Technical data

100 ServerIron ADX NAT64 Configuration Guide
53-1002288-02
Forwarding packets without NAT translation
6
DRAFT: BROCADE CONFIDENTIAL
Forwarding packets without NAT translation
When ServerIron ADX receives a non-SYN packet for a TCP flow from an internal NAT client and no
sessions are found, then by default ServerIron drops that packet. Optionally, you can forward that
packets without NAT translation by entering the following command.
ServerIronADX(config)# nat-forward-no-session
Syntax: [no] nat-forward-no-session
Translation timeouts
The NAT translation table contains all the currently active NAT translation entries on the device. An
active entry is one the ServerIron ADX creates for a private address when the client at that address
sends traffic.
NAT performs the following steps to provide an address translation for a source IP address:
• NAT looks in the translation table for an active NAT entry for the translation. If the table
contains an active entry for the session, the ServerIron ADX uses that entry.
• If NAT does not find an active entry in the NAT translation table, NAT creates an entry and
places the entry in the table. The entry remains in the table until the entry times out.
Each NAT entry remains in the translation table until the entry ages out.
Configuring the NAT translation aging timer
Use the ip nat translation command to alter the NAT translation aging timer.
The NAT translation table contains all the currently active NAT translation entries on the device. An
active entry is one that the ServerIron ADX created for a private address when that client at that
address sent traffic to the Internet. NAT performs the following steps to provide an address
translation for a source IP address:
• The feature looks in the NAT translation table for an active NAT entry for the translation. If the
table contains an active entry for the session, the ServerIron ADX uses that entry.
• If NAT does not find an active entry in the NAT translation table, NAT creates an entry and
places the entry in the table. The entry remains in the table until the entry times out.
ServerIronADX(config)# ip nat translation tcp-timeout 1800
Syntax: [no] ip nat translation dns-timeout | finrst-timeout | icmp-timeout | syn-timeout |
tcp-timeout | udp-timeout <secs> maximum
Syntax: [no] ip nat translation max-entries <number-of-entries>
The dns-timeout keyword indicates connections to a Domain Name Server (DNS). The default is
120 seconds.
The finrst-timeout keyword identifies TCP FIN (finish) and RST (reset) packets, which normally
terminate TCP connections. The default is 120 seconds. This timer is not related to tcp-timeout,
which applies to packets to or from a host address that is mapped to an global IP address and a
TCP port number (PAT feature). The finrst-timeout applies to packets that terminate a TCP session,
regardless of the host address or whether PAT is used.
The icmp-timeout keyword indicates timeout for NAT ICMP flows