Collecting comprehensive switch interface
information
When working with Juniper EX / QFX
switches it is often required to collect comprehensive interface status data.
Not any single show command will provide all the details and merging the output
of several commands is quite time consuming.
On top of this, it can be tricky
to find free ports on switches, because unconfigured ports are simply not shown
in many commands and the only way to find out available ports is examining the
chassis hardware components.
In the following article I would
like to show you an easy way of collecting such information quickly by using Pretty Good Terminal.
PGT is completely free for private use so you
don’t need to worry about any costs involved.
What the script does
As part of the standard installation,
PGT contains a sample Visual Script designed for Juniper EX /QFX switches to
collect switch interface information.
The script will issue the
following CLI commands and merge their output to compile the resulting CSV file
that can be opened in Excel :
- show version
- show interfaces detail
- show chassis hardware
- show configuration interfaces | display set
The resulting CSV file will have
the following columns:
- Device IP : the management ip address of the device (the one the script was using)
- Host Name : host name of the device
- FPC : the FPC (Flexible PIC Concentrator) ordinal number
- PIC : the PIC (Physical Interface Card) ordinal number in current FPC
- Port : the hardware port ordinal number in current PIC
- Interface Name : collected or calculated interface name
- Admin Status : Administrative status of the port
- Physical Status : Physical status of the port
- Description : Physical and Logical unit description separated by pipe (|)
- Speed : The configured port speed
- Duplex : The configured duplex mode
- MTU : Currently configured MTU size
- Last flapped date : The date and time the last time the interface flapped
- Stable since : The time elapsed since the last flap
- SFP Type : Type of SFP if applicable
- IntRange : not used currently
- AggregateID : The aggregate interface name this port belongs to
- RangeName : The interface range name the interface is part of
- Port mode : Access or Trunk port mode
- Vlans : The vlans the current port carries
See sample output below:
Using a vScript to collect information
There are a few tasks you need to perform to start using the script, but 80% of them is required only the first time:
- Install PGT - obviously, first time only
- Register the script - first time only
- Configure device access - first time only
- Generate an execution script - depends on your needs, the script can be saved to file for reuse
- Execute script - whenever you need
- Install PGT - obviously, first time only
- Register the script - first time only
- Configure device access - first time only
- Generate an execution script - depends on your needs, the script can be saved to file for reuse
- Execute script - whenever you need
Prerequisite – IronPython installation
If you installed PGT with default
installation options, you can safely skip this chapter.
Because the Visual Script is
written in Python, it is a prerequisite to have IronPython installed. PGT
installer will automatically install it unless the option was deselected during
installation. The latter case, the installer file named IronPython-2.7.8.msi is
copied to PGT installation folder, so it can be manually installed later.
After you installed IronPython,
start PGT and go to Tools/Options and select the Python Engine tab. Remove any
search path entry present by right clicking it and selecting Remove Folder:
When the last folder was removed,
PGT will ask if you want to add the default Python search paths. Click yes to
proceed. If IronPython was installed correctly you should see 5 paths listed by
default, similar to below screenshot:
If you see IronPython
installation path listed in the path list, PGT is configured correctly to
execute Python scripts and Python based Visual Scripts.
Registering the vScript
To use the script, it must first
be registered as a Custom Action Handler in PGT. To perform registration, go to
Tools/Options select Custom Action Handlers tab and press the yellow add button
and browse for the Visual Script file JunOS_InterfaceStatus.vs as shown below :
When the script file is selected
press Open. Depending on PGT version a “Save As” dialog may be presented,
simply press cancel to skip it. When
registration is completed, a new entry with CustomActionID name
“InterfaceStatus” should appear :
If you receive an error like
below, then IronPython was most probably not installed or its installation path
is not set correctly in PGT. In this case follow instruction in chapter “Prerequisite
– IronPython installation” above.
Running the script
To run the script on selected
devices you must first generate an execution script using Script Generator. To
launch the Script Generator select it from the Action main menu item, or press
Ctrl + G.
If this is the first time you
started the Script Generator you will need to set some basic information:
- The jump server to use : leave it empty if no jump server is required
- The default device Vendor : select JunOS
- The default connection protocol : select SSH2_Telnet if you are unsure which one will work
Above information will be
remembered for the next time you start the Script Generator.
Additionally, you will need to
define the script targets and select the commands to execute:
- In the Device List field enter the management ip addresses of the devices you want to run the script on. Enter one ip address per line.
- Click the Add Command button and from the Custom Action ID drop-down select InterfaceStatus – this actually the script you registered in previous step.
When finished, press the Generate
Script button. A new Scripting Form will be shown with similar content as shown
below:
Before you can execute the
script, you will also need to define the credentials for device logon. Of course,
this needs to be done only the first time you start PGT.
To define credentials, go to
Tools/Options and select the scripting tab. Here you can specify the default
user name and password to be used:
If you need to use jump servers, please start watching below
tutorial video at 2:48 :
When finished, you are ready to
start the script. Right click any line in the execution script to bring up the
context menu and select Execute Now, or press F5:
When execution starts a Save As
dialog box will open. Here you can specify the file name and location for the
result. After the file selected, the script will proceed to each device in the
list and execute above mentioned commands. Executing the “show interfaces
detail” may take a long time depending on switch physical configuration.
Hopefully no error will occur, then each line the script has been executed on turns green, and the Command Result column will show “Script v1.2 : Information saved to …”
When the script is finished you
will notice a Goodbye message in the Action Pane display on the bottom left and
you can open the result file. Please note, that the script keeps the file open
for about 10 secs after finishing if the application is not closed. During this
period, you may only open the file in read-only mode. Either you need to close
PGT or wait 10 seconds to have full access to the file.
A Productivity Tipp
When you need to run the script on several switches, depending
on switch configurations the script may need a long time to complete due to the
amount of data returned for the command show interfaces detail.
There is a coll scripting feature in PGT that will
come in hand in this case : you can generate and run several execution script
at the same time, even when you want to save the result to the same file.
You only need to set the number ofr allowed hosts per scriptring
form in script generator, and you will notice that many scripting form would
open.
Potential Issues
The python script makes a lot of
regex matching on command results to extract the information required. The regex
patterns used was chosen with great care, however may not work correctly for
some models. Test the script carefully
on your devices before making decisions based on the result, and if you
experience animalities in output file, you will probably need to tune the
underlying Python script.
The script operation is covered briefly in next chapter.
The script operation is covered briefly in next chapter.
A glance under the hood
The detailed analysis and
explanation of the script operation is beyond the scope of this article, but I
would like to give a brief overview in case someone want to modify it.
The vScript was written in Python
and here is how it looks like in Visual Script Editor:
Each element in the script is a
unique Python object having its own attributes and a single CLI command is
specified for them. When executed, the element will send this CLI command to
the connected device and the associated code will parse the command result to
collect the required information.
The script starts with asking the
user to provide the output file name and location, then queries version
information. The Precheck element will ensure a filename was provided and
checks if the connected device is a Juniper EX / QFX switch. If these
conditions are not met, the script is terminated returning an error message
relevant to the issue.
There is a global Python list
variable named Interfaces and it contains SwitchInterface objects. The
SwitchInterface type is defined in global script properties to describe all the
required attributes of an interface.
As execution reach to the “Get
interface details” element, the show
interfaces detail command is executed, and its result is parsed to build an
initial list of Interfaces.
In the next step, the “Get
hardware ports” element issues the show
chassis hardware CLI command to the device, and its result is used by the
associated code to update existing SwitcInterface attributes in the Interfaces
lists, and also appends any unconfigured interfaces. Unconfigured interfaces
are hardware ports on a PIC which has no configuration for some reason and
therefore not listed by the show
interfaces details command.
The last step before saving the
output file is to collect interface configuration by parsing the result of the
command show configuration interfaces |
display set. This action is performed by the “Get interface configuration”
script element.
At the end of the script, the
“Save data” element will write the content of the Interfaces list to the
specified output file.
Should you have any questions or run into difficulties feel free to contact me either on this forum or via the contact form on the website.
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