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Fa0/0 0.0.0.0 Null 255.255.255.255

sravan_235
Beginner
Beginner

Here iam enclosing sh ip cache flow output of a router.

My question is ,what do you mean by NULL interface.why these type traffic is flowing in a router .

Fa0/1 0.0.0.0 Null 255.255.255.255 11 0044 0043 1

Fa0/0 0.0.0.0 Null 255.255.255.255 11 0044 0043 1

Fa0/0 10.17.1.198 Null 255.255.255.255 11 0208 0208 1

Fa0/1 10.17.1.198 Null 255.255.255.255 11 0208 0208 1

Fa0/0 10.17.1.197 Null 224.0.0.9 11 0208 0208 1

9 Replies 9

spremkumar
Engager
Engager

Hi

The port numbers indicate the packets are being destined to port 67 and port 520.

(520 - extended file name server,

67 - Bootstrap Protocol Server)

Port belongs 520 to extended file name server and Port 67 belongs to Bootstrap Protocol Server..

regds

hi Prem,

How you know these belongs to 520 and 67 ports.

sravan kumar

Hi

Those ports are mentioned in Hexa-Decimal numbers you can decode them using our normal basic extended calculator..

regds

gokula_chandran
Beginner
Beginner

Hi sravan,

Meaning of NULL interface is the packets dropped because of ACL. The below link gives you the information

http://cisco.com/en/US/tech/tk812/technologies_white_paper09186a008022bde8.shtmlc

Regards

S. Shantharam

Hi,

Suryananraya,

Iam not able to open your URL.

Regards

sravan kumar

hi to all,

My main intention is to block 172.0.0.0 0.255.255.255 traffic.For this i have created ACL as deny ip 172.0.0.0 0.255.255.255 any ..But when i run the command "sh ip cache flow i can see the 172 series ip address traffic.

So please help in this regard . how can i block the traffic of 172 serices.

Out put if "sh ip cache flow " here enlosed.

SrcIf SrcIPaddress DstIf DstIPaddress Pr SrcP DstP Pkts

Se5/2 172.16.19.1 Null 172.23.142.126 01 0000 0000 65

Se5/2 172.23.170.16 Null 172.23.142.207 06 1266 01BD 1

Se5/2 172.23.170.16 Null 172.23.142.81 06 1242 01BD 1

Se5/2 172.23.170.17 Null 172.23.142.250 06 0408 01BD 1

sravan_235
Beginner
Beginner

Hi all,

How can i stop this traffic.

Fa0/1 0.0.0.0 Null 255.255.255.255 11 0044 0043 1

Fa0/0 0.0.0.0 Null 255.255.255.255 11 0044 0043 1

Fa0/0 10.17.1.198 Null 255.255.255.255 11 0208 0208 1

Fa0/1 10.17.1.198 Null 255.255.255.255 11 0208 0208 1

Fa0/0 10.17.1.197 Null 224.0.0.9 11 0208 0208 1

plese help me what are the command will stop the unwanted virus traffic.

regards

sravan

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