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 Post subject: GNS3 dropping double VLAN tagged packets?
PostPosted: Sun Sep 30, 2012 9:56 am 
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Joined: Fri Mar 25, 2011 11:09 am
Posts: 40
Howdy,

I'm having problems with what seems like GNS3 dropping double VLAN tagged packets. GNS3 is running on a Linux Mint computer. I downloaded the latest GNS3 dev release with Dynamips 2.8 RC3 community edition. I am using a 3550 as the breakout switch.

I've tried a couple different .net configurations. The one I use most of the time is through VLAN subinterfaces on the Linux box created with the "ip link" command. This all goes out through one "trunk" interface to the breakout switch trunk port. This works fine, most of the time. I have also tried using GNS3's internal switch with a QinQ trunk port connecting to the physical interface and access ports connecting to the virtual routers. I have never been able to get any external connectivity using GNS3's internal switch.

I'm running through INE's CCIE RnS Volume III labs and up until lab 5 it has been fine(Using the Linux sub interface method). Complete connectivity to everything, just the known issues with CDP due to the 3550 switch I am using. In lab 5 they introduce Fast Ethernet vlan subinterfaces on the routers. As soon as I use these interfaces I get 100% packet loss. I fired up wireshark to see what was happening and found that the ping packets never even got to the physical interface on the host computer, or so it seems.

Using the Linux VLAN subinterface method I can capture packets on the Linux subinterfaces and see the vlan tags, but I do not see packets leaving the physical interface. Debuging arp and IP packets on the physical switches confirms that the arps are not making it outside of the Linux box. When using the GNS3 virtual switch I can capture the packets going into the virtual switch from the routers and I see the vlan tags. I checked the virtual switch ARP table and see the appropriate arp entries for the virtual routers. But I do not see the packets getting to the physical interface. I also tried to capture directly on the virtual QinQ link from GNS3 switch to the physical interface, I get an error that there is "No device available for traffic capture".

I've tried a couple different NICs, which doesn't change anything. Both of them are supposed to be 802.1q compliant.

0b:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL-8169 Gigabit Ethernet (rev 10)
0d:00.0 Ethernet controller: Broadcom Corporation NetLink BCM57781 Gigabit Ethernet PCIe (rev 10)

I THINK that all the issues are related to the network adapters that I am using. Even though I tried a couple different ones I am thinking that they are both just dropping tagged packets from internal sources. I'm not sure how the virtual switch interfaces with the physical adapter. If the network adapter was the culprit would I see the packets in wireshark but it still not make it to the wire? Or would the packet just not show up in wireshark? I should also mention that while running the GNS3 vswitch I tried wireshark's virtual interface that is supposed to capture ALL traffic and it also didn't show the packets. They seem to have vanished ;)


My confusion with this theory is that as long as I don't use vlan subinterfaces in the routers the Linux vlan subinterfaces work fine. So I know that at some level my network adapters support transmitting internal vlan tagged traffic. Anything that creates double tagged traffic seems to fail. Furthermore, I spoke with Broadcom tech support and they claimed that my network adapter wouldn't drop any internal VLAN tagged traffic, but they said that the Linux "Vconfig" program would... which is why I used "IP link" instead

I tried both Linux NIO and Generic NIO methods, it didn't change anything.

I've also tried a 3560 and a 3750 switch as the breakout. Changing the breakout fixes CDP, which I don't care about, but it does not fix the issue with packet loss.

Here's the offending .net files and also the vlan sub interface shell script for Linux.

Thanks




Attachments:
GNS3.Switch.QinQ.topology.net [1.5 KiB]
Downloaded 248 times
vlan.setup.ip.link.add.txt [1.38 KiB]
Downloaded 230 times
topology.net [5.45 KiB]
Downloaded 212 times
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 Post subject: Re: GNS3 dropping double VLAN tagged packets?
PostPosted: Sun Sep 30, 2012 6:16 pm 
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Joined: Sat Oct 11, 2008 1:41 pm
Posts: 2668
Location: Canada
Hi,

I haven't much time to check out what could be wrong with your config. Have you read this page? -> http://www.gns3.net/switching-qinq-with ... ch-option/

The QinQ option is supposed to work well with Linux. I do use it for my CCIE lab with OSX and it works really well.

Maybe can you try with an Ubuntu Live CD or another laptop?

I will help you more when I am back from a trip (next 2 weeks).

Cheers,

_________________
Jeremy, GNS3 Programmer & Benevolent Dictator for Life.


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 Post subject: Re: GNS3 dropping double VLAN tagged packets?
PostPosted: Mon Oct 01, 2012 6:17 am 
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Joined: Fri Mar 25, 2011 11:09 am
Posts: 40
Hello,

Yes I've read that page and this is the implementation that I just cannot get to work. The one that works for me mostly is http://www.gns3.net/switching-direct-vl ... ng-option/.

I also read about the network adapter driver stripping the outer vlan tag, but my problem appears a bit different, the packets just seem to disappear. It could still be related I suppose. I actually hadn't read that Cisco document, it lists one of my network adapters as compatible, so that's good at least.

I'll try with a Live CD on another computer, thanks for that suggestion. I have previously tried Scientific Linux on this same computer with the Broadcom NIC only. This gave the same results.

I found a posting on another blog that seems to also report similar issues as I am having

http://ieoc.com/forums/p/18754/170303.aspx#170303

He was able to fix it with an IOS upgrade on the breakout switch. I'm not sure which version of IOS i am using there, but obviously it's not the IPbase image as it doesn't support QinQ

Edited to add: The image I am using is c3550-ipservicesk9-mz.122-46.SE.bin

Another post in the same thread reported fixing a similar issue with a different NIC

http://ieoc.com/forums/p/18754/179781.aspx#179781

Another thread in a different forum reports fixing this issue with an older Linux Kernel

http://7200emu.hacki.at/viewtopic.php?t=9120

I'm patient, as I have other things I can do in the mean time. But I do look forward to your assistance with this.

Thanks!


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 Post subject: Re: GNS3 dropping double VLAN tagged packets?
PostPosted: Mon Oct 01, 2012 11:29 am 
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Joined: Fri Mar 25, 2011 11:09 am
Posts: 40
I re-downloaded the drivers for my Realtek card and re-compiled them. I had to remove a line from the source code, "#include <asm/system.h>". I guess it is no longer supported in my Kernel... I don't remember doing this the first time... I think that I may have previously compiled the driver with a different kernel installed then though.

After I did this I got the direct vlan mapping method working. Now I have limited connectivity with double tagged packets. But it also seems like there are some issues with some tags getting stripped, not dropped though. Hosts on one physical switch have connectivity eachother, but a host on another switch does not connect to hosts on the first switch. The arp replies are coming in on the GNS3 router's FastEthernet interface instead of the vlan subinterface, thus getting filtered. It says "wrong cable". With that said, this issue definitely does not seem to belong to GNS3 or Dynamips. Single tagged packets work fine as before.

I still can't get the GNS3 vswitch to work. But oh well, at least now I have forward progress with my network adapter.


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 Post subject: Re: GNS3 dropping double VLAN tagged packets?
PostPosted: Sun Oct 07, 2012 12:04 pm 
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Joined: Fri Mar 25, 2011 11:09 am
Posts: 40
Wow... so I finally figured out why I had selective connectivity... and it was a stupid problem. When I was messing with my configs I tried different nio methods. The two that had great connectivity were the only two routers in my topology that i had selected as nio_gen interfaces. I guess the nio_linux interfaces were stripping the vlan tags, I completely forgot that I had change those two.

I did as you said and tried it on a different computer with a fresh install of Ubuntu. It also had problems, this laptop had an intel network adapter built in so it was a completely different set of hardware. Which is why I revisted my configs (what is common between the two computer... just the stuff I copied onto it)


Here's the two routers that worked:
[[Cloud C1]]
x = 195.5
y = -203.0
z = 1.0
connections = R1:f0/0:nio_gen_eth:eth1.901

[[Cloud C3]]
x = -236.5
y = -221.0
z = 1.0
connections = R3:f0/0:nio_gen_eth:eth1.903

Here's one of the ones that did not:

[[Cloud C9]]
x = -362.5
y = -107.0
z = 1.0
connections = R6:f0/0:nio_linux_eth:eth1.909

So, is this a bug or just part of why we recomend that nio_gen us used an not nio_linux? If so why do we even have nio_linux?

It's kind of confusing actually, see this post. You'd think that nio_linux is the one to use with Linux...
http://forum.internetworkexpert.com/for ... spx#154363


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 Post subject: Re: GNS3 dropping double VLAN tagged packets?
PostPosted: Mon Oct 08, 2012 7:59 am 
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Site Admin

Joined: Sat Oct 11, 2008 1:41 pm
Posts: 2668
Location: Canada
Excellent findings! I wasn't aware of that as I always use nio_gen.

Quote:
So, is this a bug or just part of why we recomend that nio_gen us used an not nio_linux? If so why do we even have nio_linux?


I recommend to always use nio_gen. I will consider removing it or giving a warning in future GNS3 version.

Thanks for your troubleshooting :)

_________________
Jeremy, GNS3 Programmer & Benevolent Dictator for Life.


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 Post subject: Re: GNS3 dropping double VLAN tagged packets?
PostPosted: Tue Oct 09, 2012 5:32 am 
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Joined: Fri Mar 25, 2011 11:09 am
Posts: 40
No problem, just glad I got it figured out. In the end it turns out that i had multiple issues that only came to a head when I used the vlan subinterfaces in the routers, what's the odds of that ;)


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 Post subject: Re: GNS3 dropping double VLAN tagged packets?
PostPosted: Mon Feb 18, 2013 10:21 pm 
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Joined: Fri Nov 07, 2008 12:04 pm
Posts: 179
Location: Netherlands
zeeshan wrote:
I have limited connectivity with double tagged packets,but it also seems like there are some issues with some tags getting stripped, not dropped though. Hosts on one physical switch have connectivity each other, but a host on another switch does not connect to hosts on the first switch. The warp replies are coming in on the GNS3 router's Fast Ethernet interface instead of the van sub interface.

(Spam Link Removed)


Interesting spam. Xrummer 101%.

_________________
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Last edited by claydon_dan on Mon May 13, 2013 10:16 am, edited 1 time in total.
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 Post subject: Re: GNS3 dropping double VLAN tagged packets?
PostPosted: Mon Feb 18, 2013 11:48 pm 
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Joined: Thu Jun 24, 2010 3:58 pm
Posts: 411
Location: [email protected]
xsimio wrote:
Interesting spam. Xrummer 101%.
How can we ever fight this ;))
Interesting strategy, by reading a genuine post from this topic, then posting back almost same text (manipulated a little bit) + a stupid link...
I'll ban the IP address... (this will definitely "NOT" solve the problem)

Spamer: 182.186.200.6, Islamabad, Pakistan (Forum User: zeeshan)




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