Questions tagged [vlan]

For questions about Virtual LANs (VLANs) which are used to divide what otherwise would be a single OSI layer-2 broadcast domain into multiple, logical OSI layer-2 broadcast domains.

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WHY and HOW do routers and vlans break broadcast domains?

Everybody says routers (and vlans) break broadcast domains, but nobody goes into WHY that is, it seems. What's the router logic? Say I have three routers on my lan, with one main router and the ...
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  • 333
1 vote
7 answers
1k views

IP Helper in Multiple Access Switches

Just a dumb question.. I have 1 core switch and 5 access switches. Just wondering if it would be best to setup the IP helper on all access switches rather than just on the core switch? Does this ...
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1 vote
2 answers
406 views

VLANS - Layer 2 vs Layer 3 Juniper & Netgate/PfSense

I am working on setting up VLANS on a basically default switch configuration for my SMB network. They have 5 juniper ex2200 switches that are all on the same subnet and have only a default vlan. I ...
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3 votes
1 answer
217 views

cisco switchport trunk native vlan

we have switch catalyst 3850 and we need to enable the PXE boot on a port configured in trunk with configured three VLAN (4040, 4050 and 4060). To permit the PXE boot and deploy to work we set on the ...
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2 answers
293 views

Cisco router on a stick with public ip wan (ISP)gateway

I am trying to create a router on a stick with an outside facing sub-interface with a public IP from an ISP. I have tried to configure NAT and routing but I just cant get to ping the internet. I'm ...
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1 vote
1 answer
204 views

How do (LANCOM) Tag-Based vlan groups work and on which vlan does the device respond?

I just started a new job and part of it is to manage and maintain the ICT. As the previous network/system engineer left the company i'm on my own to figure out how everything works. I have ...
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  • 189
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1 answer
171 views

Connect VLANs switch SF300 in the same switch

I have 5 VLANs in a switch SF300 configured in Layer3. I Set the switch to general mode so I could connect all the vlans. After 2 weeks that connection has been lost. Now you can only communicate with ...
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1 vote
4 answers
275 views

setting up a VLAN and joining 2 buildings through underground cabling

I am pretty much a newbie when it comes to networks so forgive me in advance if this question seems odd. So here's a situation I am trying to figure out. There's a company who operates in 2 adjacent ...
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2 answers
184 views

Correctly Setting up DHCP for Intervlan Routing

I am currently building a network and would like my two switches connected to my router to automatically assign ip addresses through DHCP pools to my PC's and devices. I have 4 separate VLans being ...
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1 vote
1 answer
2k views

Switch doesn't learn MAC of a connected device

I am new to networks. What does it mean when a switch doesn't learn the MAC address of the connected device? And how can VLANs can impact that?
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0 votes
1 answer
739 views

Managing a Juniper EX4300 In Band

Currently, our ex4300 are managed in band using irb.20. show configuration interfaces irb unit 20 { family inet6 { address 2001:db8:1::252/64; show configuration routing-options rib inet6.0 {...
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  • 157
-1 votes
2 answers
52 views

Switch Operation Beyond VLAN Segmentation

What are the other operations performed by a switch which are outside the VLAN's boundaries. Is Logical (VLAN) Segregation is exactly same as breaking a switching network physically via a Router?
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1 answer
770 views

How to combine multiple ADSL lines?

Before beginning, I'm totally new to advanced network topics and not working as a professional network engineer or so. Just trying to learn some stuff. My problem is, I have 3 different ADSL (or VDSL)...
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1 vote
2 answers
763 views

Losing connectivity after creating a VLAN other than the default VLAN

I have a 192.168.0.0/24 network that serves three computers. There are no issues with this part of the existing network. I have purchased a new Cisco SG350-28P 28-Port Gigabit PoE Managed Switch. I ...
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0 votes
1 answer
49 views

What is the difference in packet structure for tag VLAN and port VLAN

I am new to networking. I just want to know the difference in ethrenet packet structure for tag based VLAN and port based VLAN. For tag VLAN, a VLAN tag is added to the ethernet packet frame so that ...
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1 vote
1 answer
83 views

How to define trunk port between vmware esxi host 6.5 and switch? [closed]

I create some virtual machine in different vlan but i can not set trunk port from vmware to transfer vlan information.
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0 answers
56 views

How to allow traffic through vlan

I have router connected directly to Antenna from G0/4 and when connected PC to G0/1 the internet working normally as Fig. 1 in below Photo. I need to change the router place so i create vlan 500 in ...
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2 answers
140 views

VLAN based subnets, where should I untag a VLAN?

I have attempted to search this problem but I don't really know how to explain it properly (possibly a sign I've taken on more project than I can handle). Anyway I am currently working on chopping ...
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5 votes
2 answers
3k views

Whats the difference between VOICE VLAN and ACCESS VLAN

Can someone please tell me the difference in Layman's termsfor these 2 configurations? interface FastEthernet0/1 description PHONES switchport mode access **switchport voice vlan 51** spanning-...
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3 votes
0 answers
55 views

Arp Protect in dynamic VLAN environment

I am using 802.1x authentication with dynamic Vlan assignment(CPPM). As you may know, when a user logges in to their computer, SW attaches the user port to related Vlan. Thinking the scenario in which ...
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0 votes
0 answers
137 views

Cannot create connection between two routers in same VLAN via switch

I currently have a Cisco 2960-24TT switch (switch1) and a Cisco 1841 router (router1) that form part of my core network connecting other VLANs and devices. The two ports on router1 have been ...
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0 answers
41 views

LAG and VLAN Problems

I have an extended star network between two buildings. In each building I have a "Main" switch. The two Dell N1524 switches are connected via 4 fibre optic links over SFP+. Now the 4 links are ...
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0 votes
1 answer
304 views

Why is this subnet config required by my vlan "snake topology"?

I must validate the bandwidth on all 8 ports of a switch. We intend to do this with a "snake" topology as described in this article: http://thenetworksherpa.com/test-throughput-alchemy-using-a-snake-...
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0 votes
3 answers
236 views

Configuring a network for 100% isolation (for security)

I'm configuring a LAN for an office. It's a new setup, and therefore there are desktops but no servers and no PC-to-PC communications - everything is on the cloud. The exception to this are several ...
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0 votes
2 answers
153 views

Using a VLAN to Completely Isolate Devices from the Internet & Other VLANs

I have a Cisco SG350-10P Managed Switch, and currently have two VLANS on it, the default VLAN 1 and VLAN 10. I want devices connected to VLAN 10 to have no ability to communicate with the internet or ...
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2 votes
1 answer
266 views

Correct vlan/interface config for connection to upstream provider network

We have recently switched from HP Procurve series to HP Comware based switches. A configuration which has been working on Procurve doesn't seem to work on Comware. Here are the details: The provider ...
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0 votes
1 answer
49 views

Is performance worse routing between two vlans on one interface than routing between two NICs with no vlans?

I have a Linux router with one interface that is connected to a switch in port 2. Port 2 on the switch is a member of vlan2(ISP) and vlan3 (office devices). My router is currently routing between ...
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  • 125
4 votes
0 answers
128 views

PVLANs/Port isolation in IPv6 networks

We're currently using port isolation to prevent communication between computers on the same vlan and use client isolation on our guest wifi. The reason for having this enabled is to prevent unwanted ...
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  • 161
1 vote
3 answers
78 views

Typical LANs with VLANs

When using switches which support VLANs with switches which doesn't support VLANs, can they be mixed with each other in the same network?
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0 votes
2 answers
607 views

VLANs vs subnets pros and cons

What are the pros and cons of designing an entire network using VLANs rather than design the network only using subnets?
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0 votes
1 answer
97 views

CSMA/CD in VLANs query

Ethernet is based on CSMA/CD. When using VLANs, the number of stations can become very high, making CSMA/CD inefficient. Are there any mechanisms that VLANs use to overcome this?
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10 votes
5 answers
6k views

VLANs over internet

How does VLANs work over the internet and span across multiple geographical locations? VLAN headers are removed when frames move to another switch or a router? How does it happen?
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1 vote
3 answers
191 views

Cisco Switch without VLAN support?

I've been reading about VLAN and wondering is there any Cisco Switches that do not support VLAN? So far, all switches that I found do support VLAN. This is one of the example in my lab. Cisco-Switch-...
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  • 301
2 votes
1 answer
97 views

ICMP message doesn't leave NIC of PC

I got an interVLAN configuration a.k.a 'Router on a Stick'. I can ping all the workstations with each other, except PC9 (refer to image). I did a simulation and found that the packet does not even ...
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  • 23
2 votes
4 answers
1k views

Are VLANs the same on different brands of devices?

I have 3 switches from different brand and I want to configure VLAN on them Do these switches have to be from the same brand (Cisco or others)to be able to configure VLANs?
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1 vote
1 answer
96 views

How can I get OSPF to see the VLANS that are trunked through the gigabit port

I am relatively new to this and I have been trying various configs but nothing is catching. I have three routers, with various vlans. The vlans are working. The routers are seeing each other using ...
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  • 11
3 votes
1 answer
211 views

Router can ping and resolve hostnames, but VLANs and switch cannot

I recently installed an Adtran Netvanta 4430 to perform some basic VLANs on a network with a little bit of inter-VLAN routing, and I'm having a few odd issues, probably attributed to my inexperience ...
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3 votes
1 answer
4k views

What is the purpose of native VLAN on a trunk link?

Most VLAN articles I've read recommend avoid using VLAN1 for ports with untagged traffic (aka access ports). I've heard enough of this nonsense. Except for the reserved values of 0x000 and 0xFFF, a ...
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  • 391
0 votes
2 answers
75 views

Is there a way to manage IP space with only a switch?

Is this scheme possible? External provider = External provider of the internet Generally speaking, is there a way to assign a public IP address individually for each server to be used when SFP+ port ...
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0 votes
1 answer
67 views

Access a device connected in another switch

I have theses two switches, 3Com 4500 and 3Com 2928. 3Com 4500 - IP: 20.20.X.X ; Mask: 255.255.240.0 3Com 2928 - IP: 192.168.1.X; Mask: 255.255.255.0 There is a printer(20.20.2.1) connected in the ...
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  • 3
6 votes
6 answers
5k views

packet routing between subnets on same vlan

I am trying to understand how packets are routed within the same VLAN. I understand that typically there should be a 1:1 mapping between VLANs and Subnets. However if i deploy the following ...
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0 votes
3 answers
457 views

Ip phone problem cannot get an ip address from dhcp using other vlans except from vlan 1

i am trying to understand native vlans. when i use vlan 1 it worked and it provides an ip address to my ip phone. When using vlan 100 it does not work even i tried using native trunking on it. please ...
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0 votes
1 answer
47 views

Device on VLAN is accessible from VPN but not from LAN

I have a Meraki MX84 with two VLANs, 192.168.213.0/24 (main subnet), and 10.4.213.0/24. I have an EdgeRouter 12P connected to the MX with static WAN IP 10.4.213.2. The issue is: when I VPN into the MX ...
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1 vote
0 answers
2k views

How to check vlan interface traffic on Cisco nexus 9k

I have Cisco N9K-C9396PX L3 switch which has VLAN interface configured for my LAN gateway and i want to monitor how much traffic vlanXXX handling, I have configured SNMP monitoring to pull interface ...
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  • 4,227
5 votes
1 answer
1k views

juniper vlan-ccc vs ethernet-ccc for eompls

In juniper ethernet-ccc transports customer's vlan end to end. Does vlan-ccc also transport customer's vlan across as well?
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1 vote
2 answers
87 views

Does Network segmentation work using different switches connecting to router?

I just learnt basic networking. If I have 2 departments which I do not want them to access each other's networks, does using two layer 2 switches connecting to the router does the job or do I need a ...
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2 votes
3 answers
821 views

Cisco ASA 5512X does not allow connections across VLANs to internet

First time doing a network, I'm a software guy normally. I am setting up a network to share and internet connections to multiple properties. The goal is to segment each property onto its own VLAN. I ...
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0 votes
1 answer
813 views

EIGRP Holding Time Expire on VLAN Interfaces

I configure 2 Layer 3 Switches with VLANs and EIGRP route. But it always return a message like this : %DUAL-5-NBRCHANGE: IP-EIGRP 2019: Neighbor 192.168.20.253 (Vlan20) is down: holding time expired ...
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1 vote
2 answers
107 views

Cisco Catalyst 9410 - Using Default Gateway versus ARPing for locally connected host

I may be missing something extremely simple here, but im at loss trying to figure out what this Nexus switch is doing. Here is the topology: DISCLAIMER! I had made a mistake on the diagram by ...
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  • 13
0 votes
1 answer
129 views

Cisco 3750: SNMP

On my Cisco 3750G, i have SNMPV3 enabled, this is working perfectly with Zabbix. I would like to separate production flows from supervision flows, Do you know if it's possible to enable SNMP ...
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