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39

You need to use the following command to add your VLAN 30 to an existing Dot1Q trunk on a Cisco Catalyst switch: switchport trunk allowed vlan add 30 Otherwise IOS just thinks you're trying to overwrite the existing configuration and you are left with an accidentally deleted set of allowed VLANs. You could similarly use "remove" in place of "add" to ...


9

To add VLANs to a trunk you have to use the following syntax: switchport trunk allowed vlan add 30 To remove a VLAN from the trunk you need to use the remove syntax: switchport trunk allowed vlan remove 30 When you don't use add/remove you're telling the port to only configure the new VLAN. This is a common error. If your platform supports it you can ...


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

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

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

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 ...


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 ...


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

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

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 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 ...


1

The first thing I'd verify is that the phone is actually tagging frames with that VLAN ID, perhaps with a network tap or port mirror (which might not quite work right on this switch) If you manually had configured the phone to do that and you know it's working, this is probably a bug in the software. If not, manually set it on the phone or configure LLDP-...


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