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·          Private VLANs allow for additional security between devices in a common subnet. ·          Private edge VLANs can be configured to prevent connectivity between devices on access switches. ·          Private VLANs can be configured on the Catalyst 6000 and Catalyst 4000 series products. ·          Within a private VLAN, you can isolate devices to prevent connectivity between devices within the isolated VLAN. ·          Within a private VLAN, communities can be created to allow connection between some devices and to prevent them from communicating with others. ·          Promiscuous ports are mapped to private VLANs to allow for connectivity to VLANs outside of this network. Configuring Private VLANs Private VLANs provide a mechanism to control which devices can communicate within a single subnet. The private VLAN uses isolated and community secondary VLANs to control how devices communicate. The secondary VLANs are assigned to the primary VLAN, and ports are assigned to the

·          VTP sends messages between trunked switches to maintain VLANs on these switches in order to properly trunk. ·          VTP is a Cisco proprietary method of managing VLANs between switches and runs across any type of trunking mechanism. ·          VTP messages are exchanged between switches within a common VTP domain. ·          VTP domains must be defined or VTP disabled before a VLAN can be created. ·          Exchanges of VTP information can be controlled by passwords. ·          VTP manages only VLANs 2 through 1002. ·          VTP allows switches to synchronize their VLANs based on a configuration revision number. ·          Switches can operate in one of three VTP modes: server, transparent, or client. ·          VTP can prune unneeded VLANs from trunk links. Enabling VTP for Operation VTP exists to ensure that VLANs exist on the local VLAN database of switches in a trunked path. In addition to making sure the VLANs exist, VTP can further synchronize name settings and

                                 Normally, there are only two steps to setting up swap space,creating the partition and adding it to /etc/fstab. A typical fstab entry for a swap partition at /dev/hda6 would look like this: /dev/hda6 swap swap defaults 0 0 The next time you reboot, the initialization scripts will activate it automatically and there's nothing more to be done. However, if you want to make use of it right away, you'll need to activate it maually. As root, type: mkswap -f /dev/hda6 swapon /dev/hda6 Swap Files There might be times when you've run out of swap space and it is not practical to repartition a drive or add a new one. In this case, you can use a regular file in an ordinary partition. All you have to do is create a file of the size you want dd if=/dev/zero of=/var/my_swap bs=1024 count=131072 and activate it mkswap -f /var/my_swap swapon /var/my_swap This invocation creates a file called my_swap