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4

Can you explain what happens to the frames tagged 100 as they go through (or try to go through) this Gi0/0/0.1 sub-interface? First, let's be a little more clear about your configuration for other readers. More than likely, you also have an interface in the router configured like this: interface Dialer1 mtu 1492 ip address negotiated ip nat outside ip ...


3

So here is the working solution... First of all - bridge-domains are not supported under sub-interfaces! Test stand looks like this I've created two logical systems on vMX to simulate two different routers. ls1 contains interfaces ge-0/0/0.200 (tagged, VLAN 200, 192.168.200.1/24) and ge-0/0/0.100 (tagged, VLAN 100, 192.168.100.1/24); ls2 - interface ge-0/...


3

Sounds like you need "Selective Q-in-Q" documented here E.g. interface GigabitEthernet1/23 switchport mode trunk switchport vlan mapping 21 dot1q-tunnel 211 switchport vlan mapping 31 dot1q-tunnel 311


2

When VLAN 10 is tagged on egress from switch A but unknown in switch B the frames will be sent on the link and dropped by switch B. When VLAN 10 is untagged on the egress port all frames enter the untagged VLAN on switch B. The same with your second question: the switch sends traffic for all allowed VLANs on the link, whatever the receiver chooses to do ...


2

If your router supports span ports you can anaylze the traffic using Wireshark. Wireshark understands both ISL and dot1q, for more information: Wireshark ISL reference http://www.wireshark.org/docs/dfref/i/isl.html An example of a capture containing both techniques: http://wiki.wireshark.org/SampleCaptures?action=AttachFile&do=get&target=isl-2-...


2

Before there was 802.1Q trunking, Cisco came up with ISL trunking. The IEEE bowed to the other industry vendors and came up with 802.1Q. Cisco added that to its repertoire, and the switches required you to choose one or the other. Cisco deprecated ISL, and the modern Cisco access switches only do 802.1Q. The Cisco distribution switches and routers still ...


2

Private VLAN is a feature that prevent hosts within a single VLAN to communicate with each others. VLAN separate different networks. A site may consists of thousands computers, belonging to dozens of business unit or department, segregated by different VLANs. One VLAN for the accounting department, one for human ressources, one for IT, etc... Each VLAN ...


2

The switchport trunk encapsulation dot1q command tells the switch that the interface should use IEEE 802.1Q encapsulation on the frames when the interface is configured as a trunk. Basically 802.1Q inserts a VLAN tag on the frames. This contrasts with ISL that actually encapsulates the frames with an ISL frame. Many newer Cisco switches have dropped support ...


2

As @andreyprokhorov mentions, you can create a bridge group. On IOS-XE, it's called a bridge domain. Cisco has a full explanation, but here is a sample: interface GigabitEthernet0/0/0.1 no ip address negotiation auto cdp enable service instance 100 ethernet encapsulation dot1q 200 bridge-domain 100 ! interface GigabitEthernet0/0/0.2 no ip address ...


1

The newer Cisco switches only support dot1Q encapsulation. You do not need to do anything because it is already configured that way. Older Cisco switches could support switchport trunk encapsulation isl or switchport trunk encapsulation dot1Q, but newer switches do not need the switchport trunk encapsulation command because they only support the 802.1Q ...


1

I was able to achieve the desired outcome by using a Mikrotik routerboard and getting the trunk to run through it. I used the packet sniffer function which saved the capture to a file and I was able to download the file to my PC and view it with Wireshark. The 802.1Q field was a sight for sore eyes :).


1

the basic way is to use ping with the don't fragment bit set to ping with various packet size until you find the correct value: On a Mac OS system use ping -D -s <packetsize> <pingable IP accross the tunnel> On Windows ping -f -l <packetsize> <pingable IP accross the tunnel> On linux, the Don't Fragment bit is set by default: ...


1

Like stated in previous answers, "add/remove/none" is your (only) friend... switchport trunk allowed vlan add 30 As mentionned by ytti, I recommend dropping dangerous commands like this in TACACS that you cannot do 'switchport trunk allowed vlan X' without add/remove/none. Why I added this answer is because Brett's second suggestion switchport trunk ...


1

As you've drawn this, you can't do it. You can't have the same subnet in two locations (separated by a layer 3 link). To make this work, you need 4 VLANS, two at each site. You can make the ones on the left 192.168.1.0/25 and 192.168.2.0/25, and the ones on the right 192.168.1.128/25 and 192.168.2.128/25. The lower two routers will have a subinterface on ...


1

You have a traditional 2-port router trunking to an 8-port switch. The 891 has two router ports which can be used like traditional router ports. These two ports are usually used for WAN connections, but one or both can be set up with subinterfaces, etc. as traditional router ports. The other eight ports are switch ports and act like a switch, and cannot be ...


1

You say you are already running virtualized OSes on the host, which are running in different VLANs. Hence I guess you already have the switch configured to perform dot1q trunking (Cisco terminology), otherwise you would not be able to have different VLANs. Regarding the main host, you can configure Hyper-V either to use a tagged VLAN or send the management ...


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