Timeline for answer to Native VLAN between switch and router by m1x
Current License: CC BY-SA 3.0
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7 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Dec 28, 2014 at 3:05 | review | First posts | |||
| Dec 28, 2014 at 12:47 | |||||
| Dec 22, 2014 at 23:32 | comment | added | Peregrino69 | Tagged / untagged is 802.1Q terminology. Usually you assign a different subnet for each VLAN, 10.0.8.0 for VLAN 8 and 10.0.69.0 for VLAN 69. Assume that the HP device port is untagged on VLAN 8 and tagged on VLAN 69; Cisco port access VLAN is 69 and VLAN 8 is trunked. The traffic will pass on both VLANs, but you have a PVID mismatch. The purpose of VLANs is limiting bcast domains, and if the VLAN tagging doesn't match (as in my example above) you will have bcasts from VLANs 8 and 69 spilling into each other. That's not a desirable situation, so standard (good) practice is to match the tagging. | |
| Dec 22, 2014 at 15:54 | comment | added | NewCT96 | That makes sense. I'm wondering of this works behind the scenes. Weither it's fabric or visible in any sort. I think a wireshark session would give me that answer. Have a good day. | |
| Dec 22, 2014 at 15:53 | vote | accept | NewCT96 | ||
| Dec 22, 2014 at 15:49 | comment | added | m1x | Yes, vlan tag is removed when leaving the router interface facing switch. 1) VLAN 8 tag is added when arrives at switch if no tag included; 2) VLAN tag info maintained if traffic already have the tag. | |
| Dec 22, 2014 at 15:40 | comment | added | NewCT96 | Indeed I wanted to give as many information as I can :) You're right saying tag/untag makes more sense because this is what's happening technically. In HP world, a trunk is a port aggregation. So I guess the router is stripping vlan "tag" information before forwarding the traffic to the next port? When the packet hits the interface (port 20 of the HP) it attaches the native vlan 8 for this side? | |
| Dec 22, 2014 at 15:15 | history | answered | m1x | CC BY-SA 3.0 |