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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.

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Cisco Nexus 7K: Can you create a policy map that NATs the source address of specified traffic
AND sets the ip next hop?

Current:
route-map gohere-or-pbr deny 10
  match ip address bypass-pbr
route-map gohere-or-pbr permit 20
  match ip address send-to-pbr
set ip next-hop 10.10.3.244

Imagined:
route-map gohere-or-pbr deny 10
  match ip address bypass-pbr
route-map gohere-or-pbr permit 20
  match ip address send-to-pbr
set source-ip-address 74.55.166.77
set ip next-hop 10.10.3.244

Or would that not be possible?
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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.
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Hi

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?

3com:

Device Name
3CRBSG5293

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

Software Version
5.20 Release 1101P10

Hardware Version
REV.B

Bootrom Version
119

Running Time:
195 days 23 hours 25 minutes 45 seconds

Thanks
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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.

 Regards
 Patrick
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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?
Thanks!
Jack
Map-IP-Phone.png
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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.
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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 …
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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
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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.
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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?
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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.
screenshot-trunk.jpg
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.
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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 224.0.1.75)

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?
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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.
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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.
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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?
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Hi all,
I have an Aruba 5412R zl2 with a mix of v2 and v3 modules installed (one of the v3 modules I needed was not released at the time). I am attempting to replace 2 x J9548A v2 modules with J9990A v3 modules but I am receiving an error stating their is a module\configuration mismatch when the new module is inserted. I have tried rebooting the switch as advised when changing modules types but still no joy. I have re-inserted the old module for the time being but I am clearly missing a trick when swapping modules with different part numbers.
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I am looking at switching from my physical old Cisco switches to a Meraki solution.  Anybody has any thoughts about Meraki, I'm planning to use their Firewall, switches and APs.

I currently am using Sophos for my firewall and the renewal cost for my subscription is a bit more than if I were to just outright purchase a Meraki hardware and subscription for 3 yrs.

Any major pros/cons?  The demo looked great for Meraki, but how does it work when it's actually in production and not just demo mode?

The other option is to purchase new Cisco physical switches, but those are more expensive than the Meraki solution.
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I am at a new site and there are SVI interfaces in the core switch, which is fine but one thing I see is that the customer have the line

ip router ospf 21 area 0.0.0.21


Can I please have someone experience tell me if this is correct?
what does it mean, I looked at the ospf configuration and I have never seen any command in this syntax.

Thank you
0
Is it going to be feasible to setup a single VLAN for IP phones and a separate VLAN for each port with the phone VLAN on rash port?
0
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Meaning of Port number in Show spanning Tree

in the output of the command below  I see:

 Port        1 (Ethernet0/0)

I wonder what Port 1 means?  I thought the port is the same as interface.

Thank you


SW1#sh spanning-tree  vlan 20

VLAN0020
  Spanning tree enabled protocol ieee
  Root ID    Priority    24596
             Address     aabb.cc00.0400
             Cost        200
             Port        1 (Ethernet0/0)
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    32788  (priority 32768 sys-id-ext 20)
             Address     aabb.cc00.0100
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time 300

Interface           Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Et0/0               Root FWD 100       128.1    Shr 
Et0/1               Altn BLK 100       128.2    Shr 

SW1#

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How STP influence the Traffic

on the diagram below, PC2 is connected to  Switch SW3 that has a blocked port on the link to SW1. Now Traffic from PC2 to PC1 will it go from SW3 to SW2 then to SW1 or it stiil can go straight from SW3 to SW1 then to PC1

Thank you
stp
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This is a networking question involving routing through L3 switch.
I have the following setup:
existing flat network with blackbox switch, which we will call SW0.  All ports are on default vlan, so it is operating at L2.
SW0 has a network of 10.1.1.0/24, with an IP address of 10.1.1.209.
The gateway/firewall, which we shall call GW1 (CradlePoint for now), is 10.1.1.199, and has a static route of 10.1.2.0/23 next hop=10.1.1.208 (SW1)
SW1 is an HP 2930F operating at L3 with IP Routing enabled.
SW1 has the following config:

Running configuration:

; JL259A Configuration Editor; Created on release #WC.16.07.0002
; Ver #14:01.4f.f8.1d.9b.3f.bf.bb.ef.7c.59.fc.6b.fb.9f.fc.ff.ff.37.ef:02
hostname "SBT_SW01"
module 1 type jl259a
ip route 0.0.0.0 0.0.0.0 10.1.1.199
ip route 10.1.1.0 255.255.255.0 vlan 2
ip route 10.1.2.0 255.255.254.0 vlan 12
ip routing
no snmp-server enable
vlan 1
   name "DEFAULT_VLAN"
   no untagged 1-23,25-28
   untagged 24
   ip address 10.1.1.208 255.255.255.0
   ipv6 address dhcp full
   exit
vlan 12
   name "VLAN_12"
   untagged 1-23,25-28
   ip address 10.1.3.254 255.255.254.0
   exit
spanning-tree
allow-unsupported-transceiver
no tftp server

SW2 is also an HP2930F, but it is operating at L2.
It's config is:

SBT_SW02# show running-config

Running configuration:

; JL259A Configuration Editor; Created on release #WC.16.07.0002
; Ver
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Hi

I have a port on an HP 2910 switch that is configured for port mirroring according to the running config.  The switch port mirroring global option is disabled though.  
To cure my OCD how can i disable this port mirroring config?  Do i need to enable the global mirroring and then remove the port?

Thanks
0
I have a HP 2530-48G network switch that I use in the lab. I have 2x Synology NAS, both with Dual-Nics. I am trying to get them both LACP bonded to the switch (on seperate trunks) but am having problems I believe with the 2530-48G.

NAS1 - Trk1
Ports 45 + 46

NAS2 - Trk10
Ports 41 + 42

At this time, I can connect fine to NAS1 on it's bonded interface. However, I cannot connect to NAS2 on it's bonded interface. If I switch the cables round so that NAS2 is plugged into 45 + 46, I am able to connect to it immediately, which leads me back to the 2530-48G and it's configuration.

If I CLI into the switch and run
show LACP

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I get the following output
LABCORESW(config)# show lacp

                                    LACP

           LACP      Trunk     Port                LACP      Admin   Oper
   Port    Enabled   Group     Status    Partner   Status    Key     Key
   -----   -------   -------   -------   -------   -------   ------  ------
   41      Active    Trk10     Up        Yes       Success   0       63
   42      Active    Trk10     Up        Yes       Success   0       63
   45      Active    Trk1      Up        Yes       Success   0       54
   46      Active    Trk1      Up        Yes       Success   0       54

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Nothing seems to be untoward. Any ideas?
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Hi

We are adding a 4th switch to our network.  Not sure how best to configure.

Currently (see attached (new in red)) we have 3 connected switches:

HP 2910 L3 as core with two older v1910 and 3com 2952 switches connected via cat5.   The core switch routes traffic out to firewall.
The 2910 also has two vlans configured for data and voice.  The older switches are data only.

The new 4th switch will be in another office (c10-20m run away) and is a 2910al POE also.  We need to hook up poe phones here and desktops on vlans 20 and 1 respectively.

Main questions are:
  • Do we need two cable runs from the main 3 switches to the 4th?  i..e switch 1 to 4 and switch 3 to 4 (chain mode instead of looped?)
  • If two, can we mix the connections used to connect the switches i.e. fibre and cat5 or do they need to be the same throughout the switches e.g. cat5 only?
And if two connections do they have to be routing between the vlans e.g. vlan1 connected to vlan1 on switch 1 and 4 and vlan20 between switch 1 and 4?  Or does iprouting resolve this?

Thanks
Network.jpg
0

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.