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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.

I am a network admin and looking at our switching infrastructure. I feel like it is not efficiently built, and it is aging. It consists of HP Procurve switches, some of them are V1910's, newer ones are 2530's. (Several were purchased to support a VoIP phone system). All switches are connected with trunks- this takes up 4 ports per trunk and only communicates at linespeed. What I think needs to happen is I need to build a new core switch infrastructure, remove the aging equipment, relegate the newer switches to edge roles for client connections, and select adequate infrastructure for the core equipment... whatever I get, I am planning to use cascades so we don't end up using half the ports to trunk and get better performance. Our network is not complex- we have an MPLS, an inter-building fiber link, 2 VoIP VLANs, and 3 subnets at this location. so we wouldn't need more than 8 VLAN's- right now everything except the fiber and the phones are on the same VLAN and separated by routers- I think that using the VLAN capabilities of the new infrastructure could replace routing equipment and optimize the network further. So my question is, assuming we are keeping the newer HP Procurves (The newest are actually Aruba's), which have GBIC's but no cascade ports, should we use Cisco's for the core switches, or stay brand-consistent with HPe/Aruba, which will become the edge switches? Any model or feature recommendations?
Thanks for the help!

I need to set QOS on my Cisco switches for a new UCASS phone system.  I have not used QOS before and want to make sure I do it correctly.   The phones will be on their own VLAN so I am not sure if I can set this at a level that everything on that VLAN uses this QOS.    What I need to set is DSCP 46 and L2P 5.  and will this need to be set on all switches or just the ones that the phones physically plug into.  Thank you for any assistance you can provide.
Hi guys, I have bought some mellanox gear pretty cheap off Ebay. I need to set some time aside to properly read through everything and learn what i am doing. But i am just trying to get it online to do some basic testing and even that seems to be a bit of a pita.

My setup is blade M1000e with 2x M4001T switches both showing as online. I then have 40Gb NICs in two R730 servers. Both these connections are showing as disconnected. (if they connect direct without the switch they work perfectly)

I purchased a 56Gb/s card for a blade server and installed that. I then installed OpenSM / mellanox software and i created the mellanox service. I then started the service and the first port came online. I assigned it a static Ip address but none of the other ports came online.

The documentation for this specific switch is eluding me. If anyone has some information on what i need to do for the config it would be appreciated!

I have ordered a serial cable to plug in to the device but from what i read, i was led to believe i wouldnt need one as i can use opensm to configure the switches and bring them online.
EIGRP Equal Cost Load-Balancing

in the display below, I would like to know if R1 will reach network  in Load-balancing way.. I mean one packet will go out of fa0/0 and another fa0/1.
How is  load-balancing done in the equal cost ?

Thank you

R1#sh ip eigrp topology 
EIGRP-IPv4 Topology Table for AS(1)/ID(
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
       r - reply Status, s - sia Status 

P, 1 successors, FD is 30720
        via (30720/28160), FastEthernet0/0
P, 1 successors, FD is 30720
        via (30720/28160), FastEthernet0/1
P, 1 successors, FD is 28160
        via Connected, FastEthernet0/0
[b]P, 2 successors, FD is 158720
        via (158720/156160), FastEthernet0/0
        via (158720/156160), FastEthernet0/1

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BGP Configuration to Receive Directly-Connected Routes

I am looking at BGP example from this Link: https://www.cisco.com/c/en/us/support/docs/ip/border-gateway-protocol-bgp/23675-27.html

when it gets to this step : Configuration to Receive Directly-Connected Routes

It is not clear about what the step achieves.

Any Expert to explain  it with comments after each command ?

Thank you
Multiple Internet Connections to Multiple ISPs

when planning to have internet connections to Multiple ISPs, initially I thought it can be just as having Internet Connections at home, but you will have 2 routers connecting to 2 different providers , for instance Comcast and ATT.

I know in Work environment you need redundancy, if one ISP is not available  the other ISP should be.. or if one of Customer routers is not available , internet connection will be available through other Customer router...

-- In the diagram below, we have 2 company Sites :Site 1 and Site 2 connected between each other , either through WAN or Ethernet.

Site 1 is connected to ISP1 and Site 2 is connected to ISP 2

I would like to have a configuration example based on the diagram below , that will enable Site 1 and Site 2 to have always Network connection.
I know that BGP will be involved to accomplish this Goal.

I would like an expert to paste a configuration example with comments detailing what each line of the configuration is intended to achieve.

Thank you

I have new c9300 switches (pair), When I program an interface, the interface auto adds:

 ipv6 address dhcp
 ipv6 address autoconfig
 ipv6 enable
 ipv6 dhcp client request vendor
I have tried the 'no' cmd to all these entries - no luck
I have also tried the global no ipv6 unicast-routing
Am I missing something?
My OS is win 7 64 bit and I am shopping for a USB Hub which is reliable.  Can the experts please  suggest a model for my Laptop E6500 Lattitude. thank u and regards
Automatic Update Software I use
  ** WSUS = Windows Updates
  ** Ninite = Firefox, etc
  ** PDQ Deploy = other Software
  ** SolarWinds = currently only using Alerts

How can I automatically do the below #1 and #2 on my 10 different models of HP Network Switches, then after confirming the backup is good, manually click a BUTTON to DEPLOY #3 ?
   1. firmware download
   2. backup
   3. upgrade

We have a switch 3560 where two physical ports are configured and two ports are put into channel as the below.  On the channel, do we need to add the same configuration on the channel as the physical port? Thank you

interface GigabitEthernet0/20
 switchport trunk encapsulation dot1q
 switchport trunk allowed vlan 10
 switchport mode trunk
 switchport nonegotiate
 channel-group 10 mode on
Two Cisco switches(A and B) are connected via two ports on each switch. SwitchA g0/1 and g0/2 are connected to switch B g0/1 and g0/2 and bound by etherchannel.  udld are used at each physical ports. Question is if loop guard can be used to replaced the udld. It also means if loop guard is also used at the four physical ports, channel or both? If udld and loop guard are used at the same time, is that Ok? Thank you
I'm looking at installing 14 switches in a data closet and I wanted to know exactly how many amps will that draw at startup, to ensure I have enough power circuits.
I've looked at the technical specs found below, but I'm trying to calculate exactly how many amps each switch will draw, so I know if I need 2 or 3 circuits?

I'm planning to have (7) 2960X -48-FPD-L in a stack, and each one on a APC.  Also was trying to figure out if I need a 20amp or 30amp circuit, I'm guess if I get a 30 amp circuit,
it gives me more options for the APC to use.

Any thoughts?
After we configured several router and switches with aaa/tacacs, all of them began to work. but recently we cannot access two of these routers. When we try to access the two with ssh, we are denied with authentication issue Which one we need to check first and resolve the issue? thanks
It's been a while since I've had to troubleshoot vSwitch and physical switch issues so I'm a bit rusty. Our VMWare environment has two 10GbE switches stacked and each ESXi host two 10 GbE NIC ports, one to each switch. Both NICS are active inside the Teaming and Failover settings under the port group.

What I'm noticing is if I copy a file from one server to another I am not getting the full 10GBE. I know I won't use all of it but what I'm seeing is during the first few seconds on the file transfer it goes to about 600MBps, then it quickly goes down to less than GB speed (maybe around 50-60MBps.

VMWare tools is up to date on all the servers/ I'm not seeing any errors on the physical switched. I'm just not sure what other settings I need to check. Whether it's on the physical switch side, vSwitch side or VM itself.

I'm running Windows 2012 R2 for both servers sharing the files and transfering back and forth.
We are moving into 2 new buildings.  One is a church and the other is an admin building, corporate.  There will be fiber connecting both buildings.

Option 1
I'm debating whether it's better for the church to have it's own separate ISP connection, firewall, it's own switches and not be tied to the admin building in any way, or option 2.

Option 2
Or should I just have one ISP connection for both the admin and church buildings, and have switches that I manage on their own vlans for the church, but have one big network for both buildings?

Any idea's for best practice.  For management purposes, it's easier to just have one large network instead of creating two separate ones, with each having their own ISP connections.

Any recommendations, and why for each case.
We are moving into a new building, and we will have all newer Cisco switches, 2960X and 3850's for the cores.
I'm planning to have different vlans for the servers, PCs, VoIP phones, but I was thinking, since all of the different equipment need to communicate with the servers,
I will need to allow and route all the different vlans to access the servers vlan.  If that's the case, is then better to just create one flat network, everyone in one vlan, a /22 instead?
I guess I need to find some good articles on line to dig deeper into vlans, but on the surface, besides having a smaller broadcast domain, it just adds more complexity.

Any thoughts?
Ive a new netgear jgs524PE switch and a netgear orbi rbk50 I would like help to setup correctly.

Currently the isp router is giving a gateway on one port of that runs to the Netgear orbi, The orbi in turn has created its own network on, my switch is connected to the orbi with an ip

I have nas connected to the switch, previously it was on but I guess that now needs to be changed?

What is the best way to set up here? The Orbi provides netgear circle which allows me to control the kids devices with devices on the orbi network. So I think the switch has to stay as currently connected.

I am not sure if I should have the Router providing dhcp.

Your advice would be welcome.

This is a home setup but I do require 1gb cable speeds as I zoom a lot. The  synology nas server needs to be accessible from outside.

I have a Cisco SG200 Switch and a Sonicwall TZ400.  I need to isolate 9 networks from each other. Each network has its own DHCP.

Here's my config:


Sonicwall interfaces
Sonicwall DHCP
 I've read and followed the instructions on setting up VLAN on the CG200 but maybe I'm missing something or maybe I'm missing that magical matching combination of correct settings and a router/switch reboot at the right time.  I've checked with Sonicwall and they say that I have everything configured right on the TZ400.  They say that my SG200 is not properly tagging the traffic going to the Sonicwall is not seeing the tag so it's not going to the proper VLAN.  Here's a screenshot of my Port VLAN Membership:

cg200 port vlan membership
I've spent hours trying to get this figured out and it feels like I've hit a wall now.  Any help is greatly appreciated!

I am trying to setup VSS and VLAN in Cisco 6807. I followed the steps in the link


I have questions (Any help will be appreciated)
- This steps must be done in one of the switches. Is that correct?
- I have 9300 switches that need to be connected to 6807 switch. I must connect two physical fiber connection one from each switch  (6807) to (9300 switches). Is that correct?
- I want to configure 10 VLAN's (,,...... with VTP domain in the (6807) switch ( I will need to assign IP address for each VLAN and create Management VLAN). How I can do that?
- I will change all the port that connect the 9300 and 6807 switch to trunk mode and use encapsulation Dot1Q.
- DHCP server (Multi scopes) address is So, I will need to configure IP helper address under each VLAN.
- Port 10 of Cisco (6807)  in switch 1 are connected inner interface of ASA [IP address and outer (public IP address 85.X.X.X)]. I need to be able to connect all VLAN's to be able to connect to internet and can see each other. How I can configure that?

Switch6807-1(config)#switch virtual domain 6
Switch6807-1(config-vs-domain)# switch 1
Switch6807-1(config-vs-domain)# switch 1 priority 110
Switch6807-1(config-vs-domain)# switch 2 priority 100
Switch6807-1(config)# interface port-channel 1
Switch6807-1(config-if)# no shutdown
Switch6807-1(config-if)# description VSL to switch 2

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Please, I am not an expert and I need help. I am planning to buy core switch and I have questions. Can Cisco C6807-XL be stacked? Do I need to buy stack power and data cable only? or I have to buy modular to achieve stack? if yes what modular I need to buy?

These are the specifications that I have for the core switch

C6807-XL      Catalyst 6807-XL 7-slot chassis, 10RU
CON-SNT-C6807XLC      SNTC-8X5XNBD Catalyst 6807-XL 7-s
C6800-OTHER      Catalyst 6800 Other PIN; For Tracking Only
C6807-XL-FAN      Catalyst  6807-XL Chassis Fan Tray
C6800-XL-CVR      Catalyst 6807-XL line card slot cover
C6800-PS-CVR      Catalyst 6800 power supply blank cover
VS-S2T-10G      Cat 6500 Sup 2T with 2 x 10GbE and 3 x 1GbE with MSFC5 PFC4
VS-F6K-PFC4      Cat 6k 80G Sys Daughter Board Sup2T PFC4
MEM-C6K-INTFL1GB      Internal 1G Compact Flash
MEM-SUP2T-2GB      Catalyst 6500 2GB memory for Sup2T and Sup2TXL
VS-SUP2T-10G      Catalyst 6500 Supervisor Engine 2T Baseboard
C6800-48P-TX-XL      C6k 48-port 10/100/1000 GE Mod: fabric enabled, RJ-45 DFC4XL
C6800-48P-TX-XL      C6k 48-port 10/100/1000 GE Mod: fabric enabled, RJ-45 DFC4XL
C6800-48P-SFP-XL      C6k 48-port 1GE Mod:fabric-enabled with DFC4XL
GLC-SX-MMD      1000BASE-SX SFP transceiver module, MMF, 850nm, DOM
C6800-48P-SFP-XL      C6k 48-port 1GE Mod:fabric-enabled with DFC4XL
VS-S2T-10G      Cat 6500 Sup 2T with 2 x 10GbE and 3 x 1GbE with MSFC5 PFC4
VS-F6K-PFC4      Cat 6k 80G Sys …
Hi One switch 3560 is connected to 4500 through two interfaces, which are bound as port-channel and as layer 2. Under the 3560, there are some PC and ip phone. so we use auto qos at each interface of 3560. Now we also need to configure auto qos voice trust on the port-channel. but 3560 port-channel does not support auto qos. How can we resolve the issue? Thank you
I would like to be able to turn off the internet connections to wired computers. I was thinking of adding a managed switch next to my isps router and then using that to turn the ports on or off.

I am not sure what to buy tplink have l2 type with poe on 8 ports so might be good in the future. They have l2+ 16 port no poe managed switches at a reasonable price too. I would also like to give my computer full bandwith when I teach online, at present everyone affects it I think when I am in classes. Will a managed switch get me what I desire?

my choices seem to be TL-SG1016PE or
TP-Link Switch T2600G-18TS(TL-SG3216) 16x1000/2xSFP L2 Managed

I also would like a better wifi access point I think my tplink wa901 is struggling.

advice would be welcome.
I have a Cisco 3560 L2/L3 that will be connecting to an HP 2910al access switch.

On the 3560, I have a few VLans set up. because of the amount of data going across the switches, I want to aggregate the link between the switches.  I have been looking for information on aggregating trunks and have not found much useful information. I find information on aggregating access ports all day  long.

Can someone assist with commands and examples.

ARP and Proxy-ARP

I have been reading about ARP and Proxy-ARP , but could not get a good grasp of it.
If I understand when there is Layer3  between 2 hosts in different subnets, the router will take care of ARP Requests/Replies between the Hosts.
in some articles they call that Proxy-ARP when the L3 device is handling the ARP Request/Reply.
if that's true , then ARP is within the same subnet and Proxy-ARP between 2 subnets connected by L3 device ?

Thank you
I am a newbie at this. I assumed that all HP Procurve switched had a public snmp community but I guess not. I am trying to add one but must be missing something. Attached is what I need to supply but I can never seem to get it added. Any ideas?

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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Switches / Hubs