- Jumbo Frames System Requirement
- -------------------------------
-
- Memory allocation failures have been observed on Linux systems with 64 MB
- of RAM or less that are running Jumbo Frames. If you are using Jumbo
- Frames, your system may require more than the advertised minimum
- requirement of 64 MB of system memory.
-
- Performance Degradation with Jumbo Frames
- -----------------------------------------
-
- Degradation in throughput performance may be observed in some Jumbo frames
- environments. If this is observed, increasing the application's socket
- buffer size and/or increasing the /proc/sys/net/ipv4/tcp_*mem entry values
- may help. See the specific application manual and
- /usr/src/linux*/Documentation/
- networking/ip-sysctl.txt for more details.
-
- Jumbo frames on Foundry BigIron 8000 switch
- -------------------------------------------
- There is a known issue using Jumbo frames when connected to a Foundry
- BigIron 8000 switch. This is a 3rd party limitation. If you experience
- loss of packets, lower the MTU size.
-
- Multiple Interfaces on Same Ethernet Broadcast Network
- ------------------------------------------------------
-
- Due to the default ARP behavior on Linux, it is not possible to have
- one system on two IP networks in the same Ethernet broadcast domain
- (non-partitioned switch) behave as expected. All Ethernet interfaces
- will respond to IP traffic for any IP address assigned to the system.
- This results in unbalanced receive traffic.
-
- If you have multiple interfaces in a server, either turn on ARP
- filtering by entering:
-
- echo 1 > /proc/sys/net/ipv4/conf/all/arp_filter
- (this only works if your kernel's version is higher than 2.4.5),
-
- NOTE: This setting is not saved across reboots. The configuration
- change can be made permanent by adding the line:
- net.ipv4.conf.all.arp_filter = 1
- to the file /etc/sysctl.conf
-
- or,
-
- install the interfaces in separate broadcast domains (either in
- different switches or in a switch partitioned to VLANs).
-
- 82541/82547 can't link or are slow to link with some link partners
- -----------------------------------------------------------------
-
- There is a known compatibility issue with 82541/82547 and some
- low-end switches where the link will not be established, or will
- be slow to establish. In particular, these switches are known to
- be incompatible with 82541/82547:
-
- Planex FXG-08TE
- I-O Data ETG-SH8
-
- To workaround this issue, the driver can be compiled with an override
- of the PHY's master/slave setting. Forcing master or forcing slave
- mode will improve time-to-link.
-
- # make EXTRA_CFLAGS=-DE1000_MASTER_SLAVE=<n>
-
- Where <n> is:
-
- 0 = Hardware default
- 1 = Master mode
- 2 = Slave mode
- 3 = Auto master/slave
-
- Disable rx flow control with ethtool
- ------------------------------------
-
- In order to disable receive flow control using ethtool, you must turn
- off auto-negotiation on the same command line.
-
- For example:
-
- ethtool -A eth? autoneg off rx off
+Dropped Receive Packets on Half-duplex 10/100 Networks
+------------------------------------------------------
+If you have an Intel PCI Express adapter running at 10mbps or 100mbps, half-
+duplex, you may observe occasional dropped receive packets. There are no
+workarounds for this problem in this network configuration. The network must
+be updated to operate in full-duplex, and/or 1000mbps only.
+
+Jumbo Frames System Requirement
+-------------------------------
+Memory allocation failures have been observed on Linux systems with 64 MB
+of RAM or less that are running Jumbo Frames. If you are using Jumbo
+Frames, your system may require more than the advertised minimum
+requirement of 64 MB of system memory.
+
+Performance Degradation with Jumbo Frames
+-----------------------------------------
+Degradation in throughput performance may be observed in some Jumbo frames
+environments. If this is observed, increasing the application's socket
+buffer size and/or increasing the /proc/sys/net/ipv4/tcp_*mem entry values
+may help. See the specific application manual and
+/usr/src/linux*/Documentation/
+networking/ip-sysctl.txt for more details.
+
+Jumbo Frames on Foundry BigIron 8000 switch
+-------------------------------------------
+There is a known issue using Jumbo frames when connected to a Foundry
+BigIron 8000 switch. This is a 3rd party limitation. If you experience
+loss of packets, lower the MTU size.
+
+Allocating Rx Buffers when Using Jumbo Frames
+---------------------------------------------
+Allocating Rx buffers when using Jumbo Frames on 2.6.x kernels may fail if
+the available memory is heavily fragmented. This issue may be seen with PCI-X
+adapters or with packet split disabled. This can be reduced or eliminated
+by changing the amount of available memory for receive buffer allocation, by
+increasing /proc/sys/vm/min_free_kbytes.
+
+Multiple Interfaces on Same Ethernet Broadcast Network
+------------------------------------------------------
+Due to the default ARP behavior on Linux, it is not possible to have
+one system on two IP networks in the same Ethernet broadcast domain
+(non-partitioned switch) behave as expected. All Ethernet interfaces
+will respond to IP traffic for any IP address assigned to the system.
+This results in unbalanced receive traffic.
+
+If you have multiple interfaces in a server, either turn on ARP
+filtering by entering:
+
+ echo 1 > /proc/sys/net/ipv4/conf/all/arp_filter
+(this only works if your kernel's version is higher than 2.4.5),
+
+NOTE: This setting is not saved across reboots. The configuration
+change can be made permanent by adding the line:
+ net.ipv4.conf.all.arp_filter = 1
+to the file /etc/sysctl.conf
+
+ or,
+
+install the interfaces in separate broadcast domains (either in
+different switches or in a switch partitioned to VLANs).
+
+82541/82547 can't link or are slow to link with some link partners
+-----------------------------------------------------------------
+There is a known compatibility issue with 82541/82547 and some
+low-end switches where the link will not be established, or will
+be slow to establish. In particular, these switches are known to
+be incompatible with 82541/82547:
+
+ Planex FXG-08TE
+ I-O Data ETG-SH8
+
+To workaround this issue, the driver can be compiled with an override
+of the PHY's master/slave setting. Forcing master or forcing slave
+mode will improve time-to-link.
+
+ # make CFLAGS_EXTRA=-DE1000_MASTER_SLAVE=<n>
+
+Where <n> is:
+
+ 0 = Hardware default
+ 1 = Master mode
+ 2 = Slave mode
+ 3 = Auto master/slave
+
+Disable rx flow control with ethtool
+------------------------------------
+In order to disable receive flow control using ethtool, you must turn
+off auto-negotiation on the same command line.
+
+For example:
+
+ ethtool -A eth? autoneg off rx off
+
+Unplugging network cable while ethtool -p is running
+----------------------------------------------------
+In kernel versions 2.5.50 and later (including 2.6 kernel), unplugging
+the network cable while ethtool -p is running will cause the system to
+become unresponsive to keyboard commands, except for control-alt-delete.
+Restarting the system appears to be the only remedy.