Switches / Hubs

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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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Hello, I have a query regarding Spanning Tree / Loop Prevention across MC-LAG links.

We've recently taken over a network of a hub / spoke design with all of the access switches feeding back to our Core (two HP 8400's). The core is setup with MC-LAG link which prevents Spanning-Tree being enabled. Reading the 8400's documentation my understanding was that this was by deign, and MC-LAG would handle any loops.

Recently, one of our onsite technicians introduced a newly built edge switch which brought the entire network down. Unfortunately part of the config on this switch had missed enabling STP, and when he plugged this new switch in it had a looped cable back to itself. My issue with this is why this would have introduced such a massive loop across the entire infrastructure, while I would accept there will be a loop in the edge of network location, taking the new switch down, how it carried on through to the core is my concern.

My query is to what I'm missing with the Core switch. We have Loop-prevention enabled on both nodes. Is there a method to enable spanning tree, or is there a better protocol I should be using instead.

Hoping the above makes sense, apologies if not.
Thanks in advance!
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Cloud Class® Course: Microsoft Office 2010
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Cloud Class® Course: Microsoft Office 2010

This course will introduce you to the interfaces and features of Microsoft Office 2010 Word, Excel, PowerPoint, Outlook, and Access. You will learn about the features that are shared between all products in the Office suite, as well as the new features that are product specific.

What is the best way to achieve implementation of 42 cisco switches at client location? Also I need help with how to prepare or what to include in SOW(scope of work). I really appreciate your help.
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Need assistance creating Visio drawings.  I've never done any and don't know where to start.  Tutorials would be great, if any.
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I have a server with multiple virtual servers on it, was wondering is adding a network card with more ports will help for performance, since I use gigabit switches so the most throughput on the network is a gigabit how will I gain with a card with 4 ports each a gigabit if the switch highest capacity of the switch is a gigabit plus the switch is handling not only the server?

Any recommendation for a nic card and if not much more expensive can do nic teaming.
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How do I verify is a layer 2/3 switch is operating in either layer?  I was asked to verify if certain devices in our network are working in either layer.
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We have a couple of Cisco 3560 devices and since they are end of life now, I can't get support.  I wanted to upgrade the IOS to the latest version, but need assistance.  We presently have the following IOS version:

C3560 Software (C3560-IPBASE-M), Version 12.2(35)SE5,

I also wanted to know which version would be best, if optionable.
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We have purchase the new Aruba 2530F and our HQ instruct us to create the SVI’s in the switch and perform the intervlan on this switch. I have some doubt regrading this configuration and hope that expert can advise me.
1.      For all the printer we should use which vlans
2.      From the switch I can see that have option for us to check primary and management in vlan interface, let said in this information provide by HQ should I enable “management” in  VLANS 4
3.      What is native VLANS
4.      We try to enable the management in VLANS 4 ,we lost access or web console but we still have connectivity ?
5.     we should connect all the configure all the management port in VLANS 4 ?


MGMT_VLANS: 4        10.10.4.1
OFFICE_VLANS: 5(Native) 10.10.5.1
STAFFWiFi_VLANS: 6         10.10.6.1
GUESTWIFI_VLANS :7        10.10.7.1
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I have a Cisco nexus switch (48-port) and wanted to setup for the first 24 ports on a vlan and the next 24 ports on a separate VLAN.  How do I do this on a Nexus switch?
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Cisco 3750G switches, with high FCS errors.  I've been having a problem where a link between two switches just dies, and sometimes, it comes back by itself, maybe 30 min or an hour later.  Most of the time, I have to manually move the cable to another port, to get it to come back up, even a reboot of the switch doesn't do the trick.
I have already replaced one of the switches, but the problem persists. I have looked at the logs, and nothing there stands out, most of the errors just state the port went down or came back up.  I started looking at the fcs errors, and I noticed that especially on one switch, it's a really high number.
I have attached the screenshots, any idea's what can be causing this?  I would like to replace the cable, but I don't have another cable and it's a large task to install another one., as the distance traverses a different building. I am not using port security.  Both sides of the link are trunk ports.

I tried to clear the counters and controllers, but the commands I have tried are not working.   Any ideas what could be causing the high fcs errors and what the exact commands are for clearing both the counters, I viewed a few Cisco sights, but they didn't work.

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I have a lab environment with 7 48-port switches (Ubiquiti ES-48-500W).

All of them are connected to 3 16-port aggregation switches (Ubiquiti ES-16-XG) via fiber.

All of the switches are brand new, and all of them are in the same room. Fiber modules are brand new, as are the fiber cables.

The only computers plugged into this network are:

- one windows 2016 Server domain controller with DNS (but no internet access)
- one linux VM running UNMS (Ubiquiti's free switch management software)
- one windows 10 workstation running a third-party program called EMCO Ping Monitor

Before deploying these switches to my production environment, I conigured each switch and joined them all to UNMS.

I have the latest firmware installed on each switch.

Basically, just sitting there doing nothing, UNMS reports outages all throughout the day. Sometimes the outage is for a few seconds. Sometimes the outage is more than 20 seconds. And the outage is not between specific switches. Switch 104 will go down for a few seconds. Then switch 114. Then switch 100. It's all over the place.

Each 48-port switch is connected to 2 ES-16-XGs for redundancy. Using spanning tree protocol.

Should I be concerned about this? Are intermittent drops "normal" for switches? Or does this indicate a problem?

Thinking the UNMS /may/ not be 100% accurate (since it is still in beta), I installed a third-party program called EMCO Ping Monitor on a Window 10 workstation, which I then plugged into a…
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Cloud Class® Course: Python 3 Fundamentals
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Cloud Class® Course: Python 3 Fundamentals

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Hello,

I am trying to add a 3750x to a stack. It is a mixed stack and all the members only use non-cryptographic IPBASE images.

Switch   Ports  Model              SW Version              SW Image            
------   -----  -----              ----------              ----------          
     1   52     WS-C3750G-48TS     12.2(35)SE5             C3750-IPBASE-M      
     2   52     WS-C3750G-48TS     12.2(35)SE5             C3750-IPBASE-M      
*    3   30     WS-C3750E-24PD     12.2(35)SE5             C3750E-UNIVERSAL-M  

I am trying to add the below
WS-C3750X-48P      12.2(55)SE10           C3750E-IPBASEK9-M  

As you can see the 3750x I am trying to add has the IPBASEK9 image. Does anyone have a mixed cryptographic/non-cryptographic image environment.

These will not stack. The stack does not even seem to recognize the switch is there at all or gives version mismatch.

Is there a way I can downgrade the IPBASEK9 to just IPBASE? I am not in a position to get a K9 license for the other switches.

Thanks!
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Hey all
Moving to a new office, was going to go with a TZ400 for a router/firewall/vpn solution.

Have two separate factory areas, both have metal covered walls. We are going to want to have Wi-Fi in each of these rooms for the factory workers handhelds etc.  Ceilings could be 24’ ft plus, I need solid reliable solution that just works for Wi-Fi.  It would require multiple points so therefore a controller to hand off from point to point as they make their way around the factory floor etc.  Hoping for simple/reliable – easy to administrate.  Thoughts/ideas?
Thanks!!!
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Experts, I am looking for a paid CA Devtest Service Virtualization tutorial online. The tutorial offered by CA requires me to provide a company email address which I can't at the moment. Does anyone have information about any websites that offer the training? Any inputs appreciated.
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I am trying to build a 4 LED smart tv video wall[arranged like a square] for teaching purposes. I have a Windows 7 machine with a

 GIGAbyte AMD R7 360 128 Bit GDDR5 2 GB 2XDVI HDMI DP Overclocked Graphics Card GV-R736OC-2GD REV 2.0
ASUS H81M CS

The output from the display port goes to the
Tripp Lite 4 Port DisplayPort 1.2 Multi Stream Transport MST Hub

The HDMI output from the MST hub to the 4 TV on the video wall.

The Problem is:

During system start up, the 4 tv screens are enabled, after that only two screens are enabled at a time.

Any ideas on how sort this out.

Thank you.
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I just picked up 2 used Cisco Catalyst 3750G-48TS-S switches and  I am  getting this error message.  Can anyone tell me how to correct it?

Base ethernet MAC Address: 00:1c:57:18:9a:80
Xmodem file system is available.
The password-recovery mechanism is enabled.
Initializing Flash...
flashfs[0]: 0 files, 1 directories
flashfs[0]: 0 orphaned files, 0 orphaned directories
flashfs[0]: Total bytes: 32514048
flashfs[0]: Bytes used: 1024
flashfs[0]: Bytes available: 32513024
flashfs[0]: flashfs fsck took 7 seconds.
...done Initializing Flash.
Boot Sector Filesystem (bs) installed, fsid: 3
done.
Loading "flash:c3750-ipbasek9-mz.122-35.SE2.bin"...flash:c3750-ipbasek9-mz.122-35.SE2.bin: no such file or directory

Error loading "flash:c3750-ipbasek9-mz.122-35.SE2.bin"

Interrupt within 5 seconds to abort boot process.
Boot process failed...

The system is unable to boot automatically.  The BOOT
environment variable needs to be set to a bootable
image.
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I just picked up 2 used Cisco Catalyst 3750G-48TS-S switches and  I getting this error message.  Can anyone tell me how to correct it?

Base ethernet MAC Address: 00:1c:57:18:9a:80
Xmodem file system is available.
The password-recovery mechanism is enabled.
Initializing Flash...
flashfs[0]: 0 files, 1 directories
flashfs[0]: 0 orphaned files, 0 orphaned directories
flashfs[0]: Total bytes: 32514048
flashfs[0]: Bytes used: 1024
flashfs[0]: Bytes available: 32513024
flashfs[0]: flashfs fsck took 7 seconds.
...done Initializing Flash.
Boot Sector Filesystem (bs) installed, fsid: 3
done.
Loading "flash:c3750-ipbasek9-mz.122-35.SE2.bin"...flash:c3750-ipbasek9-mz.122-35.SE2.bin: no such file or directory

Error loading "flash:c3750-ipbasek9-mz.122-35.SE2.bin"

Interrupt within 5 seconds to abort boot process.
Boot process failed...

The system is unable to boot automatically.  The BOOT
environment variable needs to be set to a bootable
image.
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We have a small number of Cisco 3560 switches and most are presently on IOS version 12.2 and need to move them to the latest and greatest IOS version.  Since most of them do not have the SSH feature that we'd like to move to for connection, This is one reason for the upgrade.  I also need the process for migrating the IOS version as well on the switches.  

I'm assuming that there are no drawbacks to moving to the new IOS and would also like to know the time the switch should take for about 10 devices?
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We have a new Cisco core switch and planning on retiring the Cisco old switch; however, there are still between 5 to 10 cables connected to the device, but we don't know where or whom they are connected to...
We do not have a Fluke device or toner to verify connections.  Is there another way we can figure out where things connections go to?
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Hi All,

I had capture the packet within our intranet where I place the sniffing tool at core switch to only capture conversation between all client to one server. I had observer the almost packet was captured is TCP SYN/ACK packet and TCP RST packet. The TCP SYN packet only below then 10% of captured packet. Its is abnormal in happen in this conversation?
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Cloud Class® Course: C++ 11 Fundamentals
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Cloud Class® Course: C++ 11 Fundamentals

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I need to create a document, not sure of the proper name, but it has to do with explaining why we need an additional Cisco switch and other hardware, as spare, in case we loose another switch.  Can someone share such a document as a template so I can provide to management for approval?
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Trying to setup a Nexus 3524 for the first time . i have a mix of copper sfp and twinax.  eth1/1 connected to Inside interface of an ASA.  Have 3 vlans.  Vlan 1, Vlan 5, and vlan 80.  I configure an ip on vlan 5 but still cant reach the asa and vice versa.. saying no route to host. I've configured the default route to point to the inside interface of the asa.  Any help would be greatly appreciated
Nexus-3k-config.txt
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Jul 18 08:29:03.166: %IP-3-LOOPPAK: Looping packet detected and dropped -
src=10.15.13.69, dst=172.22.1.164, hl=20, tl=56, prot=1, sport=0, dport=0
in=Vlan122, nexthop=172.22.1.237, out=Vlan122
options=none -Process= "IP Input", ipl= 0, pid= 154
-Traceback= 115ADDF0z 119EFE1Cz 119F0030z 119F0CD4z 119F28ACz 119DE990z 119DF3F0z 119DF4E0z
119DF774z 10E75B4Cz 10E71B28z
Jul 18 08:39:22.743: %IP-3-LOOPPAK: Looping packet detected and dropped -
src=10.15.13.69, dst=172.22.1.164, hl=20, tl=56, prot=1, sport=0, dport=0
in=Vlan122, nexthop=172.22.1.237, out=Vlan122
options=none -Process= "IP Input", ipl= 0, pid= 154
ie-gsmr-cisco2#show interface vlan122
Vlan122 is up, line protocol is up
Hardware is Ethernet SVI, address is 7081.051b.21ff (bia 7081.051b.21ff)
Internet address is 172.22.1.237/29
MTU 1500 bytes, BW 1000000 Kbit/sec, DLY 10 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive not supported
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:00, output never, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
L3 in Switched: ucast: 0 pkt, 0 bytes - mcast: 0 pkt, 0 bytes
L3 out Switched: ucast: 0 pkt, 0 bytes - mcast: 0 pkt, 0 bytes
IPv6 L3 in Switched: ucast: 0 pkt, 0…
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I have installed Cisco Network Assistant and have forgotten my password.  I've tried uninstalling it and installing it again, but it won't prompt me to create a password.  Tried googling how to reset the password for it, but have not had much luck finding an answer.  Can anyone please give me some information on how to create/change my password for Cisco Network Assistant I'd greatly appreciate it.

Thanks
Steve Backhus
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Need to recover passwerd for cisco switch 4507R-E without removing the configuration
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help with setting up VLAN on a few switches for phone and data equipment.

i have a series of managed switches that are uplinked together.  I would like to set up a VLAN 100 for a dedicated router that is on port 48 of one switch. This router will listen to requests from phones that are plugged into any other random ports on the switch.  This switch is a ubiquiti unit that allows me to set port 48 to listen to vlan 100 traffic only.

The phones are set to 802.1Q with a vlan of 100.  there are other computers and servers on the switch that are on a 192.168.0.x subnet.  The server is handing out DHCP as well as the router on port 48.  The idea is to isolate the traffic for the phones to ONLY communicate with the DHCP server on port 48.  

Right now, this setting is working. However my question to you, is since the phones are all plugged into random ports 1-47 and set to vlan100  and these ports are set to listen to both default lan traffic as well as vlan100...am i simply congesting the switch with added default and vlan traffic vs setting the actual ports that the phones are plugged into to ONLY vlan 100?

Also, if i plug in another switch,, do i need to set the uplink from one switch to another switch with a vlan100 for them to comminicate or will they pass the phones traffic that is tagged 802.1Q VLAN 100 traffic to the other where the port 48 will ultimately listen and grab it? Thank you!
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Switches / Hubs

21K

Solutions

17K

Contributors

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.