128
Security
Multimedia Client IP address and port mapping stored by the Session
Manager is replaced with the new value, and the Multimedia Client is
properly registered again.
The Multimedia Client is able to recover from a brief firewall, NAT or NAPT
outage. For example, if a user is engaged in a voice conversation and is
at the same time participating in an IM Chat session when their home
router resets they may still be able to rejoin both the conversation and the
chat session. Assuming this user has their SIP PING rate set to every 30
seconds, the maximum loss of connectivity is the amount of time their
router takes to come back into service plus approximately 30 seconds for
the Multimedia PC Client to recover from the external address and port pair
change imposed on it by the router when it comes back into service.
The Multimedia Client detects that its externally visible address has changed
and initiates a reregistration with the Session Manager and the MAS IM
Chat service. After the reregistration is successfully completed, all media is
routed to the new externally visible address and port pair of the Multimedia
Client. If the SIP PING timer is set to a higher value, the Multimedia Client
can still go through the reregistration process, but it is unlikely that the other
parties the user was communicating with remain on the line for a prolonged
period of time without any feedback from the temporarily disconnected user.
SNMP security properties
The Simple Network Management Protocol (SNMP) is a network
management standard widely used in TCP/IP networks. SNMP provides
a method of managing network devices running SNMP agents to be
managed by SNMP network management clients running anywhere in the
network. For security reasons, Microsoft SNMP Service is turned off on
MAS servers by default. If a Management Server IP address and SNMP
Community String are provisioned in the MAS Console (see
Figure 51
"MAS Console" (page 129)
) only traps generated by a MAS service are
sent to the designated Management Server IP address. Nortel supports
SNMP version 3.
Nortel Media Application Server
Media Application Server Planning and Engineering
NN42020-201
01.04
Standard
4.0
27 July 2007
Copyright © 2007, Nortel Networks
.
