Provide Internet Access to a Large Number of
Private IPv4 Subscribers of a Telecom Service Provider (Large Scale NAT)
The Internet's phenomenal growth has resulted in a
shortage of public IPv4 addresses. Large Scale NAT (LSN/CGNAT) provides
a solution to this issue, maximizing the use of available public IPv4
addresses by sharing a few public IPv4 addresses among a large pool of
Internet users. LSN translates private IPv4 addresses into public IPv4
addresses. It includes network address and port translation methods to
aggregate many private IP addresses into fewer public IPv4 addresses.
LSN is designed to handle NAT on a large scale.
The NetScaler supports LSN and is compliant with RFC
6888, 5382, 5508, and 4787. The NetScaler LSN feature is very useful
for Internet Service Providers (ISPs) and carriers providing millions
of translations to support a large number of users (subscribers) and at
very high throughput. The LSN architecture of an ISP using Citrix
products consists of subscribers (Internet users) in private address
spaces accessing the Internet through a NetScaler appliance deployed in
ISP's core network.
The following lists some of the LSN features supported
on a NetScaler appliance:
* ALGs: Support of application Layer Gateway (ALG) for
SIP, PPTP, RTSP, FTP, ICMP, and TFTP protocols.
* Deterministic/ Fixed NAT: Support for pre-allocation
of block of ports to subscribers for minimizing logging.
* Mapping: Support of Endpoint-independent mapping
(EIM), Address-dependent mapping ( ADM), and Address-Port dependent
* Filtering: Support of Endpoint-independent filtering
(EIF), Address-dependent filtering, and Address-Port-dependent
* Quotas: Configurable limits on number of ports and
sessions per subscriber.
* Static Mapping: Support of manually defining an LSN
* Hairpin Flow: Support for communication between
subscribers or internal hosts using public IP addresses.
* LSN Clients: Support for specifying or identifying
subscribers for LSN NAT by using IPv4 addresses and extended ACL rules.
* Logging: Support for logging LSN session for law
enforcement. In addition, the following are also supported for logging:
** Reliable SYSLOG: Support of sending SYSLOG messages
over TCP to external log servers for a more reliable transport
** Load balancing of Log Servers. Support for load
balancing of external log servers for preventing storage of redundant
** Minimal Logging: Deterministic LSN configurations or
Dynamic LSN configurations with port block significantly reduces the
LSN log volume.
For more information about the Large Scale NAT feature,