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Fix several typos on macvlan docs

Signed-off-by: Erich Cordoba <erich.cm@yandex.com>
This commit is contained in:
Erich Cordoba 2016-07-19 21:14:57 -05:00
parent d8ef832bc1
commit 829a4ee4be

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@ -7,9 +7,9 @@ The Macvlan driver provides operators the ability to integrate Docker networking
The Linux implementation is considered lightweight because it eliminates the need for using a Linux bridge for isolating containers on the Docker host. The VLAN driver requires full access to the underlying host making it suitable for Enterprise data centers that have administrative access to the host.
Instead of attaching container network interfaces to a Docker host Linux bridge for a network, the driver simply connects the container interface to the Docker Host Ethernet interface (or sub-interface). Each network is attached to a unique parent interface. Containers in a network share a common broadcast domain and intra-network connectivity is permitted. Two seperate networks will each have a unique parent interface and that parent is what enforces datapath isolation between two networks. In order for inter-network communications to occour, an IP router, external to the Docker host, is required to route between the two networks by hair-pining into the physical network and then back to the Docker host. While hairpinning traffic can be less efficient then east/west traffic staying local to the host, there is often more complexity associated with desiagregating services to the host. It can be practical for some users to leverage existing network services, such firewalls and load balancers that already exist in a data center architecture.
Instead of attaching container network interfaces to a Docker host Linux bridge for a network, the driver simply connects the container interface to the Docker Host Ethernet interface (or sub-interface). Each network is attached to a unique parent interface. Containers in a network share a common broadcast domain and intra-network connectivity is permitted. Two separate networks will each have a unique parent interface and that parent is what enforces datapath isolation between two networks. In order for inter-network communications to occur, an IP router, external to the Docker host, is required to route between the two networks by hair-pining into the physical network and then back to the Docker host. While hairpinning traffic can be less efficient then east/west traffic staying local to the host, there is often more complexity associated with disaggregating services to the host. It can be practical for some users to leverage existing network services, such firewalls and load balancers that already exist in a data center architecture.
When using traditional Linux bridges there are two common techniques to get traffic out of a container and into the physical network and vice versa. The first method to connect containers to the underlying network is to use Iptable rules which perform a NAT translation from a bridge that represents the Docker network to the physical Ethernet connection such as `eth0`. The upside of Iptables using the Docker built-in bridge driver is that the NIC does not have to be in promiscous mode. The second bridge driver method is to move a host's external Ethernet connection into the bridge. Moving the host Ethernet connection can at times be unforgiving. Common mistakes such as cutting oneself off from the host, or worse, creating bridging loops that can cripple a VLAN throughout a data center can open a network design up to potential risks as the infrastructure grows.
When using traditional Linux bridges there are two common techniques to get traffic out of a container and into the physical network and vice versa. The first method to connect containers to the underlying network is to use Iptable rules which perform a NAT translation from a bridge that represents the Docker network to the physical Ethernet connection such as `eth0`. The upside of Iptables using the Docker built-in bridge driver is that the NIC does not have to be in promiscuous mode. The second bridge driver method is to move a host's external Ethernet connection into the bridge. Moving the host Ethernet connection can at times be unforgiving. Common mistakes such as cutting oneself off from the host, or worse, creating bridging loops that can cripple a VLAN throughout a data center can open a network design up to potential risks as the infrastructure grows.
Connecting containers without any NATing is where the VLAN drivers accel. Rather then having to manage a bridge for each Docker network containers are connected directly to a `parent` interface such as `eth0` that attaches the container to the same broadcast domain as the parent interface. A simple example is if a host's `eth0` is on the network `192.168.1.0/24` with a gateway of `192.168.1.1` then a Macvlan Docker network can start containers on the addresses `192.168.1.2 - 192.168.1.254`. Containers use the same network as the parent `-o parent` that is specified in the `docker network create` command.
@ -28,17 +28,17 @@ There are positive performance implication as a result of bypassing the Linux br
### MacVlan Bridge Mode Example Usage
- Macvlan driver networks are attached to a parent Docker host interface. Examples are a physical interface such as `eth0`, a sub-interface for 802.1q VLAN tagging like `eth0.10` (`.10` representing VLAN `10`) or even bonded `bond0` host adaptors which bundle two Ethernet interfaces into a single logical interface and provide diversity in the server connection.
- Macvlan driver networks are attached to a parent Docker host interface. Examples are a physical interface such as `eth0`, a sub-interface for 802.1q VLAN tagging like `eth0.10` (`.10` representing VLAN `10`) or even bonded `bond0` host adapters which bundle two Ethernet interfaces into a single logical interface and provide diversity in the server connection.
- The specified gateway is external to the host that is expected to be provided by the network infrastructure. If a gateway is not specified using the `--gateway` paramter, then Libnetwork will infer the first usable address of a subnet. For example, if a network's subnet is `--subnet 10.1.100.0/24` and no gateway is specified, Libnetwork will assign a gateway of `10.1.100.1` to the container. A second example would be a subnet of `--subnet 10.1.100.128/25` would receive a gateway of `10.1.100.129`.
- The specified gateway is external to the host that is expected to be provided by the network infrastructure. If a gateway is not specified using the `--gateway` parameter, then Libnetwork will infer the first usable address of a subnet. For example, if a network's subnet is `--subnet 10.1.100.0/24` and no gateway is specified, Libnetwork will assign a gateway of `10.1.100.1` to the container. A second example would be a subnet of `--subnet 10.1.100.128/25` would receive a gateway of `10.1.100.129`.
- Containers on separate networks cannot reach one another without an external process routing between the two networks/subnets.
- Each Macvlan Bridge mode Docker network is isolated from one another and there can be only one network attached to a parent interface at a time. There is a theoretical limit of 4,094 sub-interfaces per host adaptor that a Docker network could be attached to.
- Each Macvlan Bridge mode Docker network is isolated from one another and there can be only one network attached to a parent interface at a time. There is a theoretical limit of 4,094 sub-interfaces per host adapter that a Docker network could be attached to.
- The driver limits one network per parent interface. The driver does however accommodate secondary subnets to be allocated in a single Docker network for a multi-subnet requirement. The upstream router is responsible for proxy-arping between the two subnets.
- Any Macvlan container sharing the same subnet can communicate via IP to any other container in the same subnet without a gateway. It is important to note, that the parent will go into promiscous mode when a container is attached to the parent since each container has a unique MAC address. Alternatively, Ipvlan which is currently a experimental driver uses the same MAC address as the parent interface and thus precluding the need for the parent being promiscous.
- Any Macvlan container sharing the same subnet can communicate via IP to any other container in the same subnet without a gateway. It is important to note, that the parent will go into promiscuous mode when a container is attached to the parent since each container has a unique MAC address. Alternatively, Ipvlan which is currently a experimental driver uses the same MAC address as the parent interface and thus precluding the need for the parent being promiscuous.
In the following example, `eth0` on the docker host has an IP on the `172.16.86.0/24` network and a default gateway of `172.16.86.1`. The gateway is an external router with an address of `172.16.86.1`. An IP address is not required on the Docker host interface `eth0` in `bridge` mode, it merely needs to be on the proper upstream network to get forwarded by a network switch or network router.
@ -223,7 +223,7 @@ docker network rm $(docker network ls -q)
ip link
```
Hosts on the same VLAN are typically on the same subnet and almost always are grouped together based on their security policy. In most scenarios, a multi-tier application is tiered into different subnets because the security profile of each process requires some form of isolation. For example, hosting your credit card processing on the same virtual network as the front-end web-server would be a regulatory compliance issue, along with circumventing the long standing best practice of layered defense in depth architectures. VLANs or the equivelant VNI (Virtual Network Identifier) when using the built-in Overlay driver, are the first step in isolating tenant traffic.
Hosts on the same VLAN are typically on the same subnet and almost always are grouped together based on their security policy. In most scenarios, a multi-tier application is tiered into different subnets because the security profile of each process requires some form of isolation. For example, hosting your credit card processing on the same virtual network as the front-end web-server would be a regulatory compliance issue, along with circumventing the long standing best practice of layered defense in depth architectures. VLANs or the equivalent VNI (Virtual Network Identifier) when using the built-in Overlay driver, are the first step in isolating tenant traffic.
![Docker VLANs in Depth](images/vlans-deeper-look.png)
@ -425,4 +425,3 @@ ip link del foo
```
As with all of the Libnetwork drivers, networks of various driver types can be mixed and matched. This even applies to 3rd party ecosystem drivers that can be run in parallel with built-in drivers for maximum flexibility to the user.