All Questions
86
questions
13
votes
3
answers
18k
views
Tracking down an invalid source mac address
I have inherited support of a remote site which contains a Cisco 4500 and is connected to ~2 dozen cisco access switches - primarily 2960s with a couple of 3750s and 3560s. Not all access switches ...
- 859
8
votes
6
answers
5k
views
How Does A Layer 2 Switch Differentiate Between Different Networks?
I know that different IP-based networks can be connected to the same layer-2 switch. and I know each network's nodes can communicate just fine, however, no normal traffic can occur between two nodes ...
- 285
8
votes
2
answers
13k
views
Why each and every single port on Layer 2 switches need to have it's own MAC address?
A switch doesn't alter the frame, and source/destination mac addresses remain how sending host specified them,so let me say it again Layer 2 Switching never changes the frames means no changes in MAC ...
- 435
8
votes
3
answers
7k
views
Does a switch understand packets? If yes, what is the frame terminology for?
I was a little confused between packet and frame. The confusion was based on, if a switch is a layer 2 device, how does it reads a packet from a layer 3 device, and where is the 'frame' thing which is ...
- 83
7
votes
2
answers
54k
views
Enabling flow control on my ethernet NIC
When running "ethtool eth0",
I get a line in the output that states -> Supported pause frame use: No
Does this mean my Ethernet card does not support flow control at all?
I try to enable the flow ...
- 634
7
votes
3
answers
10k
views
Posible to connect VLAN switch through dumb switch?
Is it possible to connect a VLAN switch into a dumb switch ?
The router will know how to reach network connected by a VLAN through the dumb switch please ?
No edge effect ?
By example, a schema of ...
- 71
6
votes
2
answers
13k
views
Should I disable STP on my access ports?
I'm going to replace some old "central" access switches to some Cisco Catalyst 2960X, and I'm not sure what to do on their STP configurations.
For this network, we have some "central" access switches,...
6
votes
2
answers
4k
views
How do I know the switch is layer 2 or layer 3?
Is it possible to find the switch is Layer3 or Layer2 in (Switch)CLI? Is there any command to check whether the switch Layer(Layer 3 or 2) in CLI?
- 125
6
votes
2
answers
495
views
How to connect a special device in a network
I have a question which is puzzling me.
I have a couple of custom electronic devices (are identical, one is a master and the other is a slave) which implement only up to level 2 of the ISO/OSI layer, ...
- 61
5
votes
3
answers
2k
views
'interface vlanX' or 'interface loopbackX'
VLANs are a layer 2 concept. We can all agree on that but why, then, do we use the 'interface vlanX' to allow routing on a switch. If we want to setup a default gateway for VLAN X on a Layer 3 switch ...
- 1,005
5
votes
5
answers
560
views
What blocks a computer from another network in the same switch from answering an ARP request?
Let's suppose I have 3 computers A, B and C connected to the same switch with only the native VLAN active. A and B belong to the same network, let's say that their IP addresses are 192.168.1.1/24 for ...
- 65
5
votes
2
answers
656
views
Network topology suggestions?
Looking for guidance on network topology changes. Currently our network has 2 different stacks of switches running in layer 2. These switches then connect to a stack of layer 3 switches to do internal ...
- 453
5
votes
2
answers
7k
views
How does a layer-2 switch work with UDP?
If UDP and/or TCP send packets via IP to an Internet Protocol Address, how can a layer-2 switch forward these?
Is this possible or do you need a layer-3 switch?
- 634
4
votes
3
answers
1k
views
Collision domain question
I'm studying for my CCENT exam, and not quite sure why the book (official Cisco) says that there are 5 collision domains in this example. Isn't it supposed to be 4? The hub on the left, the hub in the ...
4
votes
2
answers
3k
views
Nexus 3172T MTU
I am attempting to set the L3 mtu on a Nexus port.
The mtu option is only available if I set "no switchport" which then prevents me configuring VLAN related settings.
Am I missing something obvious? ...
- 127