Documentation > Userspace Application Arguments > --eamt



  1. Description
  2. Syntax
  3. Arguments
    1. Operations
    2. Options
  4. Overlapping EAM Entries
  5. Examples


Interacts with Jool’s Explicit Address Mapping Table (EAMT). See the introduction for a swift overview, our RFC summary for more details, or the EAM RFC for the full story.


jool_siit --eamt (
	[--display] [--csv]
	| --count
	| --add <IPv4-prefix> <IPv6-prefix> [--force]
	| --remove <IPv4-prefix> <IPv6-prefix>
	| --flush



  • --display: The EAMT is printed in standard output. This is the default operation.
  • --count: The number of entries in the EAMT are printed in standard output.
  • --add: Combines <IPv4-prefix> and <IPv6-prefix> into an EAM entry, and uploads it to Jool’s table.
  • --remove: Deletes from the table the EAM entry described by <IPv4-prefix> and/or <IPv6-prefix>.
  • --flush: Removes all entries from the table.


Flag Description
--csv Print the table in Comma/Character-Separated Values format. This is intended to be redirected into a .csv file.
--force Upload the entry even if overlapping occurs (See the next section).

Overlapping EAM entries

By default, EAMT entries are not allowed to overlap. You can use --force while --adding to override this property. When overlapping EAMT entries exist, Jool picks based on longest match prefix.

For example:

IPv4 Prefix IPv6 Prefix 2001:db8:aaaa::/120 2001:db8:bbbb::/125

Address matches better than, so it will get translated as 2001:db8:bbbb::1, not 2001:db8:aaaa::9.

Notice this creates assymetry. 2001:db8:aaaa::9 gets translated as, which in turn gets translated as 2001:db8:bbbb::1. Depending on your use case, this can break communication.

Overlapping EAMT entries exist to help EAM coexist with IVI. Other use cases might arise in the future.


Add a handful of mappings:

# jool_siit --eamt --add      2001:db8:aaaa::
# jool_siit --eamt --add   2001:db8:bbbb::b/128
# jool_siit --eamt --add  2001:db8:cccc::/124
# jool_siit --eamt --add 2001:db8:dddd::/64
# jool_siit --eamt --add 64:ff9b::/127

Display the new table:

$ jool_siit --eamt --display
64:ff9b::/127 -
2001:db8:dddd::/64 -
2001:db8:cccc::/124 -
2001:db8:bbbb::b/128 -
2001:db8:aaaa::/128 -
  (Fetched 5 entries.)

Dump the database on a CSV file:

$ jool_siit --eamt --display --csv > eamt.csv


Display the number of entries in the table:

$ jool_siit --eamt --count

Remove the first entry:

# jool_siit --eamt --remove 2001:db8:aaaa::

Empty the table:

# jool_siit --eamt --flush