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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.

I have a question on SFPs, the customer's switch is DEell S4048, I heard that it is 10G Dist. sw Does it always need to have 10G Transceiver for connecting to site WAN router (Cisco ISR) ?
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We are planning to set up 802.1x on Cisco Catalyst 2960-X switches using Windows RADIUS server. What is the best way to include IP phones, and printers? Printers I suppose we can use mac addresses, but our pc's plug into the IP phones so they're on the same port.
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Hi,

I have Cisco 3750 switch. I configured 3 Vlans on it. VLAN 10,20,and 30. Is there anyway that I can give VLAN 10 access to  VLAN 20 and deny it from access VLAN 30? I mean I want network of VLAN 10 and 20 to see each other and communicate but can not access network of VLAN 30

VLAN 10 network 192.168.1.0
VLAN 20 network 192.168.2.0
VLAN 30 network 192.168.3.0

Thx
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Dear Experts, I'm testing the ARP inspection in Cisco switch 3750 and get this result when using show ip arp inspection command

Capture.PNG
Can you explain the results and suggest? Many thanks!
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Dear Experts, I have server farm at network 192.168.55.0/24 (Exchange 2016)

I can access the servers from other network but CANNOT from some servers in the same network 55

What can be the reasons? Many thanks!
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Hello Experts,

I want to add a WIFI access point to a clients network.

These are the four results I am after:

1. Limit bandwidth  to WIfi AP- Can do this with my firewall.

2. Time access control - can do this with a LYNKSYS WIFI access point device

3. Limit or strip off Webmail attachments.

4. Monitor Data Usage on the access point and limit it.

1. And 2. Above are no problem but I don’t know how to a achieve 3. Or 4.

Does anyone know how to make 3. And 4. Work?

Thanks!
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Hello fellow Experts Exchange members:

I request assistance with a confounding problem.

I have an office that uses Cisco Meraki access points all connected to a Cisco SG300-52P switch.

The office uses a separate vendor for their VoIP phone system.

The event log on the Meraki cloud controller is filled with entries that read "Multiple DHCP servers detected."

The entries state that the second DHCP server has an IP address that is not on any of our equipment with a MAC address that identifies it as a Cisco device.

When I put a secondary IP address on one of our devices in the same subnet as the unidentified device, the unidentified device responds to pings.  Using telnet to connect on port 22 brings up the text "SSH-2.0-Cisco-1.25" but typing any character immediately results in "Connection to host lost."

The unidentified device does not respond on port 80 or 443.

Reviewing the MAC address tables on our Cisco switch, the MAC address of the unidentified device is seen on a port that is physically connected to the VoIP phone system vendor equipment.

(There are multiple MAC addresses listed in the MAC address table for this port besides the unidentified device.)

However, when troubleshooting with the VoIP phone system vendor, their technician reports they cannot detect the MAC address of the unidentified device on any of their equipment.

The first part of my question is if it is possible for a MAC address to appear on the MAC address tables in a …
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Dear Experts,

I've completed my basic home network setup by configuring VLAN with router and switch. I was able to make it happen with ubiquiti Edgerouter and cisco Sg200 switch. I setup the Vlan10, 20, and 30. I am able to communicate between the vlan as well. I will later setup the rules in the router to restrict the access between the vlans. The funny thing is that I've configured my router under 192.168.10.1 and my switch under 192.168.10.2. I was able to access my router via the IP but I cannot see my switch. My computer is on 192.168.10.100. The setting of the switch port that my computer connected to has this setting:
 switchport #20:
 vlan 10
switch port mode: access, untagged (excluded from other vlan)

I can set my PC's IPv4 configuration to auto which I will be assigned to one of the IP under 192.168.10.x/24 I can see other devices on the same network and have the access to internet as well. I just can't access the switch portal on IP 192.168.10.2 and I cannot ping it.

If I connect to a different switch port with a different setting like this:
switchport: #24:
vlan 1 (default vlan)
switch port mode: trunk, untagged (excluded from other vlan)

I will need to configure my PC's IP in Windows10 to IP: 192.168.10.100, submask 255.255.255.0, gateway: 192.168.10.1 then I will be able to access the switch portal at 192.168.10.2. If I don't manually configure my window's IP then I will not be assigned into an IP under 192.168.10.0/24 range.  Under this …
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HP 1910 and LACP link aggregation

trying to get another trunk port into existing BAGG and whatever i do it doesnt work, change the port and nothing. created new BAGG , same thing...

the idea is to use two ports (BAGG) and windows teaming LACP hyper-v
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Can we setup VPC for out of band in Nexus7K?  or can you send some link for that? Thank you
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Any recommendations for a cisco switch, IOS, 48 port, fiber on all ports, 10G on each port, and also, another switch with 40G on every port as well.
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I want to replace several WS-C3560X-48PF-E Cisco switches with 2960X. I want the same features enabled and configuration for the ports, the VTY, AAA - everything. What would be the fastest way to clone the old with the new? Copy/paste would need to consider encrypted secrets go to clear text, the self-signed cert section I think should just be omitted and leave what comes with the box. Any other thoughts on speeding the process but not missing anything?
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What is the difference between these flavors of the Cisco 2960-X switch:

48FPS-L
48FPD-L
48LPS-L
48TS-L
48TD-L
48TS-LL
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I need to use PuTTY to TelNet to multiple timing systems, each with their own ip address, but daisy chained to one another as well.  How can I do that?  I need live streaming to happen from each timing box to a local file (different file for each timing system).  I have hardly used PuTTY but it looks like I can only connect to one ip address with PuTTY.  Can I run multiple instances of PuTTY simultaneously?

Thanks in advance!
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Hi;
I have a question on setting up distribution switches, the LAN  network connects to two L2 distribution running VLT (Virtual link Trunk). Both switches are connected to Routers (Pri MPLS and backup Internet). The customer plans to run HSRP between the two ISP routers and use RFC 1918 for the IP Addressing (Physical and virtual addresses for the routers). Do you see any spanning tree issues here, esp. during the failover? I am quote new to VLT and that's why asking this question.

Thanks
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I am planning on replacing an amount of Cisco WS-C2960S-48FPS-L switches in out environment. My basic plan is as follows;
1. Upgrade new switches to latest recommended software
2. Install stack modules where appropriate
3. tftp the config from the existing switch(es) to tftp server
4. tftp the config to the replacement switch(es) from tftp server
5. physically swap old/new (paying attention to VLAN/significant connections)
 
Questions;
1, Does this sound like a good approach?
2. How best to handle instances where switches are stacked? Do I need to tftp the image to each switch in stack or just the first (ie will stacked switches adopt the config from the first)?
3. In instance of stacked switch upgrade do I need to replace all switches in the stack at the same time (to ensure hardware/software compatibility)?
4. Is there anything I am missing or need to pay attention to?
 
This is the first time I have had to go through this process so your expert advice would be appreciated.
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Need to VLAN a flat network.  
I currently have a network and it is one large flat network with one subnet of 255.255.252.0 with a range of IP's 192.168.0.1 - 192.168.3.254.
All of my servers, routers firewalls, printers , copiers  and switches are within 192.168.1.1 - 192.168.1.254
My Workstations (Windows 10 )  are all receiving IP addresses from DHCP server and in the range of 192.168.2.50 - 192.168.2.250

I have been tasked with setting up vlan's for the entire network to improve security and performance

I currently have a 5 switches which are all 48 port switches and in  a stacked configuration with 40 GB uplink to a "Central" Switch. These 5 switches are considered our user segment which has workstations and Printers connected.

The Central switch is actually two 48 port switches that are stacked and have the Servers, routers and firewall connected.

my default gateway is a cisco Switch .

I'm looking for some guidance in multiple areas,
1. design ? how many Vlans , do I use vlan 1 ? I think my current configuration would mean everything is VLAN 1
2. Will I need to change my IP addressing of my enire network ? if so what would my new IP addressing look like. how would I g about changing without taking down the whole network.
3. Can the job be done slowly ?
4. Can a server ( DHCP ) on one Vlan provide IP Addresses toWorkstations on a separate Vlan ?

Thanks for any feedback
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I tried to restrict SSH access to one of my Cisco Nexus 9508. Earlier I was permitting all RFC 1918 to SSH
and now it's limited to two bastions. BUT after modifying my ACL to have just two bastion hosts I am
still able to ssh to the 9508 at its management address from my desktop machine which shouldn't
be possible. What am I missing?

line vty
  exec-timeout 15
  access-class 5 in

core11-las# sho access-list 5

IP access list 5
        40 permit ip 10.132.17.27/32 any
        50 permit ip 10.183.57.250/32 any


core11-sf# sho users
NAME     LINE         TIME         IDLE          PID COMMENT
babadoo  pts/3        Feb 28 16:01   .          5121 (172.20.100.50) session=ssh *
1
Just met with carrier tech.  He left me bunch of blue sc-lc fiber cables.
 Mentioned blue is a new yellow and aqua is a new orange.   Better throughput and better flex.
 is there a specs somewhere to learn about these new cables?
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HP 2930 switches use VSF for stacking. Documentation describes "chain" and "ring" configurations.  Is it possible to use VSF in a "star" configuration?
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Switchport in an err-disable state due to MAC Adress conflict.

Have cleared the DHCP bindings which cleared the err-disable error, but now have no connectivity.
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Computer showed err-disabled in the switch port.

Cleared the error.

Device shows connected in the switch.

Can ping the loopback of the PC.

Gateway shows "destination unreachable" message.

Can ping the PC from the shop PC.
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Hi everyone,

This may be a DNS issue - maybe not.

I had a user who was encountering some printing problems yesterday.  I got the printing problem solved but in doing so discovered that I was able to ping the PC using two different hostnames, but having only one IP address.  I've verified that the inaccurate hostname belonged to a workstation I've already removed from the network 30-45 days ago.

On a side note, I've since upgraded the OS from WIN 7 to WIN 10.

Now, 24 hours later, I'm still able to ping the one workstation by the two different hostnames.  Is there something else I need to take a look at?  We do have some special vlans that live in our enviornment.  Is it possible that, maybe, the MAC of the PC got assigned on a vlan and is somehow associated to the old PC name - or is that really thin possibility?  Just tossing ideas around.

Thanks.
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We have an HP 2530-24G-PoE+ (J9773A) where our port 11 keeps going on-line and then off-line. The device that we have connected to it is a wireless AP that uses POE. When I go into the logs of the switch all it says is that Port 11 is now on-line and then the next line is that it has gone offline. With no other information. What can I do to find out what's wrong with that port? I'm still very new to programming on a switch.
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I need help with how to enter a IPHELPER address for a VLAN on my Cisco 9300 switch.  it is currently set to an address, and I want to change it.
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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.

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