Category: Cisco Switch
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Basic VTP
VTP stands for VLAN Trunk Protocol. VTP is used to propagate VLAN cconfiguration. VTP advertisements are multicasted. They are sent every 5 minutes or whenever there is a change in VLAN configuration. VTP revision number is included in these advertisements. Whenever a client receives a VTP advertisement with a higher revision number, the client will […]
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Basic DHCP Configuration
This is a simple DHCP configuration on a Layer 3 Switch: SW1(config)# ip dhcp excluded-address 10.10.10.1 SW1(config)# ip dhcp pool VLAN20POOL SW1(dhcp-config)# network 10.10.10.0 255.255.255.0 SW1(dhcp-config)# default-router 10.10.10.1 SW1(dhcp-config)# lease 2 Lease is in hours. Default-router IP indicates the default hop for the 10.10.10.0/24 network. The excluded-address will not be available to the DHCP client […]
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Cisco Nexus – Ping Sweep
The following script can be utilized to execute a ping sweep of a /24 network on Cisco Nexus switch. This has been tested and verified on Cisco Nexus 7K running 6.2.8a code version. Actual script: tclsh for {set i 1} {$i < 255} {incr i} { cli “ping 192.168.1.$i count 2 time 1 vrf VRF_A” […]
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Ansible – Config Generator III
For Part I & Part II of this series. The goal of this playbook is to be able to generate unique configuration for each switch. In this case, we are configuring a port to work as an access-port for a specific vlan. The port and vlan variable is different for each switch. config-gen.yml — – […]
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Identifying the Right Module – Cisco Nexus
N7K.LON# locator-led ? chassis Blink chassis led fan Blink Fan led module Blink module led powersupply Blink powersupply led xbar Xbar When you are in a remote location and the data center tech can’t identify the right module, “locator-led” command in Nexus 7000 can be used to identify the right […]
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Automating Cisco Switch Changes
Recently, I was involved in a project to re-architect the VLANs for 1000+ Servers. The idea was to move about 1000+ servers to their new VLANs in batches of about 250 servers. This process involved creating: New VLANs Configuring the ports of multiple switches Each server was dual-homed to 2 switches (odd & even switches – […]