Network attributes

Find instructions for managing network attributes.

You can use several of the Virtual I/O Server commands, including chdev, mkvdev, and cfglnagg, to change device or network attributes. This section defines attributes that can be modified.

Ethernet Attributes

You can modify the following Ethernet attributes:

Attribute	Description
Maximum Transmission Unit (mtu)	Specifies maximum transmission unit (MTU). This value can be any number from 60 through 65535, but it is media dependent.
Interface State (state)	detach Removes an interface from the network interface list. If the last interface is detached, the network interface driver code is unloaded. To change the interface route of an attached interface, that interface must be detached and added again with the chdev -dev Interface -attr state=detach command. down Marks an interface as inactive, which keeps the system from trying to transmit messages through that interface. Routes that use the interface, however, are not automatically disabled. (chdev -dev Interface -attr state=down) up Marks an interface as active. This parameter is used automatically when setting the first address for an interface. It can also be used to enable an interface after the chdev -dev Interface -attr state=up command.
Network Mask (netmask)	Specifies how much of the address to reserve for subdividing networks into subnetworks. The mask includes both the network part of the local address and the subnet part, which is taken from the host field of the address. The mask can be specified as a single hexadecimal number beginning with 0x, in standard Internet dotted-decimal notation. In the 32-bit address, the mask contains bits with a value of 1 for the bit positions reserved for the network and subnet parts, and a bit with the value of 0 for the bit positions that specify the host. The mask contains the standard network portion, and the subnet segment is contiguous with the network segment.

Attribute

Description

Maximum Transmission Unit (mtu)

Specifies maximum transmission unit (MTU). This value can be any number from 60 through 65535, but it is media dependent.

Interface State (state)

detach: Removes an interface from the network interface list. If the last interface is detached, the network interface driver code is unloaded. To change the interface route of an attached interface, that interface must be detached and added again with the chdev -dev Interface -attr state=detach command.
down: Marks an interface as inactive, which keeps the system from trying to transmit messages through that interface. Routes that use the interface, however, are not automatically disabled. (chdev -dev Interface -attr state=down)
up: Marks an interface as active. This parameter is used automatically when setting the first address for an interface. It can also be used to enable an interface after the chdev -dev Interface -attr state=up command.

Network Mask (netmask)

Specifies how much of the address to reserve for subdividing networks into subnetworks.

The mask includes both the network part of the local address and the subnet part, which is taken from the host field of the address. The mask can be specified as a single hexadecimal number beginning with 0x, in standard Internet dotted-decimal notation.

In the 32-bit address, the mask contains bits with a value of 1 for the bit positions reserved for the network and subnet parts, and a bit with the value of 0 for the bit positions that specify the host. The mask contains the standard network portion, and the subnet segment is contiguous with the network segment.

Shared Ethernet Adapter attributes

You can modify the following Shared Ethernet Adapter attributes:

Attribute	Description
PVID (pvid)	Specifies the PVID to use for the Shared Ethernet Adapter.
PVID adapter (pvid_adapter)	Specifies the default virtual adapter to use for non-VLAN tagged packets.
Physical adapter (real_adapter)	Specifies the physical adapter associated with the Shared Ethernet Adapter.
Thread (thread)	Activates or deactivates threading on the Shared Ethernet Adapter. Activating this option adds approximately 16% to 20% more overhead for MTU 1500 streaming and 31% to 38% more overhead for MTU 9000. The threading option has more overhead at lower workloads due to the threads being started for each packet. At higher workload rates, such as full duplex or the request/response workloads, the threads can run longer without waiting and being redispatched. Threaded mode should be used when Virtual SCSI will be run on the same Virtual I/O Server partition as Shared Ethernet Adapter. Threaded mode helps ensure that Virtual SCSI and the Shared Ethernet Adapter can share the processor resource appropriately. However, threading adds more instruction path length, which uses additional processor cycles. If the Virtual I/O Server partition will be dedicated to running shared Ethernet devices (and associated virtual Ethernet devices) only, the adapters should be configured with threading disabled. You can enable or disable threading using the -attr thread option of the mkvdev command. To enable threading, use the `-attr thread=1` option. To disable threading, use the `-attr thread=0` option. For example, the following command disables threading for Shared Ethernet Adapter `ent1`: mkvdev -sea ent1 -vadapter ent5 -default ent5 -defaultid 1 -attr thread=0
Virtual adapters (virt_adapter)	Lists the virtual Ethernet adapters associated with the Shared Ethernet Adapter.
TCP segmentation offload (largesend)	Enables TCP largesend capability (also known as segmentation offload) from logical partitions to the physical adapter. The physical adapter must be enabled for TCP largesend for the segmentation offload from the partition to the Shared Ethernet Adapter to work. Also, the partition must be capable of performing a largesend operation. On AIX®, largesend can be enabled on a partition using the ifconfig command. You can enable or disable TCP largesend using the -a largesend option of the chdev command. To enable it, use the '-a largesend=1' option. To disable it, use the '-a largesend=0' option. For example, the following command enables largesend for Shared Ethernet Adapter ent1: chdev -l ent1 -a largesend=1 By default the setting is disabled (largesend=0).
Jumbo frames (jumbo_frames)	Allows the interface configured over the Shared Ethernet Adapter to increase its MTU to 9000 bytes (the default is 1500). If the underlying physical adapter does not support jumbo frames and the jumbo_frames attribute is set to `yes`, then configuration fails. The underlying physical adapter must support jumbo frames. The Shared Ethernet Adapter automatically enables jumbo frames on its underlying physical adapter if jumbo_frames is set to `yes`. You cannot change the value of jumbo_frames at run time.
GARP VLAN Registration Protocol (GVRP) (`gvrp`)	Enables and disables GVRP on a Shared Ethernet Adapter.

Shared Ethernet Adapter failover attributes

You can modify the following Shared Ethernet Adapter failover attributes:

Attribute	Description
High availability mode (ha_mode)	Determines whether the devices participate in a failover setup. The default is `disabled`. Typically, a Shared Ethernet Adapter in a failover setup is operating in `auto` mode, and the primary adapter is decided based on which adapter has the highest priority (lowest numerical value). A shared Ethernet device can be forced into the standby mode, where it will behave as the backup device as long as it can detect the presence of a functional primary.
Control Channel (ctl_chan)	Sets the virtual Ethernet device that is required for a Shared Ethernet Adapter in a failover setup so that it can communicate with the other adapter. There is no default value for this attribute, and it is required when the ha_mode is not set to `disabled`.
Internet address to ping (netaddr)	Optional attribute that can be specified for a Shared Ethernet Adapter that has been configured in a failover setup. When this attribute is specified, a shared Ethernet device will periodically ping the IP address to verify connectivity (in addition to checking for link status of the physical devices). If it detects a loss of connectivity to the specified ping host, it will initiate a failover to the backup Shared Ethernet Adapter. This attribute is not supported when you use a Shared Ethernet Adapter with a Host Ethernet Adapter (HEA).

INET attributes

You can modify the following INET attributes:

Attribute	Description
Host Name (hostname)	Specify the host name that you want to assign to the current machine. When specifying the host name, use ASCII characters, preferably alphanumeric only. Do not use a period in the host name. Avoid using hexadecimal or decimal values as the first character (for example `3Comm`, where `3C` might be interpreted as a hexadecimal character). For compatibility with earlier hosts, use an unqualified host name of fewer than 32 characters. If the host uses a domain name server for name resolution, the host name must contain the full domain name. In the hierarchical domain naming system, names consist of a sequence of subnames that are not case-sensitive and that are separated by periods with no embedded blanks. The DOMAIN protocol specifies that a local domain name must be fewer than 64 characters, and that a host name must be fewer than 32 characters in length. The host name is given first. Optionally, the full domain name can be specified; the host name is followed by a period, a series of local domain names separated by periods, and finally by the root domain. A fully specified domain name for a host, including periods, must be fewer than 255 characters in length and in the following form: host.subdomain.subdomain.rootdomain In a hierarchical network, certain hosts are designated as name servers that resolve names into Internet addresses for other hosts. This arrangement has two advantages over the flat name space: resources of each host on the network are not consumed in resolving names, and the person who manages the system does not need to maintain name-resolution files on each machine on the network. The set of names managed by a single name server is known as its zone of authority.
Gateway (gateway)	Identifies the gateway to which packets are addressed. The Gateway parameter can be specified either by symbolic name or numeric address.
Route (route)	Specifies the route. The format of the Route attribute is: route=destination, gateway, [metric]. destination Identifies the host or network to which you are directing the route. The Destination parameter can be specified either by symbolic name or numeric address. gateway Identifies the gateway to which packets are addressed. The Gateway parameter can be specified either by symbolic name or numeric address. metric Sets the routing metric. The default is 0 (zero). The routing metric is used by the routing protocol (the routed daemon). Higher metrics have the effect of making a route less favorable. Metrics are counted as additional hops to the destination network or host.

Attribute

Description

Host Name (hostname)

Specify the host name that you want to assign to the current machine.

When specifying the host name, use ASCII characters, preferably alphanumeric only. Do not use a period in the host name. Avoid using hexadecimal or decimal values as the first character (for example 3Comm, where 3C might be interpreted as a hexadecimal character). For compatibility with earlier hosts, use an unqualified host name of fewer than 32 characters.

If the host uses a domain name server for name resolution, the host name must contain the full domain name.

In the hierarchical domain naming system, names consist of a sequence of subnames that are not case-sensitive and that are separated by periods with no embedded blanks. The DOMAIN protocol specifies that a local domain name must be fewer than 64 characters, and that a host name must be fewer than 32 characters in length. The host name is given first. Optionally, the full domain name can be specified; the host name is followed by a period, a series of local domain names separated by periods, and finally by the root domain. A fully specified domain name for a host, including periods, must be fewer than 255 characters in length and in the following form:

host.subdomain.subdomain.rootdomain

In a hierarchical network, certain hosts are designated as name servers that resolve names into Internet addresses for other hosts. This arrangement has two advantages over the flat name space: resources of each host on the network are not consumed in resolving names, and the person who manages the system does not need to maintain name-resolution files on each machine on the network. The set of names managed by a single name server is known as its zone of authority.

Gateway (gateway)

Identifies the gateway to which packets are addressed. The Gateway parameter can be specified either by symbolic name or numeric address.

Route (route)

Specifies the route. The format of the Route attribute is: route=destination, gateway, [metric].

destination: Identifies the host or network to which you are directing the route. The Destination parameter can be specified either by symbolic name or numeric address.
gateway: Identifies the gateway to which packets are addressed. The Gateway parameter can be specified either by symbolic name or numeric address.
metric: Sets the routing metric. The default is 0 (zero). The routing metric is used by the routing protocol (the routed daemon). Higher metrics have the effect of making a route less favorable. Metrics are counted as additional hops to the destination network or host.

Adapter attributes

You can modify the following adapter attributes. The attribute behavior can vary, based on the adapter and driver you have.

Attribute	Adapters/Drivers	Description
Media Speed (media_speed)	2-Port 10/100/1000 Base-TX PCI-X Adapter 10/100/1000 Base-T Ethernet PCI-X Adapter Device Driver	The media speed attribute indicates the speed at which the adapter attempts to operate. The available speeds are 10 Mbps half-duplex, 10 Mbps full-duplex, 100 Mbps half-duplex, 100 Mbps full-duplex and autonegotiation, with a default of autonegotiation. Select auto-negotiate when the adapter should use autonegotiation across the network to determine the speed. When the network will not support autonegotiation, select the specific speed. 1000 MBps half and full duplex are not valid values. According to the IEEE 802.3z specification, gigabit speeds of any duplexity must be autonegotiated for copper (TX)-based adapters. If these speeds are desired, select auto-negotiate.
Media Speed (media_speed)	2-Port Gigabit Ethernet-SX PCI-X Adapter Gigabit Ethernet-SX PCI-X Adapter Device Driver	The media speed attribute indicates the speed at which the adapter attempts to operate. The available speeds are 1000 Mbps full-duplex and autonegotiation. The default is autonegotiation. Select auto-negotiate when the adapter should use autonegotiation across the network to determine the duplexity. When the network does not support autonegotiation, select 1000 Mbps full-duplex.
Media Speed (media_speed)	10/100 Mbps Ethernet PCI Adapter Device Driver	The media speed attribute indicates the speed at which the adapter attempts to operate. The available speeds are 10 Mbps half-duplex, 10 Mbps full-duplex, 100 Mbps half-duplex, 100 Mbps full-duplex and autonegotiation, with a default of autonegotiation. When the adapter should use autonegotiation across the network to determine the speed, select autonegotiate. When the network will not support autonegotiation, select the specific speed. If autonegotiation is selected, the remote link device must also be set to autonegotiate to ensure the link works correctly.
Media Speed (media_speed)	10/100/1000 Base-T Ethernet PCI adapter Gigabit Ethernet-SX PCI Adapter Device Driver	The media speed attribute indicates the speed at which the adapter attempts to operate. The available speeds are 10 Mbps half-duplex, 10 Mbps full-duplex, 100 Mbps half-duplex, 100 Mbps full-duplex and autonegotiation, with a default of autonegotiation. Select autonegotiate when the adapter should use autonegotiation across the network to determine the speed. When the network will not support autonegotiation, select the specific speed. For the adapter to run at 1000 Mbit/s, the autonegotiation setting must be selected. Note: For the Gigabit Ethernet-SX PCI Adapter, the only selection available is autonegotiation.
Enable Alternate Ethernet Address (use_alt_addr)		Setting this attribute to `yes` indicates that the address of the adapter, as it appears on the network, is the one specified by the Alternate Ethernet Address attribute. If you specify the `no` value, the unique adapter address written in a ROM on the adapter card is used. The default value is `no`.
Alternate Ethernet Address (alt_addr)		Allows the adapter unique address, as it appears on the LAN network, to be changed. The value entered must be an Ethernet address of 12 hexadecimal digits and must not be the same as the address of any other Ethernet adapter. There is no default value. This field has no effect unless the Enable Alternate Ethernet Address attribute is set to `yes` value, in which case this field must be filled in. A typical Ethernet address is 0x02608C000001. All 12 hexadecimal digits, including leading zeros, must be entered.
Enable Link Polling (poll_link)	10/100Mbps Ethernet PCI Adapter Device Driver	Select `no` to cause the device driver to poll the adapter to determine the status of the link at a specified time interval. The time interval value is specified in the Poll Link Time Interval field. If you select `no`, the device driver will not poll the adapter for its link status. The default value is `no`.
Poll Link Time Interval (poll_link_time)	10/100Mbps Ethernet PCI Adapter Device Driver	The amount of time, in milliseconds, between polls to the adapter for its link status that the device driver is allowed. This value is required when the Enable Link Polling option is set to `yes`. A value between 100 through 1000 can be specified. The incremental value is 10. The default value is 500.
Flow Control (flow_ctrl)	10/100/1000 Base-T Ethernet PCI-X Adapter Device Driver Gigabit Ethernet-SX PCI-X Adapter Device Driver 2-Port 10/100/1000 Base-TX PCI-X Adapter 2-Port Gigabit Ethernet-SX PCI-X Adapter Gigabit Ethernet-SX PCI Adapter Device Driver	This attribute specifies whether the adapter should enable transmit and receive flow control. The default value is `no`.
Transmit Jumbo Frames (jumbo_frames)	10/100/1000 Base-T Ethernet PCI-X Adapter Device Driver Gigabit Ethernet-SX PCI-X Adapter Device Driver 2-Port 10/100/1000 Base-TX PCI-X Adapter 2-Port Gigabit Ethernet-SX PCI-X Adapter Gigabit Ethernet-SX PCI Adapter Device Driver	Setting this attribute to `yes` indicates that frames up to 9018 bytes in length might be transmitted on this adapter. If you specify `no`, the maximum size of frames transmitted is 1518 bytes. Frames up to 9018 bytes in length can always be received on this adapter.
Checksum Offload (chksum_offload)	10/100/1000 Base-T Ethernet PCI-X Adapter Device Driver Gigabit Ethernet-SX PCI-X Adapter Device Driver 2-Port 10/100/1000 Base-TX PCI-X Adapter 2-Port Gigabit Ethernet-SX PCI-X Adapter Gigabit Ethernet-SX PCI Adapter Device Driver Virtual Ethernet adapters	Setting this attribute to `yes` indicates that the adapter calculates the checksum for transmitted and received TCP frames. If you specify `no`, the checksum will be calculated by the appropriate software. When a virtual Ethernet adapter has checksum offload enabled, the adapter advertises it to the Hypervisor. The Hypervisor tracks which virtual Ethernet adapters have checksum offload enabled and manages inter-partition communication accordingly. When network packets are routed through the Shared Ethernet Adapter, there is a potential for link errors. In this environment, the packets must traverse the physical link with a checksum. Communication works in the following way: When a packet is received from the physical link, the physical adapter verifies the checksum. If the packet's destination is a virtual Ethernet adapter with checksum offload enabled, the receiver does not have to perform checksum verification. A receiver that does not have checksum offload enabled will accept the packet after checksum verification. When a packet originates from a virtual Ethernet adapter with checksum offload enabled, it travels to the physical adapter without a checksum. The physical adapter will generate a checksum before sending the packet out. Packets originating from a virtual Ethernet adapter with checksum offload disabled generate the checksum at the source. To enable checksum offload for a Shared Ethernet Adapter, all constituent devices must have it enabled as well. The shared Ethernet device will fail if the underlying devices do not have the same checksum offload settings.
Enable Hardware Transmit TCP Resegmentation (large_send)	10/100/1000 Base-T Ethernet PCI-X Adapter Device Driver Gigabit Ethernet-SX PCI-X Adapter Device Driver 2-Port 10/100/1000 Base-TX PCI-X Adapter 2-Port Gigabit Ethernet-SX PCI-X Adapter Gigabit Ethernet-SX PCI Adapter Device Driver	This attribute specifies whether the adapter is to perform transmit TCP resegmentation for TCP segments. The default value is `no`.

Link Aggregation (EtherChannel) device attributes

You can modify the following Link Aggregation, or EtherChannel, attributes:

Attribute	Description
Link Aggregation adapters (adapter_names)	The adapters that currently make up the Link Aggregation device. If you want to modify these adapters, modify this attribute and select all the adapters that should belong to the Link Aggregation device. When you use this attribute to select all of the adapters that should belong to the Link Aggregation device, its interface must not have an IP address configured.
Mode (mode)	The type of channel that is configured. In standard mode, the channel sends the packets to the adapter based on an algorithm (the value used for this calculation is determined by the Hash Mode attribute). In round_robin mode, the channel gives one packet to each adapter before repeating the loop. The default mode is standard. The 8023ad mode enables the Link Aggregation Control Protocol (LACP) to negotiate the adapters in the Link Aggregation device with an LACP-enabled switch. If the Hash Mode attribute is set to anything other than default, this attribute must be set to standard or 8023ad. Otherwise, the configuration of the Link Aggregation device will fail.
Hash Mode (hash_mode)	If operating under standard or IEEE 802.3ad mode, the hash mode attribute determines how the outgoing adapter for each packet is chosen. Following are the different modes: `default`: uses the destination IP address to determine the outgoing adapter. `src_port`: uses the source TCP or UDP port for that connection. `dst_port`: uses the destination TCP or UDP port for that connection. `src_dst_port`: uses both the source and destination TCP or UDP ports for that connection to determine the outgoing adapter. You cannot use round-robin mode with any hash mode value other than default. The Link Aggregation device configuration will fail if you attempt this combination. If the packet is not TCP or UDP, it uses the default hashing mode (destination IP address). Using TCP or UDP ports for hashing can make better use of the adapters in the Link Aggregationdevice, because connections to the same destination IP address can be sent over different adapters (while still retaining the order of the packets), thus increasing the bandwidth of the Link Aggregation device.
Internet Address to Ping (netaddr)	This field is optional. The IP address that the Link Aggregation device should ping to verify that the network is up. This is only valid when there is a backup adapter and when there are one or more adapters in the Link Aggregation device. An address of zero (or all zeros) is ignored and disables the sending of ping packets if a valid address was previously defined. The default is to leave this field blank.
Retry Timeout (retry_time)	This field is optional. It controls how often the Link Aggregation device sends out a ping packet to poll the current adapter for link status. This is valid only when the Link Aggregation device has one or more adapters, a backup adapter is defined, and the Internet Address to Ping field contains a non-zero address. Specify the timeout value in seconds. The range of valid values is 1 to 100 seconds. The default value is 1 second.
Number of Retries (num_retries)	This field is optional. It specifies the number of lost ping packets before the Link Aggregation device switches adapters. This is valid only when the Link Aggregation device has one or more adapters, a backup adapter is defined, and the Internet Address to Ping field contains a non-zero address. The range of valid values is 2 to 100 retries. The default value is 3.
Enable Gigabit Ethernet Jumbo Frames (use_jumbo_frame)	This field is optional. To use this attribute, all of the underlying adapters, as well as the switch, must support jumbo frames. This will work only with a Standard Ethernet (en) interface, not an IEEE 802.3 (et) interface.
Enable Alternate Address (use_alt_addr)	This field is optional. Setting this to yes will enable you to specify a MAC address that you want the Link Aggregation device to use. If you set this option to no, the Link Aggregation device will use the MAC address of the first adapter.
Alternate Address (alt_addr)	If Enable Alternate Address is set to `yes`, specify the MAC address that you want to use. The address you specify must start with `0x` and be a 12-digit hexadecimal address.

VLAN attributes

You can modify the following VLAN attributes:

Attribute	Value
VLAN Tag ID (vlan_tag_id)	The unique ID associated with the VLAN driver. You can specify from 1 to 4094.
Base Adapter (base_adapter)	The network adapter to which the VLAN device driver is connected.