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Implementing Carrier Grade NAT on Cisco IOS XR Software
CGSE Multi-Chassis Support
The CGSE line card is supported in a multi-chassis configuration. 16 CGSE line cards are supported on each
Cisco CRS Router chassis. A maximum of 32 CGN instances are supported.
For CGN applications, such as NAT44, NAT64, XLAT, DS-Lite and 6RD, a maximum of 20 million sessions
are supported by each CGSE line card.
CGSE Plus PLIM
CGSE Plus is a mutli-service PLIM for the Cisco CRS-3 Router. The module has a maximum packet processing
speed of 40 Gbps full-duplex with a reduced boot time and latency.
The actual throughput of the application depends on the software logic and the CPU cycles consumed by
Note
the software.
It also supports services redundancy and QoS for service applications.
CGSE Plus is brought up in two modes:
• CGN mode — The Cisco IOS XR and Linux software are tuned to host CGN applications such as NAT44
• SESH mode — The Cisco IOS XR and Linux software are tuned to host future applications such as
For more information on CGSE Plus PLIM, see Cisco CRS Carrier Grade Services Engine Physical Layer
Interface Module Installation Note.
Information About Carrier Grade NAT
These sections provide the information about implementation of NAT using ICMP and TCP:
Implementing NAT with ICMP
This section explains how the Network Address Translation (NAT) devices work in conjunction with Internet
Control Message Protocol (ICMP).
The implementations of NAT varies in terms of how they handle different traffic.
ICMP Query Session Timeout
RFC 5508 provides ICMP Query Session timeouts. A mapping timeout is maintained by NATs for ICMP
queries that traverse them. The ICMP Query Session timeout is the period during which a mapping will stay
active without packets traversing the NATs. The timeouts can be set as either Maximum Round Trip Time
(Maximum RTT) or Maximum Segment Lifetime (MSL). For the purpose of constraining the maximum RTT,
the Maximum Segment Lifetime (MSL) is considered a guideline to set packet lifetime.
OL-32659-01
and 6RD.
Arbor DDoS services.
Cisco IOS XR Carrier Grade NAT Configuration Guide for the Cisco CRS Router, Release 5.2.x
CGSE Plus PLIM
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