Extreme Networks ExtremeWare Command Reference Manual page 1044

ESRP Commands
• For a VLAN to be recognized as participating in ESRP, the assigned IP address or the IPX NETid for
the separate switches must be identical. Other aspects of the VLAN, including its name, are ignored.
• ESRP must be enabled on the desired VLANs for each switch. ESRP cannot be enabled on the VLAN
"default."
• Extreme Discovery Protocol (EDP) must be enabled on the ports that are members of the ESRP
VLANs. (The default setting is enabled.)
ESRP can also be enabled on super-VLANs. The super-VLAN must be configured with all the ports as
the sub-VLANs.
It is highly recommended that all switches participating in ESRP run the same version of ExtremeWare.
Not all ESRP features are available in all ExtremeWare software releases.
Extreme Loop Recovery Protocol (ELRP) is a feature of ExtremeWare that allows you to prevent, detect,
and recover from layer 2 loops in the network. You can use ELRP with other protocols such as ESRP.
With ELRP, each switch, except for the sender, treats the ELRP PDU as a layer 2 multicast packet. The
sender uses the source and destination MAC addresses to identify the packet it sends and receives.
When the sender receives its original packet back, that triggers loop detection and prevention. Once a
loop is detected, the loop recovery agent is notified of the event and takes the necessary actions to
recover from the loop. ELRP operates only on the sending switch; therefore, ELRP operates
transparently across the network.
NOTE
Because ELRP introduces the pre-master state to ESRP, you must upgrade all ESRP-enabled switches
within an ESRP domain to ExtremeWare 6.2.2b134 (or later) for ESRP to operate correctly. Earlier
ExtremeWare releases do not recognize the pre-master state.
Extreme Link Status Monitoring (ELSM)
The Extreme Link Status Monitoring (ELSM) protocol allows you to detect remote CPU failures in the
network. A software or hardware fault might prevent the CPU from transmitting or receiving, leading
to the sudden failure of the CPU. If the CPU cannot process or send packets, ELSM isolates the
connections to the faulty switch from the rest of the network. If the switch fabric continues to send
packets during a CPU failure, the switch may appear to be healthy when it is not.
An Extreme Networks device with ELSM enabled can detect remote CPU failures by exchanging hello
packets between two ELSM peers. When ELSM detects a CPU failure as a result of not hearing from its
neighbor, it brings down the connection to the neighbor. 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.
1044 ExtremeWare Software 7.3.0 Command Reference Guide