Timeline for Unable to ping/Scan Profinet PLC Device Through Siemens SCALANCE X108 connected to Cisco VLAN-Based Switches
Current License: CC BY-SA 4.0
18 events
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| Aug 19 at 13:32 | answer | added | Eleanor Brooks | timeline score: -2 | |
| Aug 19 at 9:02 | answer | added | Zac67♦ | timeline score: 1 | |
| Aug 18 at 12:20 | history | edited | Khaalidi | CC BY-SA 4.0 |
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| Aug 18 at 12:09 | history | edited | Khaalidi | CC BY-SA 4.0 |
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| Aug 17 at 21:07 | comment | added | Khaalidi | @RonMaupin I've found this about Profinet specification about VLAN and VLAN Priority 6. PROFINET real-time communication to be possible also in a Virtual Local Area Network (VLAN) and thus also over switches that can evaluate the VLAN tag. Can you please take a look at this and guide me how to evaluate the tag in the Cisco Catalyst Switches. | |
| Aug 17 at 20:40 | history | edited | Khaalidi | CC BY-SA 4.0 |
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| Aug 17 at 18:37 | comment | added | Khaalidi | @RonMaupin Thank you so much for following up on my issue. It's really valuable to learn from your experience in networking. Your strong grasp of the fundamentals really comes through, and I appreciate the time and effort you've put into helping me. Thanks again! | |
| Aug 17 at 18:27 | comment | added | Khaalidi | @RonMaupin Yes, that understandable, But I'm not sure if Profinet RT based device even use CDP for discovery and negotiation. I cant modify any VLAN or QoS configuration on the Profinet device and the Siemens Industrial Switch. But i'll dig more into the Profinet protocol on how it does discovery and negotiation. | |
| Aug 17 at 17:35 | comment | added | Ron Maupin♦ | As i explained, a switch interface with a voice VLAN will only use that when a Cisco phone uses CDP to negotiate a trunk. It does nothing when a normal device is connected to the interface as it will only use the data VLAN at that point. The switch requires a CDP negotiation to use the voice VLAN configured on a switch interface. | |
| Aug 17 at 16:45 | comment | added | Khaalidi | @RonMaupin I know there is series of Cisco Industrial switches that natively support Profinet. In a typical Industrial network, they keep it isolated from the rest of the enterprise IT architecture because those enterprise class switches do not support Profinet natively. It is crazy you know when it works in the same Unmanaged Dlink switch where the PC is , the switch is connected to an an access port of VLAN 101. | |
| Aug 17 at 16:45 | comment | added | Khaalidi | Yes an access port for sure will drop tagged VLAN traffic to prevent VLAN hopping attacks, but an access port with voice VLAN will actually forward VLAN 0 traffic. | |
| Aug 17 at 16:33 | comment | added | Khaalidi | Yes I'm not using a Cisco Phone. It is Profinet PLC device. Profinet devices use Vlan 0 for discovery and some other aspects of the protocol. dot1p—Configures the switch to accept voice and data IEEE 802.1p priority frames tagged with VLAN ID 0 (the native VLAN). By default, the switch drops all voice and data traffic tagged with VLAN 0. If configured for 802.1p the Cisco IP Phone forwards the traffic with an IEEE 802.1p priority of 5. | |
| Aug 17 at 12:54 | comment | added | Ron Maupin♦ | If it is attached to an access switch interface assigned to VLAN 101, it should drop any frames with a VLAN tag to prevent a VLAN hopping attack. Also, restricting a trunk to VLAN 101 will not allow any frames tagged with a different VLAN number. A voice VLAN uses CDP with a Cisco phone to negotiate a trunk, and you are not using a Cisco phone or anything with CDP. | |
| Aug 17 at 11:54 | history | edited | Khaalidi | CC BY-SA 4.0 |
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| Aug 17 at 11:50 | history | edited | Khaalidi | CC BY-SA 4.0 |
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| Aug 17 at 11:49 | history | edited | Khaalidi | CC BY-SA 4.0 |
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| S Aug 17 at 11:26 | review | First questions | |||
| Aug 19 at 8:48 | |||||
| S Aug 17 at 11:26 | history | asked | Khaalidi | CC BY-SA 4.0 |