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port neutron

asked 2020-01-13 06:00:05 -0500

lelunicu gravatar image

updated 2020-01-13 06:01:18 -0500

hi, i like to see if i undrerstood why we need port. when a VM is created then the vnic will connect to the external bridge through a port?I seen that a port can has ethernet and IP.why this?the IP that an vnic has will send or receive traffic to and from this port?

a port connect a nic to a vlan.right?cen we have multiple port per nic-each connect to a different vlan?

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answered 2020-01-13 07:50:43 -0500

A port is the abstraction of a layer 2 network connection. As you say yourself, it carries a MAC and (if there is a subnet) an IP address.

You ask why - my guess is that it is easier to manage this way. There is a diversity of resources, instances, routers, DHCP servers etc that are connected to Neutron networks with ports. They are different, but they all need MAC and IP addresses. Instead of creating different MAC and IP address implementations on each of those resources, it's simpler to just move the addresses to the port abstraction. This is entirely my assumption; I was not there when the design was discussed.

the vnic will connect to the external bridge through a port?

This sentence mixes a Neutron resource (port) with a Neutron implementation concept (VNIC) and an operating system concept (bridge). You mix three things that are located at three different abstraction levels, and the end result is a sentence that is not even wrong. It's as if you said that the engine of a car is connected to the road via the driver.

a port connect a nic to a vlan.right?

No. A port connects an OpenStack object to a Neutron network.

There is no concept of VLAN in Neutron, except when you enable the VLAN Transparency Extension, which only exists to implement very specific NFV requirements.

cen we have multiple port per nic

Not as far as I know.

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that mean that the instance ip is the port ip that connect the VM(instance) to neutron network? if i need that this instance to be monitored than we use anothe neutrin network.right? in this case inside the instance are 2 vnics or a vnic that use vlan?

lelunicu gravatar imagelelunicu ( 2020-01-13 08:06:32 -0500 )edit

Hi Bernd I think question user put in wrong way. What I understood he is interested in configure ports "a port connect a nic to a vlan.right?cen we have multiple port per nic-each connect to a different vlan" Yes we can have mutiple vlan and multiple port to same nic using OVS Plugins.

piyushsrivastava gravatar imagepiyushsrivastava ( 2020-01-13 08:53:40 -0500 )edit

when u create VM, basically it will create tap port and that is connected with virtual bridge and then comes to linux bridge and end it will connected to you physical nics,To have segregate network we have vlan or Vxlan coming from same physical nics.So we need port, basically a tap port for your VM

piyushsrivastava gravatar imagepiyushsrivastava ( 2020-01-13 08:58:41 -0500 )edit

the instance ip is the port ip that connect the VM(instance) to neutron network?

Yes.

if i need that this instance to be monitored than we use anothe neutrin network

You say you need a second network to monitor the instance? In this case, the instance needs a second NIC.

Bernd Bausch gravatar imageBernd Bausch ( 2020-01-13 09:49:13 -0500 )edit

in this case inside the instance are 2 vnics or a vnic that use vlan?

I think you ask if a single NIC can be connected to several VLANs. The answer is yes if you enable VLAN transparency. However I am not sure if this helps your need to monitor the instance.

Bernd Bausch gravatar imageBernd Bausch ( 2020-01-13 09:51:00 -0500 )edit

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Asked: 2020-01-13 06:00:05 -0500

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Last updated: Jan 13