AudioCodes Mediapack mp-11x, User Manual

Page: 370 / 390

SIP User's Manual 370 Document #: LTRT-65409
MediaPack Series
The gateway initiates a PPPoE discovery phase to discover a PPPoE Access
Concentrator. It does this by broadcasting a discovery initialization packet (PADI). If an
Access Concentrator exists and replies, the gateway tries to connect to this Access
Concentrator. If this initial connection succeeds, then the PPP LCP phase starts - each
side of the PPPoE connection sends an LCP configuration request to configure the PPP
link.The gateway PPPoE client supports both PAP and CHAP authentications. The type of
authentication protocol used is according to the request from the authentication server. In
the LCP configuration phase, the server requires a specific authentication (none, PAP or
CHAP are supported). The
ini
file parameters PPPoEUserName, PPPoEPassword, and
PPPoEServerName are used to configure the authentication parameters. If the Access
Concentrator is configured to operate in PAP, the PPPoEUserName and PPPoEPassword
are used as Username and Password (in this case, the PPPoEServerName parameter is
not used). If the Access Concentrator is configured to operate in CHAP, the
PPPoEUserName parameter functions as Client Name (sent in the CHAP response
packet), while the PPPoEPassword functions as the shared secret (calculated along with
the challenge to produce the response). In this case, the PPPoEServerName is the name
of the server (some hosts can be configured to authenticate to multiple servers. In such
hosts, the server name is used to identify which secret should be used).
Note:
The AudioCodes gateway, being a PPPoE client, requests no authentication.
After the gateway has been authenticated, it needs to configure a network layer protocol.
The gateway uses the IP protocol. Therefore, the used NCP will be IPCP (IP Configuration
Protocol). In this phase, if the
ini
file parameter PPPoEStaticIPAddress is defined, the
gateway requests the remote host to assign this address for its use.
When working in a PPPoE environment, the gateway negotiates for its IP address (as
described above). However, if you want to disable the PPPoE client, the gateway can be
configured to use default values for IP address, subnet mask and default gateway. This
can be done using
ini
file parameters PPPoERecoverIPAddress,
PPPoERecoverSubnetMask and PPPoERecoverDfgwAddress. These parameters indicate
to the gateway that if the PPPoE is disabled and no BootP server is activated, as required
in the gateway to use a PPPoE environment, then the gateway should use these defaults
for its IP configuration.
For a description of the
ini
file parameters for PPPoE, refer to 'Networking Parameters' on
page 256 .
8.4 IP Multicasting
The gateway supports IP Multicasting level 1 according to RFC 2236 (i.e., IGMP version 2)
for RTP channels. The gateway is capable of transmitting and receiving Multicast packets.
8.5 Robust Reception of RTP Streams
This mechanism filters out unwanted RTP streams that are sent to the same port number
on the gateway. These multiple RTP streams can result from traces of previous calls, call
control errors, and deliberate attacks.
When more than one RTP stream reaches the gateway on the same port number, the
gateway accepts only one of the RTP streams and rejects the rest of the streams. The RTP
stream is selected according to the following procedure: