root port vs designated port

It's probably easy to configure a switch to be a root switch. However, I've just realized that I missed something that I didn't understand the concept of what the root switch is.

There are two type of port, i.e.:

1. root port
2. designated port

Root port is a port telling us the path toward the root switch. While designated port is a port in direction of leaving away from the root switch.

By that definition, a root port will always a pair with designated port on its direct neighbor switch. And when a switch doesn't have any root port, it is definitely the root switch itself.

Day #1 - root bridge and VLAN path

It's about the time to start again the CCIE journey that I've skipped for quite a while. Unfortunately I have to start everything again from zero. The good news, I think that I can start quicker at this time. I used to spend more time on GNS3, but at this time this is not an issue anymore.

Well, today I've started with some bridging configuration. And I decided to write all notes here to help me remembering the lesson

Q: How to configure a switch to be root bridge
A: Here are some items that I noticed

• configure at the global configuration
• command is spanning-tree vlan XXX root primary

Q: how to prevent VLAN traverse to a switch?
A: Here are the noted points

• by restricting the VLAN on the interface level
• use switchport command

Enough for today. Will continue tomorrow.

Inverse-arp

frame-relay scenario 1
---------------------------


R6:
interface Serial0/0
   encapsulation frame-relay
   ip address x.x.x.x y.y.y.y

by default, frame-relay inverse-arp will be on. To confirm, check:
    show frame-relay map

To clear inverse-arp:
    clear inarp

To make sure PVC is active,
    show frame-relay pvc

How to reset Cisco configuration

Cat2950# write erase
Erasing the nvram filesystem will remove all files! Continue? [confirm]y[OK]
Erase of nvram: complete
Cat2950#
Cat2950# reload

System configuration has been modified. Save? [yes/no]: n    

!--- Do not save the configuration at this prompt. Otherwise, the switch
!--- reloads with the current running configuration and does not reset to default.

Proceed with reload? [confirm]y                              

2w0d: %SYS-5-RELOAD: Reload requested

C2950 Boot Loader (C2950-HBOOT-M) Version 12.1(11r)EA1, RELEASE SOFTWARE (fc1)
Compiled Mon 22-Jul-02 18:57 by antonino
WS-C2950G-12-EI starting...

source: http://www.cisco.com/en/US/products/hw/switches/ps607/products_tech_note09186a00800c4546.shtml

send break on ILOM

• Log in to 2 ILOM.
• go to /HOST namespace.

-> cd /HOST

• Type the following command and standby

-> set send_break_action="break"

• In your second ILOM session, first start the system by typing the following command

-> start /SYS

• After that, accessing the console through this command.

-> start /SP/console

how to find out what port is listening

netstat command to find open ports

# netstat --listen
To display open ports and established TCP connections, enter:
$ netstat -vatn
To display only open UDP ports try the following command:
$ netstat -vaun
If you want to see FQDN (full dns hostname), try removing the -n flag:
$ netstat -vat

lsof Command Examples

To display the list of open ports, enter:
# lsof -i
To display all open files, use:
# lsof
To display all open IPv4 network files in use by the process whose PID is 9255, use:
# lsof -i 4 -a -p 9255

turn off firewall on redhat

Here are the command:

service iptables save
service iptables stop
chkconfig iptables off