Arp Request Threshold Recommendations - Avaya 8800 Planning And Engineering, Network Design

Network security
You can disable CP-Limit and instead, configure the amount of broadcast and/or multicast control or
exception frames per second that are allowed to reach the CPU before the responsible interface is
blocked and disabled. Based on your environment (severe corresponds to a high-risk environment),
the recommended values are shown in the following figure.
Table 29: CP Limit recommended values
Severe
Workstation (PC)
Server
NonIST
Interconnection
Moderate
Workstation (PC)
Server
NonIST
Interconnection
Relaxed
Workstation (PC)
Server
NonIST
Interconnection
Important:
The 8692 SF/CPU with SuperMezz requires additional processing to send control packets from
the CP to the SuperMezz and to program any hardware records in the I/O modules. Both
operations now require an additional hop because they require CP involvement. To
accommodate this additional processing, you must use the cp-limit broadcast-limit
<value> and cp-limit multicast-limit <value> commands to lower the broadcast
and multicast thresholds to 3000 packets per second.

ARP request threshold recommendations

The Address Resolution Protocol (ARP) request threshold limits the ability of the Avaya Ethernet
Routing Switch 8800/8600 to source ARP requests for workstation IP addresses it has not learned
within its ARP table. The default setting for this function is 500 ARP requests per second. To avoid
excessive amounts of subnet scanning caused by a virus (like Welchia), Avaya recommends that
you change the ARP request threshold to a value between 100 to 50. This helps to protect the CPU
June 2016
CP Limit Values when using the 8895
SF/CPU
Broadcast Multicast
1000 1000
2500 2500
7500 6000
2500 2500
5000 5000
9000 9000
4000 4000
7000 7000
10 000 10 000
Planning and Engineering — Network Design
Comments on this document? infodev@avaya.com
CP Limit Values when using the 8692
SF/CPU with SuperMezz
Broadcast Multicast
1000 1000
2500 2500
3000 3000
2500 2500
3000 3000
3000 3000
3000 3000
3000 3000
3000 3000
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