Design Reference

Table Of Contents
untagged and tagged IEEE 802.1Q VLAN link configurations. You determine to which VLANs
a switch sends SLPP test packets to. 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:
VSP 4000 SLPP design is different from that of ERS 8800 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 goes down.
The originating CP receives the SLPP-PDU. All other switches regard 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 5 SLPP-PDU 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 11: 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
44 Network Design Reference for Avaya VSP 4000 February 2014
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