Alteon Application Switch Operating System Application Guide
Filtering and Traffic Manipulation
390
Document
ID:
RDWR-ALOS-V2900_AG1302
To configure overlapping NAT
1. Configure a gateway per VLAN. Default Gateway 5 or above must be used for the VLAN gateway,
as gateways 1 through 4 are reserved for default gateways.
2. Configure the source NAT filter. Select the appropriate filter. In this example, Filter 2 is used.
3. Enable overlapping NAT.
SIP NAT and Gleaning Support
The IP end points on a network are typically assigned private addresses. Voice calls from and to the
public network need to reach end points on the private network. As a result, NAT is required to allow
proper routing of media to end points with private addresses.
The Session Initiation Protocol (SIP) carries the identification of the IP end point (IP address and
port) within the body of the message. The voice media which gets directed to the private IP address
identified in the signaling message cannot be routed and results in a one-way path. Therefore,
Alteon allows you to translate the address (using NAT) for the Session Description Protocol (SDP)
and create sessions for the media communication.
How SIP NAT Works
All occurrences of the internal client's private IP address and port in the outgoing SIP message is
replaced with the translated address. This procedure is reversed when the SIP messages come from
an external source, in which case the public IP is replaced with the private client's IP and port.
Alteon translates the IP address and port.
Setting Up SIP NAT
To set up SIP NAT, configure a NAT filter and enable SIP parsing. The SIP NAT modifies the signaling
to reflect the public IP addresses and ports. These pinholes and NAT bindings are assigned
dynamically based on stateful inspection. The SIP NAT performs the necessary translation of the IP
addresses embedded in the SIP messages and updates the SIP message before sending the packet
out.
To support SIP NAT and gleaning
1. Enable VMA.
2. Configure a NAT filter.
Note:
Dynamic NAT is supported only.
>> Main# /cfg/l3/gw 5
>> Default Gateway 5# addr <IP address>
>> Default Gateway 5# vlan 100
>> Main# /cfg/slb/filt 2/action na
>> Main# /cfg/slb/adv/pvlantag enable