FaceMgmt » History » Revision 48
Revision 47 (Yukai Tu, 08/23/2015 10:12 AM) → Revision 48/118 (Junxiao Shi, 09/04/2015 10:03 PM)
# Face Management
{{toc}}
**Face Management** is a module of [[Management|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)
* `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)
### TCP
`tcp[4|6]://<IP-or-host>[:<port>]`
Examples:
* `tcp4://192.0.2.1:6363` (canonical form)
* `tcp6://[2001:db8::1]:6363` (canonical form)
* `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 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://<ifname>`
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 TCP | tcp4 | tcp4
IPv6 TCP | tcp6 | tcp6
UNIX stream | fd (file descriptor on NFD side) | unix (socket path)
Ethernet multicast | ether | dev
## Static Face Attributes
**FaceScope** indicates whether the face is local for [[ScopeControl|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
## Control Commands
[[ControlCommand]] **management-module**: `faces`
### Create a face
**command-verb**: `create`
ControlParameters fields:
* Uri (required): a canonical UDP unicast or TCP FaceUri
* FacePersistency (optional): either *persistent* or *permanent*; creating on-demand faces is disallowed.
The default is *persistent*.
See "static face attributes" for more information.
This command allows creation of UDP unicast and TCP faces only.
If another face with same underlying protocol and remote address exists, the command is considered successful, and FaceId of that face is returned;
If the existing face has a different FacePersistency property, the transition on the direction of *on-demand* -> *persistent* -> *permanent* is allowed.
If the command succeeds, \<Body> in ControlResponse block contains updated ControlParameters:
* FaceId
* FacePersistency
### 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.
### Enable a LocalControlHeader feature
**command-verb**: `enable-local-control`
ControlParameters fields:
* LocalControlFeature (required): 1=IncomingFaceId, 2=NextHopFaceId, 3=CachingPolicy
This command can only operate on the requesting face.
### Disable a LocalControlHeader feature
**command-verb**: `disable-local-control`
ControlParameters fields:
* LocalControlFeature (required): 1=IncomingFaceId, 2=NextHopFaceId, 3=CachingPolicy
This command can only operate on the requesting face.
## Face Dataset
Description and counters of all active faces are published as a [[StatusDataset|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
NInInterests
NInDatas
NInNacks
NOutInterests
NOutDatas
NOutNacks
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 [[ScopeControl|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.
* **NInInterests**: number of incoming Interest packets since the face is established.
* **NInDatas** 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.
* **NOutDatas** 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 DNS name, include port number
* all TCP tunnels: UriScheme=tcp
note: "tcp" permits both "tcp4" and "tcp6", "udp" permits both "udp4" and "udp6"
* all UDP multicast faces: UriScheme=udp & LinkType=multi-access
* all Ethernet faces: UriScheme=ether
note: UriScheme matches on 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 [[StatusDataset|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 local endpoint.
## Face Status Change Notification
Face status change events are published as a [[Notification|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
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
## TLV-TYPE assignments
Type | Assigned value | Assigned value (hex)
------------------------------------------- | ----------------- | --------------------
FaceStatus | 128 | 0x80
LocalUri | 129 | 0x81
ChannelStatus | 130 | 0x82
FaceScope | 132 | 0x84
FacePersistency | 133 | 0x85
LinkType | 134 | 0x86
NInInterests | 144 | 0x90
NInDatas | 145 | 0x91
NInNacks | 151 | 0x97
NOutInterests | 146 | 0x92
NOutDatas | 147 | 0x93
NOutNacks | 152 | 0x98
NInBytes | 148 | 0x94
NOutBytes | 149 | 0x95
FaceQueryFilter | 150 | 0x96
UriScheme | 131 | 0x83
FaceEventNotification | 192 | 0xc0
FaceEventKind | 193 | 0xc1
(reserved, formerly FaceFlags) | 194 | 0xc2