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300-820 · Question #91

Which attribute in the SDP for a call is affected by the static NAT address configuration in an Expressway-E?

The correct answer is A. connection. When Expressway-E is configured with a static NAT address (its public IP), it updates the SDP 'connection' attribute - the 'c=' line - to advertise the public IP address instead of the private DMZ address. The connection line tells remote endpoints where to send media…

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Question

Which attribute in the SDP for a call is affected by the static NAT address configuration in an Expressway-E?

Options

  • Aconnection
  • Bname
  • Cversion
  • Dbandwidth

How the community answered

(39 responses)
  • A
    92% (36)
  • C
    5% (2)
  • D
    3% (1)

Explanation

When Expressway-E is configured with a static NAT address (its public IP), it updates the SDP 'connection' attribute - the 'c=' line - to advertise the public IP address instead of the private DMZ address. The connection line tells remote endpoints where to send media (audio/video). Without static NAT configuration, Expressway-E would advertise its internal DMZ IP in the SDP, which is unroutable from the internet. By configuring the static NAT public IP, Expressway-E ensures external callers can reach it for media exchange. The other SDP attributes - name (s=), version (v=), and bandwidth (b=) - are not affected by NAT address configuration.

Topics

#Expressway-E NAT#SDP connection attribute#NAT traversal#Media negotiation

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