Wireshark-users: Re: [Wireshark-users] Using Wireshark for a DSL "link no surf" problem [UPDATE]
From: Kok-Yong Tan <ktan@xxxxxxxxxxxxxxxxxxx>
Date: Wed, 02 Jul 2014 18:46:02 -0400
Just wanted to update the community on my problem (which has been
resolved). It had nothing to do with PPPoE after all. It seems that my
ISP, Megaputz/Megapath, changed the VPI/VCI numbers for my circuit from
0/35 (the default) to 0/40 and had set my DSL modem remotely. I suspect
that Tier 1 tech support foolishly remotely reset my DSL modem to
defaults without taking into consideration the VPI/VCI settings, thus
completely knocking me offline. When Megaputz sent out a tech with a
new DSL modem because the ISP's tech support Tier 1, Tier 2, NOC
Operations Team and Network Engineer all insisted it was due to "CPE
failure" (despite having sent them screenshots of the Broadxent/Innoband
DSL modem's setup screens where the VPI/VCI settings were prominently
displayed), he also couldn't connect until he noticed that the VPI/VCI
was set to 0/40 instead of the new modem's 0/35 (it seems 0/35 is the
factory default for most modems since the new and the old modem were
from different manufacturers--ZyXEL versus Broadxent/Innoband,
respectively). Once he set the VPI/VCI settings to 0/40 to match the
circuit (I watched him like a hawk and he changed nothing else), I was
back up instantly. Examining the setup screens of the old
Broadxent/Innoband modem which Megaputz claimed to be defective, I
noticed that its VPI/VCI was also set to 0/35. Since I had no admin
passwords, that is not something I could have set or reset. And I
didn't reset it to defaults myself.
This segues to my next question: Is there any way to use Wireshark to ascertain the VPI/VCI of the ATM circuit from the Layer 2 packets that were said to have been flowing? Or must I have specialized software or hardware to do this? I noticed that the rep had nothing more than his laptop connected via ethernet cable to the DSL modem when he noticed the different VPI/VCI settings on a possibly in-house-only software running on it.
On 6/19/14 03:36, Martin Visser wrote:
There seems to be a lot of contradicting answers on this thread. PPPoE is used for authentication AND link negotiation (ie providing IP addresses) AND encapsulation. If you have a PPPoE modem in passthrough (which is what it sounds you are doing), the modem is just pretty much doing physical level translation between your DSL and Ethernet, and then your router (normally) is establish the PPPoE session. If you aren't able to capture traffic at the router and/or want to test locally you can use a PPPoE client on a laptop, for instance, and which also can run wireshark. Not sure what you have a available, but if you plug your Windows laptop into your modem directly, and then run through the Internet connection wizard (as per the example here - http://www.tp-link.com.au/article/?faqid=339 ) while running Wireshark you may have a better clue as to what is going on (or not). Regards, Martin MartinVisser99@xxxxxxxxx <mailto:MartinVisser99@xxxxxxxxx> On 19 June 2014 16:14, Kok-Yong Tan <ktan@xxxxxxxxxxxxxxxxxxx <mailto:ktan@xxxxxxxxxxxxxxxxxxx>> wrote: The service provider doesn't use DHCP to hand out my static IPs. I was assigned them via an email. The DHCP server is on the DSL modem (not the DSLAM) and it hands out a single IP address in the 192.168.1.0/24 <http://192.168.1.0/24> private range, namely 192.168.1.10. This is known as out-of-band management and only used for accessing the DSL modem itself and nothing else. The actual static addresses I'm assigned are in the public range while my DSL modem is supposedly set to bridging mode, i.e., it's not in the 10.0.0.0/8 <http://10.0.0.0/8>, 172.16.0.0/12 <http://172.16.0.0/12> or 192.168.0.0/16 <http://192.168.0.0/16> ranges. -- Reality Artisans, Inc. # Network Wrangling and Delousing P.O. Box 565, Gracie Station # Apple Certified Consultant New York, NY 10028-0019 # Apple Consultants Network member <http://www.realityartisans.com <http://www.realityartisans.com/>># Apple Developer Connection member Cell: (646) 327-2918# Ofc: (212) 369-4876 On Jun 18, 2014, at 21:02 , Frank Bulk <frnkblk@xxxxxxxxx <mailto:frnkblk@xxxxxxxxx>> wrote:If your service provider uses DHCP to hand out those “static” IPs, or their access gear allows that IP address to be entered (which is the case with our vendor’s gear), the access gear prevents someone else taking your static IP.____ Frank____ *From:*wireshark-users-bounces@xxxxxxxxxxxxx <mailto:wireshark-users-bounces@xxxxxxxxxxxxx> [mailto:wireshark- <mailto:wireshark->users-bounces@xxxxxxxxxxxxx <mailto:users-bounces@xxxxxxxxxxxxx>]*On Behalf Of*Kok-Yong Tan *Sent:*Wednesday, June 18, 2014 1:58 PM *To:*Community support list for Wireshark *Subject:*Re: [Wireshark-users] Using Wireshark for a DSL "link no surf" problem____ __ __ Yes, I understand why they gave me a /24 but with a /24, all it takes is for somebody else on the same subnet to accidentally (not intentionally or maliciously for obvious reasons) take my static IP and thus blow me out of the water without affecting them too much. I had this happen once. With a subnet between /24 and /30, they'd notice when their accidentally typo-ed IP address didn't work because it didn't match their gateway info. ____ -- ____ Reality Artisans, Inc. # Network Wrangling and Delousing P.O. Box 565, Gracie Station # Apple Certified Consultant New York, NY 10028-0019 # Apple Consultants Network member <http://www.realityartisans.com <http://www.realityartisans.com/>># Apple Developer Connection member____ Cell: (646) 327-2918# Ofc: (212) 369-4876____ __ __ On Jun 18, 2014, at 10:59 , "Jamie O. Montgomery" <Jamie.Montgomery@xxxxxxxxxxxxx <mailto:Jamie.Montgomery@xxxxxxxxxxxxx>> wrote:____ ____ PPPoE is used for authentication. If you have a static IP, they know who has it and you don't need authentication. PPPoE would be the termination point for the address, but since it will reside on your firewall, the modem needs to bridge the dsl network to the Ethernet network on the public side if the firewall____ __ __ They give you a /24 because they'd be burning up more IPv4 addresses giving you a smaller subnet. Other static IP customers use addresses in that subnet along with you. ____ *Jamie Montgomery | Comporium*____ Network Facilities Engineering | Engineering Associate II____ www.comporium.com <http://www.comporium.com/>____ jamie.montgomery@xxxxxxxxxxxxx <mailto:jamie.montgomery@xxxxxxxxxxxxx>____ ____ /The information contained in this e-mail message and any attachments thereto are confidential, privileged, or otherwise protected from disclosure, and are intended for the use of the individual or entity named above. Dissemination, distribution or copying of this message and any attachments by anyone other than the intended recipient, or an employee or agent responsible for delivering the message to the intended recipient, is prohibited. If you have received this communication in error, please immediately notify the sender by telephone or e-mail and destroy the original message, attachments, and all copies./____ On Jun 18, 2014, at 1:34 PM, "Kok-Yong Tan" <ktan@xxxxxxxxxxxxxxxxxxx <mailto:ktan@xxxxxxxxxxxxxxxxxxx>> wrote:____ No, the DSL modem is bridging, not routing. I've been assigned two static IPs (although they've given me a /24 net mask!!!) and my firewall is assigned one of them. The firewall is connected directly to the DSL modem by Cat6 patch cable. The other IP is unused (I use it for testing VPN configurations).____ __ __ I'm not sure but since the Broadxent Briteport is a PPPoE modem, I assume PPPoE. But the tech says that's not correct (WTF?). And he can't explain what they use. Sigh.____ -- ____ Reality Artisans, Inc. ____ # Network Wrangling and Delousing P.O. Box 565, Gracie Station ____ # Apple Certified Consultant New York, NY 10028-0019 ____ # Apple Consultants Network member <http://www.realityartisans.com <http://www.realityartisans.com/>>____ # Apple Developer Connection member____ Cell: (646) 327-2918____ # Ofc: (212) 369-4876____ __ __ On Jun 17, 2014, at 22:13 , Pedro Tumusok <pedro.tumusok@xxxxxxxxx <mailto:pedro.tumusok@xxxxxxxxx>> wrote:____ ____ Well if the tech can see stuff, its not what I thought might be the problem, which was PVC settings.____ __ __ But does your modem get an IP address, ie is it setup as a router or does your computer get the ip address?____ Are you using PPPoA/PPPoE etc?____ __ __ On Wed, Jun 18, 2014 at 5:52 AM, Frank Bulk <frnkblk@xxxxxxxxx <mailto:frnkblk@xxxxxxxxx>> wrote:____ Some Comtrend modems can do a port mirror of the WAN (DSL) side. Frank____ -----Original Message----- From:wireshark-users-bounces@xxxxxxxxxxxxx <mailto:wireshark-users-bounces@xxxxxxxxxxxxx> [mailto:wireshark-users-bounces@xxxxxxxxxxxxx <mailto:wireshark-users-bounces@xxxxxxxxxxxxx>] On Behalf Of Kok-Yong Tan Sent: Tuesday, June 17, 2014 4:53 PM To: Community support list for Wireshark Subject: Re: [Wireshark-users] Using Wireshark for a DSL "link no surf" problem > On Jun 17, 2014, at 14:28, Jaap Keuter <jaap.keuter@xxxxxxxxx <mailto:jaap.keuter@xxxxxxxxx>> wrote: > >> On 06/17/2014 08:42 PM, Kok-Yong Tan wrote: >> Is it possible to use Wireshark to troubleshoot a DSL "link no surf" problem? The ISP insists it's a CPE issue but the problem only started after their Tier 1 tech monkeyed with the DSLAM and/or the CPE (remotely) in some manner. I find it suspicious that the problem was intermittent packet loss until they tinkered, whereupon the problem became a "link no surf" issue (i.e., there's Layer 2 connectivity but zero Layer 3 traffic passing). > > Depends on what you can trace in the CPE, as in, how close to the DSL interface. > Otherwise you'll need capture hardware on the DSL.... > > Good luck, > Jaap > I can get up to the DSL modem itself. In hindsight, I'm thinking this isn't going to be of much use and the only way to debug this is with capture hardware on the DSL side as you suggested. Drat.
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