Avaya 555-245-600 Benutzerhandbuch

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SIP
Issue 6 January 2008
139
 
SIP deployment scenarios
SIP and DNS
In all SIP configurations it is highly recommended to use both Dynamic Name System (DNS) 
and Dynamic Host Configuration Protocol (DHCP). The customer must have DNS running in the 
enterprise for external lookups. Proper DNS configuration allows for proper server resolution, 
including external domains, as well as ease of provisioning within the intranet. The SIP domain 
is used for addressing at the SIP level, such as sending an invite to user1@avaya.com. DNS is 
used for looking up individual host addresses in a network. This allows a SIP user to move 
around the SIP network, registering at different locations in the IP network, and even using 
different phones, while maintaining a common public address – e.g. user1@avaya.com. 
SES only supports a single SIP domain in a deployment. This domain is usually the top level 
domain for that enterprise, e.g. avaya.com. Often people reference the cs.columbia.edu 
configuration which at first glance looks like a sub-domain of columbia.edu. From the SES 
perspective, configuring a system like cs.columbia.edu and columbia.edu would be two 
separate domains and each one would view the other as an external domain. Each system 
would be viewed like any other deployment, having it’s own administration, users, etc.
Home-edge single box solution
SES is available as a single box solution in any of the releases. The home/edge system is the 
most straightforward configuration and includes configuration of surrounding services for proper 
operation. An Access Layer Gateway (ALG) is required for traversing the firewall. SIP capable 
ALGs are required to handle the appropriate ports/address translation needed for SIP signaling 
and RTP media.
on page 140 shows a typical home/edge 
configuration which is valid for any release. Additionally a remote-end user using a VPN tunnel 
is shown. While SES may support TLS, TCP and UDP as transport protocols, the use of 
Transport Layer Security (TLS) is recommended whenever possible. The 2.0 and 2.1 releases 
include presence between Softphone clients, but no subscriptions to Communication Manager 
extensions and no presence server. The 3.0 release includes the presence server for additional 
presence features and policy management.