ifgrp destroy ifgrp_name
ifgrp delete ifgrp_name interface_name
ifgrp add ifgrp_name interface_list
ifgrp { favor | nofavor } interface
ifgrp status [ ifgrp_name ]
ifgrp stat ifgrp_name [ interval ]
In the ifgrp commands, ifgrp_name stands for the name of an interface group. The name must be a string that is no longer than 15 characters and meets the following criteria:
Once created, an interface group is indistinguishable from a physical network interface. You can inspect and modify statistical and configuration information using the ifconfig and netstat commands, among others.
You can create an interface group in one of three modes: multi, single or LACP.
Multi-mode interface groups are partly compliant with IEEE 802.3ad. Multi-mode interface groups support static configuration but not dynamic aggregate creation. In a multi-mode interface group, all links are simultaneously active. This mode is only useful if all the links are connected to a switch that supports trunking/aggregation over multiple port connections. The switch must be configured to understand that all the port connections share a common media access control (MAC) address and are part of a single logical interface.
Dynamic multi-mode (LACP) interface groups are completely compliant with IEEE 802.3ad. LACP protocol is used determine which of the underlying links can be aggregated. LACP protocol is also used to monitor the link status. If the configuration on both ends of the links is correct, then all the interfaces of an interface group are active.
While the switch is responsible for determining how to forward incoming packets to the node, the node supports load balancing on the network traffic transmitted over a multi-mode/LACP interface group. The user can choose from any of the following four methods:
In single-mode interface groups, only one of the links is active at a time. No configuration is necessary on the switch. If Data ONTAP detects a fault in the active link, a standby link of the interface group, if available, is activated. Note that load balancing is not supported on single-mode interface groups.
Network interfaces belonging to an interface group do not have to be on the same network card. With the ifgrp command, you can also create second-level single or multimode interface groups. For example, a subnetwork has two switches that are capable of trunking over multiple port connections. The storage system has a two-link multi-mode interface group to one switch and a two-link multi-mode interface group to the second switch. You can create a second-level single-mode interface group that contains both of the multi-mode interface groups. When you configure the second-level interface group using the ifconfig command, only one of the two multi-mode interface group is brought up as the active link. If all the underlying interfaces in the active interface group fail, the secondlevel interface group activates its standby interface group. Please note that multi-level LACP interface groups are not permitted.
You can destroy an interface group only if you have configured it down using the ifconfig command.
If all the links in an interface group are broken, the ifgrp driver issues a system log message similar to this:
Fri Oct 16 15:09:29 PDT [toaster: pifgrp_monitor]: ifgrp0: all links are down
If all links on an interface group are broken and a link subsequently comes back up, the ifgrp driver issues a system log message similar to this:
Fri Oct 16 15:09:42 PDT [toaster: pifgrp_monitor]: ifgrp0: switching to e3a
In the case of LACP interface groups, LACP frames are exchanged periodically. Failure to receive LACP frames within a specified time period is construed as a link failure and the corresponding link is marked down.
In the case of single-mode interface groups, broadcast frames are sent out from each interface periodically. Failure to receive these periodic frames provides a hint on the link status.
ifgrp create multi ifgrp0 -b ip e3a e3b
The status option prints out results in the following form. Here is an example of the output for ifgrp0:
ifgrp status
default: transmit 'IP Load balancing', IFGRP Type 'multi_mode', fail 'log'
ifgrp0: 2 links, transmit 'none', IFGRP Type 'multi-mode' fail 'default'
IFGRP Status Up Addr_set
up:
e10: state up, since 05Oct2001 17:17:15 (05:23:05)
mediatype: auto-1000t-fd-up
flags: enabled
input packets 2000, input bytes 12800
output packets 173, output bytes 1345
up indications 1, broken indications 0
drops (if) 0, drops (link) 0
indication: up at boot
consecutive 3, transitions 1
broken:
e5: state broken, since 05Oct2001 17:18:03 (00:10:03)
mediatype: auto-1000t-fd-down
flags: enabled
input packets 134, input bytes 987
output packets 20, output bytes 156
up indications 1, broken indications 1
drops (if) 0, drops (link) 0
indication: broken
consecutive 4, transitions 1
In this example, one of the ifgrp0 links are is in the active (up) state. The second interface e5 is broken on detection of a link failure. ifgrp0 is configured to transmit over multiple links and its failure behavior is the default (send errors to the system log). Links are in one of three states:
Links constantly issue either up or broken indications based on their interaction with the switch. The consecutive count indicates the number of consecutively received indications with the same value (in this example, up). The transitions count indicates how many times the indication has gone from up to down or from down to up.
If ifgrp0 is a link in a second-layer interface group (for example, ifgrp create ifgrp2 ifgrp0), an additional line is added to its status information:
trunked: ifgrp2
ifgrp stat ifgrp0
Interface group (trunk) ifgrp0
e10 e5
In Out In Out
8637076 47801540 158 159
1617 9588 0 0
1009 5928 0 0
1269 7506 0 0
1293 7632 0 0
920 5388 0 0
1098 6462 0 0
2212 13176 0 0
1315 7776 0 0
1. The local node must specify, using the partner option of the ifconfig command, the mapping of the partner's interface group. For example, to map the partner's ifgrp2 interface to the local ifgrp1 interface, the following command is required:
ifconfig ifgrp1 partner ifgrp2
Note that the interface must be named, not the address. The mapping must be at the top-level trunk, if trunks are nested. You do not map link-by-link.
2. After takeover, the partner must "create" its interface group. Typically, this takes place in the /etc/rc file. For example:
ifgrp create ifgrp2 e3a e3b
When executed in takeover mode, the local node does not actually create an interface group. Instead, it looks up the mapping (in this example partner ifgrp2 to local ifgrp1) and initializes its internal data structures. The interface list (in this example, e3a and e3b) is ignored because the local node can have different mappings of devices for its ifgrp1 trunk.
3. After the partner interface group has been initialized, it must be configured. For example:
ifconfig ifgrp2 `hostname`-ifgrp2
Only the create, stat, and status options are enabled in partner mode. The create option does not create new interface group in partner mode. Instead, it initializes internal data structures to point at the mapped local ifgrp interface. The status and stat options reference the mapped interface group. However, all links are printed using the local device names.
When using multi-mode interface groups with HA pairs, connecting
the interface groups into a single switch constitutes
a single point of failure. By adding a second
switch and setting up two multi-mode interface groups on
each node in the HA pair so that the multi-mode interface
groups on each node are connected to separate switches the
interface groups will continue to operate in the face of
single switch failure. The following /etc/rc file
sequence illustrates this approach:
# configuration for node 1 # first level multi interface group: # attach e4a and e4b to Switch 1 ifgrp create multi ifgrp0 e4a e4b # first level multi interface group: # attach e4c and e4d to Switch 2 ifgrp create multi ifgrp1 e4c e4d # second level single interface group consisting of both # first level interface groups; only one active at a time ifgrp create single ifgrp10 ifgrp0 ifgrp1 # use ifgrp0 unless it is unavailable ifgrp favor ifgrp0 # configure the interface group with an interface and partner ifconfig ifgrp10 `hostname-ifgrp10` partner ifgrp10
The partner node is configured similarly; the favored first level interface in this case is the interface group connected to "Switch 2".
