Enables the ELSM protocol for the specified ports.
| port_list | Specifies the port or ports for which ELSM should be enabled. |
The default is disabled.
The ELSM protocol allows you to detect CPU and remote link failures in the network. ELSM operates on a point-to-point basis; you only configure ELSM on the ports that connect to other devices within the network, but you must configure ELSM on both sides of the peer connections.
The Layer 2 connection between the ports determines the peer. You can have a direct connection between the peers or hubs that separate peer ports. In the first instance, the peers are also considered neighbors. In the second instance, the peer is not considered a neighbor.
An Extreme Networks device with ELSM enabled detects CPU and remote link failures by exchanging hello messages between two ELSM peers. If ELSM detects a failure, the ELSM-enabled port responds by blocking traffic on that port. For example, if a peer stops receiving messages from its peer, ELSM brings down that connection by blocking all incoming and outgoing data traffic on the port and notifying applications that the link is down.
When you enable ELSM on a port, ELSM immediately blocks the port and it enters the Down state. When the port detects an ELSM-enabled peer, the peer ports exchange ELSM hello messages. At this point, the ports enter the transitional Down-Wait state. If the port receives Hello+ messages from its peer and does not detect a problem, the peers enter the Up state. If a peer detects a problem or there is no peer port configured, the port enters the Down state.
For more information about the types of ELSM hello messages, see the configure elsm ports hellotime command.
Note
ELSM and mirroring are mutually exclusive. You can enable either ELSM, or mirroring, but not both.
If you try to enable ELSM on a port that is already configured as a mirrored port, the switch displays a message similar to the following:Cannot enable ELSM on port 1. Port is configured as mirror monitor port
ELSM ports use hello messages to communicate information about the health of the network to its peer port. You can also configure the interval by which the ELSM-enabled ports sends hello messages. For more information about configuring the hello interval, see the command configure elsm ports hellotime.
ELSM works between two connected ports, and each ELSM instance is based on a single port. When you disable ELSM on the specified ports, the ports no longer send ELSM hello messages to their peers and no longer maintain ELSM states. To disable ELSM, use the following command:
disable elsm ports port_listThe following command enables ELSM for ports 1-2 on the switch:
enable elsm ports 1-2
This command was first available in ExtremeXOS 11.4.
This command is available on ExtremeSwitching 5320, 5420, 5520, and 5720 series switches.