All Questions
15
questions
30
votes
4
answers
75k
views
How does a switch learn a switch table?
Say the switch table is empty. If computer A sends a frame destined to computer B, the switch will broadcast asking who has the MAC address of B. What if C suddenly sends a frame to A? What is the ...
- 835
34
votes
1
answer
91k
views
Using SNMP to retrieve the ARP and mac-address tables from a switch
I would like to get ARP tables from a switch to a syslog-ng server that has been set up on Ubuntu Server 12.04 LTS. I have read about SNMP and I know the server will act as a manager and the switch as ...
- 695
22
votes
4
answers
19k
views
Why is the CAM table in a switch called CAM table and not MAC table even though it holds MAC addresses?
I know the CAM table in a switch holds MAC addresses and the ports that are associated with the respective MAC addresses. There are no such thing as CAM addresses from my knowledge, so why is it ...
- 1,541
9
votes
3
answers
29k
views
Assign an IP address based on switch port
Short:
I want DHCP server to assign a preconfigured IP address based on a port (on a switch, ideally) a device is connected to.
Long:
My situation:
I am building an automated indoor farm (for ...
- 193
19
votes
2
answers
28k
views
Ethernet autonegotiation differences between (10M | 100M | 1G) Ethernet
I am studying for CCNA and on Wendell Odom's book is said that(regarding autonegotiation):
When autonegotiation fails on one node, to choose (half/full-duplex) we must use the rule:
If you have a 10/...
- 821
13
votes
2
answers
47k
views
What purpose is the Uplink port in layman's terms and do I need it?
I have an old Linksys switch (EZXS55W) and it has worked fine for many years now, but I tried to hook something up today to the last open port and noticed the device didn't work when I did this. When ...
- 233
7
votes
3
answers
6k
views
Is there any reason to use a hub over a switch?
Given that hubs are essentially the same as switches, as far as I know, except they share bandwidth between all connected devices, while switches do not, resulting in faster connections. I am simply ...
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
3
votes
1
answer
451
views
question about switches and frame and forwarding table
hey guys was wondering if someone can potentially explain this to me
but lets say switch-A just learned a Ethernet address on port 4 (00:0f:4b:02:63:ae) based on the forwarding table
now a station ...
- 41
44
votes
15
answers
84k
views
How can I diagnose a bridging (ethernet) loop?
Given that spanning tree has failed (or you don't have any spanning tree) and get an ethernet loop, what's the best way to diagnose where the problem is?
Which switch?, which cable? and so on.
- 783
10
votes
4
answers
193k
views
What can cause "FastEthernet is up, line protocol is down" on a Cisco Switch?
I wonder what can cause the first line output of the command show interfaces to be: FastEthernet is up, line protocol is down.
In other words,
Is the cable that is connected to the local interface, ...
- 101
8
votes
1
answer
3k
views
Something is filling my force10 ARP table
I have 2 force10 s25 switches that are used for a dark fiber link between two school buildings. One of my switches is filling its ARP table to the brim and then failing. This can happen as often as ...
- 852
6
votes
2
answers
31k
views
End-to-End delay
I’m working through questions from computer networking top down approach and was hoping to get some clarity on the end-to-end delay calculation. At this stage we are not considering processing, ...
- 499
4
votes
2
answers
5k
views
Is the CSMA/CD protocol active in modern ethernet networks that use LAN switches? If it is active, does it ever detects a collision?
I am interested to know if the CSMA/CD protocol is still active in modern Networks and if it is active why and what is his role now?
- 1,541
2
votes
1
answer
4k
views
What is the EtherType of a BPDU frame sent by a switch which runs Spanning Tree Protocol
I want to know what is the EtherType field of a BPDU frame in various versions and variants of the Spanning Tree Protocol.
- 1,541