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PBX does not need to run on a client - only on master and media servers. Verify that vnetd (1724) is still open (bi-directional) between master & client and media server and client.

Created: 13 Jul 2012 • Updated: 14 Jul 2012 | 7 comments
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PBX does not need to run on a client - only on master and media servers.
Verify that vnetd (1724) is still open (bi-directional) between master & client and media server and client.

What does PBX does on media and master server?

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mph999's picture

At NetBackup 7.x it does run on a client, BUT, at the moment a client can still use vnetd or even bpcd.

What does it do, it sits there waiting for an incoming connection, and then hands it off the the relevant process.

For example, a media server used to connect to a client directly to bpcd, if using pbx, then the media server connects to pbx, and pbx then hands the connection to bpcd.

It is the same on master and media servers.  Incoming connections go to PBX and PBX then hand the connection across to another process.

For example, if you run nbemmcmd -listhosts on a media server the connection goes to PBX on the master, PBX then hands the connectio to nbemm.


Regards,  Martin
Setting Logs in NetBackup:
NIKHIL2346565959's picture

what is the main use of pbx then, if it hands the connection to other process?

When pbx was not there,what was used?

What is the importance of pbx?

ssumi's picture

With older NBU versions the dozens of processes connected directly to each other. In heavily firewalls environments (like the one I'm in) this is a nightmare to manage. So, for me, the biggest advantage to PBX is that I only have to open a few ports and not every single port for e wry single NBU application. PBX handles transporting the connections over it's session to the client and media servers, and even to the master. Makes firewall life way easier.

CRZ's picture

I'm sorry, but I feel like this needs to be asked in every thread you start.

Why were you asking these questions, and did you do any research on your own before you started this thread?

Now that the thread is marked resolved, what do you feel you've gained from getting the answers you have received?

Is there ANY chance we have convinced you that, in the future, you might want to try looking up answers to simple questions on your own before you bring them here?

Finally, is there any chance I will get a response from you to this reply?

PS vnetd is 17324, not 1724. | APPLBN | 761LBN

Marianne's picture

PBX = Private Branch Exchange

It's function is exactly what it says  - a switchboard/connection exchange.
As per ssumi's post - using a single port in a firewall environment is much better than many versions ago when a whole LOT of ports needed to be opened.

NBU version 6.0 - 7.0 used PBX for media and device level comms and vnetd for rest of NBU comms.
Since 7.0.1, ALL comms are directed via PBX (NBU comms will try vnetd if comms via PBX fails).

Some reading matter (you will find a lot more if you Google 'what is netbackup PBX'):   (shared with you yesterday)
From 7.0.1 onward VRTSpbx is required on client and NetBackup services have dependency on PBX service, even legacy client services listen under PBX .   There are two drivers behind these changes. One is preparation work for IPv6 support which is introduced in NetBackup 7.1.  The other is to ease firewall and host administration by the further consolidation of connections to a single port across NetBackup.  Because of these dependencies you cannot disable the PBX service, but if you kill the process manually, it will fall back to vnetd and legacy ports as stated in TECH136791.


We are moving more towards the goal of a single port - PBX, and this change is a step towards this.

(legacy client services include bpcd.)
Also see Troubleshooting Guide for PBX info.

Supporting Storage Foundation and VCS on Unix and Windows as well as NetBackup on Unix and Windows
Handy NBU Links

ssumi's picture


The Technotes end up forwarding to Symantec's support portal.

Also, I've just done our 7.5 deployment and had quite a bit of trouble finding all the ports that were not using PBX yet.  I found "Since 7.0.1, ALL comms are directed via PBX (NBU comms will try vnetd if comms via PBX fails)." to be not true.

Especially during installation, the media server tries to use the old VNETD port (I believe) to talk to the master server -- it never even tries PBX.  When setting up MSDP, that used VNETD and didn't even try PBX.

The documentation right now on ports required is a bit confusing.  Myself and my sales engineer have worked through quite a bit piecing together documents to come up with the port list, and I think I have it now.  But the documentation really needs a review for the ports.  If everything eventually goes over PBX I am going to be ecstatic!

Thanks for the information.

RonCaplinger's picture

FYI, those links work, but sometimes the Symantec portal pops up instead of the actual link.  It's some sort of bug in the portal. 

If it does that, go back and click on the link a second time and it usually comes right up to the linked technote.