Tip
This is the documentation for the 21.07 version. Looking for the documentation of the latest version? Have a look here.
Shared Memory Packet Interfaces (memif)¶
A Shared Memory Packet Interface (memif) has two components: A socket and an
interface. A memif also requires a role
, either server
or client
. In
most TNSR applications, it will be the server and the other endpoint will be a
client. A single socket may only be associated with one role type.
Memif Configuration¶
The interface memif socket
command has two forms, both of which are required
in most cases. The first creates an association between a socket ID and a
filename. The second creates a memif interface using a specific socket.
Creating a memif Socket¶
To create the socket-filename association, use: interface memif socket
<socket-id> filename <socket-filename>
.
Note
An exception to this is socket 0
which is special and locked to
/run/vpp/memif.sock
. It cannot be changed to another file. This entry is
always present and does not need to be manually configured.
When defining a filename for a socket, the available parameters are:
- socket-id:
A required identifier unique to this memif instance. This is an integer in the range
1..4294967294
.- socket-filename:
The full path to a socket file used for establishing memif connections. A socket can be used for either server or client interfaces, but not both. A socket can have more than one server, or it can have more than one client.
Warning
Sockets cannot be edited or deleted if they are in use by a memif. To change or remove a socket, first remove the associated memif.
Creating a memif interface¶
Next, the interface memif socket <socket-id> interface <if-id>
command
creates a memif object. This command requires its own interface identifier, and
it must be tied to the socket using the same ID from the previous command. This
results in a new TNSR interface named memif<socket-id>/<if-id>
.
Note
The combination of socket ID and interface ID must be unique, but
multiple sockets may use the same interface ID. For example, memif0/0
and
memif1/0
.
Warning
Each socket can only be used by a single memif.
This command enters config-memif
mode, where the following commands are
available:
- buffer-size <size>:
The size of the buffer allocated for each ring entry. Default
2048
.- mac-address <mac>:
MAC address for the memif interface.
- mode <mode>:
Sets the mode for the memif interface. Mode must be one of:
- ethernet:
Ethernet (L2) mode.
Note
When
ethernet
mode is active and amac-address
is not set, TNSR will generate a random MAC for the interface.- ip:
IP (L3) mode.
- punt/inject:
Reserved for future use. Not yet implemented.
- ring-size <size>:
Number of entries in receive and transmit rings. Value is
8..32
and is used as a power of 2. Default value is10
for1024
(2^10
) entries.- role <role> [<options>]:
Sets the role of the memif interface. The default role is
server
and this is the most common role for TNSR. The following modes and options are available:- server:
Server role. The server does not expose its memory to the client peer.
- client [(rx-queues|tx-queues) <num-queues>]:
Client role. Allocates and shares memory with the server to transfer data. When operating in client mode, the number of receive or transmit queues may be set as an option:
- rx-queues <n-rx-qs>:
Number of receive queues. May be between
1..255
.- tx-queues <n-tx-qs>:
Number of transmit queues. May be between
1..255
.
- secret <sec-str>:
A quoted secret string, up to 24 characters.
Memif Example¶
First, create a socket with an ID of 23
, using a socket file of
/tmp/memif23.sock
:
tnsr(config)# interface memif socket 23 filename /tmp/memif23.sock
Next, run commands to create a memif interface with an interface ID of 100
taking on the role server
on the socket created previously:
tnsr(config)# interface memif socket 23 interface 100
tnsr(config-memif)# role server
tnsr(config-memif)# exit
Now the interface will be available to TNSR. In this example with a socket ID of
23
and an interface ID of 100
, the full interface name is
memif23/100
.
Memif status¶
For a list of all current memif entries, along with their names and
configuration, use the show interface memif
command:
tnsr# show interface memif
Socket Id Filename
---------- --------------------------------------------------
0 /run/vpp/memif.sock
23 /tmp/memif23.sock
memif23/100:
Socket id: 23
Interface id: 100
Interface: memif23/100
Role: server
Mode: ethernet
MAC address: 02:fe:2d:e2:87:a8
Ring size: 0
Buffer size: 0
Admin up: false
Link up: false