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ETHERCHANNEL

1.Etherchannel (NIB):
Network Interface Backup (NIB) can be used to achieve network redundancy. Two adapters are used to create an Etherchannel that consists of one primary adapter and one backup adapter. The interface is defined on the Etherchannel. If the primary adapter becomes unavailable, the Network Interface Backup switches to the backup adapter.

2. Link Aggregationl
Link Aggregationl is a network port aggregation technology that allows several Ethernet adapters to be aggregated together to form a single pseudo Ethernet adapter. (There are for example 2 primary adapters).

The main benefit of a Link Aggregationl is that it has the network bandwidth of all of its adapters. If an adapter fails, the packets are automatically sent on the next available adapter without disruption to existing user connections. A link or adapter failure will lead to a performance degradation, but not a disruption.

There are some differences between Etherchannel and IEEE 802.3ad Link Aggregationl. Consider the differences given in to determine which would be best for your situation.

Table 1. Differences between Etherchannel and IEEE 802.3ad Link Aggregationl.

Etherchannel IEEE 802.3ad
Requires switch configuration. Little, if any, configuration of switch required to form aggregation. Some initial setup of the switch may be required.
Supports different packet distribution modes. Supports only standard distribution mode.

The main benefit of a Link Aggregationl is that it has the network bandwidth of all of its adapters. If an adapter fails, the packets are automatically sent on the next available adapter without disruption to existing user connections. A link or adapter failure will lead to a performance degradation, but not a disruption.

#entstat -d <Etherchannel device> | head
Link Aggregationl between dedicated HEA port and PCI/PCI-E adapter is supported. This is supported for both manual aggregation and LACP aggregation..

Recommendations before configuring Etherchannel

  • You can have up to eight primary Ethernet adapters and only one backup Ethernet adapter per Etherchannel.
  • You can configure multiple Etherchannels on a single system, but each Etherchannel constitutes an additional Ethernet interface
  • All adapters in the Etherchannel should be configured for the same speed (100 Mbps, for example) and should be full duplex.
  • The adapters used in the Etherchannel cannot be accessed by the system after the Etherchannel is configured. To modify any of their attributes, such as media speed, transmit or receive queue sizes, and so forth, you must do so before including them in the Etherchannel.
  • The adapters that you plan to use for your Etherchannel must not have an IP address configured on them before you start this procedure

#entstat -d <Etherchannel device> | head

Etherchannel for Network Interface Backup (primary – standby):
ETHERNET STATISTICS (ent6) :
Device Type: Etherchannel
Hardware Address: 00:11:25:a5:9b:2a
Elapsed Time: 0 days 12 hours 10 minutes 35 seconds

Etherchannel for Link Aggregationl (primary – primary):
ETHERNET STATISTICS (ent4) :
Device Type: IEEE 802.3ad Link Aggregationl
Hardware Address: 00:11:25:c5:bf:1d
Elapsed Time: 45 days 2 hours 37 minutes 55 seconds
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man ethchan_config            manual for configuring Etherchannel with commands
smitty Etherchannel           smitty menu for configuring Etherchannel
lsattr -El entX               it will show the adapters belongin to the Etherchannel (and other useful settings
entstat -d entX | grep Act    shows which adapter (Primary or Backup) is the active in the Etherchannel (enX)

Creating an Etherchannel:

1. before creating make sure no ip on either adapter 
(easiest way: first remove enX/etX/entX before starting to configure, then cfgmgr)

2. when you have clean adapters: smitty Etherchannel
- choose the adapters which you want as primary adapter
- add additional adapter if needed a backup adapter
- set mode and hash mode if needed (for Link Aggreagtion once I needed  8023ad and src_dst_port)

Adding adapter to Etherchannel:
(make sure no ip is configured, if needed put to detach state)
smitty Etherchannel -> Add Main/Backup Adapter
/usr/lib/methods/ethchan_config -a -b <Etherchannel physical device> <physical device>         <–adding as backup adapter
/usr/lib/methods/ethchan_config -a <Etherchannel physical device> <physical device>            <–adding as primary adapter
/usr/lib/methods/ethchan_config -a ent4 ent0
(For me once, only command line worked, when smitty has been used for removing, it always said: resource is busy…)

1. check active channel:
entstat -d ent2| grep Active                    <–Active channel: primary channel

2. unplug cable from primary channel or testing it with command:
/usr/lib/methods/ethchan_config -f ent2         <–it will do a failover

3. checking:
entstat -d ent2 | grep Active                   <–Active channel: backup adapter
errpt | head                                    <–ETHERCHANNEL FAILOVER

4. switch back:
/usr/lib/methods/ethchan_config -f ent2         <–it will do a switch again

5. checking:
entstat -d ent2 | grep Active                   <–Active channel: primary channel
errpt | head                                    <–ETHERCHANNEL RECOVERY