Category Archives: Networking

JunOS : Alarm Management Ethernet Link Down

Having the red alarm led on but nothing is wrong with your JunOS powered Juniper device? First, look out what alarm is triggered by issuing the following command :

If absolutely nothing is really wrong, you will see the following alarm : Alarm time Class Description 2016-01-20 07:11:59 UTC Major Management Ethernet Link Down… Read More »

IOS : Extended VLAN(s) not allowed in current VTP mode

Having the following output message while trying to create a VLan outside higher than 1000 on your Cisco device?

This mean that you are running VTP mode 1 or 2, which only support VLan range between 1 – 1000. To be able to create anything outside of that scope, you need to run VTP… Read More »

JunOS : Packet loss (ICMP drop) observed with rapid pings

You probably noticed that rapid pings toward a JunOS device result in a loss of packet as the example shown below. In our case we are issuing the ping from a Cisco router : Sending 100, 500-byte ICMP Echos to, timeout is 2 seconds: Packet sent with a source address of .!!!!!!!!!.!!!!!!!!!.!!!!!!!!!.!!!!!!!!!.!!!!!!!!!.!!!!!!!!!.!!!!!!!!! .!!!!!!!!!.!!!!!!!!!.!!!!!!!!!… Read More »

Networking : DWDM channels reference chart

Here is a chart for the various DWDM optic channels below. Wavelenght band overview : O-Band : 1270nm to 1370nm E-Band : 1371nm to 1470nm S-Band : 1471nm to 1530nm C-Band : 1531nm to 1570nm L-Band : 1571nm to 1611nm Channel Wavelength (nm) Frequency (THz) 72   (DWDM Channel C72) 1520,25 197,20 71   (DWDM… Read More »

IOS : Configuring the out-of-band on Cisco router

If you have a Cisco ASR or smaller service router, you probably noticed that the device have a dedicated management interface. This special interface is a mapped to a Vritual Routing and Forwarding (VRF) instance. VRF allow multiple routing tables to coexist within the same router. You will first ensure that you have the VRF… Read More »

JunOS : Change a EX4200 from linecard to routing-engine

If you have a Ex4200 unit in hand that was pulled out from a virtual chassis stack, configured as linecard (LC), you may want to convert it back to “routing-engine” (RE) for future usage. I would suggest first to reset the unit to factory default (in CLI mode) :

Apply the change :

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FabricOS : How to remotely backup your Brocade FC switch configuration

Here is how to remotely copy your Brocade device running FabricOS to a remote TFTP server. To copy the currently running configuration :

To copy the configuration saved to the flash memory :

To restore the remote config to your device :