Chapter 16: Network Address Translation Configuration Guide

Managing Dynamic Bindings

As mentioned previously, dynamic address bindings expire only after a period of non-use or when they are manually deleted. The default timeout for dynamic address bindings is 1440 minutes (24 hours). You can manually delete dynamic address bindings for a specific address pool or delete all dynamic address bindings.

To set the timeout for dynamic address bindings, enter the following command in Configure mode.

Set timeout for dynamic address bindings.

nat set dynamic-binding-timeout <minutes> disable

To flush dynamic address bindings, enter the following command in Enable mode.

Flush all dynamic address

nat flush-dynamic-binding all

bindings.

 

 

 

Flush dynamic address bindings

nat flush-dynamic-binding pool-specified

based on local and global ACL

local-acl-pool <local-acl>global-pool

pools.

<ip-addr/ip-addr-range/ip-addr-list/ip-addr-

 

mask>

 

 

Flush dynamic address bindings

nat flush-dynamic-binding type-specified

based on binding type.

dynamicoverloaded-dynamic

 

 

Flush dynamic address bindings

nat flush-dynamic-binding owner-specified

based on application.

dnsftp-controlftp-data

 

 

NAT and DNS

NAT can translate an address that appears in a Domain Name System (DNS) response to a name or inverse lookup. For example, if an outside host sends a name lookup to an inside DNS server, the inside DNS server can respond with a local IP address, which NAT translates to a global address.

You create NAT dynamic bindings for DNS by entering the following command in Configure mode.

Enable NAT with dynamic address binding for DNS query/reply.

nat create dynamic local-acl-pool <outside- local-acl>global-pool <ip-addr/ip-addr-range/ip-addr-list/ip-addr-mask>

DNS packets that contain addresses that match the ACL specified by outside-local-acl- pool are translated using local addresses allocated from inside-global-pool.

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Cabletron Systems 9032578-05 manual Managing Dynamic Bindings, NAT and DNS