| Where allowed to run: All environments (*ALL) Threadsafe: No |
Parameters Examples Error messages |
The Change TCP/IP Interface (CHGTCPIFC) command is used to change an existing interface in the Transmission Control Protocol/Internet Protocol (TCP/IP) configuration. The interfaces changed by the CHGTCPIFC command are logical interfaces. They are not physical interfaces. Each interface is associated with a line description. The line description is the physical connection from the system to the TCP/IP network.
The IBM i TCP/IP implementation supports multihoming. This allows either a single interface or multiple interfaces to be specified per line description. The system can appear as any one or combination of the following:
Notes:
Attention: Before attempting to start an X.25 interface, ensure that the remote system information (RSI) for non-DDN X.25 interfaces that use a permanent virtual circuit (PVC) is configured. Use the Add TCP/IP Remote System (ADDTCPRSI) command to do this. Incoming data from a remote system on the X.25 network is not processed unless an RSI entry for the PVC is configured on the X.25 interface before the interface is started.
Restrictions:
| Top |
| Keyword | Description | Choices | Notes |
|---|---|---|---|
| INTNETADR | Internet address | Character value, *IP4DHCP, *IP6SAC | Optional, Positional 1 |
| LIND | Line description | Name, *SAME, *LOOPBACK, *VIRTUALIP, *OPC | Optional, Positional 2 |
| SUBNETMASK | Subnet mask | Character value, *SAME, *HOST | Optional, Positional 3 |
| ADRPFXLEN | Address prefix length | 1-128, *SAME | Optional |
| ALIASNAME | Alias name | Simple name, *SAME, *NONE | Optional |
| LCLIFC | Associated local interface | Character value, *SAME, *NONE | Optional |
| TOS | Type of service | *SAME, *MINDELAY, *MAXTHRPUT, *MAXRLB, *MINCOST, *NORMAL | Optional |
| MTU | Maximum transmission unit | 576-16388, *SAME, *LIND | Optional |
| AUTOSTART | Autostart | *SAME, *YES, *NO | Optional |
| PVCLGLCHLI | PVC logical channel identifier | Values (up to 64 repetitions): Character value, *SAME, *NONE | Optional |
| IDLVCTTIMO | X.25 idle circuit timeout | 1-600, *SAME | Optional |
| MAXSVC | X.25 maximum virtual circuits | 0-64, *SAME | Optional |
| DDN | X.25 DDN interface | *SAME, *YES, *NO | Optional |
| BITSEQ | TRLAN bit sequencing | *SAME, *MSB, *LSB | Optional |
| IFCID | Interface ID | 0000000000000001-FFFFFFFFFFFFFFEF, *SAME, *LIND, *GEN | Optional |
| DADMAXTRN | DAD maximum transmits | 0-10, *SAME | Optional |
| PVYEXN | Privacy extensions | *SAME, *NO, *YES | Optional |
| PREFIFC | Preferred interfaces | Single values: *SAME, *NONE, *AUTO Other values (up to 10 repetitions): Character value |
Optional |
| PREFLIND | Preferred line descriptions | Single values: *SAME, *NONE Other values (up to 10 repetitions): Name |
Optional |
| TEXT | Text 'description' | Character value, *BLANK, *SAME | Optional |
| DHCPDYNDNS | DHCP dynamic DNS updates | *SAME, *NO, *YES | Optional |
| DHCPCLTID | DHCP client identifier | *SAME, *ADPTADR, *DHCPUNQID | Optional |
| IP6GENGLBA | IPv6 SAC generate global addr | *SAME, *YES, *NO | Optional |
| Top |
Specifies the IPv4 or IPv6 internet address.
An IPv4 internet address is specified in the form nnn.nnn.nnn.nnn, where nnn is a decimal number ranging from 0 through 255. An IPv4 internet address is not valid if it has a value of all binary ones or all binary zeros for the network identifier (ID) portion or the host ID portion of the address.
An IPv6 internet address is specified in the form x:x:x:x:x:x:x:x, where x is a hexadecimal number ranging from 0 through X'FFFF'. "::" may be used once in the IPv6 address to indicate one or more groups of 16 bits of zeros. The "::" may be used to compress leading, imbedded, or trailing zeros in the address.
An IPv6 internet address must be a unicast address and must not contain an imbedded IPv4 address (compatibility or mapped). If *VIRTUALIP is specified for LIND, the IPv6 address must be a global unicast address. If the IPv6 internet address is a link-local unicast address, the line description (LIND) parameter must also be specified in order to identify the interface being changed.
If the internet address is entered from a command line, the address must be enclosed in apostrophes.
Note: If an internet address is not provided with the command, the alias name must be provided and it will be used as the key value for the command.
| Top |
Specifies the name of the line description associated with the interface being changed. The line description must exist before the TCP/IP interface can be changed.
The following conditions are based on the type of line description:
TCP/IP can also be used on certain line descriptions attached to these network interfaces (NWI):
| Top |
Specifies the subnet mask, which is a bit mask that defines the part of the network where this IPv4 interface attaches. The mask is a 32-bit combination that is logically ANDed with the IPv4 internet address to determine a particular subnetwork. The bits of the mask set to the value one (1) determine the network and subnetwork portions of the address. The bits set to the value zero (0) determine the host portion of the address.
The bits that identify the subnetwork are not required to be adjacent in the address. However, if this subnet mask value is changed, it might invalidate or affect the routes using this interface. To prevent this, keep the subnet bits contiguous and located in the most significant bits of the host address.
Note: The network portion must be equal to one bits in the subnetmask. The host portion of an address must be at least two bits wide. This parameter is ignored if INTNETADR specifies an IPv6 address, *IP4DHCP, or *IP6SAC.
| Top |
Specifies the address prefix length in bits. The address prefix length specifies how much of the leftmost portion of an IPv6 address is the subnet prefix. This parameter applies only if INTNETADR is an IPv6 address.
| Top |
Specifies a name that can be used in place of the internet address. The name must be unique among all of the interfaces on the system.
Note: If an internet address is not provided with the command, the alias name will be the key for the command. If an internet address is provided, the alias name can be changed from its current value.
| Top |
Use this parameter to associate the IPv4 interface being changed with an existing local IPv4 TCP/IP interface. This parameter is ignored if INTNETADR specifies an IPv6 address, *IP4DHCP, or *IP6SAC.
The associated local interface (LCLIFC) is used to allow 'transparent subnetting' (also known as 'Proxy Arp') between the associated interfaces, to define unnumbered networks, or for load balancing.
Conditions for using the LCLIFC for unnumbered networks:
Conditions for using LCLIFC for transparent subnetting:
Condition for using the LCLIFC for load balancing:
Note: LCLIFC can only be used to associate this interface with another interface that is already added. Once associated, the interface specified in LCLIFC and this interface must both be started in order for them to work together properly.
| Top |
Specifies the type of service to be used. The type of service specifies how the internet hosts and routers should make trade-offs between throughput, delay, reliability, and cost. This parameter is ignored if INTNETADR specifies an IPv6 address, *IP4DHCP, or *IP6SAC.
| Top |
Specifies the maximum size (in bytes) of IP datagrams that can be transmitted through this interface. A datagram is a basic unit of information passed over an internet network. For an IPv4 interface, the minimum MTU value is 576 bytes. For an IPv6 interface, the minimum MTU value is 1280 bytes. If this value is changed it affects the MTUs of routes using this interface.
Notes:
| Top |
Specifies whether the interface is automatically started when the TCP/IP stack is activated by the Start TCP/IP (STRTCP) command.
Note: The Start TCP/IP Interface (STRTCPIFC) command can be used to start an interface after TCP/IP has been started.
| Top |
Specifies the permanent virtual circuit (PVC) logical channel identifiers that can be established on an X.25 interface by the TCP/IP protocol stack. Up to 64 unique channel identifiers may be specified. These logical channel identifiers must be specified in the X.25 line description.
With this parameter the line can be shared with other communications software, such as Systems Network Architecture (SNA). It prevents the TCP/IP protocol stack from monopolizing the PVCs defined for the line.
Notes:
| Top |
Specifies the duration (in seconds) that TCP/IP waits before clearing an idle virtual circuit established on an X.25 link. Clearing an idle virtual circuit frees resources on the network. TCP/IP automatically reestablishes virtual circuits when required to send or receive data. Virtual circuits are transparent to a TCP/IP client and have no noticeable effect on TCP connections.
Note: This parameter is valid only for switched virtual circuits (SVCs) on an interface defined on an X.25 line description. It is not valid for permanent virtual circuits (PVCs).
| Top |
Specifies the maximum number of concurrent switched virtual circuits (SVC) that can be established on an X.25 interface by the TCP/IP protocol stack.
With this parameter the line can be shared with other communications software such as Systems Network Architecture (SNA). It prevents the TCP/IP protocol stack from monopolizing the SVCs defined for the line. This parameter is valid only for an interface defined on an X.25 line description.
Note: The sum of the maximum switched virtual circuits (MAXSVC) and the number of PVCs cannot exceed 64.
| Top |
Specifies whether the X.25 interface is connected to the Defense Data Network (DDN). The DDN network is a special type of X.25 network used by TCP/IP customers with special security needs.
Note: This parameter is valid only for switched virtual circuits (SVCs) on an interface defined on an X.25 line description. It is not valid for permanent virtual circuits (PVCs).
Warning:
If multiple interfaces are specified to the same X.25 network, the DDN value should be equal for all of those interfaces. This is not enforced by the ADDTCPIFC or CHGTCPIFC commands.
If the X.25 network is on the DDN network, do not define the remote system information for any of the remote systems on the network. The remote system information for the DDN X.25 network is determined from the destination IP address.
| Top |
Specifies the order, most or least significant bit first, in which the Address Resolution Protocol (ARP) places the bits in the hardware address. This parameter is valid only for a token-ring local area network (TRLAN) line.
Note: All interfaces defined to a single token-ring line must have the same BITSEQ value. This is checked to ensure consistent values.
| Top |
Specifies the interface ID portion of the IPv6 address(es) generated when INTNETADR is *IP6SAC. The interface ID is the low-order 64 bits of an IPv6 address created as a result of IPv6 stateless address auto-configuration.
| Top |
Specifies the maximum number of neighbor solicitation messages to send for IPv6 duplicate address detection (DAD). This parameter applies only if INTNETADR is an IPv6 address or *IP6SAC.
| Top |
Specifies whether privacy extensions are to be used for IPv6 stateless address auto-configuration. This parameter applies only when INTNETADR is *IP6SAC.
Note: Privacy extensions are not supported for communications resource types 2743, 2838, and 2849. If the line description associated with this interface specifies a resource name that is associated with one of these resource types, PVYEXN must be *NO.
| Top |
Specifies a list of preferred IPv4 interfaces that are to be used with the IPv4 interface being changed for proxy Address Resolution Protocol (ARP) agent selection. The IPv4 interface being changed must have a LIND value of *VIRTUALIP or specify a LIND for a virtual Ethernet line. Up to 10 associated interfaces may be specified in order of preference -- the first being the most preferred, the second the next preferred, etc. Each associated interface must be a standard IPv4 interface, not a virtual interface.
Single values
Other values (up to 10 repetitions)
| Top |
Specifies a list of preferred line descriptions that are to be used with the IPv6 interface being changed for virtual IP address (VIPA) proxy Neighbor Discovery agent selection. The IPv6 interface being changed must have a LIND of *VIRTUALIP. Up to 10 line descriptions may be specified in order of preference -- the first being the most preferred, the second the next preferred, etc. Each line description must be used by at least one IPv6 interface.
Single values
Other values (up to 10 repetitions)
| Top |
Specifies text that briefly describes the interface.
| Top |
Specifies whether the DHCP server should update the client's records in the Domain Name Server (DNS). This parameter is ignored unless the INTNETADR parameter is *IP4DHCP or *IP6SAC.
| Top |
Specifies whether the DHCP client uses an identifier based on the hardware address of the interface or the system-wide DHCP unique identifier specified by the TCP/IP attributes. This parameter is ignored unless the INTNETADR parameter is *IP4DHCP.
| Top |
Specifies whether IPv6 Stateless Address Auto-configuration (SAC) will generate global addresses for this interface. This parameter is ignored unless the INTNETADR parameter is *IP6SAC.
| Top |
Example 1: Changing Autostart Value
CHGTCPIFC INTNETADR('130.14.3.5') AUTOSTART(*NO)
Assuming that an interface identified by 130.14.3.5 exists, this command changes the autostart value from *YES to *NO. The interface is not automatically started when the STRTCP command is entered.
Example 2: Changing MAXSVC and IDLVCTTIMO
CHGTCPIFC INTNETADR('8.77.0.21') INDLVCTTIMO(45) MAXSVC(15)
This command changes the idle virtual circuit time-out to 45 seconds and the maximum number of concurrent SVCs allowed to be used by TCP/IP on this interface to 15.
Example 3: Change an Interface for a Twinax Line that is Using an Associated Local Interface
CHGTCPIFC INTNETADR('199.1.1.99') LCLIFC('199.1.1.1')
This command will change the TCP/IP interface for the twinax line named TDLCLINE. This interface will be associated with local interface 199.1.1.1. This means that the devices attached to twinax line 199.1.1.99 can take advantage of 'appearing' to be on the same network as the local 199.1.1.1 interface (transparent subnetting). No special routing is required to ensure packets from the twinax connnected hosts can travel to the local 199.1.1.0 network. Also, hosts on the 199.1.1.0 network can also reach the twinax hosts without any additional routing on the host systems.
Example 4: Changing ALIASNAME
CHGTCPIFC INTNETADR('132.15.7.32') ALIASNAME(TEST_NETWORK)
This command changes the alias name for this interface to TEST_NETWORK.
Example 5: Changing the interface using the ALIASNAME
CHGTCPIFC ALIASNAME(TEST_NETWORK) AUTOSTART(*YES)
This command changes the auto start value for the interface named TEST_NETWORK.
Example 6: Changing an IPv4 Virtual Interface
CHGTCPIFC INTNETADR('192.168.2.1')
PREFIFC('192.168.2.2' '192.168.2.3')
This command changes virtual IPv4 interface 192.168.2.1 to have two interfaces as preferred IPv4 interfaces. Interface 192.168.2.2 is preferred over 192.168.2.3. Interface 192.168.2.1 was previously added specifying a LIND value of *VIRTUALIP.
Example 7: Changing an IPv6 Virtual Interface
CHGTCPIFC INTNETADR('1234::5678')
PREFLIND(ETHLINE3 ETHLINE1 ETHLINE2)
This command changes virtual IPv6 interface 1234::5678 to have three line descriptions to be used for VIPA proxy Neighbor Discovery agent selection. Line description ETHLINE3 is preferred over ETHLINE1 and ETHLINE2, and ETHLINE1 is preferred over ETHLINE2.
| Top |
*ESCAPE Messages
| Top |