253 lines
8.2 KiB
Plaintext
253 lines
8.2 KiB
Plaintext
[[mgw_pooling]]
|
||
== MGW Pooling
|
||
|
||
OsmoBSC is able to use a pool of media gateway (MGW) instances since mid 2021.
|
||
The aim of MGW pooling is to evenly distribute the RTP voice stream load across
|
||
multiple MGW instances. This can help to scale out over multiple VMs or physical
|
||
machines. Until osmo-mgw includes multithreading support, it may also be used to
|
||
scale-out to multiple cores on a single host.
|
||
|
||
The load distribution is managed in such a way that when a new call is placed,
|
||
the pool will automatically assign the call to the MGW with the lowest load.
|
||
|
||
MGW pooling is recommended for larger RAN installations. For small networks and
|
||
lab installations the classic method with one MGW per BSC offers sufficient
|
||
performance.
|
||
|
||
=== VTY configuration
|
||
|
||
In OsmoBSC the MGW is controlled via an MGCP-Client. The VTY commands to
|
||
configure the MGCP-Client are part of the 'msc' node due to historical reasons.
|
||
Unfortunately this concept does not allow to configure multiple MGCP-Client
|
||
instances as required by MGW pooling. In order to support MGW pooling a new
|
||
'mgw' node has been added under the 'network' node.
|
||
|
||
=== Existing configuration files
|
||
|
||
Existing OsmoBSC configuration files will continue to work, but as soon as an
|
||
MGW pool is configured the 'mgw' settings under the 'msc' node will be ignored.
|
||
|
||
Example configuration with only one MGCP-Client under the 'msc' node:
|
||
----
|
||
msc 0
|
||
mgw remote-ip 127.0.0.1
|
||
mgw remote-port 2428
|
||
----
|
||
|
||
=== MGW pool configuration
|
||
|
||
To setup an MGW pool, the user must first install multiple OsmoMGW instances, so
|
||
that they won’t interfere with each other. This can be done using different
|
||
local host IP addresses or different ports. When OsmoMGW is installed from
|
||
packages, the systemd configuration may also require adjustment.
|
||
|
||
The VTY settings under the 'mgw' node works the same way as the VTY settings for
|
||
the MGW under the 'msc' node.
|
||
|
||
Example configuration with two MGCP-Client instances in a pool:
|
||
----
|
||
mgw 0
|
||
description media-gw-0 <2>
|
||
mgw remote-ip 127.0.0.1
|
||
mgw remote-port 2432
|
||
mgw local-ip 127.0.0.1
|
||
mgw local-port 2431
|
||
mgw endpoint-domain mgw0 <1>
|
||
mgw 1
|
||
description media-gw-1 <2>
|
||
mgw remote-ip 127.0.0.1
|
||
mgw remote-port 2430
|
||
mgw local-ip 127.0.0.1
|
||
mgw local-port 2429
|
||
mgw endpoint-domain mgw1 <1>
|
||
----
|
||
|
||
<1> When working with multiple MGW / MGCP-Client instances, the domain name for
|
||
each MGW should be different. Otherwise it won't be possible to distinguish the
|
||
endpoint names in the log. It should also be noted that the domain name must
|
||
match the configuration of the related OsmoMGW instance.
|
||
|
||
<2> It is also possible to assign a descriptive name to each MGW instance. The
|
||
MGCP client specific log lines will then use this name as logging context. If
|
||
no description is set, the domain name will be used.
|
||
|
||
=== MGW pool management
|
||
|
||
While it was not possible to change the MGCP-Client configuration under the
|
||
“msc” node at runtime, the pool is fully runtime-manageable. The only limitation
|
||
is that an MGCP-Client can not be restarted or removed as long as it is serving
|
||
calls (see also: <<mgw_pooling_blocking>>).
|
||
|
||
==== MGW pool status
|
||
|
||
The VTY implements a 'show mgw-pool' command that lists the currently configured
|
||
MGW pool members, their status and call utilization.
|
||
|
||
----
|
||
OsmoBSC> show mgw-pool
|
||
% MGW-Pool:
|
||
% MGW 0:media-gw-0
|
||
% mgcp-client: connected
|
||
% service: unblocked
|
||
% ongoing calls: 1
|
||
% MGW 1:media-gw-1
|
||
% mgcp-client: connected
|
||
% service: unblocked
|
||
% ongoing calls: 0
|
||
----
|
||
|
||
==== Adding an MGW / MGCP-Client to the MGW pool
|
||
|
||
To add a new MGCP-Client to the pool, the 'mgw' node is used. Like with the
|
||
'bts' or the 'msc' node a reference number is used that usually starts at 0.
|
||
However it is still possible to assign any number from 0-255. The enumeration
|
||
also may contain gaps.
|
||
|
||
----
|
||
OsmoBSC> enable
|
||
OsmoBSC# configure terminal
|
||
OsmoBSC(config)# network
|
||
OsmoBSC(config-net)# mgw 2
|
||
OsmoBSC(config-mgw)# mgw
|
||
local-ip local bind to connect to MGW from
|
||
local-port local port to connect to MGW from
|
||
remote-ip remote IP address to reach the MGW at
|
||
remote-port remote port to reach the MGW at
|
||
endpoint-domain Set the domain name to send in MGCP messages, e.g. the part 'foo' in 'rtpbridge/*@foo'.
|
||
reset-endpoint Add an endpoint name that should be reset (DLCX) on connect to the reset-endpoint list,e.g. 'rtpbridge/*'
|
||
----
|
||
|
||
The newly added MGW will immediately appear in the mgw-pool list but it won't
|
||
be used until its configuration finished by reconnecting it.
|
||
|
||
----
|
||
% MGW-Pool:
|
||
% MGW 0:media-gw-0
|
||
% mgcp-client: connected
|
||
% service: unblocked
|
||
% ongoing calls: 2
|
||
% MGW 1:media-gw-1
|
||
% mgcp-client: connected
|
||
% service: unblocked
|
||
% ongoing calls: 3
|
||
% MGW 2:mgw <1>
|
||
% mgcp-client: disconnected
|
||
% service: unblocked
|
||
% ongoing calls: 0
|
||
----
|
||
|
||
<1> In this example a description is not set yet, so the domain name ("mgw")
|
||
is displayed.
|
||
|
||
==== Reconnecting an MGW / MGCP-Client
|
||
|
||
It may become necessary to reconnect an MGCP-Client. This is the case when the
|
||
VTY configuration was changed at runtime. In order to make the changes effective
|
||
the MGW configuration must be reloaded by reconnecting the MGW connection. Also
|
||
newly created MGW instances require a reconnect once their configuration is
|
||
done.
|
||
|
||
To reconnect an MGCP-Client use the 'reconnect' VTY command:
|
||
----
|
||
OsmoBSC# mgw 2 reconnect
|
||
----
|
||
|
||
The mgcp-client status should immediately change to 'connected'. The MGW is now
|
||
ready to be used for new calls.
|
||
|
||
----
|
||
OsmoBSC# show mgw-pool
|
||
% MGW-Pool:
|
||
% MGW 0:media-gw-0
|
||
% mgcp-client: connected
|
||
% service: unblocked
|
||
% ongoing calls: 2
|
||
% MGW 1:media-gw-1
|
||
% mgcp-client: connected
|
||
% service: unblocked
|
||
% ongoing calls: 3
|
||
% MGW 2:mgw
|
||
% mgcp-client: connected
|
||
% service: unblocked
|
||
% ongoing calls: 0
|
||
----
|
||
|
||
It should be noted that MGCP a protocol is used via UDP, the connect only
|
||
happens locally to forward the UDP datagrams properly. Also (unless a reset
|
||
endpoint is configured like in the example config above) there will be no
|
||
immediate interaction with the MGW. However, the log should at least confirm
|
||
the the connect worked and the MGCP client has been created successfully.
|
||
|
||
----
|
||
Mon Aug 2 17:15:00 2021 DLMGCP mgcp_client.c:788 MGCP client: using endpoint domain '@mgw'
|
||
Mon Aug 2 17:15:00 2021 DLMGCP mgcp_client.c:908 MGCP GW connection: r=127.0.0.1:2427<->l=127.0.0.1:2727
|
||
----
|
||
|
||
It is strongly advised to check the activity on the related MGW and to follow
|
||
the log in order to see that the communication between OsmoBSC and the MGW is
|
||
working correctly.
|
||
|
||
[[mgw_pooling_blocking]]
|
||
==== Blocking an MGW / MGCP-Client
|
||
|
||
If it becomes apparent that an MGCP-Client must be restarted or removed from
|
||
the config (maintenance) the operator can put that MGCP-Client into a blocked
|
||
mode. A blocked MGCP-Client will still serve the ongoing calls but it will not
|
||
be picked for the assignment of new calls.
|
||
|
||
To block an MGCP-Client use the 'block' VTY command:
|
||
----
|
||
OsmoBSC# mgw 2 block
|
||
OsmoBSC# show mgw-pool
|
||
% MGW-Pool:
|
||
% MGW 0:media-gw-0
|
||
% mgcp-client: connected
|
||
% service: unblocked
|
||
% ongoing calls: 11
|
||
% MGW 1:media-gw-1
|
||
% mgcp-client: connected
|
||
% service: unblocked
|
||
% ongoing calls: 12
|
||
% MGW 2:mgw
|
||
% mgcp-client: connected
|
||
% service: blocked
|
||
% ongoing calls: 10
|
||
----
|
||
|
||
When the number of ongoing calls has tapered off, the MGW / MGCP-Client can be
|
||
restarted or removed if necessary.
|
||
|
||
----
|
||
OsmoBSC# show mgw-pool
|
||
% MGW-Pool:
|
||
% MGW 0:media-gw-0
|
||
% mgcp-client: connected
|
||
% service: unblocked
|
||
% ongoing calls: 15
|
||
% MGW 1:media-gw-1
|
||
% mgcp-client: connected
|
||
% service: unblocked
|
||
% ongoing calls: 14
|
||
% MGW 2:mgw
|
||
% mgcp-client: connected
|
||
% service: blocked
|
||
% ongoing calls: 0
|
||
----
|
||
|
||
If the blockade should be reverted, the 'unblock' VTY command can be used in
|
||
the same way to remove the blockade. (Reconnecting will not remove the
|
||
blockade.)
|
||
|
||
==== Removing an MGW / MGCP-Client
|
||
|
||
An MGCP-Client is removed from the pool using the 'no mgw' command from the
|
||
configure terminal. The MGCP-Client instance will automatically be terminated
|
||
and the related resources are freed. The only requirement is that there are no
|
||
ongoing calls on the selected instance.
|
||
|
||
----
|
||
OsmoBSC# configure terminal
|
||
OsmoBSC(config)# network
|
||
OsmoBSC(config-net)# no mgw 2
|
||
----
|