Xlat Instance Configuration - Cisco GRS Configuration Manual

Configuring IPv4/IPv6 Stateless Translator (XLAT)

XLAT Instance Configuration

• IPv4 ServiceApp name
• IPv6 ServiceApp name
• XLAT prefix
• Ubit enabled/disabled
• IPv4 & IPv6 TCP MSS configuration
• Traceroute pool
• IPv4 TOS Setting
• IPv6 Traffic Class Setting
• IPv4 DF override
Cisco IOS XR Carrier Grade NAT Configuration Guide for the Cisco CRS Router, Release 5.2.x
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◦ Service App on which IPv4 traffic enters/leaves
◦ Service App on which IPv6 traffic enters/leaves
◦ IPv6 prefix corresponding to XLAT translation
◦ whether bits 64..71 are reserved or can be used for xlat purposes
◦IPv4 TCP traffic's MSS value will be set to the smaller of (incoming MSS value)
◦IPv6 TCP traffic's MSS value will be set to the smaller of (incoming MSS value)
◦ Non Translatable IPv6 source addresses are translated to the IPv4 addresses in this range using a
hash mechanism
◦ Algorithm to chose IPv4 address from traceroute pool
TTL based – Chose address based on hop count of the pkt
Hash based – Hash IPv6 Source Address and use it for selection
Random – Randomly select an IPv4 address
◦ By default IPv4 TOS field is copied from IPv6 Traffic Class field
◦ This value can be overridden based on the configured TOS value
◦ By default IPv6 Traffic Class field is copied from IPv4 TOS field
◦ This value can be overridden based on the configured Traffic Class value
◦ When translating a IPv6 packet when the no Fragment Header IPv4 DF bit is set to 1.
Implementing Carrier Grade NAT on Cisco IOS XR Software
OL-32659-01