Design Reference

SLPP configuration considerations and recommendations
SLPP uses an individual VLAN hello packet mechanism to detect network loops. Sending hello
packets on an individual VLAN basis allows SLPP to detect VLAN-based network loops for
untagged and tagged IEEE 802.1Q VLAN link configurations. You determine to which VLANs a
switch sends SLPP test packets. All port members of the SLPP-enabled VLAN replicate the
packets.
Use the information in this section to understand the considerations and recommendations to
configure SLPP in your network:
• You must enable SLPP packet receive on each port to detect a loop.
• SLPP test packets (SLPP-PDU) are forwarded for each VLAN.
• SLPP-PDUs are automatically forwarded on VLAN ports configured for SLPP.
• The SLPP-PDU destination MAC address is the switch MAC address, with the multicast bit set;
the source MAC address is the switch MAC address.
Note:
Avaya Virtual Services Platform 4000 Series SLPP design is different from that of Avaya
Ethernet Routing Switch 8800/8600 SLPP. On the ERS 8800, the source MAC address is
the switch VLAN MAC address.
• The SLPP-PDU is sent out as a multicast packet and is constrained to the VLAN on which it is
sent.
• If an MLT port receives an SLPP-PDU, the port is removed from service.
• The originating CP receives the SLPP-PDU. All other switches treat the SLPP-PDU as a
normal multicast packet, and forward it to the VLAN.
• SLPP is port-based; therefore, a port is disabled if it receives SLPP-PDU on one or more
VLANs on a tagged port. For example, if the SLPP packet receive threshold is 5, a port is shut
down if it receives five SLPP-PDUs from one or more VLANs on a tagged port.
• The switch does not act on SLPP packets other than on the SLPP packets that it transmits.
• For square and full-mesh configurations that use a routed core, create a separate core VLAN.
Enable SLPP on the core VLAN and the square or full-mesh links between switch clusters. This
configuration detects loops created in the core, and loops at the edge do not affect core ports.
• You can tune network failure behavior by selecting the number of SLPP packets that must be
received before a switch takes action.
Avaya recommends the values in the following table.
Table 17: SLPP recommended values
Parameter
Configuration
Primary switch
Packet Rx threshold 5
Transmission interval 500 milliseconds (ms) (default)
Secondary switch
Packet Rx threshold 50
Layer 2 loop prevention
46 Network Design Reference for Avaya VSP 4000 Series December 2014
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