Avaya 8800 Planning And Engineering, Network Design page 104

Layer 2 loop prevention
Figure 34: Tagged SMLT links
The configuration is changed to:
• SLPP-Tx is enabled on SMLT VLANs 10, 20, and 30. A loop in any of these VLANs triggers an
event and resolves the loop.
• On switches A and B, SLPP-Rx is enabled on tagged SMLT access links.
• On switch A, the SLPP Rx threshold is set to 5.
• On SMLT switch B, the SLPP Rx threshold is set to 50 to avoid edge isolation in case of a
network failure.
In this scenario, Avaya recommends that you enable the untagged-frames-discard parameter on the
SMLT uplink ports.
SLPP configuration considerations and recommendations
SLPP uses a per-VLAN hello packet mechanism to detect network loops. Sending hello packets on
a per-VLAN basis allows SLPP to detect VLAN-based network loops for untagged and tagged IEEE
802.1Q VLAN link configurations. The network administrator decides which VLANs to which a switch
should send SLPP hello packets. The packets are replicated out of all ports that are members of the
SLPP-enabled VLAN.
Use the information in this section to understand the considerations and recommendations when
configuring SLPP in an SMLT network.
• You must enable SLPP packet receive on each port to detect a loop.
• Vary the SLPP packet receive threshold between the two core SMLT switches so that if a loop
is detected, the access ports on both switches do not go down, and SMLT client isolation is
avoided.
• SLPP test packets (SLPP-PDU) are forwarded for each VLAN.
• SLPP-PDUs are automatically forwarded VLAN ports configured for SLPP.
June 2016 Planning and Engineering — Network Design
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