This chapter describes various issues that may occur when using a Gigabit Ethernet network. It includes the following sections:
This section explains the following:
The Fiber-Optic and Copper Gigabit Ethernet boards have light-emitting diodes (LEDs) that indicate whether the board is configured correctly and connected to an active Ethernet, as discussed in the following sections.
Figure 1-2 shows the location of the two small LEDs on the Fiber-Optic Gigabit Ethernet board. Table 3-1 describes the functions of these LEDs.
Table 3-1. LEDs on the Fiber-Optic Gigabit Ethernet Board
LED | State | Purpose |
|---|---|---|
ACT | Blinking Off | Data detected No data detected |
LINK1000 | On Off | Good link No link: faulty cable, faulty connector, or communication mismatch |
During normal operation, the link LED is on; the data LED blinks whenever the board is receiving traffic.
The Copper Gigabit Ethernet board has four small LEDs, one for each port speed option (10 Mbps, 100 Mbps, and 1 Gbps). These LEDs indicate which link speed is active and the status of data transfer. Figure 1-3 shows the location of these LEDs. Table 3-2 describes the functions of these LEDs.
Table 3-2. LEDs on the Copper Gigabit Ethernet Board
LED | State | Purpose |
|---|---|---|
ACT | Blinking On Off | Brief bursts of data detected on the port Streams of data detected on the port No data detected on the port |
10 | On Off | Good 10-Mbps Ethernet link No 10-Mbps link; possible link at different speed, possible bad cable, bad connector, or configuration mismatch |
100 | On Off | Good 100-Mbps Fast Ethernet link No 100-Mbps link; possible link at different speed, possible bad cable, bad connector, or configuration mismatch |
1000 | On Off | Good Gigabit Ethernet link No 1000-Mbps link; possible link at different speed, possible bad cable, bad connector, or configuration mismatch |
The network interface name for the Fiber-Optic and Copper Gigabit Ethernet boards is tg<N>, where <N> is 0 for the first board, 1 for the second board (if installed), and so on. Use the commands in the example below to display the network interface names.
To verify that the operating system has located the Gigabit Ethernet board, enter the following:
% /bin/hinv |
A line similar to the following should appear:
Gigabit Ethernet: tg<N>, module 001c10, PCI bus 0 slot 1 |
where tg<N> is the number of the board, (for example, tg0).
To verify that the network interface is configured properly and is enabled, enter the following:
% /usr/etc/netstat -ina |
Columns with the following headings should appear:
Name Mtu Network Address |
In the Name column, the tg number should appear. If it is followed by an asterisk (*), the interface is disabled for some reason.
In the Mtu column, the size of the current Maximum Transmission Unit (MTU) should appear. The MTU size is set via the -mtu switch of the ifconfig command. If no size is specified by the -mtu switch, the board defaults to an MTU size of 1500.
In the Network column, the IP network address should appear.
In the Address column, the canonical MAC address of the Gigabit Ethernet board should appear, which looks similar to
08:00:69:0b:e0:41 |
In this address, the organizationally unique identifier (OUI) of the board vendor is represented by the first three sets of numbers (for example, 08:00:69). The last three sets vary, depending on the system.
See also the netstat(1) man page for more details.
In the unlikely event that you need to reset the Fiber-Optic or Copper Gigabit Ethernet board, enter the following:
ifconfig tg<N> down ifconfig tg<N> up |
where <N> is the board number.
The configuration of your Gigabit Ethernet board is controlled by a number of parameters, which are discussed in the following sections:
To change the configuration of your board, use the tgconfig utility. For more information, enter man tgconfig at the command prompt.
The autonegotiation parameter controls the negotiation process between the Gigabit Ethernet board and its link partner. If autonegotiation is enabled in the etc/config/tgconfig.options file, each link partner will advertise which link speeds and duplex modes it can support. Table 3-3 describes the settings for the autoneg parameter.
Table 3-3. Autonegotiation Settings
Setting | Result |
|---|---|
ON (default) | The Gigabit Ethernet board will attempt to negotiate the link speed and duplex mode with its link partner. The board with initiate and respond to autonegotiation requests. Note that the Gigabit standard requires autonegotiation. |
OFF | The board with not initiate or respond to autonegotiation requests. Note that autonegotiation should only be disabled if the board is being linked to a non-gigabit device that does not support autonegotiation. Also, note that the link_pref parameter cannot be set to AUTO or 10-100 when autonegotiation is disabled. |
The link_pref parameter controls the link speed and duplex mode of the connection. Table 3-4 describes the settings for the link_pref parameter.
Table 3-4. Link Preference Settings
Setting | Result | Board Version |
|---|---|---|
AUTO (Default) | The link speed and duplex setting are determined by the autonegotiation process. | All |
10_100 | Link speeds are limited to 10 or 100 Mbps and full- or half- duplex. | Copper |
1000_FULL | When autonegotiation is enabled, the card will only advertise at 1000 Mbps full-duplex. With autonegotiation disabled, the card is locked down to 1000 Mbps full-duplex. | Copper |
1000_HALF | When autonegotiation is enabled, the card will only advertise at 1000 Mbps half-duplex. With autonegotiation disabled, the card is locked down to 1000 Mbps half-duplex. | Copper |
100_FULL | When autonegotiation is enabled, the card will only advertise at 100 Mbps full-duplex. With autonegotiation disabled, the card is locked down to 100 Mbps full-duplex. | Copper |
100_HALF | When autonegotiation is enabled, the card will only advertise at 100 Mbps half-duplex. With autonegotiation disabled, the card is locked down to 100 Mbps half-duplex. | Copper |
10_FULL | When autonegotiation is enabled, the card will only advertise at 10 Mbps full-duplex. With autonegotiation disabled, the card is locked down to 10 Mbps full-duplex. | Copper |
10_HALF | When autonegotiation is enabled, the card will only advertise at 10 Mbps half-duplex. With autonegotiation disabled, the card is locked down to 10 Mbps half-duplex. | Copper |
The flow_cntrl parameter controls the sending and receiving of 802.3x XON/XOFF PAUSE frames for flow control. The possible settings are as follows:
ON (Default): If the autonegotiation parameter is enabled, the board will advertise flow control capability. If autonegotiation is disabled, the board will force flow control to be enabled.
OFF: If the autonegotiation parameter is enabled, the board will not advertise flow control capability. If autonegotiation is disabled, the board will force flow control to be disabled.
The Gigabit Ethernet board can reduce network overhead related to interrupt handling. It does this by sending and receiving multiple Ethernet frames between driver interrupts. This is referred to as “interrupt coalescence.” Interrupts are generated whenever a certain number of packets are transmitted or received.
The following parameters control transmit interrupts:
coal_frames_tx
This parameter controls the number of frames that are transmitted between interrupts.
coal_usecs_tx
This parameter controls the number of microseconds between interrupts.
If both of these parameters are set to zero, which is the default, the driver will use predetermined values that are based on the Maximum Transmission Unit (MTU) size. Transmit interrupts can usually be delayed without sacrificing performance, so the default settings should not usually be changed.
The following parameters control receive interrupts:
coal_frames_rxa
This parameter controls the number of frames that are received between interrupts.
coal_usecs_rx
This parameter controls the number of microseconds between interrupts.
If both of these parameters are set to zero, which is the default, the driver will use predetermined values that are based on the Maximum Transmission Unit (MTU) size. These default values were chosen to optimize overall throughput and should probably not be changed in most systems.
The Maximum Transmission Unit (MTU) size is controlled by the “mtu <mtu_size>” switch of the ifconfig command. There are two possible MTU sizes: 1500 bytes (standard-size Ethernet frames) and 9000 bytes (“jumbo” Ethernet frames). Configuring the Gigabit Ethernet board to use jumbo frames will increase network bandwidth and reduce CPU load, but only if the network supports jumbo frames. To configure the MTU size, follow these steps:
At the command prompt, enter the following command:
netstat -i |
The output will display information about the network adapters currently installed in the system, as shown below:
Name Mtu Network Address Ipkts Ierrs Opkts Oerrs Coll tg1 1500 10.50.1 system.name 0 0 1 0 0 |
To bring down the Gigabit Ethernet board, enter the following command:
ifconfig tg<n> down |
where <n> is the number of the board.
To change the MTU size of the Gigabit Ethernet adapter and restart the board, enter the following command:
ifconfig tg<n> mtu 9000 up |
where <n> is the number of the board.
Enter the following command to verify that the MTU size has been changed:
netstat -i |
The output should look similar to the following:
Name Mtu Network Address Ipkts Ierrs Opkts Oerrs Coll tg1 9000 10.50.1 system.name 0 0 3 0 0 |