The values for the following graphs are collected by Cacti. The look of the graphs are defined with a host template which i made for cacti. You may download it here.

   cacti_host_template_squid-cache_v0.1.xml

To allow access to Squid's SNMP agent, define an snmp_access ACL and community strings according to your needs. For example:

snmp_port 3401
acl snmppublic snmp_community public
snmp_access allow snmppublic
snmp_incoming_address 0.0.0.0
snmp_outgoing_address 255.255.255.255

Since i'm monitoring other OID on that server too and I don't want to have a second device in cacti I'm using the SNMP proxy function to integrate the branch from Squid into the Net-SNMP agent. Add the following to your Net-SNMP configuration.

proxy -v2c -c public localhost:3401 .1.3.6.1.4.1.3495.1

I'm using a simple bash script to create these graphs because i don't want to log in to cacti just to check the state of my squid. The script runs every five minute.