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New and Changed Features

The features listed in this section are new or changed as of Contrail Release 2.20. A brief description of each new feature is included.

Discovery Clients Honor Discovery Server Response

Once the load-balancer is triggered, the discovery server responds with a new set of servers in response to the subscriber. Clients must honor the new set of services, irrespective of the current connection being up or down.

The following are rules to honoring the new set of published services:

  • For active-active connections, if both services are disrupted, the client applies only one service at a time.
  • If the discovery server responds with a smaller subset of services, the stale services are not cleaned up.
  • If the discovery server responds with a NULL list, the clients continue to function with the older list.
  • Clients now support resubscribing if the connections are detected as being DOWN. For faster convergence, the client waits at least 3 intervals (heart-beat time (=15secs)) to trigger a resubscribe request .

The introspect command is provided to view the discovery list and the current active connections.

Note: Discovery servers ensure only one set of services are changed at any given time, but the client also needs to ensure it handles the new set gracefully.

Note: The above feature applies to subscribers that maintain active-active connections.

Discovery Client Library Provides Publish Reevaluation

The discovery publish reevaluation enhancement provides the following:

  • The client library provides the ability to publish a service with the oper-state up or down.
  • The application must register a callback so the service can be reevaluated and the oper-state can be updated accordingly.
  • Reevaluation of a published service is triggered every heartbeat interval.
  • The discovery server must honor the operational state of published services and provide a new set of services in response to the next subscribe request.

Two new states are introduced, the admin-state and the oper-state which are displayed in the discovery-server:5998 URL.

Clients can change the oper-state based on the internal state of services which enables the discovery server to deallocate or reallocate resources.

The admin-state can only be changes using the python CLI to pull services permanently DOWN.

Layer 3 Only Forwarding Mode

Contrail Release 2.21 and later supports the integrated routing and bridging (IRB) model in which the traffic flowing within the same subnet is bridged while the traffic across subnets and virtual networks is routed.This mode is referred to as Layer 2 plus Layer 3 (Layer2 + Layer3) and it is the default mode in which a cluster operates and a virtual network is created. In Layer 2 plus Layer 3 mode, ARP requests are flooded. The Contrail solution minimizes ARP flooding by having the vRouter proxy for ARP where possible.

In some cases it might not be desirable to have this type of flooding. It might also be desirable to run the cluster or virtual network in the same mode used in previous releases. To support this, Contrail Release 2.21 also supports a Layer 3 only mode and a Layer 2 only mode.

When Layer 3-only mode is used:

  • The IP routes learned from an IP VPN are used to route the traffic irrespective of whether the hosts are in the same subnet.
  • Traffic coming from the fabric that uses MPLS over GRE (MPLSoGRE) or MPLS over UDP (MPLSoUDP) encapsulation, is routed at Layer 3.
  • An EVPN IP address to MAC address binding is not used. Instead, any packet with a destination MAC address that is not the VRRP MAC address and is not an IP routable packet, is bridged.

The forwarding mode can be configured at the global level to set the default or it can be set at the virtual network level to override the default setting and set the mode for a specified virtual network. To configure the global forwarding mode in the Contrail Controller, select Configure -> Global Config -> Forwarding Mode. To configure the forwarding mode of a virtual network in the Contrail Controller, select Configure -> Networking -> Create >Network -> Advanced Options -> Forwarding Mode.

Improved ISSU Support in QFX Series TOR Switches

A Contrail TOR Agent retains the MAC addresses learned from a TOR switch for five minutes after the OVSDB protocol connection between the TOR switch and TOR Agent goes down. This avoids churn in route distribution for short connection drops and helps in supporting ISSU on a QFX Series switch. For more information about the improved ISSU support, see the Release Notes: Junos® OS Release 14.1X53-D30 for QFX Switches.

Supported Platforms

Contrail Release 2.21, is supported on the OpenStack Juno and Icehouse releases. Juno is supported on Ubuntu 14.04.2 and Centos 7.1.

Contrail networking is supported on Red Hat RHOSP 5.0, which is supported only on OpenStack Icehouse

In Contrail Release 2.21, support for VMware vCenter 5.5. vCenter is limited to Ubuntu 14.04.2 (Linux kernel version: 3.13.0-40-generic).

Other supported platforms include:

  • CentOS 6.5 (Linux kernel version: 2.6.32-358.el6.x86_64)
  • CentOS 7.1 (Linux kernel version: 3.10.0-229.el7)
  • Redhat 7/RHOSP 5.0 (Linux kernel version: 3.10.0-299.el7.x86_64)
  • Ubuntu 12.04.04 (Linux kernel version: 3.13.0-34-generic)
  • Ubuntu 14.04. (Linux kernel version: 3.13.0-40-generic)

Modified: 2015-10-13