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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First, If I am correct:
Standard Access-list  can match traffic based on Source IP address only
Extended Access-list can match traffic based on Source/Destination IP address , port number, protocol, etc...

well, there is also  Named Access-list. We can have Standard Named Access-list and Extended Named Access-list
  Is Standard Named Access-list similar to Standard Access-list, it can match traffic based on Source IP address only ?
Is Extended Named Access-list  similar to Extended  Access-list ,it can match traffic based on Source/Destination IP address , port number, protocol, etc. ?

Thank you
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We have been asked to connect a 200Mbps fibre connection (expandable to 1Gb) to 10 independent business units in a small business park. The fibre provider will put a Cisco 1921 router on the end. They have no interest in managing the ongoing connections to the individual business units. That's down to us. Someone recommended a Cisco SG500 switch to add to this to satisfy the requirements:

1. control of bandwidth to each unit so they each get what they have asked for (and paid for) and no more
2. separate public IP assigned to each business unit (one each)
3. each unit can only access internet and not each other's networks

This is a little outside my day-to-day networking experience so rather than fumble my way forward, any pointers, issues to watch out for would be much appreciated.

Thanks,  Andy.
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Which VLAN   to enable ARP inspection

I would like to know which VLAN to enable ARP Inspection. Is it going to be on the same VLAN where the Trusted DHCP server resides on ?
Or on every VLAN in the network ?

Switch(config)#ip arp inspection vlan <VLAN Name>



I also wants to know about the DHCP Option 82 configuration.
Using IP helper-address <IP address> is enough or  we need to add:
ip dhcp relay information option

Thank you
0
Hi, does anyone know any weakness of Cisco devices (router, switch, Firewall)? Is there any way/tool to assess their vulnerabilities?
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Hi All,

I'd like to get the config file off both these makes of cisco equipment does anyone know the proper command config to do so/

thank you for your help
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If I am correct, BPDU Guard on all switch ports , protects the switch from a loop. If a user plugs in another switch to a port, it will go into err-disable state.


Switch-port port-security violation , will achieve the same purpose in that regard.

the only difference I see is  Switch-port port-security violation has other option such as, Protect, Restrict, Shutdown.

I would like to know form Network Experts, which command is mostly used in switches access ports to prevent rogue switch from being introduced to the network ?

Thank you
0
I am planning to upgrade the firmware of catalyst 2960
I checked the version I saw below

Switch#sho ver
Cisco IOS Software, C2960X Software (C2960X-UNIVERSALK9-M), Version 15.0(2a)EX5, RELEASE SOFTWARE (fc3)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2015 by Cisco Systems, Inc.
Compiled Mon 16-Feb-15 08:16 by prod_rel_team
ROM: Bootstrap program is C2960X boot loader
BOOTLDR: C2960X Boot Loader (C2960X-HBOOT-M) Version 15.2(3r)E1, RELEASE SOFTWARE (fc1)
Switch uptime is 46 weeks, 2 days, 1 hour, 0 minutes
System returned to ROM by power-on
System restarted at 07:50:33 UTC Fri Jul 22 2016
System image file is "flash:/c2960x-universalk9-mz.150-2a.EX5/c2960x-universalk9-mz.150-2a.EX5.bin"

I downloaded below files and I have TFTP server ready to upload the files.
c2960x-universalk9-mz.152-5b.E.bin
c2960x-universalk9-tar.152-5b.E.tar

How to upgrade to 152.5?
Your help is appreciated
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Hi, the title said it all. Can anyone draft me some pros and cons of stacking switches?

And is it possible to simulate this techniques in GNS3, Packet Tracer or something else?
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Assuming I have 2 switches connecting to each other.
on one switch I configure  Port-channel Load-balance src-mac
and on the other switch I configure Port-channel Load-balance dst-mac

I have not tried yet it, but wonder if it will work

Thank you
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Here is my router's configurations (with fake public IP addresses;-)

interface GigabitEthernet0/0
 ip address 113.160.61.14 255.255.255.252

 ip nat outside
 ip virtual-reassembly
 duplex auto
 speed auto

interface GigabitEthernet0/1
 ip address 101.96.10.141 255.255.255.192

 ip nat outside
 ip virtual-reassembly
 duplex auto
 speed auto
 
interface GigabitEthernet0/2
 ip address 172.16.2.28 255.255.255.248
 ip flow ingress
 ip nat inside
 ip virtual-reassembly
 duplex auto
 speed auto

ip nat inside source list ftth interface GigabitEthernet0/0 overload

ip route 0.0.0.0 0.0.0.0 113.160.61.13 100
ip route 0.0.0.0 0.0.0.0 101.96.10.129 200


ip access-list extended ftth
 permit ip 192.168.7.0 0.0.0.255 any
 permit ip 192.168.1.0 0.0.0.255 any
 permit ip 192.168.8.0 0.0.0.255 any
 permit ip 192.168.9.0 0.0.0.255 any

This is a result from "show ip int b"
Interface                            IP-Address         OK?     Method Status            Protocol
GigabitEthernet0/0         113.160.61.14    YES        NVRAM  up                    up
GigabitEthernet0/1         101.96.10.141  YES        manual up                    up
NVI0                          113.160.61.14    YES         unset  up                    up

==================================================================

So as you can see we have 2 WAN interfaces to 2 different ISPs, we change some configurations and saw …
0
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Hi guys, is there an software/environment which can simulate HP Aruba Switch/router? Or can we simulate it on GNS3? If so, does anyone got any link of ISO/IMAGE file?
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I have cisco 5508 lan controller and 2702i WAPs with static IP address. I want to remove static ip address and assign through cisco ios dhcp server. I'll do the following:

On cisco switch:
ip dhcp pool <pool name>
network <ip network> <netmask>
default-router <default-router IP address>
dns-server <dns server IP address>
option 43 hex <hexadecimal string>

Then go to WLC GUI and go to each AP and click "Clear all config"

On switch the ports are configured as:
switchport access vlan 111
switchport mode trunk
switchport trunk native vlan 111
switchport trunk allowed vlan 9-11, 111
spanning-tree portfast

All WAPs are in flexconnect mode.

Are these steps correct? If not, please list detailed steps. Thanks.
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Hello,

I have inherited responsibility for this issue.

There is a Cisco router which is presently connected to a Riverbed device which is to be retired, while I have access to the Riverbed Management Console I can't see how the Riverbed interface to the Cisco is configured and the support agreement for the Riverbed has expired (which is why it is being retired) so I can't ask them about this.

So the plan is to move the Cisco connection from the Riverbed to the HP Aruba switch.

I can see the config of the Cisco port
interface FastEthernet0
switchport trunk native vlan50
switchport trunk allowed vlan 1,49-51,61,90,1002-1005
switchport mode trunk
no ip address
duplex full
speed 100

Open in new window


I have tried configuring a port on the Aruba switch with all the vlans tagged, this didn't work, I'm unable to ping the Cisco.

I have also tried configuring the port on the Aruba switch in Trunk mode with all the vlans tagged, same result.

I haven't had much to do with Cisco and FWIW I don't understand the setting above
no ip address

Open in new window

as naturally the Cisco does have an IP address. Not sure whether this is significant or not.

Would appreciate advice on how to resolve

Thank you
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Dear Wizards, I am testing the Switch layer 3 <Cisco IOS Software, 3700 Software (C3725-ADVENTERPRISEK9-M), Version 12.4(15)T5, RELEASE SOFTWARE (fc4)> on GNS3.

This is my TEST diagram:

PC1 -----------f1/1---------->
                                            SwitchL3 ------------f1/15--------------> Router  
PC2 -----------f1/2---------->

I created 2 VLANs:  10 and 20 for PC1, PC2 respectively. On f1/1, f1/2 I did "switchport mode acc vlan 10,20", respectively. On f1/15 I did "switchport mode trunk", on Router I had sub-interfaces and theirs IP address, encapsulation dot1Q 10, 20.

However, in SwitchL3, I got this error:
" ..*Mar  1 01:28:50.359: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet1/1 (10), with ESW1 FastEthernet1/2 (20).
ESW1#
*Mar  1 01:29:08.079: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet1/2 (20), with ESW1 FastEthernet1/1 (10)..."


I did the same setup in Packet Tracer and it worked normally. The PC1 and PC2 got IP addresses from Router's DHCP and can ping to each other. So not sure why the error happened on GNS3. Can you help please?
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Hi, I am testing the GNS3 with switching module. I test with cisco 3725/3640/3660 to simulate a switch but when I entered "conf t" mode, it cannot have the "switchport mode " command, why?

Does anyone know any better way to simulate a switch? I knew Packet tracer but sadly, it does not support many model of ASA (but GNS3 does) which I need to play with Switches
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If I understand when you plug a computer to a switch port, the switch will learn the computer Mac Address.
Now, if we have Multiple computers plugged to multiple switches in the network, would all switches have the Mac Addresses of all computers even of the computers that are not directly connected to their own ports ?

for Instance if ComputerA is connected to SwitchA and computerB is connected to SwitchB, will switchA  and SwitchB Mac address tables both have Mac addresses of ComputerA and ComputerB ?
OR

SwitchA will only have Mac address of ComputerA
SwitchB will only have Mac address of ComputerB



Thanks
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If I understand when configuring switch ports with Porfast, then if we plug then unplug the Host there will be no TCN (Topology Change Notifications) sent to Root Bridge.
Well, in case Portfast is not configured on the Switch and we Plug / Unplug hosts, is this going to create any issue in the Network when considering TCN that will be sent by the  Non-Root switch to the Root Switch ?

Thank you
0
I have a HP 2530-24G (H9776A) switch.
With the previous firmware I did have a manager user with an empty password.
After upgrading to the last firmware YA.16.03.0004 (the one with the new GUI) I cannot login with "manager".

I tried to clear the passwords using the clear button, didn't work, it keeps asking me for password (an empty one won't work).
I tried to reset the switch, same results.

Front panel security is all enabled:

HP-2530-24G> show front-panel-security
Clear Password       - Enabled
  Reset-on-clear      - Disabled
Factory Reset        - Enabled
Password Recovery    - Enabled
Diagnostic Reset     - Enabled
  clear-button       - Enabled
  serial-console     - Enabled

Any help will be appreciated.

Thanks!
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I am trying to setup our client side pc's to use the pass-through Ethernet port on our Avaya 1608-i phones. I am having an issue that I can only connect one device to the port on the Cisco switch at a time. If I plug the phone in to the switch it works and if I plug the PC in to the switch that will work fine. If I use the pass-though port on the phone then only either the phone or the pc will pick up an IP.

We are not using a separate Vlan for VoIP.

is there a setting on the switch that I am missing?
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I need a L3 switch that can respond to two IP addresses.
ex: Two subnets of 10.10.0.0 and 10.20.0.0 can use one L3 switch as the default gateway because it responds to 10.10.0.1 and 10.20.0.1.

Does the HP 2910al-48g have this functionality?

I've looked in the manual and can't find anything regarding that. (Maybe that means the capability isn't there?)
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Hello,

How can I capture traffic coming from a switch through a DMVPN? Specifically, I need to do see traffic from Wifi using clients, I need to see what kind of communication is going on. Seems like I am missing syn-ack from some clients that are trying to get on a specific ssid and I need to see whats happening behind the scenes. Netflow does not work on this router, I am assuming it's a very basic IOS. Any ideas? It's a remote site.
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I am new to switch management.  I have a stack of 4 switches. One of the switches in the stack is down. In the web interface of the stack it says "Unit Down" for one of the 4 switches in the device physical view.  The stack was power cycled but this switch did not come back up.  It still has power but nothing else. I do have config backups of the stack.  Should I just try to restore a backup? The rest of the switches are working fine.  The switch is a Nortel 4548gt-pwr.
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Any Expert to shade some lights on the difference between MPLS and Q-in-Q tunneling.

If I understand both technologies are used by Customers to transfer their data from one site to another site going through Service Provider.

Any clarification will be very appreciated.


Thank you
0
I have a secondhand Edge-Core ECS2000-18P, the manual does not describe a Factory Reset Option that I can use.
I have no access at all. My MAC only gets a self assigned IP.
The manual describes the option to factory reset from the console but I do not have access to the console.

I can reboot it with a 0-5sec "Reset Button" push, but 10sec30sec30-30-30 do not work.

Does anyone have a definitive answer to factory reseting this bad boy?

This post I thought would be the answer but it does not work: https://www.experts-exchange.com/questions/27325851/Reset-Ethernet-Switch.html

But then again maybe I have reset it to factory and I just don't know how to get access???
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Hi, I've purchased 4 Sonicwall(Dell) Sonicpoint ACi units, connected to my Sonicwall NSA2600 firewall (WLAN port X4). Everything's working fine using PoE injectors (+ unmanaged switch) but I'm not able to get it working using a UniFi POE-150W PoE switch. All requirements describled here https://support.sonicwall.com/sonicwall-sonicpoint-series/kb/sw12867 are met, the switch supports 802.3at and max output pr port is 34W (min is 25 or 30 W). I'm able to connect to the WLAN (set up as virtual APs) but I'm not able to connect to internet, not getting IPs from DHCP. Any ideas how to solve this? (in my head this should be straightforward, maybe I'm wrong?)
0

Switches / Hubs

20K

Solutions

6

Articles & Videos

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.