Introduction
It is a best practice to configure CUBE for Call Admission Control to make sure it adheres to certain user-defined thresholds. If it exceeds these thresholds, CUBE will stop accepting new calls to prevent any catastrophic effects like crashing the router, or security violation of your network policies. These thresholds can be based on CPU, memory, call spikes, SIP based Denial of Service attacks, etc.
Configuring Call Admission Control on CUBE
Configure CUBE for the following requirements:
1. CAC based on call spike to manage call arrival rate
2. CAC based on maximum simultaneous connections per destination
3. CAC based on different thresholds like total call count, CPU or memory
1. CAC based on call spike:
CUBE rejects calls if call spike is detected
Call spikes can occur due to SIP based Denial of service attacks, e.g., a spike of REGISTER messages, INVITE messages etc. CUBE can detect these spikes defined as a surge in incoming requests within a short window by use of following commands:
Call spike <call-number 1-2147483647> steps <3–10> size <100–250>
Example 1: To configure 10 incoming call requests per 300 milliseconds, configure
CUBE(config)#call spike 10 steps 3 size 100
CUBE(config)#call spike 12
CUBE#show call spike status
2. CAC based on Max Connections:
“Max Connection” feature restricts the number of calls that can be active on a VOIP dial-peer. This feature provides CAC on a per dial-peer basis. For example make sure that only 2 long-distance call is allowed:
To achieve this, configure max-conn 2
dial-peer voice 100 voip
description *Long distance call to SP*
translation-profile outgoing longdistcall
max-conn 2
destination-pattern 91[2-9]..[2-9]......$
session protocol sipv2
session target ipv4:66.27.30.1
session transport udp
voice-class sip bind control source-interface GigabitEthernet0/1
voice-class sip bind media source-interface GigabitEthernet0/1
dtmf-relay rtp-nte
codec g711ulaw
no vad
3. CAC based on different thresholds like total call count, CPU or memory
“Call Threshold” command is used to configure two thresholds, high and low. “Call treatment” is triggered when the current value of a resource goes beyond the configured high. The “call treatment” remains in effect until the current resource value falls below the configured low.
CUBE(config)#call threshold global ?
cpu-5sec the CPU utilization in the last 5 seconds
cpu-avg the average CPU utilization
io-mem the IO memory utilization
proc-mem the Processor memory utilization
total-calls the total number of calls
total-mem the total memory utilization
Call threshold global total-calls low <low threshold> high <high-threshold>
Let’s configure the following thresholds:
CUBE(config)#Call threshold global total-calls low 1 high 1
CUBE(config)#Call threshold global cpu-avg low 75 high 85
CUBE(config)#Call threshold global total-mem low 75 high 85
CUBE(config)#call treatment on
CUBE#show call threshold status
Related Information
