Which two statements about Expressway-C / Expressway-E Firewall Traversal are correct? (Choose two.)

Question

Options

• ASIP or H.323 "fixup" ALG or awareness functionality must be enabled on the NAT firewalls.
• BThe communications between Expressway-C and Expressway-E are always initiated from the
• CThe communications between Expressway-C and Expressway-E are always initiated from the
• DSIP or H.323 "fixup" ALG or awareness functionality must be disabled on the NAT firewalls.
• ESIP or H.323 "fixup" ALG or awareness functionality must be enabled on the NAT firewall

• B
  94% (44)
• C
  4% (2)
• E
  2% (1)

Explanation

Two key design principles govern Expressway firewall traversal. First, all TCP connections between Expressway-C (inside) and Expressway-E (DMZ/outside) are always initiated outbound from Expressway-C. This means no inbound firewall rules are needed from E to C, which is the core of the 'traversal' design. Second, SIP and H.323 ALG (Application Layer Gateway) or 'fixup' functionality on NAT firewalls must be DISABLED. ALG attempts to inspect and rewrite signaling packets, but Expressway already handles protocol traversal natively. An enabled ALG will corrupt or interfere with the signaling, causing call failures. The firewall must pass the traffic transparently and let Expressway manage the protocol-level traversal.

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