Home » Cisco » 640-878 » Which two statements about carrier-grade NAT are true?
Which two statements about carrier-grade NAT are true? (Choose two.)
A. It conserves IPv4 addresses.
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Cisco 640-878 Exam
B. A service provider issues private IP addresses to its customers.
C. A service provider translates the private IP address of its customer to another private IP address.
D. It is implemented on the CE and PE routers.
E. It is designed to simplify IPv6 addressing.
Correct Answer: AB
Explanation/Reference:
Explanation: Explanation/Reference:
http://www.cisco.com/en/US/docs/routers/crs/software/crs_r3.9.1/cg_nat/configuration/guide/cgc39 1cgn.html#wp1268988
Carrier Grade NAT Overview
Carrier Grade Network Address Translation (CGN) is a large scale NAT that is capable of providing private IPv4 to public IPv4 translation in the order of millions of translations to support several hundred thousand subscribers and bandwidth throughput of at least 10 Gbps full-duplex.
CGN is a workable solution to the IPv4 address depletion problem while offering a way for service provider subscribers and content providers to implement a graceful transition to IPv6. CGN employs network address and port translation (NAPT) methods to aggregate many private IP addresses into fewer public IPv4 addresses. For example, a single public IPv4 address with a pool of 32 K port numbers supports 320 individual private IP subscribers assuming each subscriber requires 100 ports (for example, each TCP connection needs one port number). A CGN requires IPv6 to assist with the transition from IPv4 to IPv6.
