on Container Networking

calcotestudios.com/talks

http://calcotestudios.com/techsummit-over-under

Over lay
Under lay

The

Lee Calcote
March 2nd, 2017

Lee Calcote

linkedin.com/in/leecalcote

@lcalcote

blog.gingergeek.com

lee@calcotestudios.com

clouds, containers, infrastructure, applications and their management

Show of Hands

Container Networking

...it's complicated.

Preset Expectations

Reliability & Performance

same demands and measurements

developer-friendly and application-driven
simple to use and deploy for developers and operators

@lcalcote

better or on par with existing

virtual data center networking

Experience & Management

Intent-based networking

Preset Expectations

Container Networking Specifications

Very interesting

but no need to actually know these

@lcalcote

Container Network Model (CNM)

...is a specification proposed by Docker, adopted by projects such as libnetwork

Plugins built by projects such as Weave, Contiv, Calico, Plumgrid and Kuryr.

Container Network Interface (CNI)

...is a specification proposed by CoreOS and adopted by projects such as rkt, Kurma, Kubernetes, Cloud Foundry, and Apache Mesos.

Plugins created by projects such as Weave, Project Calico, Plumgrid, Midokura and Contiv.

Container Networking Specifications

@lcalcote

Container Network Model
Specification

@lcalcote

Local Drivers

Docker Runtime

Bridge

Container Network Model (libnetwork)

Remote Drivers

None

Overlay

Third-party

Container Network Model
Topology

Network Sandbox

Endpoint

Network

Container

Network Sandbox

Endpoint

Container

Network Sandbox

Endpoint

Container

Endpoint

Network

@lcalcote

Docker Engine

Network Driver

IPAM Driver

Microsegmentation - traffic is not relayed

Container Network Interface
Specification

@lcalcote

Container Runtime

Container Network Interface
(CNI)

Loopback
Plugin

Bridge
Plugin

PTP
Plugin

MACvlan
Plugin

IPvlan
Plugin

Third-party
Plugin

Container Network Interface
Flow

Container runtime needs to:
1. allocate a network namespace to the container and assign a container ID
2. pass along a number of parameters (CNI config) to network driver.
Network driver needs to:
1. attach container to a network
2. then, report the assigned IP address back to the container runtime (via JSON schema)

@lcalcote

CNI Network

                                
                                    {
                                        "name": "mynet",
                                        "type": "bridge",
                                        "bridge": "cni0",
                                        "isGateway": true,
                                        "ipMasq": true,
                                        "ipam": {
                                            "type": "host-local",
                                            "subnet": "10.22.0.0/16",
                                            "routes": [
                                                { "dst": "0.0.0.0/0" }
                                            ]
                                        }

(JSON)

@lcalcote

CNI and CNM

Similar in that each...

...are driver-based ( pluggable ), and therefore
- democratize the selection of which type of container networking
...allow multiple network drivers to be active and used concurrently
- each provide a one-to-one mapping of network to that network’s driver
...allow containers to join one or more networks.
...allow the container runtime to launch the network in its own namespace
- segregate the application/business logic of connecting the container to the network to the network driver.

@lcalcote

CNI and CNM

Different in that...

CNI supports any container runtime
- CNM only support Docker runtime
CNI is simpler, has adoption beyond its creator
CNM acts as a broker for conflict resolution
- CNI is still considering its approach to arbitration

@lcalcote

Types of Container Networking

None
Links and Ambassadors
Container-mapped
Bridge
Host
Overlay

Underlay
- MACvlan
- IPvlan
- Direct Routing
- Point-to-Point
- Fan Networking

@lcalcote

bridge

eth0

eth1

container

Host

None

good ol' l0

container receives a network stack, but lacks an external network interface.

it does, however, receive a loopback interface.

@lcalcote

Ambassadors

facilitate multi-host connectivity
- uses a tcp port forwarder (socat)

Web Host

MySQL
Ambassador

PHP

DB Host

PHP
Ambassador

MySQL

link

@lcalcote

Bridge

Ah, yes, docker0

default networking for Docker
uses a host-internal network
leverages iptables for network address translation (NAT) and port-mapping

@lcalcote

Container-Mapped

one container reuses (maps to) the networking namespace of another container.

may only be invoked when running a docker container (cannot be defined in Dockerfile):

--net=container=some_container_name_or_id

@lcalcote

Host

container created shares its network namespace with the host

@lcalcote

suffers port conflicts

secure?

better performance

easy to understand and troubleshoot

default Mesos networking mode

Overlay

use networking tunnels to delivery communication across hosts

Most useful in hybrid cloud scenarios
- or when shadow IT is needed
Many tunneling technologies exist
- VXLAN being the most commonly used
Requires distributed key-value store

@lcalcote

K/V Store for Overlays

BYOKV?

Docker -
- 1.11 requires K/V store
- built-in as of 1.12
  - uses raft implementation from etcd
  - uses gomemdb and Serf from HashiCorp
WeaveNet - limited to single network; does not require K/V store
WeaveMesh - does not require separate K/V store
Flannel - requires K/V store
Plumgrid - requires K/V store; built-in and not pluggable
Midokura - requires K/V store; built-in and not pluggable
Calico - requires K/V store
NSX - requires K/V store
Romana - requires K/V store
Cilium - requires K/V store

@lcalcote

Underlays

expose host interface(s) directly to container(s)

(e.g. the physical network interface at eth0)

Point-to-Point
MACvlan
IPvlan
Direct Routing
Fan Networking

not necessarily public cloud friendly

@lcalcote

Point-to-Point

default rkt networking mode

Uses NAT (IPMASQ) by default
Creates a virtual ethernet pair
- placing one on the host and the other into the container pod
leverages iptables to provide port-forwarding for inbound traffic to the pod
internal communication between other containers in the pod over the loopback interface

Internet

@lcalcote

MACvlan

allows creation of multiple virtual network interfaces behind the host’s physical interface
Each virtual interface has unique MAC and IP addresses assigned
- with restriction: the assigned IP address needs to be in the same broadcast domain as the physical interface
eliminates the need for the Linux bridge, NAT and port-mapping
- allowing you to connect directly to physical interface

@lcalcote

                                
                                    switchport port-security mac-address sticky

IPvlan

allows creation of multiple virtual network interfaces behind a host’s physical interface
Each virtual interface has unique IP addresses assigned
- Same MAC address used for all containers
L2-mode containers must be on same network as host (similar to MACvlan)
L3-mode containers must be on different network than host
- Network advertisement and redistribution into the network still needs to be done.

@lcalcote

MACvlan and IPvlan

While multiple modes of networking are supported on a given host, MACvlan and IPvlan can’t be used on the same physical interface concurrently.
ARP and broadcast traffic, the L2 modes of these underlay drivers operate just as a server connected to a switch does by flooding and learning using 802.1d packets
IPvlan L3-mode - No multicast or broadcast traffic is allowed in.
In short, if you’re used to running trunks down to hosts, L2 mode is for you.
If scale is a primary concern, L3 has the potential for massive scale.

@lcalcote

Direct Routing

Benefits of pushing past L2 to L3
resonates with network engineers
leverage existing network infrastructure
use routing protocols for connectivity; easier to interoperate with existing data center across VMs and bare metal servers
Better scaling
More granular control over filtering and isolating network traffic
- Easier traffic engineering for quality of service
Easier to diagnose network issues

@lcalcote

Fan Networking

a way of gaining access to many more IP addresses, expanding from one assigned IP address to 250 more IP addresses

“address expansion” - multiplies the number of available IP addresses on the host, providing an extra 253 usable addresses for each host IP
Fan addresses are assigned as subnets on a virtual bridge on the host,
- IP addresses are mathematically mapped between networks
uses IP-in-IP tunneling; high performance
particularly useful when running containers in a public cloud
- where a single IP address is assigned to a host and spinning up additional networks is prohibitive or running another load-balancer instance is costly

@lcalcote

Fan Networking

@lcalcote

diagram courtesy Dustin Kirkland

Network Capabilities and Services

IPAM, multicast, broadcast, IPv6, load-balancing, service discovery, policy, quality of service, advanced filtering and performance are all additional considerations to account for when selecting container networking that fits your needs.

@lcalcote

IPv6 and IPAM

IPv6

lack of support for IPv6 in the top public clouds
- reinforces the need for other networking types (overlays and fan networking)
- some tier 2 public cloud providers offer support for IPv6

IPAM

most container runtime engines default to host-local for assigning addresses to containers as they are connected to networks.
Host-local IPAM involves defining a fixed block of IP addresses to be selected.
DCHP is universally supported across the container networking projects.
CNM and CNI both have IPAM built-in and plugin frameworks for integration with IPAM systems

@lcalcote

Docker 1.12 (Load-balancing)

@lcalcote

Swarm and multi-host networking are simpatico
- user-defined overlay networks that are micro-segmentable
- uses Hashicorp's Serf gossip protocol for quick convergence of neighbor tables between hosts
- facilitates container name resolution via embedded DNS server (previously via etc/hosts)
Load-balancing based on IPVS
- expose Service's port externally; L4 load-balancer
Mesh routing
- send a request to any one of the nodes and it will be routed automatically
- send a request to any one of the nodes and it will be internally load balanced