[pve-devel] [PATCH docs] Add a paragraph to explain how network models match use cases
Emmanuel Kasper
e.kasper at proxmox.com
Mon Oct 2 17:17:26 CEST 2017
Also :
* explain more clearly when PVE switched to persistent device naming. (5.0)
* use eno1 instead of eno0 everywhere when refering to the first onboard device
* use IP addresses from the range IPv4 Address Blocks for Documentation
(rfc5737) instead of private IPv4 addresses when giving examples of public IPs
---
pve-network.adoc | 101 ++++++++++++++++++++++++++++++++++---------------------
1 file changed, 62 insertions(+), 39 deletions(-)
diff --git a/pve-network.adoc b/pve-network.adoc
index beb69ae..5d53924 100644
--- a/pve-network.adoc
+++ b/pve-network.adoc
@@ -5,44 +5,32 @@ ifdef::wiki[]
:pve-toplevel:
endif::wiki[]
-{pve} uses a bridged networking model. Each host can have up to 4094
-bridges. Bridges are like physical network switches implemented in
-software. All VMs can share a single bridge, as if
-virtual network cables from each guest were all plugged into the same
-switch. But you can also create multiple bridges to separate network
-domains.
-
-For connecting VMs to the outside world, bridges are attached to
-physical network cards. For further flexibility, you can configure
-VLANs (IEEE 802.1q) and network bonding, also known as "link
-aggregation". That way it is possible to build complex and flexible
-virtual networks.
+Network configuration can be done either via the GUI, or by manually
+editing the file `/etc/network/interfaces`, which contains the
+whole network configuration. The `interfaces(5)` manual page contains the
+complete format description. All {pve} tools try hard to keep direct
+ user modifications, but using the GUI is still preferable, because it
+protects you from errors.
-Debian traditionally uses the `ifup` and `ifdown` commands to
-configure the network. The file `/etc/network/interfaces` contains the
-whole network setup. Please refer to to manual page (`man interfaces`)
-for a complete format description.
+Once the network is configured, you can use the Debian traditional tools `ifup`
+and `ifdown` commands to bring interfaces up and down.
NOTE: {pve} does not write changes directly to
`/etc/network/interfaces`. Instead, we write into a temporary file
called `/etc/network/interfaces.new`, and commit those changes when
you reboot the node.
-It is worth mentioning that you can directly edit the configuration
-file. All {pve} tools tries hard to keep such direct user
-modifications. Using the GUI is still preferable, because it
-protect you from errors.
-
-
Naming Conventions
~~~~~~~~~~~~~~~~~~
We currently use the following naming conventions for device names:
-* New Ethernet devices: en*, systemd network interface names.
+* Ethernet devices: en*, systemd network interface names. This naming scheme is
+ used for new {pve} installations since version 5.0.
-* Legacy Ethernet devices: eth[N], where 0 ≤ N (`eth0`, `eth1`, ...)
-They are available when Proxmox VE has been updated by an earlier version.
+* Ethernet devices: eth[N], where 0 ≤ N (`eth0`, `eth1`, ...) This naming
+scheme is used for {pve} hosts which were installed before the 5.0
+release. When upgrading to 5.0, the names are kept as-is.
* Bridge names: vmbr[N], where 0 ≤ N ≤ 4094 (`vmbr0` - `vmbr4094`)
@@ -52,8 +40,7 @@ They are available when Proxmox VE has been updated by an earlier version.
separated by a period (`eno1.50`, `bond1.30`)
This makes it easier to debug networks problems, because the device
-names implies the device type.
-
+name implies the device type.
Systemd Network Interface Names
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -78,12 +65,46 @@ The most common patterns are:
For more information see https://www.freedesktop.org/wiki/Software/systemd/PredictableNetworkInterfaceNames/[Predictable Network Interface Names].
+Choosing a network configuration
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Depending on your current network organization and your resources you can
+choose either a bridged, routed, or masquerading networking setup.
+
+{pve} server in a private LAN, using an external gateway to reach the internet
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The *Bridged* model makes the most sense in this case, and this is also
+the default mode on new {pve} installations.
+Each of your Guest system will have a virtual interface attached to the
+{pve} bridge. This is similar in effect to having the Guest network card
+directly connected to your LAN.
+
+{pve} server at hosting provider, with public IP ranges for Guests
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+For this setup, you can use either a *Bridged* or *Routed* model, depending on
+what your provider allows.
+
+{pve} server at hosting provider, with a single public IP address
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+In that case the only way to get outgoing network accesses for your guest
+systems is to use *Masquerading*. For incoming network access to your guests,
+you will need to configure *Port Forwarding*.
+
+For further flexibility, you can configure
+VLANs (IEEE 802.1q) and network bonding, also known as "link
+aggregation". That way it is possible to build complex and flexible
+virtual networks.
Default Configuration using a Bridge
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Bridges are like physical network switches implemented in software.
+ All VMs can share a single bridge, or you can create multiple bridges to separate network domains. Each host can have up to 4094 bridges.
The installation program creates a single bridge named `vmbr0`, which
-is connected to the first Ethernet card `eno0`. The corresponding
+is connected to the first Ethernet card `eno1`. The corresponding
configuration in `/etc/network/interfaces` looks like this:
----
@@ -123,9 +144,9 @@ You can avoid the problem by ``routing'' all traffic via a single
interface. This makes sure that all network packets use the same MAC
address.
-A common scenario is that you have a public IP (assume `192.168.10.2`
+A common scenario is that you have a public IP (assume `198.51.100.5`
for this example), and an additional IP block for your VMs
-(`10.10.10.1/255.255.255.0`). We recommend the following setup for such
+(`203.0.113.16/29`). We recommend the following setup for such
situations:
----
@@ -134,17 +155,17 @@ iface lo inet loopback
auto eno1
iface eno1 inet static
- address 192.168.10.2
+ address 198.51.100.5
netmask 255.255.255.0
- gateway 192.168.10.1
+ gateway 198.51.100.1
post-up echo 1 > /proc/sys/net/ipv4/ip_forward
post-up echo 1 > /proc/sys/net/ipv4/conf/eno1/proxy_arp
auto vmbr0
iface vmbr0 inet static
- address 10.10.10.1
- netmask 255.255.255.0
+ address 203.0.113.17
+ netmask 255.255.255.248
bridge_ports none
bridge_stp off
bridge_fd 0
@@ -154,19 +175,21 @@ iface vmbr0 inet static
Masquerading (NAT) with `iptables`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-In some cases you may want to use private IPs behind your Proxmox
-host's true IP, and masquerade the traffic using NAT:
+Masquerading allows guests having only a private IP address to access the
+network by using the host IP address for outgoing traffic. Each outgoing
+packet is rewritten by `iptables` to appear as originating from the host,
+and responses are rewritten accordingly to be routed to the original sender.
----
auto lo
iface lo inet loopback
-auto eno0
+auto eno1
#real IP address
iface eno1 inet static
- address 192.168.10.2
+ address 198.51.100.5
netmask 255.255.255.0
- gateway 192.168.10.1
+ gateway 198.51.100.1
auto vmbr0
#private sub network
--
2.11.0
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