I couldn't start a mrtg machine to analyze the routers.
The package was installaed, snmp running , see:
# snmpwalk -v 2c -c netcomrw 172.27.252.3 1.3.6.1.2.1.1
SNMPv2-MIB::sysDescr.0 = STRING: Extreme Networks, Inc. S8 Chassis Rev 08.22.01.0
023 04/07/2014--16:18 ofc
SNMPv2-MIB::sysObjectID.0 = OID: SNMPv2-SMI::enterprises.5624.2.1.133
DISMAN-EVENT-MIB::sysUpTimeInstance = Timeticks: (2137016558) 247 days, 8:09:25.5
8
SNMPv2-MIB::sysContact.0 = STRING: Info.Telecomunicacoes
SNMPv2-MIB::sysName.0 = STRING: NC3DB2
SNMPv2-MIB::sysLocation.0 = STRING: BRA_SP_SaoPaulo_Matriz_DinoBueno_2Andar_CPD_N
C03DB02_Nucleo
SNMPv2-MIB::sysServices.0 = INTEGER: 79
SNMPv2-MIB::sysORLastChange.0 = Timeticks: (0) 0:00:00.00

[root@li1964 libgd-2.2.0]# snmpwalk -v 2c -c netcomro 172.27.252.3 1.3.6.1.2.1.1
SNMPv2-MIB::sysDescr.0 = STRING: Extreme Networks, Inc. S8 Chassis Rev 08.22.01.0
023 04/07/2014--16:18 ofc
SNMPv2-MIB::sysObjectID.0 = OID: SNMPv2-SMI::enterprises.5624.2.1.133
DISMAN-EVENT-MIB::sysUpTimeInstance = Timeticks: (2137017551) 247 days, 8:09:35.5
1
SNMPv2-MIB::sysContact.0 = STRING: Info.Telecomunicacoes
SNMPv2-MIB::sysName.0 = STRING: NC3DB2
SNMPv2-MIB::sysLocation.0 = STRING: BRA_SP_SaoPaulo_Matriz_DinoBueno_2Andar_CPD_N
C03DB02_Nucleo
SNMPv2-MIB::sysServices.0 = INTEGER: 79
SNMPv2-MIB::sysORLastChange.0 = Timeticks: (0) 0:00:00.00

But when I try to make a .cfg file, comes this error:
But when I try, comes this:
# cfgmaker netcomro@172.27.252.3 netcomrw@172.27.252.3
SNMP Error:
no response received
SNMPv1_Session (remote host: "172.27.252.3" [172.27.252.3].161)
community: "netcomro"
request ID: -375667813
PDU bufsize: 8000 bytes
timeout: 2s
retries: 5
backoff: 1)
at /usr/bin/../lib64/mrtg2/SNMP_util.pm line 629
SNMPWALK Problem for 1.3.6.1.2.1.1 on netcomro@172.27.252.3::::::v4only
at /usr/bin/cfgmaker line 950
WARNING: Skipping netcomro@172.27.252.3: as no info could be retrieved

SNMP Error:
no response received
SNMPv1_Session (remote host: "172.27.252.3" [172.27.252.3].161)
community: "netcomrw"
request ID: 536901122
PDU bufsize: 8000 bytes
timeout: 2s
retries: 5
backoff: 1)
at /usr/bin/../lib64/mrtg2/SNMP_util.pm line 629
SNMPWALK Problem for 1.3.6.1.2.1.1 on netcomrw@172.27.252.3::::::v4only
at /usr/bin/cfgmaker line 950
WARNING: Skipping netcomrw@172.27.252.3: as no info could be retrieved

See what you think.
Tks,

Please don't use text-speak..it's "Thanks", not 'tks'...see the LQ Rules.

And did you look at what you posted? You perform the snmpwalk with version 2c of SNMP...and cfgmaker is running with version 1. See the man page for cfgmaker:
http://oss.oetiker.ch/mrtg/doc/cfgmaker.en.html

Now snmpwalk is working, but don't .
The mrtg is installed, but without .cfg file, I can't test the script.
See that.
Thanks

Now I read better,how Can I change thecfgmaker to accept v2 ?

Yes, I saw it, thanks.
You can READ THE DOCUMENTATION I HANDED YOU. It tells you how to do this.