Shared Ethernet Adapter:(SEA)

Shared Ethernet Adapter:

The Virtual I/O Server allows shared access to external networks through the Shared Ethernet Adapter (SEA). TheShared Ethernet Adapter supports the following features:
Link Aggregation:Bundling of several physical network adapters into one logical device using EtherChannel functionality.

SEA failover: The SEA failover feature allows highly available configurations by using two Shared Ethernet Adapters running in two different Virtual I/O Servers.

TCP segmentation offload: The SEA supports the large send and large receive features.

GVRP:GVRP (GARP VLAN Registration Protocol) is a protocol that facilitates control of VLANs within larger networks. It helps to maintain VLAN configurations dynamically based on network adapter configurations.

A Shared Ethernet Adapter is a Virtual I/O Server component that bridges a physical Ethernet adapter and one or more virtual Ethernet adapters:

1. The real adapter can be a physical Ethernet adapter, a Link Aggregation or EtherChannel device, or a Logical Host Ethernet Adapter . The real adapter cannot be another Shared Ethernet Adapter or a VLAN pseudo-device.
2. The virtual Ethernet adapter must be a virtual I/O Ethernet adapter. It cannot be any other type of device or adapter.

It is a layer-2 network bridge to securely transport network traffic between virtual Ethernet networks and physical network adapters. The Shared Ethernet Adapter service runs in the Virtual I/O Server. It cannot be run in a general purpose AIX or Linux partition.

There are some things to consider on the use of SEA:

1. [1]Virtual Ethernet requires the POWER Hypervisor and PowerVM feature (Standard or Enterprise Edition) and the installation of a Virtual I/O Server.
2. [1] Virtual Ethernet cannot be used prior to AIX 5L Version 5.3. Thus, an AIX 5L Version 5.2 partition will need a physical Ethernet adapter.

In order to bridge network traffic between the virtual Ethernet and external networks, the Virtual I/O Server has to be configured with at least one physical Ethernet adapter. One SEA can be shared by multiple virtual Ethernet adapters and each can support multiple VLANs.configuration example of an SEA with one physical and two virtual Ethernet adapters. An SEA can include up to 16 virtual Ethernet adapters on the Virtual I/O Server that share the physical access.

Note: A Shared Ethernet Adapter does not need to have IP configured to be able to perform the Ethernet bridging functionality.It is very convenient to configure IP on the Virtual I/O Server. This is because the Virtual I/O Server can then be reached by TCP/IP, for example, to perform dynamic LPAR operations or to enable remote login. This can be done by configuring an IPaddress directly on the SEA device, but it can also be defined on an additional virtual Ethernet adapter in the Virtual I/O Server carrying the IP address.This leaves the SEA without the IP address, allowing for maintenance on the SEA without losing IP connectivity if SEA failover has been configured. Neither has a remarkable impact on Ethernet performance.

To configure a Shared Ethernet Adapter using versions prior to the HMC, version 7 release 3.4.2, complete the following steps from the Virtual I/O Server command-line interface:

1. Verify that the virtual Ethernet trunk adapter is available by running the following command: #lsdev -virtual
2. Identify the appropriate physical Ethernet adapter that will be used to create the Shared Ethernet Adapter by running the following command:#lsdev -type adapter

Notes:

1. Ensure that TCP/IP is not configured on the interface for the physical Ethernet adapter. If TCP/IP is configured, the mkvdev command in the next step fails.
2. You can also use a Link Aggregation, or EtherChannel, device as the Shared Ethernet Adapter.
3. If you plan to use the Host Ethernet Adapter or Integrated Virtual Ethernet with the Shared Ethernet Adapter, ensure that you use the Logical Host Ethernet Adapter to create the Shared Ethernet Adapter.

Configure the Shared Ethernet Adapter by running the following command:

#mkvdev -SEA physical_ethernet_adapters  -vadapter virtual_ethernet_adapters -defaultDefaultVirtualEthernetAdapter    -defaultid SEADefaultPVID
Where:
physical_ethernet_adapters: The physical adapter being used as part of the Shared Ethernet Adapter device.

virtual_ethernet_adapters: The virtual Ethernet adapter or adapters that will use the Shared Ethernet Adapter.
DefaultVirtualEthernetAdapter: The default virtual Ethernet adapter used to handle untagged packets. If you have only one virtual Ethernet adapter for this logical partition, use it as the default.

SEADefaultPVID: The PVID associated with your default virtual Ethernet adapter.

Shared Ethernet Adapter Failover :

Shared Ethernet Adapter (SEA) Failover is implemented on the Virtual I/O Server using a bridging (layer-2) approach to access external networks. SEA failover supports IEEE 802.1Q VLAN-tagging, unlike Network Interface Backup.

With SEA failover, two Virtual I/O Servers have the bridging function of the Shared Ethernet Adapter to automatically fail over if one Virtual I/O Server is unavailable or the Shared Ethernet Adapter is unable to access the external network through its physical Ethernet adapter. A manual failover can also be triggered.

Both Virtual I/O Servers attach to the same virtual and physical Ethernet networks and VLANs, and both virtual Ethernet adapters of both Shared Ethernet Adapters have the access external network flag enabled. An additional virtual Ethernet connection must be set up as a separate VLAN between the two Virtual I/O Servers and must be attached to the Shared Ethernet Adapter (SEA) as a control channel. This VLAN serves as a channel for the exchange of keep-alive or heartbeat messages between the two Virtual I/O Servers that controls the failover of the bridging functionality. No network interfaces have to be attached to the control channel Ethernet adapters. The control channel adapter should be dedicated and on a dedicated VLAN that is not used for any other purpose.

In addition, the Shared Ethernet Adapter in each Virtual I/O Server must be configured with different priority values. The priority value defines which of the two Shared Ethernet Adapters will be the primary (active) and which will be the backup (standby). The lower the priority value, the higher the priority (for example, priority=1 is the highest priority). You can also configure the Shared Ethernet Adapter with an IP address that it will periodically ping to confirm that network connectivity is available. This is similar to the IP address to ping that can be configured with Network Interface Backup (NIB). If you use NIB, you have to configure the reachability ping on every client compared to doing it once on the SEA.
Configure the Shared Ethernet Adapter Failover:

#mkvdev -SEA  physical_ethernet_adapter  -vadapter virtual_ethernet_adapters   -default  DefaultVirtualEthernetAdapter  

-defaultid  SEADefaultPVID   -attr  ha_mode=auto  ctl_chan= control_channel_adapter

Shared Ethernet Adapter Failover With Load sharing:

The Shared Ethernet Adapter failover configuration provides redundancy only by configuring a backup Shared Ethernet Adapter on a different Virtual I/O Server (VIOS) logical partition. This backup Shared Ethernet Adapter is in the standby mode and can be used only if the primary Shared Ethernet Adapterfails. Hence, the bandwidth of the backup Shared Ethernet Adapter is not used.

On the VIOS Version 2.2.1.0, or later, you can use the Shared Ethernet Adapter failover with load sharingconfiguration to use the bandwidth of the backup Shared Ethernet Adapter without any impact to reliability.

In the Shared Ethernet Adapter failover with load sharing configuration, the primary and the backup Shared Ethernet Adapters negotiate the set of virtual local area network (VLAN) IDs that they are responsible for bridging. After successful negotiation, each Shared Ethernet Adapter bridges the assigned trunk adapters and the associated VLANs. Thus, both the primary and the backup Shared Ethernet Adapter bridge the workload for their respective VLANs. If a failure occurs, the active Shared Ethernet Adapter bridges all trunk adapters and the associated VLANs. This action helps to avoid disruption in network services.

To configure Shared Ethernet Adapter failover with load sharing, you must have two or more trunk adapters with identical VLAN definitions assigned to each Shared Ethernet Adapter.

If you already have a suitable SEA running you can change its mode with (assuming you SEA device is ent10) – this can be dynamically changed:

Note:

1. Load sharing must be enabled first on the Primary SEA first – the Secondary SEA initiates the load sharing for you want the primary to be ready.
2. Obviously, both SEA‘s need to be in Load sharing mode.
3. The VLAN id’s of the Trunk adapters must match – If VIOS a has trunk adapter 1 with VLAN id’s say 10 and 20 and a second trunk adapter with VLAN id’s 40 and 50 then the other VIOS needs to have the same combination. This needs careful planned.
4. To disable Load sharing shave the ha_mode to auto.The other options are standby or disabled.Find the current state of the SEA and which is primary but getting to root on the VIOS (oem_setup_env) then
5. entstat -d ent10 | grep -i state
6. The entstat command on the VIOS SEA has other good information like the VLAN id’s.
7. If you have a VIOS failure or take a SEA down then once back up, you can restart the Load sharing with the chdev command

#chdev -dev ent10  -attr ha_mode=sharing

• If you already have a suitable SEA running you can change its mode with (assuming you SEA device is ent10) – this can be dynamically changed with chdev command.

Configure the Shared Ethernet Adapter Failover With Load sharing:

#mkvdev -SEAphysical_ethernet_adapter -vadapter virtual_ethernet_adapter1, virtual_ethernet_adapter2 -default DefaultVirtualEthernetAdapter1 defaultid  SEADefaultPVID   -attr ha_mode=sharing ctl_chan = control_channel_adapter