Design Reference

Table Of Contents
queues to guarantee proper handling of control packets regardless of the switch load. In turn,
this guarantees the stability of the network. Prioritization also guarantees that applications that
use many broadcasts are handled with lower priority.
You cannot view, configure, or modify control traffic queues.
ARP request threshold recommendations
The Address Resoluion Protocol (ARP) request-threshold defines the maximum number of
outstanding, unresolved ARP requests. The default value for this function is 500 ARP requests.
To avoid excessive amounts of subnet scanning that a virus can cause, Avaya recommends
that you change the ARP request threshold to a value between 100 to 50. This configuration
protects the CPU from causing excessive ARP requests, protects the network, and lessens
the spread of the virus to other PCs. The following list provides further recommended ARP
threshold values:
default: 500
severe conditions: 50
continuous scanning conditions: 100
moderate: 200
relaxed: 500
For more information about how to configure the ARP threshold, see Avaya Virtual Services
Platform 4000 Configuration — IP Routing , NN46251-505.
Multicast Learning Limitation
The Multicast Learning Limitation feature protects the CPU from multicast data packet bursts
generated by malicious applications. If more than a certain number of multicast streams enter
the CPU through a port during a sampling interval, the port is shut down until the user or
administrator takes the appropriate action.
For more information, see Avaya Virtual Services Platform 4000 Configuration — IP Multicast
Routing Protocols, NN46251-504.
Damage prevention
To further reduce the chance that unauthorized users can use your network to damage other
existing networks, take the following actions:
1. Prevent IP spoofing.
You can use the spoof-detect feature.
2. Prevent the use of the network as a broadcast amplification site.
3. To block illegal IP addresses, enable the hsecure flag (High Secure mode).
System and network stability and security
120 Network Design Reference for Avaya VSP 4000 February 2014
Comments? infodev@avaya.com