03-08-2003 07:14 PM - edited 03-02-2019 05:42 AM
Hi,
I am gathering network traffic stats using NetMatrix thread definition of NetFlow.
There are some entries in the output file which I can not understand:
SOURCE defrouter|FORMAT 2|AGGREGATION NetMatrix|PERIOD 5|STARTTIME 1046706600|ENDTIME 1046706900|FLOWS 6900|MISSED 0|RECORDS 125
AGGREGATION_DEFINITION src_subnet|src_mask|input|dst_subnet|dst_mask|output|pkts|octets|flows
172.17.88.94|0|2|172.16.0.0|16|1|1|78|1
My question is why the src_mask of this record has been set to zero?
Flows for the same IP (172.17.88.94) aggregated in CallRecord thread, for the same time period, look like this:
SOURCE defrouter|FORMAT 2|AGGREGATION CallRecord|PERIOD 5|STARTTIME 1046706600|ENDTIME 1046706900|FLOWS 6900|MISSED 0|RECORDS 3995
AGGREGATION_DEFINITION srcaddr|dstaddr|srcport|dstport|prot|tos|pkts|octets|flows|starttime|endtime|activetime
172.17.88.94|172.16.128.20|137|137|17|0|1|78|1|1046706834|1046706834|0
172.16.254.250|172.17.88.94|139|1292|6|0|13|2893|1|1046706834|1046706834|104
172.17.88.94|172.16.254.250|1292|139|6|0|15|2044|1|1046706834|1046706834|308
As can be seen there were other flows for this IP which have been correctly aggregated in corresponding network records in NetMatrix thread. Only the first record (UDP with activetime=0) has not been correctly aggregated and have resulted in a separate single record with subnet mask zero!
I would be gratefull if anyone can help me understand the reason.
Thanks for any comments.
Regards,
H. Badbanchi
03-14-2003 07:25 AM
I would suggest you to check your aggregation configuration on the router or on the NetFlow collector.
03-14-2003 09:48 AM
Hi.
I have no idea for what should I look for in th configurations.
Here is the relevant part of the router config:
==================================
ip subnet-zero
ip flow-cache timeout active 1
ip flow-cache feature-accelerate
!
interface FastEthernet0/0
description connected to LAN Stockdorf 172.16
ip address 172.16.128.1 255.255.0.0
no ip redirects
ip route-cache flow
duplex auto
speed auto
!
interface FastEthernet0/1
description connected to router network
ip address 172.17.1.1 255.255.255.0
no ip redirects
ip route-cache flow
speed 100
full-duplex
!
ip flow-export source FastEthernet0/0
ip flow-export version 5
ip flow-export destination 172.16.127.247 9996
ip flow-aggregation cache protocol-port
cache timeout active 1
export destination 172.16.127.247 9993
!
ip flow-aggregation cache prefix
cache timeout active 1
export destination 172.16.127.247 9994
enabled
!
ip flow-aggregation cache prefix-port
cache timeout active 1
export destination 172.16.127.247 9995
enabled
!
ip classless
ip route 0.0.0.0 0.0.0.0 Null0 254
==================================
and ofcourse this default route to null dev, follows by several static routes for those destinations which I want the router to switch the packets.
On the Flow Collector host (172.16.127.247) the NetMtrx thread has been defined like this:
==================================
Filter A-no-dropped
permit Prot 88
deny DstAddr 0.0.0.0 0.0.0.0
deny SrcAddr 0.0.0.0 0.0.0.0
permit DstAddr 0.0.0.0 255.255.255.255
permit SrcAddr 0.0.0.0 255.255.255.255
Filter NxA-no-dropped
permit Prot 88
deny NextHop 0.0.0.0 0.0.0.0
deny DstAddr 0.0.0.0 0.0.0.0
deny SrcAddr 0.0.0.0 0.0.0.0
permit NextHop 0.0.0.0 255.255.255.255
permit DstAddr 0.0.0.0 255.255.255.255
permit SrcAddr 0.0.0.0 255.255.255.255
Thread NETMTRX
Filter Nx-no-dropped
Filter A-no-dropped
Aggregation NetMatrix
Period 5
Port 9996
State Active
DataSetPath /opt/CSCOnfc/Data
Compression No
Binary No
MaxUsage 0
==================================
If the zero src_addr of this special flow is because of any of the above definitions, then how come other flows involving the same source and/or destinations have been correctly aggregated in their corresponding subnet records.
I believe there should be something with this flow on the router itself, which has resulted in a src_addr=0 flow record. It can not have anything to do with the thread definition on the collector (logically, I mean).
As we can see in the CallRecord thread the router HAS actually reported a src_addr=0 for this flow. So the NetMtrx has (correctly) acted as it should.
The question is that why the router has reported src_addr=0 for this flow.
Thanks for your help.
Regards,
H. Badbanchi
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