | udp6 | udp6 |
IPv4 UDP multicast | udp4 (multicast IP) | udp4 (local IP, same port) |
IPv4 UDP NIC-associated | udp4 | udp4+dev |
IPv6 UDP NIC-associated | udp6 | udp6+dev |
IPv4 TCP | tcp4 | tcp4 |
IPv6 TCP | tcp6 | tcp6 |
UNIX stream | fd (file descriptor on NFD side) | unix (socket path) |
Ethernet unicast | ether | dev |
Ethernet multicast | ether | dev |
WebSocket | wsclient | ws |
Static Face Attributes¶
FaceScope indicates whether the face is local for scope control purposes.
- non-local(=0)
- local(=1)
FacePersistency indicates whether the face is persistent.
- on-demand(=1), face closes if it remains idle for some time
- persistent(=0), face remains open until it's explicitly destroyed or there's a transport failure
- permanent(=2), face remains open until it's explicitly destroyed; transport failures will be recovered internally
LinkType indicates the type of communication link.
- point-to-point(=0), communication with one peer
- multi-access(=1), communication with a multicast group
- ad-hoc(=2), communication over a wireless ad hoc network
LocalFieldsEnabled indicates whether the face allows NDNLPv2 NextHopFaceId, CachePolicy, IncomingFaceId fields.
- yes(=1), allows these fields; this is valid only if FaceScope=local
- no(=0), disallows these fields
LpReliabilityEnabled indicates whether the face has the NDNLPv2 reliability feature enabled.
- yes(=1), enables this feature
- no(=0), disables this feature
CongestionMarkingEnabled indicates whether the face has congestion marking based upon send queue length enabled.
- yes(=1), enables this feature
- no(=0), disables this feature
BaseCongestionMarkingInterval indicates the base marking interval for congestion marking.
The value of this attribute is the base marking interval in nanoseconds, which is used to compute the interval at which congested packets will be marked.
DefaultCongestionThreshold indicates the default congestion threshold if the face does not support retrieving the send queue capacity.
The value of this attribute is the default congestion threshold in bytes.
Mtu contains a user-specified MTU to override the automatic MTU of the transport.
The value of this attribute is the MTU of the transport in bytes. A transport type may limit the acceptable range of this value or even ignore it altogether.
Flags and Mask¶
Some attributes are collected as inclusive OR into a Flags field in commands and datasets.
These attributes are: (bit 0 is the least significant bit)
- bit 0: LocalFieldsEnabled
- bit 1: LpReliabilityEnabled
- bit 2: CongestionMarkingEnabled
Control Commands¶
ControlCommand management-module: faces
Create a face¶
command-verb: create
ControlParameters fields:
- Uri (required): canonical remote FaceUri of the face to create.
- LocalUri (optional): canonical local FaceUri of the face to create; e.g., FaceUri of the local interface for an Ethernet unicast face.
- FacePersistency (optional): either persistent or permanent; creating on-demand faces is not permitted. The default is persistent. See "static face attributes" for more information.
- BaseCongestionMarkingInterval (optional): see "static face attributes".
- DefaultCongestionThreshold (optional): see "static face attributes".
- Mtu (optional): see "static face attributes".
- Flags (optional): see "static face attributes".
- Mask (optional): MUST be specified if Flags is present, and omitted if Flags is omitted.
This command allows the creation of UDP unicast, Ethernet unicast, and TCP faces only.
If the command succeeds, the <body> of the ControlResponse block contains the ControlParameters describing the current properties of the created face:
- FaceId
- Uri
- LocalUri
- FacePersistency
- BaseCongestionMarkingInterval (optional)
- DefaultCongestionThreshold (optional)
- Mtu (optional)
- Flags: contains effective values for the LocalFieldsEnabled, LpReliabilityEnabled, and CongestionMarkingEnabled bits.
If this creation would conflict with an existing face (e.g., same underlying protocol and remote endpoint, or a NIC-associated permanent face), the command fails with StatusCode 409, and the <body> of the ControlResponse block contains the ControlParameters describing the existing face, with the same fields as above.
If the request attempts to create a face other than UDP unicast, Ethernet unicast, or TCP, or if a static property specified in the request is not acceptable, the command fails with StatusCode 406.
If face creation fails due to a socket error (e.g. TCP connection timeout), the command fails with StatusCode 504.
If BaseCongestionMarkingInterval or DefaultCongestionThreshold are omitted from the ControlParameters sent with the creation command, the omitted static properties are left at their implementation-defined default values.
If Mtu is omitted from the ControlParameters sent with the creation command, the automatic MTU of the transport is used as the MTU of the face. In the response, the Mtu field in ControlParameters contains the effective MTU of the face (in bytes). If the MTU of the effective face is infinite, then this field is set to 0. If Mtu is omitted from the response, the face and/or forwarder does not support MTU reporting.
Update the static properties of a face¶
command-verb: update
ControlParameters fields:
- FaceId (optional)
- FacePersistency (optional): one of on-demand, persistent, or permanent. See "static face attributes" for more information.
- BaseCongestionMarkingInterval (optional): see "static face attributes".
- DefaultCongestionThreshold (optional): see "static face attributes".
- Flags (optional): allows LocalFieldsEnabled, LpReliabilityEnabled, and CongestionMarkingEnabled only. See "static face attributes" for more information.
- Mask (optional): MUST be specified if Flags is present, and omitted if Flags is omitted.
FaceId is the FaceId returned in Face Management.
If FaceId is omitted or is set to zero, it is implied to be that of the requesting face (self updating).
If the face does not exist, this command fails with StatusCode 404.
Static properties of the face are updated.
If an optional property field is omitted or a bitfield is zero in Mask, that static property remains unchanged.
If no static properties are changed, this command does nothing, but is still considered successful.
If the command succeeds, <body> in ControlResponse block contains ControlParameters describing the current properties of the face:
- FaceId
- FacePersistency
- BaseCongestionMarkingInterval (optional)
- DefaultCongestionThreshold (optional)
- Flags: contains effective values for LocalFieldsEnabled, LpReliabilityEnabled, and CongestionMarkingEnabled bits.
If any of the requested changes is invalid, none of the changes should be performed, and this command fails with StatusCode 409.
The <body> in ControlResponse block contains ControlParameters that includes only invalid fields; if some of the bit fields chosen in Flags+Mask is invalid, the <body> block should also contain a Mask field indicating which bits are invalid, and echo back the original Flags field.
If the request had been sent without those fields (or bitfields in Mask), it would have been successful.
Destroy a face¶
command-verb: destroy
ControlParameters fields:
- FaceId (required)
If the specified face does not exist, this command does nothing, but is still considered successful.
Face Dataset¶
Description and counters of all active faces are published as a Status Dataset at ndn:/localhost/nfd/faces/list
.
Each face is represented by a FaceStatus block:
FaceStatus ::= FACE-STATUS-TYPE TLV-LENGTH
FaceId
Uri (remote FaceUri)
LocalUri
ExpirationPeriod?
FaceScope
FacePersistency
LinkType
BaseCongestionMarkingInterval?
DefaultCongestionThreshold?
Mtu?
Flags
NInInterests
NInData
NInNacks
NOutInterests
NOutData
NOutNacks
NInBytes
NOutBytes
Uri ::= URI-TYPE TLV-LENGTH
FaceUri in UTF-8 encoding
LocalUri ::= LOCAL-URI-TYPE TLV-LENGTH
FaceUri in UTF-8 encoding
; other TLVs have nonNegativeInteger as value
- Uri is a FaceUri representing remote endpoint.
- LocalUri is a FaceUri representing local endpoint.
- ExpirationPeriod is the remaining lifetime of this face. If this field is omitted, the face has infinite lifetime. Currently, this is applicable to on-demand datagram faces only.
- FaceScope indicates whether the face is local for scope control purposes. See "static face attributes" for more information.
- FacePersistency indicates whether the face is persistent. See "static face attributes" for more information.
- LinkType indicates the type of communication link See "static face attributes" for more information.
- BaseCongestionMarkingInterval indicates the base interval used to compute the interval at which congested packets will be marked (in nanoseconds). See "static face attributes" for more information.
- DefaultCongestionThreshold indicates the default threshold for congestion if the face does not support retrieving the send queue capacity (in bytes). See "static face attributes" for more information.
- Mtu contains the effective MTU of the face (in bytes). If the MTU of the face is infinite, Mtu is set to 0. If this field is omitted, the forwarder and/or face does not support MTU reporting. See "static face attributes" for more information.
- Flags contains these bitfields: LocalFieldsEnabled, LpReliabilityEnabled, CongestionMarkingEnabled. See "static face attributes" for more information.
- NInInterests: number of incoming Interest packets since the face is established.
- NInData counts the number of incoming Data packets since the face is established.
- NInNacks counts the number of incoming Nack packets since the face is established.
- NOutInterests counts the number of outgoing Interest packets since the face is established.
- NOutData counts the number of outgoing Data packets since the face is established.
- NOutNacks counts the number of outgoing Nack packets since the face is established.
- NInBytes counts the number of bytes of link layer packets received via this face. This counter is initialized to zero when the face is established, and can wrap around after overflowing unsigned 64-bit integer range.
- NOutBytes counts the number of bytes of link layer packets sent via this face. This counter is initialized to zero when the face is established, and can wrap around after overflowing unsigned 64-bit integer range.
Query operation¶
The query operation allows one to retrieve a subset of face dataset that contains faces satisfying a filter.
To run a query, the consumer should express an Interest with Name: ndn:/localhost/nfd/faces/query/<filter>
, where <filter>
is a FaceQueryFilter block that specifies zero or more conditions.
FaceQueryFilter ::= FACE-QUERY-FILTER-TYPE TLV-LENGTH
FaceId?
UriScheme?
Uri?
LocalUri?
FaceScope?
FacePersistency?
LinkType?
UriScheme ::= URI-SCHEME-TYPE TLV-LENGTH
string in UTF-8
- FaceId permits a face if its FaceId equals the value
- UriScheme permits a face if the scheme part of its local FaceUri or remote FaceUri equals the value
- Uri permits a face if its remote FaceUri equals the value
- LocalUri permits a face if its local FaceUri equals the value
- FaceScope permits a face if its FaceScope attribute equals the value
- FacePersistency permits a face if its FacePersistency attribute equals the value
- LinkType permits a face if its LinkType attribute equals the value
A face must satisfy ALL conditions to satisfy the filter.
Faces that satisfy the filter are represented by FaceStatus blocks, and published as a StatusDataset under the Interest Name (a Data packet's Name would be ndn:/localhost/nfd/faces/query/<filter>/<version>/<segment>
).
Examples of filters:
- a specific face:
FaceId=260
- a specific TCP tunnel:
Uri=tcp4://192.0.2.1:6363
(note: FaceUri must precisely match the canonical form: use either "tcp4" or "tcp6" instead of "tcp", use IP address instead of domain name, include port number) - all TCP tunnels:
UriScheme=tcp
(note: "tcp" permits both "tcp4" and "tcp6", "udp" permits both "udp4" and "udp6") - all UDP multi-access faces:
UriScheme=udp
&&LinkType=multi-access
- all Ethernet faces:
UriScheme=ether
(note: UriScheme matches against both local and remote FaceUri, "dev" also works) - all faces: no condition
(note: this is equivalent to face dataset, and face dataset should be preferred for this purpose)
Channel Dataset¶
Description of all active channels is published as a Status Dataset at ndn:/localhost/nfd/faces/channels
.
Each channel is represented by a ChannelStatus block:
ChannelStatus := CHANNEL-STATUS-TYPE TLV-LENGTH
LocalUri
- LocalUri is a FaceUri representing the channel's local endpoint.
Face Status Change Notification¶
Face status change events are published as a Notification Stream at ndn:/localhost/nfd/faces/events
.
Notifications of all faces are sent into the same notification stream.
The Content of each notification Data packet is a FaceEventNotification block:
FaceEventNotification ::= FACE-EVENT-NOTIFICATION-TYPE TLV-LENGTH
FaceEventKind
FaceId
Uri
LocalUri
FaceScope
FacePersistency
LinkType
Flags
FaceEventKind ::= FACE-EVENT-KIND-TYPE TLV-LENGTH
nonNegativeInteger
FaceEventKind indicates the kind of event. Its possible values are:
- 1 = face is created
- 2 = face is destroyed
- 3 = face goes UP (from DOWN state)
- 4 = face goes DOWN (from UP state)
TLV-TYPE assignments¶
Type | Assigned value | Assigned value (hex) |
---|---|---|
FaceStatus | 128 | 0x80 |
LocalUri | 129 | 0x81 |
ChannelStatus | 130 | 0x82 |
UriScheme | 131 | 0x83 |
FaceScope | 132 | 0x84 |
FacePersistency | 133 | 0x85 |
LinkType | 134 | 0x86 |
BaseCongestionMarkingInterval | 135 | 0x87 |
DefaultCongestionThreshold | 136 | 0x88 |
Mtu | 137 | 0x89 |
NInInterests | 144 | 0x90 |
NInData | 145 | 0x91 |
NInNacks | 151 | 0x97 |
NOutInterests | 146 | 0x92 |
NOutData | 147 | 0x93 |
NOutNacks | 152 | 0x98 |
NInBytes | 148 | 0x94 |
NOutBytes | 149 | 0x95 |
FaceQueryFilter | 150 | 0x96 |
FaceEventNotification | 192 | 0xc0 |
FaceEventKind | 193 | 0xc1 |
(reserved, formerly FaceFlags) | 194 | 0xc2 |
Updated by Eric Newberry over 6 years ago · 107 revisions