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    Cisco IP phone F-up

    Good day folks. I had a little f-up over at my new shop today and it made me pretty angry, but at the same time it determined me to try and figure out what could've happened there. This is only going to be a speculative discussion since I don't know the exact layout of our network, hence I don't know what's going on past our room. So:

    The repair shop where I sit is situated in a remote building down the street from the main building. There's a Cisco IP phone in this room, a 7911, like the rest of the company uses. There's obviously some sort of networking going on between the two buildings. Simply put, there's a network cable going between the buildings. It goes into a switch (from what I briefly saw, since it is located in an adjacent room where I'm not allowed to go whenever I feel like it, only when "invited", which is when I had the chance to snap some mental pictures of the equipment there) and then another network cable enters the room. There's also a single computer there, which belongs to the old man...just as old and stubborn as him My laptop as well as other people's devices use a wireless network, also present in this building somehow. Sure enough, I saw a router amongst the switches there, though it's not entirely clear to me how it's all hooked up.

    The cable coming into the room is plugged straight into the Cisco phone and, this is where the confusion began, the computer is plugged INTO the phone itself. Sure enough, it makes sense and page 29 of the manual for the phone explains this, but gives no info regarding HOW it all works out. It seemed simple at first: the phone acts as a switch so it doesn't take up a network port all for itself...

    Today, the "shop master" suggested I'd rummage through the mountains upon mountains of junk we got there (literally) to see if I could scrounge up a working wireless router so we'd run some cables to some of the tables in the room as well, since there are no network plugs anywhere else in this huge room...actually there are, but they're not connected - more on this later. Fair enough I though, I found an Asus one, pretty fancy actually, and the first thing I did was disable its DHCP server so it wouldn't try to assign its own addresses to anything. I then unplugged the cable coming from the phone going into his computer, plugged that into a random LAN port and the computer in another port. At this time, I didn't know about the phone bit. This didn't work for some reason: IP addresses were not being assigned. I was hoping the "external" DHCP server would take over, as the router was just a switch at this point. The DHCP server, whatever that actual device might be, I assume is located somewhere in the main building, since these guys are also ISPs, though it could just be any regular router - anything that plays the DHCP role. Ok, so let's revert back: remove the router and plug the cable back into the PC. The PC continued to lack a network connection and having a look at the phone it was now displaying "Ethernet disconnected"....great. I tried the usual stuff of resetting, unplugging, it just didn't work. I HAD to bite the bullet and go to the main office to get scolded, even though technically it wasn't MY idea...this is what pissed me off and would sure love to break it again just for the hell of it It was back online without anyone actually coming there...

    Still: how could this have happened ? I have no idea what went terribly wrong to f-up my day there. Not only was I on the "output" side of the phone, but DHCP was off on the thing. I confirmed this by plugging it back into my laptop and it didn't get an IP either (which was normal in this case). Of course, had I known earlier, I would've probably tried unplugging the PHONE and then plugging both devices into the switch separately, but still: if the phone acts as a switch, why is it messing up when you plug another switch into it ? My only idea is that something "complained" at the "server" end - something in the control room in the main building so to say, and it shut down that network segment when it saw the intruding device being connected. I'll try it again as previously described, by plugging the incoming cable straight into the switch and ignoring the phone entirely...why do I bother ? Well nobody does these things: you want something, you gotta do it yourself...even though there should be guys taking care of the networking...I could handle it myself most likely, but hey...new guy Nobody cares about new guys....people don't do their jobs basically and I'm the one who gets scolded....yeah...it's getting better by the day >_>
    Wattevah...

    #2
    Re: Cisco IP phone F-up

    Your wall of text makes it hard to read so I gave up.

    Generally, phones and data are put into 2 separate vlans for security, QoS and other reasons.

    In addition, there are software features on switches that prevent certain activities. Way too many to cover here.
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    Comment


      #3
      Re: Cisco IP phone F-up

      Yes, I said in the opening that it'd be a speculative discussion and I know it's long. To sum it up: plugged router (DHCP off) in the "output" port of the phone and the phone no longer connected to the internal network, despite the network cable from the "head office" still being plugged in it....something crapped out there...
      Wattevah...

      Comment


        #4
        Re: Cisco IP phone F-up

        without a manual, i wouldnt assume that socket was a standard network port.
        some i.p. phones used to be able to drive regular POTS handsets as a bridge to the network.

        Comment


          #5
          Re: Cisco IP phone F-up

          Manual attached in the original post, but it doesn't matter because there's no explanation as to how that port works - it just says "connect computer here", so I assumed a switch would work there just as well.
          Wattevah...

          Comment


            #6
            Re: Cisco IP phone F-up

            well does the computer have to run some cisco crap in the background??

            Comment


              #7
              Re: Cisco IP phone F-up

              Nope...
              Wattevah...

              Comment


                #8
                Re: Cisco IP phone F-up

                Quick shot of the network devices used in this branch office I suppose....just for curiosity. As expected, nothing fancy: two managed switches and a wireless router thrown on there (yellow cable). The WLAN is actually incorrectly configured ATM (well, incorrectly given how I would do it), because the yellow wire goes to the "internet" WAN port, rather than the LAN ports, so there's another "sub-Network" being generated by the router, with it being the gateway, when it should just be an access point, part of the same main network, so DHCP should be off on it. I can't access the CRM platform because of this either, so there's some serious issues here....bunch of "experts"....

                Nothing here should've conflicted with my failed Wi-Fi installation, but at least now I know where everything is and how it should be done - the "antenna" should be plugged into one of the swtiches, NOT the phone....nothing should crap out, since it's should be like plugging in a regular device WTH
                Attached Files
                Wattevah...

                Comment


                  #9
                  Re: Cisco IP phone F-up

                  what a fucking rats-nest.
                  i'd offer to send you some cable ties, but i see you have used a couple - so it's a question of giving a shit, rather than resources!

                  Comment


                    #10
                    Re: Cisco IP phone F-up

                    Not my work, just so we're clear - forgot to mention that Can't go in there to arrange it the way it should be without big boss's permission first. If anything ceases to work, guess who's responsible then ?
                    Wattevah...

                    Comment


                      #11
                      Re: Cisco IP phone F-up

                      Originally posted by Dannyx View Post
                      Quick shot of the network devices used in this branch office I suppose....just for curiosity. As expected, nothing fancy: two managed switches and a wireless router thrown on there (yellow cable). The WLAN is actually incorrectly configured ATM (well, incorrectly given how I would do it), because the yellow wire goes to the "internet" WAN port, rather than the LAN ports, so there's another "sub-Network" being generated by the router, with it being the gateway, when it should just be an access point, part of the same main network, so DHCP should be off on it. I can't access the CRM platform because of this either, so there's some serious issues here....bunch of "experts"....

                      Nothing here should've conflicted with my failed Wi-Fi installation, but at least now I know where everything is and how it should be done - the "antenna" should be plugged into one of the swtiches, NOT the phone....nothing should crap out, since it's should be like plugging in a regular device WTH
                      Are the IT guys getting paid more than you? What a mess!
                      Never stop learning
                      Basic LCD TV and Monitor troubleshooting guides.
                      http://www.badcaps.net/forum/showthr...956#post305956

                      Voltage Regulator (LDO) testing:
                      http://www.badcaps.net/forum/showthr...999#post300999

                      Inverter testing using old CFL:
                      http://www.badcaps.net/forum/showthr...er+testing+cfl

                      Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                      http://s807.photobucket.com/user/budm/library/

                      TV Factory reset codes listing:
                      http://www.badcaps.net/forum/showthread.php?t=24809

                      Comment


                        #12
                        Re: Cisco IP phone F-up

                        Yes, they are - undoubtedly. The way it works in any large company is you have to prove your prowess in order to climb the hierarchy ladder, that's why I'm constantly going around hunting down stuff that's less than ideal (see aforementioned photo) and suggesting improvements to Big Boss, at least to make him see that I've got ideas and perspectives
                        Wattevah...

                        Comment


                          #13
                          Re: Cisco IP phone F-up

                          Well, I guess that the big boss did not go around and look at some of the IT setup.
                          I bet you can climb that ladder faster than some of the existing people there, you have more common sense than some of them.
                          Last edited by budm; 11-30-2018, 04:00 PM.
                          Never stop learning
                          Basic LCD TV and Monitor troubleshooting guides.
                          http://www.badcaps.net/forum/showthr...956#post305956

                          Voltage Regulator (LDO) testing:
                          http://www.badcaps.net/forum/showthr...999#post300999

                          Inverter testing using old CFL:
                          http://www.badcaps.net/forum/showthr...er+testing+cfl

                          Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                          http://s807.photobucket.com/user/budm/library/

                          TV Factory reset codes listing:
                          http://www.badcaps.net/forum/showthread.php?t=24809

                          Comment


                            #14
                            Re: Cisco IP phone F-up

                            Naah, he doesn't care as long as it "works". The rest of the shop reflects this, with stuff thrown everywhere....who cares right ? As long as the client is happy, who cares about the mess behind the counter ? It's hard to keep it orderly when there's no policy specifically enforced for this, like "if I walk in and see a screw in the nut drawer, you'll all going down !"
                            Wattevah...

                            Comment


                              #15
                              Re: Cisco IP phone F-up

                              I made another discovery today: apparently this network is fancier than I thought, because I tried the router trick again on a known working wall plug (no phone or anything) and it didn't work this time around either...moreover, that port shut down ! No joke: after a few seconds, the link just dropped....I thought my damn cable broke, because I got the "network cable unplugged" message when I tried the cable back into my laptop....I've never seen a switch to just completely disable the port like that...

                              The switch is most likely a TP-LINK TL-SG242P. It's got some fancy features built in like independent port control, but I'm not sure why it happened in the first place, I thought I did everything right...I'm no expert, but I thought cascading two switches would be easy (assuming the router acts as a switch now). I thought it did some sort of MAC filtering business, but before this failure, any PC would work on that cable - just this router bring it to its knees somehow...it detects it as an attack or some sh!t like that...
                              Attached Files
                              Wattevah...

                              Comment


                                #16
                                Re: Cisco IP phone F-up

                                Well, just in case someone is still watching the thread, forgot to wrap it up by saying that I did some more in-depth research on how these managed switches work and found the issue: BPDU guard. Simply put, you cannot plug a dumb switch into the access port of a managed switch, or else BPDU guard puts that port in "err-disable" to prevent network instability or some rubbish like that which I didn't care about and apparently this is what happened all along: plugged the router/switch in and the port shut down immediately....

                                The Wi-Fi router in that pic can get away with it because it's plugged into the WAN port which doesn't send BPDUs OR that switch port has BPDU guard disabled on it.
                                Wattevah...

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