Determine Whether The Router Uses Symmetric Or Asymmetric Nat - Cisco WRP500 Administration Manual

Configure NAT Mapping
R E V I E W D R A F T # 1 — C I S C O C O N F I D E N T I A L

Determine Whether the Router Uses Symmetric or Asymmetric NAT

To use a STUN server, the edge device—that is, the device that routes traffic between your private
network and your ISP network—must have an asymmetric NAT mechanism. You need to determine
which type of NAT mechanism is available on that device.
STUN does not work on routers with symmetric NAT. With symmetric NAT, IP addresses are mapped
from one internal IP address and port to one external, routable destination IP address and port. If another
packet is sent from the same source IP address and port to a different destination, then a different IP
address and port number combination is used. This method is restrictive because an external host can
send a packet to a particular port on the internal host only if the internal host first sent a packet from that
port to the external host.
Note This procedure assumes that a syslog server is configured and is ready to receive syslog messages.
Make sure you do not have firewall running on your computer that could block the syslog port (port 514
Step 1
by default).
Step 2 Log in as administrator.
Step 3 To enable debugging, complete the following tasks:
a.
b.
c.
d.
Step 4 To collect information about the type of NAT your router is using, complete the following tasks:
a.
b.
c.
To enable SIP signaling, complete the following task:
Step 5
a.
b.
Click Submit.
Step 6
Cisco WRP500 Administration Guide
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Under the Voice menu, click System.
In the Debug Server and Syslog Server field, enter the IP address of your syslog server. This address
and port number must be reachable from the WRP500.
From the Debug level drop-down list, choose 3.
From the Debug option drop-down list, choose dbg_all.
IMAGE WILL BE SUPPLIED (SCREENSHOT) - replaces 194558
Under the Voice menu, click SIP.
Scroll down to the NAT Support Parameters section.
From the STUN Test Enable field, choose yes.
Under the Voice menu, click Line 1 or Line 2 to choose the line interface that you want to modify.
In the SIP Settings section, choose full from the SIP Debug Option field.
Chapter 2 Configure Your System for ITSP Interoperability