User manual

46 Publication 1783-UM003D-EN-E - December 2009
Chapter 2
• You must configure each segment port; an incorrect configuration can
cause forwarding loops in the networks.
• REP can manage only a single failed port within the segment; multiple
port failures within the REP segment cause loss of network connectivity.
You should configure REP only in networks with redundancy. Configuring
REP in a network without redundancy causes loss of connectivity.
Link Integrity
REP does not use an end-to-end polling mechanism between edge ports to
verify link integrity. It implements local link failure detection. The REP Link
Status Layer (LSL) detects its REP-aware neighbor and establishes
connectivity within the segment. All VLANs are blocked on an interface until
it detects the neighbor. After the neighbor is identified, REP determines which
neighbor port should become the alternate port and which ports should
forward traffic.
Each port in a segment has a unique port ID. The port ID format is similar to
that used by the spanning tree algorithm: a port number (unique on the
bridge), associated to a MAC address (unique in the network). When a segment
port is coming up, its LSL starts sending packets that include the segment ID
and the port ID. The port is declared as operational after it performs a
three-way handshake with a neighbor in the same segment.
SNMP
The switch supports Simple Network Management Protocol (SNMP) versions
1, 2C, and 3. SNMP allows the switch to be remotely managed through other
network management software. This feature is disabled by default.
SNMP is based on three concepts:
• SNMP managers (client software)
• SNMP agents (network devices)
• Management Information Base (MIB)
Refer to Supported MIBs on page 48
for the MIBs supported on the
switch.
The SNMP manager runs SNMP management software. Network devices to
be managed, such as bridges, routers, servers, and workstations, have an agent
software module. The agent provides access to a local MIB of objects that
reflects the resources and activity of the device. The agent also responds to
manager commands to retrieve values from the MIB and to set values in the
MIB. The agent and the MIB are on the switch. To configure SNMP on the
switch, you define the relationship between the manager and the agent.