Questions tagged [trunk]

For questions about trunks, layer-2 links across which traffic for multiple VLANs travel.

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8
votes
2answers
22k views

Which VLANs are allowed on this trunk?

I'm getting some mixed signals when configuring a trunk on a Cisco switch and I'd like to know which VLANs are actually being allowed on it. The way I want it to be is that only VLANs 1,10,20,30,99 ...
7
votes
4answers
429 views

Building too large for ethernet runs

I'm pretty new to network design. I know enough to wire small buildings and such, but I'm puzzled as to how work this one out. A building I'm working on is an odd shape, and very large. ...
7
votes
1answer
180 views

What is VLAN Hopping

I am starting on my journey into the world of Networking and have come across a term called VLAN hopping. The sentence I read was that if the Native VLAN on two switches connected to each other via ...
7
votes
3answers
706 views

New VLAN across multiple Cisco switches

I have setup a new VLAN on my corporate network for use for guests only. I am trying to setup a guest WiFi service and keep all of the traffic separate from the business traffic. So far I have ...
6
votes
4answers
52k views

Switchport mode access VLAN & switchport mode trunk on one interface

Googling around to see if this setup on one port is correct (it doesn't look right to me), I'm not really seeing a straightforward answer. There is an interface with the following configuration: ! ...
6
votes
2answers
2k views

VLAN Tagging on Trunk Port

A normal (untagged) broadcast packet is sent into a trunk port on a switch, the vlans it accepts are 11, 12, and 13. What will happen to that packet? Will it be sent out all access ports with vlan 11 ...
5
votes
2answers
4k views

The best way to understand Vlans?

Every time i try reading about the configuration of a device and adding it to the network, i always face a problem. The problem is basically am not able to understand Vlan's, and how for example some ...
5
votes
1answer
387 views

Assigning a single switchport to different VLANs

I've been trying to figure out how to achieve the outcome below. VLAN Name Status Ports ---- -------------------------------- --------- ------------------------------- ...
5
votes
2answers
2k views

Juniper trunking with two links (not using LAG)

Some reason I'm drawing a blank on this. Let's say I have two EX switches connected together with 2 links to each other (xe-0/1/0 and xe-0/1/1 on both switches). I can easily setup a trunk on one of ...
5
votes
2answers
2k views

How far is VLAN broadcast propagated?

I'm not 100% sure of the vocabulary, so please bear with me. Suppose I've set up some new VLANs to better divide my network logically. I have a 4507 as a core network switch with VLANs 1 and 10-19. ...
5
votes
2answers
5k views

How to encapsulate all VLAN traffic inside VXLAN

As I understand VXLAN, it looks like it should be able to encapsulate and properly route VLAN-tagged traffic. However, in investigating how to actually configure VXLAN on network devices, it looks ...
5
votes
3answers
2k views

Extending VLANs to other switches

I am working in an inherited environment where I have basically been thrown in feet first. I'm also brand new to VLANs, and only set it up via documentation from other techs in my company. After ...
5
votes
1answer
5k views

Native VLAN on Trunk port of Zyxel GS1910

If I have a configuration on a Cisco switch; int Gi 0/48 switchport mode trunk switchport trunk native vlan 100 switchport trunk allowed vlan 101-110 Configuration on a Zyxel Switch ...
5
votes
1answer
9k views

What is most effective placement for firewall devices ?

Having attempted to research this I’m still uncertain of where best to place firewalls in an existing network due to needing to retain a common vlan between 2 core sites. The network has the ...
5
votes
1answer
2k views

What VLAN to set as trunk's native VLAN

I have 4 VLANs set up for our network. VLAN 50 for Servers / Firewall, VLAN 100 for Workstations, VLAN 150 for VOIP, and VLAN 200 for WiFi. What is the best practice for setting the trunk links VLAN ...
5
votes
1answer
2k views

Cisco iOS SNMP OID for Vlan on Port

I am working on setting up SNMP monitoring for our internal switched network in Zabbix. I have everything working now, but the template I am using discovers all ports on the switch, and I really only ...
4
votes
2answers
572 views

VLAN Tags Being Different for a VoIP Phone vs. the Host Daisy-Chained to it?

I've recently began working for a VoIP Provider and I am constantly seeing VoIP Phones pulling different VLANs than the Host that is connected to it i.e. daisy-chained. When I've tried to look more ...
4
votes
2answers
1k views

Portfast on Trunk port

Why shouldn't I activate portfast on a trunking port for a Cisco switch? I do understand that it could cause a loop on the the network, but I still cant wrap my head around the concept.
4
votes
2answers
3k views

What is native vlan tagging?

I researched a lot of native VLAN tagging resources, but I still don't understand what is the difference with VLAN tagging. Can anyone explain it simply?
4
votes
5answers
1k views

Are there any security advantages to activating VLAN tagging?

I understand the concepts of generating a VLAN. However, on a small, closed, sophisticated network, are there any security advantages to activating VLAN tagging?
4
votes
2answers
376 views

necessary and sufficient condition for vlans to communicate together

Let's say I know my switches configurations, for each, I know what port are configured in access, what port are in trunk, and what vlan is on a port. For each device. I want to group vlan that can ...
4
votes
1answer
398 views

Best Practice for Voice and Data VLAN on single port

We have multiple interfaces currently configured with the below on our Cisco 3750x switch. interface GigabitEthernet1/0/21 switchport access vlan 4 switchport trunk encapsulation dot1q switchport ...
4
votes
2answers
431 views

Neighbor switch's port doesn't change to access mode

When Switch A's port is configured to access mode from trunk mode, Switch B's port stays in trunk mode. Switch A is DTP disabled (#switchport nonegotiate). Switch B has default configuration which ...
4
votes
1answer
3k views

Cisco 3725 - ping encapsulation failed

I am unable to ping from R1 to R2. debug ip packet detail returns IP: s=172.16.12.1 (local), d=172.16.12.2 (FastEthernet0/0.12), len 100, encapsulation failed. I understand this means it can't resolve ...
4
votes
1answer
181 views

What are reasons to configure a Voice VLAN using the Auxillary VLAN feature instead of a Trunk + Native vLAN

Imagine this topology: [PC] ------- [VOIP Phone] ------- [eth0/0 on a Switch] And this configuration on the switch: vlan 22 name DATA vlan 33 name VOICE There are two ways to have both the PC'...
4
votes
1answer
2k views

What happens with tagged traffic on access port of Cisco switch?

I am broading up more this unanswered question: VLAN tagging and access port Let's assume I am trying to accomplish Double Tagging Attack. From my understanding, prerequisites of this attack is to be ...
4
votes
1answer
726 views

QoS for IP PBX behind DOCSIS modem (SIP trunk without direct routing by ISP)

I want to run a PBX behind a firewall behind a DOCSIS modem. Our ISP does not want to deploy a TA / gateway at our site. Our ISP only uses the modem for analog telephony and nothing else. QoS for ...
4
votes
2answers
3k views

SG300 - no traffic across trunk

This one's got me banging my head against a wall... likely a simple answer, but I've tried everything I know. I heard the internet's a smart place. :) Have an SG300-28MPP connected to a clients' ...
3
votes
3answers
761 views

Do VLANs within a subnet need to have their own subnet for router on a stick?

I have been creating a network lab in packet tracer for practice. I have 3 vlans in subnet A and I am trying to configure router on a stick at gig6/0 on the bottom left of the image. Do I need to ...
3
votes
3answers
6k views

Aren't Switch Access ports tagged?

I've read where frames are tagged only when going over a trunk and that Access ports do not tag frames. But don't Access ports actually tag frames? When I configure a particular port to be in a ...
3
votes
2answers
23k views

What is difference between standard VLAN extended VLAN?

I know that the range of standard VLAN is 1-1005 and in extended VLAN the range is 1-4094. But is just range is the difference?
3
votes
1answer
2k views

spanning-tree port type edge trunk on port-channel vs physical interface

If i configure spanning-tree port type edge trunk on physical interface instead of port-channel does that work? Or i have to do spanning-tree port type edge trunk on port-channel ? Example: ...
3
votes
2answers
9k views

Port channel to two different switches

We had a technician move one of two port channel links from an old switch to a new switch before telling anyone. This left the new and old switch both connected to different links of the same channel ...
3
votes
2answers
439 views

increasing bandwidth between two Cisco switches?

2 Cisco 3750 switches are connected via port 22(Trunk). First switch consists of 3 VLANs(each vlan have 7 ports such as 1-7,8-14,15-21) and 2nd switch consists of 2 VLANs. what solution can i use to ...
3
votes
1answer
55 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 ...
3
votes
2answers
481 views

Change VLAN id in trunk

I have 3 L3 switches. They're connected to each other with a trunk (in which I need to define the allowed VLAN's). On SW1 I have for example vlan 100. On SW3 I also have vlan 100, but it's another ...
3
votes
4answers
30k views

LACP Suspended Trunk Link

I have a LACP bonded trunk link between 2 switches, the bond contains 4 interfaces; all interfaces work fine except one. Cisco says you have to have matching configurations on all interfaces. The ...
3
votes
2answers
460 views

Trunking across different switch makes

I have a Dell N3132PX running 6 different VLANs. (192.xxx.xxx.10) VLAN 2 is my management VLAN for my switches. VLAN 3 is my DHCP network running production level for users. Port 25 (Untagged) VLAN ...
3
votes
1answer
342 views

Need help/advice on basic network setup involving security cameras, guest access, and VLANs

At some point, I'd like to move from a single, flat, network to having a more secure network using VLANs. I have an idea of what I would want, I just don't fully understand some details of Native ...
3
votes
2answers
438 views

Trunking MGMT Vlan Cisco x Dell

@edit: SOLVED!!! - See my answer below! how's going? Scenario: Trunk two Switches (Dell 6224 and Cisco SF300) for accessing them from the MGMT VLAN. Cisco ge2 -------TRUNK-------> Dell 1/g22 ...
3
votes
1answer
7k views

hp procurve trunk port group operation vs active lacp port group

We recently purchased some HP Procurve 2920 switches and in setting them up I noticed multiple options for port groups. I wanted to see if anyone can clarify functional differences between setting up ...
3
votes
2answers
2k views

Does 802.1Q protocol will remove the VLAN tag in the received place?

Does 802.1Q protocol will remove the VLAN tag in the received place? Such as the VLAN 10 trough 802.1Q protocol to pass frames. the 802.1Q will add 802.1q header(tag) and recalculate CRC/FCS like ...
3
votes
1answer
904 views

ACL on trunk Port

our network infrastructure as showing the image below I had to give an external company (dealing with Face recognition) software an access to both the server (172.26.33.56) and the IP Camera (172.26....
3
votes
1answer
3k views

VLAN routing using Cisco 2950 Switch and Cisco 1841 Router

I am new to networking and I have recently purchased a 1950 switch and 1841 router. What I am trying to do, is to use VLANS to segregate my network. From whaty I have read I think I need to ...
3
votes
1answer
671 views

Add links to a port channel group without downtime

There are two trunk links with the same configuration connecting two switches. Currently they are independent links and one is blocked with spanning-tree. I would like to convert these to a single ...
3
votes
1answer
876 views

Setting a loopback/management address through a layer 2 trunk

We have two EX4200 switches in the following configuration: Router (.1)=====static route=====(.2) EX_01========trunk========EX_02 I want to configure a loopback or management interface on EX_02. ...
3
votes
3answers
671 views

Force VLAN traffic through specified interfaces

I have two VLANs, VLAN1 for "clients" and VLAN2 for (web)servers. Both VLANs have two ports in etherchannel (one Cisco switch). I would like to put transparent (WAF) device in bridge mode between the ...
3
votes
3answers
3k views

Operational mode is down for one link

I am setting up a simulated Cisco Packet Tracer with three Cisco Catalyst 2960 switches S1, S2 and S3. S1 being the trunk for S2 and S3. I have three(3) interfaces F0/6, F0/11, F0/18 that are ...
3
votes
1answer
1k views

TCI ( Tag control information ) use VLAN

I have simple VLAN network diagram . I want to show how the TCI field can be used to have a VLAN number policy for this diagram. How do I do this?
3
votes
2answers
189 views

No ping between Nokia (IPSO) and Cisco switch through trunk link

I have a Nokia and a Cisco switch, connected with one RJ cable. I've configured the switch in trunk mode, and the port on the Nokia with some VLAN number. I don't have a ping between them, I don't ...