Commit 0e0266c2 authored by Thomas Huth's avatar Thomas Huth Committed by Jason Wang
Browse files

net: Get rid of 'vlan' terminology and use 'hub' instead in the doc files 

'vlan' is very confusing since it does not mean something like IEEE
802.1Q, but rather emulated hubs, so let's switch to that terminology
instead. While we're at it, move the subsection about hub a little bit
downward in the documentation (it's not as important anymore as it was
before the invention of the -netdev parameter), and extend it a little
bit.

Buglink: https://bugs.launchpad.net/qemu/+bug/658904


Reviewed-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: default avatarThomas Huth <thuth@redhat.com>
Signed-off-by: default avatarJason Wang <jasowang@redhat.com>
parent 442da403

qemu-doc.texi

+23 −19
Original line number Diff line number Diff line
@@ -714,20 +714,12 @@ state is not saved or restored properly (in particular USB). 
@node pcsys_network

@section Network emulation



QEMU can simulate several network cards (PCI or ISA cards on the PC

target) and can connect them to an arbitrary number of Virtual Local

Area Networks (VLANs). Host TAP devices can be connected to any QEMU

VLAN. VLAN can be connected between separate instances of QEMU to

simulate large networks. For simpler usage, a non privileged user mode

network stack can replace the TAP device to have a basic network

connection.



@subsection VLANs



QEMU simulates several VLANs. A VLAN can be symbolised as a virtual

connection between several network devices. These devices can be for

example QEMU virtual Ethernet cards or virtual Host ethernet devices

(TAP devices).

QEMU can simulate several network cards (e.g. PCI or ISA cards on the PC

target) and can connect them to a network backend on the host or an emulated

hub. The various host network backends can either be used to connect the NIC of

the guest to a real network (e.g. by using a TAP devices or the non-privileged

user mode network stack), or to other guest instances running in another QEMU

process (e.g. by using the socket host network backend).



@subsection Using TAP network interfaces
@@ -763,7 +755,7 @@ network). The virtual network configuration is the following: 


@example



         QEMU VLAN      <------>  Firewall/DHCP server <-----> Internet

     guest (10.0.2.15)  <------>  Firewall/DHCP server <-----> Internet

                           |          (10.0.2.2)

                           |

                           ---->  DNS server (10.0.2.3)
@@ -798,11 +790,23 @@ When using the @option{'-netdev user,hostfwd=...'} option, TCP or UDP 
connections can be redirected from the host to the guest. It allows for

example to redirect X11, telnet or SSH connections.



@subsection Connecting VLANs between QEMU instances

@subsection Hubs



QEMU can simulate several hubs. A hub can be thought of as a virtual connection

between several network devices. These devices can be for example QEMU virtual

ethernet cards or virtual Host ethernet devices (TAP devices). You can connect

guest NICs or host network backends to such a hub using the @option{-netdev

hubport} or @option{-nic hubport} options. The legacy @option{-net} option

also connects the given device to the emulated hub with ID 0 (i.e. the default

hub) unless you specify a netdev with @option{-net nic,netdev=xxx} here.



@subsection Connecting emulated networks between QEMU instances



Using the @option{-net socket} option, it is possible to make VLANs

that span several QEMU instances. See @ref{sec_invocation} to have a

basic example.

Using the @option{-netdev socket} (or @option{-nic socket} or

@option{-net socket}) option, it is possible to create emulated

networks that span several QEMU instances.

See the description of the @option{-netdev socket} option in the

@ref{sec_invocation,,Invocation chapter} to have a basic example.



@node pcsys_other_devs

@section Other Devices