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Switches / Hubs





A switch is a device that filters and forwards packets of data between LAN segments. Switches operate at the data link layer or the network layer of the Open Systems Interconnection (OSI) Reference Model and therefore support any packet protocol. LANs that use switches to join segments are called switched LANs or, in the case of Ethernet networks, switched Ethernet LANs. A hub is a connection point for devices in a network. Hubs are commonly used to connect segments of a LAN. A hub contains multiple ports; when a packet arrives at one port, it is copied to the other ports so that all segments of the LAN can see all packets.

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Please help me to change the time on my OXE WBM switchboard
OWASP Proactive Controls
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OWASP Proactive Controls

Learn the most important control and control categories that every architect and developer should include in their projects.

Cannot ping or access via ip new cisco switch

show running-config
v2.4.0.94 / RTESLA2.4_930_181_045
CLI v1.0
file SSD indicator encrypted
ssd config
ssd file passphrase control unrestricted
no ssd file integrity control
ssd-control-end cb0a31af4e4430033719968c0
unit-type unit 1 network gi uplink te
unit-type unit 2 network gi uplink te
unit-type unit 3 network gi uplink te
unit-type unit 4 network gi uplink te
spanning-tree mode mst
vlan database
vlan 3,5
voice vlan oui-table add 0001e3 Siemens_AG_phone________
voice vlan oui-table add 00036b Cisco_phone_____________
voice vlan oui-table add 00096e Avaya___________________
voice vlan oui-table add 000fe2 H3C_Aolynk______________
voice vlan oui-table add 0060b9 Philips_and_NEC_AG_phone
voice vlan oui-table add 00d01e Pingtel_phone___________
voice vlan oui-table add 00e075 Polycom/Veritel_phone___
voice vlan oui-table add 00e0bb 3Com_phone______________
bonjour interface range vlan 1
hostname SG350x
management access-list admin
ip http authentication aaa login-authentication https local radius
snmp-server server
snmp-server location "Server Room"
no ip domain lookup
ip name-server
ip telnet server
interface vlan 1
 no ip address dhcp
interface vlan 3
 name "Corpyy"
interface vlan 5
 name "Guest"
interface GigabitEthernet1/0/1
Can you "downgrade" Cisco IOS-XE from 3.7.3 to 3.6.8?

May seem like an odd question, but I have 9 other switches of the same type on 3.6.8 and wanted to see about changing this switch to coincide with the others. Not a huge issue but was curious if it could be done simply or if it's more in depth.
Looking at labelling a port number on the HP 1910 switch but cant seem to find the command for CLI or GUI.

We are using HP Pro curve POE switches.

Some of its access ports are not getting power and they are in searching mode and because of that when I try to connect any end device, it does not work.

Please assist me in this matter



Any idea how to improve the network design to ensure the network performance , link redundancy (RSTP) and compatibility on layer 2 to layer 3 are working fine on  video management system?



Looking at upgrading the firmware in out pretty old switches.  One is a HP1910 and the other is a 3com2952 but look the same.
I've found the firmware for the 1910 but cant see the 3com.

Are these the same or not?


Device Name

Product Information
3Com Baseline Switch 2952-SFP Plus Software Version Release 1101P10

Software Version
5.20 Release 1101P10

Hardware Version

Bootrom Version

Running Time:
195 days 23 hours 25 minutes 45 seconds

Our company has installed a pair of Cisco 2960x switches (Model: WS-C2960X-24TS-L) stacked with FlexStack Plus stacking module. Currently, we have configured the local user database for a few network administrators to logon and managing the switches.

<.. Extracted Running-Config..>
username mcms_admin password 7 <..Password..>
username mcms_admin2 common-criteria-policy policy1 password 7 <..Password..>
username mcms_admin3 common-criteria-policy policy1 password 7 <..Password..>
aaa new-model
aaa common-criteria policy policy1
 min-length 8
 max-length 25
 numeric-count 1
 upper-case 1
 lower-case 1
 special-case 1
 char-changes 4

ip ssh time-out 60
ip ssh version 2
ip ssh server algorithm mac hmac-sha1
ip ssh server algorithm encryption aes256-ctr
line con 0
line vty 0 4
 transport input ssh
line vty 5 15
 transport input ssh
<.. Extracted Running-Config..>

Currently, the switch does NOT trigger any audit logging if an administrator logon successfully or logon failure to the switches. When entering a "Show Log" command, the switch only show interface up/down/connect/disconnected status.

Our security team would like us to implement some kind of logging such that there will be a historical Logon audit log whenever a system admin (Or intruder) logon failure or successfully to the network switches both a SSH remote user or thru the console port.

Our team is a bit new to the Cisco network management and would like to know how can…
Our company have installed a pair of Cisco 2960x switches (Model: WS-C2960X-24TS-L) stacked with FlexStack Plus stacking module.
Currently, they are running IOS Version 15.2(2)E7. We are planning to upgrade to IOS version 15.2.(4)E7 to address some vulnerability suggested by our security department. We will follow the procedure similar/described on the URL: http://www.petenetlive.com/KB/Article/0001002 by copying the bin files to flash1: & flash2: and then reload.

As far as the IOS upgrade procedures are concerned, we have the following questions and clarifications:

Our management would like us to upgrade the switches one by one by copying the bin files, changing the boot system to one of the switch (i.e. Master or member) then reboot first then proceed with the other switch instead of updating both and reload together.

I foreseen that will cause a version mismatch problem and harmful to the stack formation but we would like to know if this is a recommended method of upgrading a pair of Cisco 2960x stackable switches and wonder if there is any Cisco official URL/documentation general prerequisite/requirement pointing out that customer should upgrade the whole stackable logical unit as a whole and reloaded together instead of doing it one by one.

Thank you so much for your technical advice/recommendation in advance.

When dealing with MTU in a networking environment, how do you verify what MTU size is being used/generated from within two systems?  Also, can you explain or share the size of MTU of the default or best practice MTU size for communication on different networks and or devices?
HTML5 and CSS3 Fundamentals
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IP address shortage on Class C network.
The company is in manufacturing business. They have Windows servers, office PCs, production PCs, network switches, internal WiFi, IP phones, machines, etc. They all consume IP addresses. Now they wanna add 40 more production PCs while there are only 20 free IP addresses.
What should be done in order to release more IPs on this network?
One thing we are considering is to create a separate network for all 20 IP phones which are used in the "sub-site". (Please see the attached diagram). We are not good at VLAN, but we can learn. Will VLAN help in this situation?  
Are there any other things we can do?
What's the best way to setup Cisco 3850 switches by copying configs over the new one. 2 identicals are already in place.  
The additional will server same functions as access switches.
Hello there,

Can someone help me locate management packs for HPE Aruba Switches? Alternatively, easy to use documentation on how to incorporate its SNMP into SCOM (System Center Operations Manager) would be helpful too.
Cisco Mobility Express - I have 2 - 2802E's and a load of 2702's
One I have setup as a controller works fine, now I want to setup the second 2802 as a failover controller.

Initially I flashed it with the lightweight firmware it joined then went into my ME controller and said convert to ME, now it comes up ME capable.
That one seems to sit on the setup wizard at least when I look at the console port.

The first time I gave it some time thinking it would get the config and eventually just come up as a controller but nothing.
It does show up in ME as ME capable. I went into my controller and clicked make ME Controller it just rebooted and went to the same place.
I ended up rebooting it there essentially killing the setup wizard. It seemed to work but the secondary controller kept disappearing in ME until I rebooted and then it would show up again for a while.

I reset it and flashed it as a CWAP again, worked fine.
I had ME convert it again and this time went through the wizard and gave it the same settings as my main controller, it came up and I click Make ME controller now they are fighting back any forth I'm guessing over the management IP which makes sense so I just shutdown the second one for now.

I can't find a single document regarding bringing up a secondary controller using on premise ME unit.
I found documentation using cloud based services and using full blown WLC's but nothing in regards to what I'm using.

I found a few brief mentions about …
hello Experts
i am facing a issue right now
i have Cisco 3850 core switch have a vlan configured for example Vlan22
port 1 confiugred as trunk mode, it connected with a Juniper SSG 550M firewall, Juniper port has sub interface confiugred in same vlan, communication between core switch and firewall sub interface without issue.
port 2 and 3 configured as trunk mode, it connected with a ESXi host, a virtual switch configured VLAN parameter in same vlan, two ports of ESXi host in the same virtual switch, communication between core switch and virtual machines without issues.

my problem is once i confiugred port channel for port 2 and 3, the virtual machines can't reach to the firewall, configuration is below, at the same time no any issue between core switch and firewall either between core switch between virtual machines, i have to remove the port channel config to fix it, so do you know whats wrong with it then? that looks not make sense.

thank you

interface Port-channel1
 switchport mode trunk
interface GigabitEthernet1/0/2
 description ESXi-VMNetwork
 switchport mode trunk
 channel-group 1 mode on
interface GigabitEthernet1/0/3
 description ESXi-VMNetwork
 switchport mode trunk
 channel-group 1 mode on
I have a 2960X-48FPD-L switch in a small office and want to connect couple of AP’s (2802I) to it.
Is the PoE requirements sufficient of the switch and the regulatory domain must be Z. Is this correct
The office is in Brazil.
I am trying to troubleshoot an issue we're having with Nexus 9000 switches and an ASA 5585 Firewall.  Our network access control software is reporting a machine at an IP address of x.x.107.100.  I can't ping that address from behind the firewall or on the user network.

I looked at some packets from the firewall and my laptop, but just have a question about the Nexus packet flow.

HSRP is enabled, and my laptop sends the packet to the destination mac 0000.0c07.ac01 (core switch HSRP MAC).  Is the Nexus switch supposed to replace this MAC address with a physical MAC address?  The firewall sees the packet coming from the active router's physical interface MAC.  I thought from CCNA studies that the packet would use that virtual MAC and the HSRP router would sort out (load-balance) once it got the packet back?
I am seeking advice regarding disabling VTP pruning within a collection of Cisco switches.

The background.  I recently introduced a new Cisco 9300 switch into the environment and it became a VTP client in the VTP domain.  We have about 25 VLANs configured in the environment.  Everything was working fine on the 9300 except that hosts on a particular vlan (14) were not able to communicate.

The picture below shows the output of "show interfaces trunk".  There is one port channel (Po30) to our core switch.  Vlan 14 is not listed under "Vlans in spanning tree forwarding state and not pruned" and that is believed to be the cause of me not being able to communicate with hosts on this switch assigned to that vlan.  I was advised to disable pruning by a Cisco technician and that should bring things into alignment.
My question is, is there any downside to doing this?  If I disable pruning, will the list in "Vlans allowed and active..." and "Vlans in spanning tree forwarding..." be the same?  I am also curious if there are any "gotchas" with disabling VTP pruning.  I am not understanding why an active vlan is pruned on this switch.
Hi -

I have two 1920 HP switches and I would like to share VLANs between the two. Coming from a Cisco background, I thought setting up a trunk would take care of it but no luck.

Basically what I did was to create a trunk port on each of the switches and directly connect them with a network cord. That did not work, the VLANs did not propagate.

What am I missing here?

Thank you for your help!
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I have  a  CISCO 3750 switch  and would like to give a restart . Please post me commands  and dose it needs to be run from enable mode?

How to I get multicast to work on an HP A5500 Switch?

I am trying to get my phones and PBX to autoprovision which requires multicast

I have the switch setup with the LAN (1) and a VLAN (50) and it is configured for auto-vlan from port 1-44
Port 45-48 are configured as VLAN50 port based

The phones, pbx and switch will all work together, but for autoprovision to function the multicast has to work  (broadcast network

On the Hp Switch I have enabled IGMP Snooping or both LAN1 and VLAN50 which I understand is suppose to allow the broadcast.

Any suggestions on how I can get mulitcast to work?
Have a new Nexus 3548, have port set as trunk that connects to a 3650 stack also set to trunk.  The link doesn't come up and when I look on the nexus i see

eth  trunk  down    BPDUGuard errDisable

not sure what to do here.
I have a brand new Cisco 9300 access layer switch that is trunked to a Dell Force 10 core switch.  The core switch is a VTP Server for several VLANs.  While the 9300 ports were configured for hosts, it was NOT a VTP client yet so it had no knowledge of our current VLAN structure.  To give an example, I had a port configured "switchport access vlan 14."  Once the server was brought online as an active access layer switch, it was configured as a VTP Client in our custom VTP domain.  However, any device on vlan 14 cannot communicate past the 9300 switch even though the port channel tagged on the Force 10.  In fact, I am simply re-using the port channel configured on the core switch to connect the trunk ports to the new 9300 switch. If I do a "show vlan" on the 9300 it shows my vlan 14 with the proper name as it is configured on the VTP server.

My question is, if a port was configured to exist on a particular VLAN before the switch was a VTP client, are there two conflicting VTP entries in the vtp.dat database on my 9300, one local and one obtained from the VTP server? It doesn't seem like this could be happening since "show vlan" looks identical to a different access layer switch that is a vtp client in the same environment.
Netflix/Amazon TV signal blocked by Linksys 5-port Unmanaged Switch

Before: Netflix/Amazon TV signal from Airport Extreme CAT5 connection to VIZIO TV via Netgear Powerline  2000 - TV reception OK

After: Same as Before, except TV CAT5 Netflix/Amazon  connection passes through Linksys 5-port Unmanaged Gigabit Ethernet Switch, - Netflix/Amazon TV reception fails, reporting no signal.

How do I get the’After’ connection to work?
We have 3 Zyxel XGS2210-52HP switches uplinked from fiber SPF ports. VLAN's have been configured on all switches. From VLAN Port Setup, I select VLAN Trunking for PVID created, (40), and SFP port, (52). When I Apply, the switch looses connectivity with network. Only option is to power cycle switch to reconnect. Please educate me on what I'm doing wrong and proper way to trunk the 3 switches.  Current Zyxel XG2210 firmware is running, (4.50)
Thank you!

VLAN Port Image

Switches / Hubs





A switch is a device that filters and forwards packets of data between LAN segments. Switches operate at the data link layer or the network layer of the Open Systems Interconnection (OSI) Reference Model and therefore support any packet protocol. LANs that use switches to join segments are called switched LANs or, in the case of Ethernet networks, switched Ethernet LANs. A hub is a connection point for devices in a network. Hubs are commonly used to connect segments of a LAN. A hub contains multiple ports; when a packet arrives at one port, it is copied to the other ports so that all segments of the LAN can see all packets.