Category Archives: 2. HP Switch

Switching

How vlan works on HP switches.

I. Overview

We all know that in cisco in order to communicate vlans between different switches is we need to create a “Trunk Links” to pass the vlan traffic.

Cisco switchport modes:
1. Dynamic – Pro-active DTP negotiation will begin and if the other-side is set to trunk, desirable, or auto. The interface will become a trunk. Otherwise the port will become an access port.

2. Access – Always force that port to be an access port with no VLAN tagging allowed except from voice vlan. DTP is not used and a trunk will never be formed.

3. Trunk – This interface will always be a trunk no matter what happens on the other side. It will also use DTP to negotiate a neighboring interface that is set to dynamic desirable or dynamic auto into a trunk.

But, In HP “Trunk” was very different from Cisco.

HP Modes:
1. Untagged – If it is untagged it sends the VLAN traffic without adding in the VLAN tag. So you would only make a port a tagged member if the device that is plugged into it is VLAN. It’s like access port on cisco switches.

2. Tagged – If a port is a tagged member it passes the VLAN information with the traffic it sends.

II. Configuration

hpproc

## Adding interface Vlan
# Configure terminal
#vlan 10
#untagged 6 (Add port 6 on vlan 10 for tagging)
#vlan 20
#untagged 12 (Add port 12 on vlan 20 for tagging)

## Configuring Tagged Port (Trunk)
#vlan 10
#tagged 47
#vlan 20
#tagged 47

Scenario 2 (Adding Tagged Port-Channel)
## Configuring Tagged Port (Trunk)
#trunk 47,48 Trk1 LACP
#vlan 10
#tagged Trk1
#vlan 20
#tagged Trk1

What’s the difference between tagged and untagged? If a port is a tagged member it passes the VLAN information with the traffic it sends. If it is untagged it sends the VLAN traffic without adding in the VLAN tag. So you would only make a port a tagged member if the device that is plugged into it is VLAN aware, i.e. another switch, router, or machine with a VLAN aware NIC. (Note: The VLAN tag is the ID that gets inserted into the head of a network packet).

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