Archives for November 2017

For some operations (for example, a yum install operation), Yum downloads the packages to install into the Yum cache. The cached packages are located in a subdirectory structure from /var/cache/yum that reflects the architecture, the distribution release, and the repository from where the packages were downloaded. After successful installation, the packages are deleted from the cache. To retain the cached packages, change the keepcache setting to 1 in the /etc/yum.conf file as follows: # vi … [Read more...] about How to clean YUM cache in CentOS / RHEL

IPv6 is enabled by default on RHEL / CenOS 7 systems. So, if IPv6 was disabled on the system intentionally, it can be re-enabled by the following either of the methods described below. 1. Enabling IPv6 in kernel module (requires reboot) 2. Enabling IPv6 using sysctl settings (no reboot required) Enabling IPv6 in kernel module (requires reboot) 1. Edit /etc/default/grub and change the value of kernel parameter ipv6.disable from 1 to 0 in line GRUB_CMDLINE_LINUX, e.g.: # cat … [Read more...] about How to enable IPv6 on CentOS / RHEL 7

At boot time (or whenever a network driver is loaded) interfaces are always assigned ethX style names by the kernel, where X is the lowest currently unused number starting with 0 (zero). The kernel has no ability to ensure drivers or interfaces are presented in the same order every time. Because of this, every time the system boots, it is necessary that some OS function ensures a given interface is always assigned the same name, so renaming of interfaces will be seen during the boot process. In … [Read more...] about CentOS / RHEL 7 : How to Enable the Old ethX Style Network Interfaces Names

A VLAN is a type of local area network that does not have its own dedicated physical infrastructure but instead uses another local area network to carry its traffic. The traffic is encapsulated so that a number of logically separate VLANs can be carried by the same physical LAN. With VLANs, you can create multiple distinct broadcast domains that are mutually isolated. With VLANs, network switches (not routers) create the broadcast domain. Each VLAN is identified by a VID (VLAN Identifier) in … [Read more...] about CentOS / RHEL 7 : How to configure VLAN Tagging using nmcli