La commande 'pmtu' permet d'afficher/effacer les information relative à la découverte MTU.
La syntaxe de base est :
# pmtu display
pmtu Command
Purpose
Displays and deletes Path MTU discovery related information.
Syntax
pmtu [-inet6] display/[delete [-dst destination] [-gw gateway] ]
Description
The pmtu command is provided to manage the Path MTU information. The command can be used to display the Path
MTU table. By default the Ipv4 pmtu entries are displayed. Ipv6 pmtu entries can be displayed using the inet6
flag. This command also enables a root user to delete a pmtu entry with the pmtu delete command. The delete can
be based on destination, gateway, or both.
A pmtu entry gets added into the PMTU table when a route add occurs with an MTU value.
A network option, pmtu_expire, is provided to expire unused pmtu entries. The default value of pmtu_expire is
10 minutes.
Flags
Item
Description
-dst
Specifies the destination of the pmtu entry to be deleted.
-gw
Specifies the gateway of the pmtu entry to be deleted.
-inet6
Specifies to display or delete Ipv6 pmtu entry.
Exit Status
Item
Description
0
The command completed successfully.
1
An error occurred.
Security
Attention RBAC users and Trusted AIX users: This command can perform privileged operations. Only privileged
users can run privileged operations. For more information about authorizations and privileges, see Privileged
Command Database in Security. For a list of privileges and the authorizations associated with this command, see
the lssecattr command or the getcmdattr subcommand.
Examples
1 To display Ipv4 pmtu entries, type:
pmtu display
The output will look similar to the following:
dst gw If pmtu refcnt redisc_t exp
----------------------------------------------------------------------
192.168.5.5 192.168.10.33 en2 1500 1 0 0
The reference count signifies the number of current TCP and UDP applications using this pmtu entry.
The redisc_t entry signifies the amount of time that is elapsed since the last Path MTU discovery attempt.
The PMTU is rediscovered after every pmtu_rediscover_interval minutes. Its default value is 30 minutes and
can be changed using the no command.
The PMTU entry expiry is controlled by the network option pmtu_expire. Its default value is 10 minutes.
This value can be changed using the no command. A value of 0 does not expire any entries. The exp entry
signifies the expiry time. PMTU entries having more than zero refcnt have exp of 0. When the refcnt
becomes zero, the exp time increases every minute and the entry gets deleted when the exp variable becomes
equal to pmtu_expire.
2 To delete an entry based on destination, type:
pmtu delete -dst 192.168.5.5
3 To display Ipv6 , type:
pmtu -inet6 display
Output will look similar to the following:
dst gw If pmtu refcnt redisc_t exp
-----------------------------------------------------------------------
fe80::204:acff:fee4:ab3b :: lo0 16896 2 2 0
Location
/usr/sbin/pmtu
Files
Item
Description
/usr/sbin/pmtu
Contains the pmtu command. xxxx
