15
No this isn't doing anything. When the port is in trunk mode, then any "switchport access" statements are not used. The same is true with a port in access mode with any "switchport trunk" statements.
In this case, you should be able to safely remove it.
The purpose for this is usually in the use of DTP (dynamic trunking protocol). So you could configure ...
15
When you configure a trunk link with the command:
(config-if)#switchport mode trunk
all the vlans will be allowed in the trunk link.
If you want to control which VLANs are allowed in a trunk link use the following commands:
(config-if)#switchport trunk allowed vlan
WORD VLAN IDs of the allowed VLANs when this port is in trunking mode
add add ...
9
It will be sent out all ports on the native (untagged) VLAN. If there is no native VLAN, the packet is dropped.
9
Having portfast on a inter-switch link is not the best of ideas, indeed.
Switches and Bridges should take the time needed (going through listening/learning phases) to converge to a loop free L2 topology. Rapid-Spanning-Tree, Rapid-PVST (Cisco), and MST are there to speed that process up from the classic 30sec of Spanning-Tree down to like 2-5 seconds.
On ...
answered Apr 11 '19 at 21:55
Marc 'netztier' Luethi
7,2491 gold badge8 silver badges26 bronze badges
8
Think of each VLAN as a single switch (or switch group).
VLANs work by logically partitioning a single physical infrastructure. Each port is logically connected to one of the VLANs = one of the imaginary switches. Only devices connected to the same VLAN or imaginary switch can talk to each other directly.
Devices in different VLANs require a router to ...
8
VLAN hopping is when a client (unauthorized node) can add VLAN tags to its frames to enter VLANs that it's not supposed to be in or when it can generate MVRP/GVRP frames to make its port a member of additional VLANs. Either the switch adds the port to the unsecured VLAN automatically or its already been a member and the tagged frames were ignored before.
...
7
The short answer is, your proposed additional fiber in the diagram will not gain you any real advantage for VLAN 3.
All traffic from Packaging or Fiberglass, destined to the server in Shipping on VLAN 3, will still traverse the Core. (Presuming that you have already properly tuned your Spanning Tree settings to make the Core switch stack the root bridge.)
...
7
VLAN are introduced by the IEEE 802.1Q standard, which doesn't have this notion of standard or extended VLAN, nor made any difference between VLAN under or above 1005.
This is Cisco implementation that introduce this segregation.
The first Cisco implementation actually supported only VLAN up to 1001, and Cisco reserved VLAN 1002-1005 for FDDI and Token Ring....
7
I'm not understanding your exact problem because you don't provide enough detail but maybe this helps:
With rare exceptions, an IP subnet is mapped to a VLAN = broadcast domain = layer-2 network on a 1:1 basis.
You can run multiple IP subnets inside a single VLAN but they need a router to communicate with each other. Most often this setup doesn't make too ...
7
Strongly suggested: Configure both port-channel and its members identically (except of course for description and the channel-group and vpc bits).
As long as an interface is not configured to be member of a LAG, or because LACP negotiation failed and the interface remains LACP individual [1], the configuration from the given (physical) interface applies, ...
6
If you use the port as trunk you can safely remove the switchport access vlan 100 line.
If you set the "mode trunk" in fact the port act as a trunk, the "switchport access vlan 100" still in the configuration doesn't affect the operational mode of the port.
To view details on the operational mode of your port try:
show interfaces GigabitEthernet 1/0/3 ...
6
Fiber is not so expensive unless you are getting fleeced. Indeed, it can be cheaper than copper cabling. It's also the right solution to long runs.
Given the installation costs, it's likewise foolish to install 5e rather than 6A at this date and into the future for copper. The cost of the cable is a tiny fraction of the cost to get it installed correctly. ...
6
I understand that this is an incorrect configuration, but what was blocking traffic to the new switch? Is this part of the port channel or spanning tree or something else?
Nothing was actually "blocking" the traffic to the new switch, the traffic was simply being forwarded to the wrong switch. This is normal operation of ports that are part of a LAG.
The ...
6
First of all an access port is by definition can only carry one Vlan.
Voice vlan is used, when if its actually a voice vlan traffic needed to be carried.
so lets say both vlans 232 and 233 are Data Vlans.
You have to apply like below.
interface Fa3/0/1,
switchport mode trunk
switchport trunk allowed vlan 232,233
end
Now , Trunk mode is used carry ...
6
Just to amplify on Zac’s answer: you have one subnet per vlan and vice versa. At the CCNA level, you can ignore the rare exceptions. The router on a stick has an (sub)interface in each subnet. Therefore all VLANs must be trunked to the router.
6
The problem is not the traffic from the server to the switch, but the return traffic, from the switch to the server.
Since the VLAN is native, the switch will sent the traffic for this VLAN untagged, while the server expect it tagged.
So this cannot work as is.
You should probably use this VLAN only for PXE boot and configure your server Operating ...
6
You have to already have a VLAN in the allowed list (not "all") before you can use the add command to append to the existing list.
So, first, use: switchport trunk allowed vlan 52
Then you can use: switchport trunk allowed vlan add 160,176,177,247
The reason being, right now it's set to "all", so there's nothing to add since they're all ...
5
Depending on the model - it may not support both tagged and untagged traffic on the same switchport. The GS1910 is one such model.
Either tag all or tag none.
Just got off the phone with Tech Support to be told what I had already figured out...
Good Luck
5
I think you are confusing a couple of concepts. Looking at the last configuration section of the document you have linked:
7.2) VXLAN without CVX
Configuration on VTEPs:
!
vlan 100
vlan 200
!
interface Ethernet 1
switchport access vlan 100
!
interface Ethernet 2
switchport mode trunk
switchport trunk allowed vlan 100,200
!
interface loopback 1
...
5
I think you're confusing what goes on internally on the switch. How it keeps track of which ports are in which VLAN is up to the manufacturer.
It's important to remember that 802.1q frames are a different format than "standard" Ethernet (802.3). Standard Ethernet frames do not have VLAN IDs. A PC or other device transmits and receives Ethernet frames (...
5
At the risk of expressing an opinion here, there is no such thing as "best practice." There are good practices, there are bad practices, and there are a lot in between. There is no best practice because there are many factors which make each situation different.
In the choice you present, you might consider the ease of maintenance/modification, the ...
5
Certainly this is the usual situation for the Cisco and Avaya phones I'm familiar with, as it's usual to keep voice and data traffic separate.
This is from a Cisco SPA504G phone web configuration; these facilities are available through any of the methods for configuring them, through their remote provisioning mechanisms (HTTP/TFTP etc)
You see that the ...
5
A VoIP phone that chains to another device is a switch, and it negotiates a trunk between the phone and the switch. This happens with CDP or LLDP.
For example, a Cisco switch interface configured as an access interface connecting to a Cisco phone will use CDP to negotiate a trunk from the access interface:
interface GigabitEthernet 1/0/1
switchport mode ...
5
Before VLANs, we used to do it like this:
Use separate sets of switches for each area (servers, desktops, whatever)
Keep those LANs completely distinct (different IP address ranges and no wires in between)
Bundle several ethernet cables with cable ties, and plug all the LANs into separate interfaces of the router, which routes between the different LANs and ...
5
The bandwidth on an interface is the bandwidth on the interface. It is possible to use multiple interfaces (up to eight) in a port channel between the switches to give you a greater aggregate bandwidth, but a single flow will still only use a single link in the channel.
This will require more links between the switches, but you have not given enough ...
5
Only Cisco switch platforms that still support isl trunking need to have the trunking protocol configured.
Newer platforms have no support for isl trunking anymore, so the interface command switchport trunk encapsulation dot1q is default/implicit/unsupported, and there's no need to configure it. Just set switchport mode trunk.
Of the ones that still ...
5
Generally, you'll want to secure VLAN membership for all ports that you don't control on both link ends. If a trunk port - or rather the link partner - can simply join any VLAN they want then an attacker can very easily penetrate each VLAN. This is called VLAN hopping.
You can leave trunk ports unsecured when the link is entirely within your control - your ...
5
Most of the time, a computer is connected to an access port--not because of security, but because most computers don't need to switch VLANs. And since they don't switch, most NIC cards can't create 802.1q frames required for tagging VLANs anyway.
On most enterprise-class switches, an access port will drop tagged frames as a security measure.
5
You should not disable spanning tree on trunk interfaces. In fact, STP needs to be on links between the switches, which should be the trunk interfaces.
You can also leave STP enabled on the access interfaces to prevent loops if someone connects two access interfaces.
Look at it this way: if the links between the switches are not running STP, and somehow ...
5
Yes. You don’t even need a trunk. If all ports on both switches are access ports on Vlan 3, then the port connecting the two switches are on Vlan 3 and both switches form one broadcast domain on that Vlan.
If switches are unmanaged then all ports would be on the one Vlan and the number is irrelevant.
A couple helpful details:
Access ports to end hosts or ...
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