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Posts in Networking
Assigning static IP addresses to Fedora Core hosts
I built a Fedora Core 10 host this weekend, and configured it to use DHCP to retrieve its IP address and network configuration during installation. Once the host was built, I decided to update the ifcfg-eth0 file to use static IP addresses. Here is the configuration I added to /etc/sysconfig/network-scripts/ifcfg-eth0 to assign the static IP address 192.168.1.50 to the server: I copied this configuration from another Fedora Core host on my network, but wanted to paste it here for future reference.
$ read more →Viewing and changing network device properties on Solaris hosts
Project brussels from the OpenSolaris project revamped how link properties are managed, and their push to get rid of ndd and device-specific properties is now well underway! Link properties are actually pretty cool, and they can be displayed with the dladm utilities "show-linkprop" option: As you can see in the above output, the typical speed, duplex, mtu and flowctrl properties are listed. In addition to those, the "maxbw" and "cpus" properties that were introduced with the recent crossbow putback are visible. The "maxbw" property is especially useful, since it allows you to limit how much bandwidth is available to an interface…
$ read more →Configuring VLAN interfaces on CentOS Linux hosts
I recently needed to configure a CentOS Linux host to use 802.1Q tagged queuing. This turned out to be super easy, and allowed me place the physical server on multiple layer-2 networks. To configure an 802.1Q interface, I first checked the ifcfg-eth0 script for the interface that was planning to participate in 802.1Q: Once I had the interface information, I created a ifcfg-vlan301 interface file with the VLAN number as well as the VLAN options: After the files were created, I used service to restart networking and everything came up smoothly. There are much better references on the Internet for Linux 802.1Q configuration, but I'm posting this here so I have a handy reference (and one I know works!).
$ read more →Determining the capabilities of a NIC on a Solaris host
There are a myriad of NIC chipsets in use by the major server vendors (Broadcom, Intel, NVidia, etc.), and each chipset typically contains a unique set of capabilities (e.g., hardware offload support, some amount of on board cache devoted to RX / TX rings, hardware flow classification, etc.). To see which capabilities a given NIC chipset supports, you can usually read through the technical white papers and engineering documents that were published when the chipset shipped. To find the NIC chipsets that are in use on a Solaris host, the kstat utility can be run with the the name of a network driver, the instance of the driver, and the "chipid" name: module: bge instance: 0 name: chipid class: net asic_rev 2416115712 bus_size 64 bit bus_speed fast bus_type PCI-X businfo 4746 cache_line_size 16 chip_type 5715 command 342 This will display a number of pieces of information, including the type of BUS in use, whether it is 32- or 64-bit, and the chipset version. In the output above, we can see that a 64-bit PCI express Broadcom model 5715 adapter is in use by the server…
$ read more →Stopping nfsmapid from querying DNS TXT records
With the introduction of NFSv4, user and group identifiers were changed to use the username@domain format. On Solaris hosts, the domain is determined using the following methods: The NFSMAPID_DOMAIN variable is checked in /etc/default/nfs DNS is queried for the_nfsv4idmapdomain TXT record The configured DNS domain is used The file /etc/defaultdomain is consulted If a site doesn't update the NFSMAPID_DOMAIN variable when deploying NFSv4, DNS will be queried for the domain to use. If the DNS server doesn't contain a_nfsv4idmapdomain TXT record, you will see failed queries similar to the following: This can of course pose a problem for large sites, since the DNS server will be inundated with queries for records that don't exist. If you want to stop these DNS queries from happening, you can add the domain to the NFSMAPID_DOMAIN variable in /etc/default/nfs…
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