Smlt And Slpp - Avaya 8600 Configuration Manual

The BackupMaster feature provides an additional benefit. VRRP normally sends a hello packet
every second. When three hello packets are not received, all switches automatically revert to
master mode. This results in a 3- second outage. When you use VRRP in an SMLT
environment, and a link goes down, traffic is automatically forwarded to the remaining ports
configured for SMLT VRRP BackupMaster. Because both switches are processing traffic, the
node immediately recognizes the VRRP state change, so there is faster failure recovery (less
than 1 second).
Follow these guidelines when you use VRRP BackupMaster with SMLT:
• The VRRP virtual IP address and the VLAN IP address cannot be the same.
• Configure the hold-down timer for VRRP to a value that is approximately 150 percent of
the Interior Gateway Protocol (IGP) convergence time to allow the IGP enough time to
reconverge following a failure. For example, if OSPF takes 40 seconds to reconverge,
configure the hold-down timer to 60 seconds.
• Stagger the hold-down timers with ARP requests. So the Avaya Ethernet Routing Switch
8800/8600 does not run ARP and SMLT at the same time causing excess CPU load. For
example, if one node has the hold-down timer configured for 60 seconds, you can
configure the other hold-down timer to 65 seconds.
• Enable hold-down times on both VRRP sides (Master and BackupMaster).

SMLT and SLPP

Simple Loop Prevention Protocol (SLPP) is used to prevent loops in a SMLT network. SLPP
is focused on SMLT networks but works with other configurations. Avaya recommends that
you always use SLPP in any SMLT environment.
Note:
When using SPBM, SLPP is not required on the B-VLAN and is not supported. The B-VLAN
active topology is controlled by IS-IS that has loop mitigation and prevention capabilities
built into the protocol. However, SLPP is still supported on C-VLANs to detect loops created
by customers in their access networks.
SLPP requires the use of 4.1.8.2 code or higher.
Do not enable SLPP Rx on IST MLT ports. You can enable SLPP on other non-SMLT ports of
any IST Core switch pair.
For information about SLPP fundamentals and configuring SLPP, see Avaya Ethernet Routing
Switch 8800/8600 Administration, NN46205-605.
For information about SMLT and SLPP configuration examples, see the Switch Clustering Split
Multi-Link Trunking Technical Configuration Guide, NN48500-518.
Configuration — Link Aggregation, MLT, and SMLT
Split MultiLink Trunking
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