Refer to the exhibit. It was noticed that after NetFlow is configured in the router, the collector stopped receiving flow information. Which action resolves the issue?
A.
Apply the ip flow egress command to the loopback2 interface.
B.
Modify the source through the ip flow-export source loopback1 command.
C.
Configure an IP address on the loopback2 interface to use as a source.
D.
Change the IP address of the loopback 2 interface to a public IP address.
In my opinion some information are missing in order to choose the correct answer.
I would need to see how It is configured loopback1 and loopback2.
If for example loopback2 is shutdown then It will make sense to use lo1 as source interface...
You pointed out the issue here, there is info missing and most likely Lo2 is shutdown. We need to assume that D is a weak answer it most likely would not show as "unknown" in the output.
I change my answer to B. What is going on here is that loopback 2 is shutdown. When the IP address is removed we see no output:
IOU1(config)#int l2
IOU1(config-if)#no ip add
IOU1(config-if)#do sh ip flow export
Flow export v9 is enabled for main cache
Export source and destination details :
VRF ID : Default
Destination(1) 4.4.4.4 (1)
Version 9 flow records
2 flows exported in 1 udp datagrams
0 flows failed due to lack of export pac
IOU1(config)#int l2
IOU1(config-if)#ip add 8.8.8.8 255.255.255.0
IOU1(config-if)#do sh ip flow export
Flow export v9 is enabled for main cache
Export source and destination details :
VRF ID : Default
Source(1) 8.8.8.8 (Loopback2)
Destination(1) 4.4.4.4 (1)
Version 9 flow records
IOU1(config-if)#
IOU1(config-if)#int L2
IOU1(config-if)#shut
IOU1(config-if)#do sh ip flow export
Flow export v9 is enabled for main cache
Export source and destination details :
VRF ID : Default
Source(1) 8.8.8.8 (Unknown)
Destination(1) 4.4.4.4 (1)
Version 9 flow records
6 flows exported in 3 udp datagrams
0 flows failed due to lack of expor
I was wrong.
Answer is D
p
IOU1#show ip flow export
Flow export v9 is enabled for main cache
Export source and destination details :
VRF ID : Default
Source(1) 22.22.22.22 (Loopback2)
Source(2) 22.22.22.22 (Loopback2)
Int L2
shutdown
IOU1#show ip flow export
*Aug 25 20:09:41.702: %SYS-5-CONFIG_I: Configured from console by console
*Aug 25 20:09:41.768: %LINK-5-CHANGED: Interface Loopback2, changed state to administratively down
IOU1#show ip flow export
Flow export v9 is enabled for main cache
Export source and destination details :
VRF ID : Default
Source(1) 22.22.22.22 (Unknown)
Source(2) 22.22.22.22 (Unknown)
B is more suitable
assuming the lo1 has been configured with a valid IP address.
D dosen´t make sense for me, since private addresses are useable as an export source.
Answer is D. Because Loopback1 is probably a 172.16.x.x address as well, meaning it is not routable as a public ip address. In this case B won't work. Making D routable public ip addresses solves the issue.
tested in the lab, D seems to be the only option, because A & B don't make sense and C disappears the line including "Source" instead of making the source "unknown":
R2(config)#do sh ip flow export | inc Source
Source(1) 172.16.1.1 (Loopback2)
R2(config)#no int lo2
R2(config)#do sh ip flow export | inc Source
R2(config)#do sh ip flow export | inc Source
okay, B is the closest correct answer - but the answer should be "no shut" on lo2
R2(config-if)#do sh ip flow export | inc Source
Source(1) 172.16.1.1 (Loopback2)
R2(config-if)#shutdown
R2(config-if)#
000045: *Dec 17 21:12:11: %LINEPROTO-5-UPDOWN: Line protocol on Interface Loopback2, changed state to down
000046: *Dec 17 21:12:11: %LINK-5-CHANGED: Interface Loopback2, changed state to administratively down
R2(config-if)#
R2(config-if)#do sh ip flow export | inc Source
Source(1) 172.16.1.1 (Unknown)
R2(config-if)#
Feb 6 23:02:11.191: %SYS-5-CONFIG_I: Configured from console by console
R1#show ip flow expo
R1#show ip flow export
Flow export v9 is enabled for main cache
Export source and destination details :
VRF ID : Default
Source(1) 172.16.1.1 (Loopback2)
Destination(1) 10.0.0.1 (500)
Version 9 flow records
0 flows exported in 0 udp datagrams
0 flows failed due to lack of export packet
0 export packets were sent up to process level
0 export packets were dropped due to no fib
0 export packets were dropped due to adjacency issues
0 export packets were dropped due to fragmentation failures
0 export packets were dropped due to encapsulation fixup failures
R1#conf t
Enter configuration commands, one per line. End with CNTL/Z.
D seems to be the only one that makes sense.
The current Lo2 Ip address is within RFC1918 and therefore not routable from/to the public IP destination.
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