Presented at Rackspace Austin (downtown) on July 27th, 2016. An inherent to component to any distributed application, networking is one of the most complicated and expansive infrastructure technologies. Container networking needs to be developer-friendly. Application-driven and portable. With developers busily adopting container technologies, the time has come for network engineers and operators to prepare for the unique challenges brought on by cloud native applications. What container networking specifications bring to the table and how to leverage them.

1. Betting on Container
Networking
Lee Calcote
July 27th, 2016
Overlay
Underlay
http://calcotestudios.com/over-under

2. http://calcotestudios.com/oubcn
Lee Calcote
clouds, containers, infrastructure, applications
and their management
linkedin.com/in/leecalcote
@lcalcote
blog.gingergeek.com
lee@calcotestudios.com

3. Show of Hands
@lcalcote

4. Container
Networking
...it's complicated.

5. Preset Expectations
Experience &
Management
Reliability &
Performance
same demands and measurements
developer-friendly and application-driven
simple to use and deploy for developers and operators
better or at least on par with their existing virtualized data
center networking

6. Container
Networking
Specifications

7. Very interesting
but no need to actually know these
@lcalcote

8. (CNM)
Container Network Model
...is a specification proposed by Docker,
adopted by projects such as
Plugins built by projects such as ,
, and
libnetwork
Weave
Project Calico Kuryr
(CNI)
Container Network Interface
...is a specification proposed by
CoreOS and adopted by projects such
as , , ,
, and
Plugins created by projects such as
, , and
rkt Kurma Kubernetes Cloud
Foundry Apache Mesos
Weave Project Calico Contiv
Networking
@lcalcote
Container Networking Specifications

9. Container Network Model
Specification
@lcalcote
Remote DriversLocal Drivers

10. Container Network Model
Topology
@lcalcote
Network Sandbox
Endpoint
Backend Network
Docker
Container
Network Sandbox
Endpoint
Docker
Container
Network Sandbox
Endpoint
Docker
Container
Endpoint
Frontend Network

11. @lcalcote
Container Network Interface
(CNI)

12. @lcalcote
Container Network Interface
Flow
1. 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.
2. Network driver attaches container to a network and then
reports the assigned IP address back to the container runtime
(via JSON schema)

13. @lcalcote
CNI Network
(JSON)
{
"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" }
]
}

14. CNI and CNM
Similar in that each...
...are driver-based, 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

15. 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

16. Types of Container Networking
None
Links and Ambassadors
Container-mapped
Bridge
Host
Overlay
Underlay
MACvlan
IPvlan
Direct Routing
Point-to-Point
Fan Networking
@lcalcote

17. None
@lcalcote
container receives a network stack, but
lacks an external network interface.
it does, however, receive a loopback
interface.

18. Links
facilitate single host connectivity
"discovery" via /etc/hosts or env vars
@lcalcote
Ambassadors
facilitate multi-host connectivity
uses a tcp port forwarder (socat)
Web Host
MySQL
Ambassador
PHP
DB Host
PHP
Ambassador
MySQL
link link

19. Container-Mapped
one container reuses (maps to) the networking
namespace of another container.
@lcalcote
may only be invoked when running a docker
container (cannot be defined in Dockerfile):
--net=container=some_container_name_or_id

20. Bridge
Ah, yes, docker0
default networking for Docker
uses a host-internal network
leverages iptables for network address translation
(NAT) and port-mapping
@lcalcote

21. Host
container created shares its network namespace with the host
default Mesos networking mode
better performance
easy to understand and troubleshoot
suffers port conflicts
secure?
@lcalcote

22. 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

23. K/V Store for Overlay
Networking
Docker - requires K/V store (built-in as experimental as of
1.12)
WeaveMesh - does not require K/V store
WeaveNet - limited to single network; requires 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
@lcalcote

24. Underlays
expose host interfaces (i.e. the physical network interface at
eth0) directly to containers running on the host
MACvlan
IPvlan
Direct Routing
@lcalcote
not necessarily public cloud friendly

25. 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
@lcalcote
Internet

26. MACvlan
allows creation of multiple virtual network interfaces behind
the host’s single physical interface
Each virtual interface has unique MAC and IP addresses
assigned
with restriction: the 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

27. IPvlan
allows creation of multiple virtual network interfaces behind the host’s single
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

28. 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

29. 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

30. 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

31. Fan Networking
@lcalcote

32. 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 networking that fits your needs.
@lcalcote

33. 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

34. Text
@lcalcote
Docker 1.12 (Load-balancing)

35. Lee Calcote
clouds, containers, infrastructure, applications
and their management
linkedin.com/in/leecalcote
@lcalcote
blog.gingergeek.com
lee@calcotestudios.com
Thank you!
Questions?