Unknown protocol drops

fred.gardner · ‎04-01-2009

I'm receiving the following display on a 2811 fast ethernet connection and am not sure what it means:

FastEthernet0/0 is up, line protocol is up

20 unknown protocol drops

lamav · ‎04-01-2009

I have researched this before and have never been able to get a definitive and authoritative answer, not even from Cisco TAC.

These oftentimes appear with absolutely no other indication that your network performance has been adversely effected.

If you cannot explain these errors, you can use a sniffer to indentify the unknown protocol.

HTH (It probably doesnt, but its the best I can do) :-)

Victor

fred.gardner · ‎04-01-2009

Thanks, Victor!

Yudong Wu · ‎04-01-2009

What device is port F0/0 connected to?

Can you do a sniffer to see what packet is received when this count increments?

By the way, you can check your IOS version to see if you hit this bug CSCsx18388.

fred.gardner · ‎04-01-2009

It's connected to a 2924-XL switch with

c2900xl-c3h2s-mz.120-5.WC15.bin.

Unfortunately, we don't have a sniffer.

I'm trying to use nGenius to identify the protocol. Fortunately it doesn't appear to be affecting performance...

mark.cronin · ‎04-01-2009

Some times you can get dropped packets

when one device is trying to negotiate ISL or dot1q trunks and the other device does not understand the trunking protocol.

Can you ensure that both the switch and router have the ports set to not trunk

fred.gardner · ‎04-01-2009

No trunking on either. Just vlan1...

mark.cronin · ‎04-01-2009

Is the switchport set to portfast

Thotsaphon Lueangwattanaphong · ‎04-01-2009

Frederick,

Well, You're gonna love MIB. (grin)

#########

ifInUnknownProtos (.1.3.6.1.2.1.2.2.1.15)

: These are counted as unclassified errors.

The variables previously listed that do not say they appear in show interfaces are not available anywhere other than SNMP.

#########

Please don't hesitate to check out this link.

http://www.cisco.com/en/US/tech/tk648/tk362/technologies_q_and_a_item09186a00800b69ac.shtml#QQ1

HTH,

Toshi

mark.cronin · ‎04-01-2009

and also

switchport mode access

You should also move your servers / hosts

off of VLAN 1 as this is not best practice

Yudong Wu · ‎04-01-2009

Hi Fred, how fast that counter increments? If you see it increase by one everytime you type "show interface", it might be related to the bug I mentioned before.

fred.gardner · ‎04-01-2009

looks like about 4 per 10 seconds...!?!

mark.cronin · ‎04-01-2009

Can you show us the output from a

show interface fa0/1 switchport

On the switchport that connect to the router

fred.gardner · ‎04-01-2009

UMB208R0#sh int fa0/0

FastEthernet0/0 is up, line protocol is up

Hardware is MV96340 Ethernet, address is 0013.8084.ae18 (bia 0013.8084.ae18)

Description: LAN interface at 700 E Santa Fe St Olathe

Internet address is 10.110.81.1/24

MTU 1500 bytes, BW 100000 Kbit/sec, DLY 100 usec,

reliability 255/255, txload 1/255, rxload 1/255

Encapsulation ARPA, loopback not set

Keepalive set (10 sec)

Full-duplex, 100Mb/s, 100BaseTX/FX

ARP type: ARPA, ARP Timeout 04:00:00

Last input 00:00:00, output 00:00:00, output hang never

Last clearing of "show interface" counters 05:58:49

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0

Queueing strategy: fifo

Output queue: 0/40 (size/max)

5 minute input rate 2000 bits/sec, 3 packets/sec

5 minute output rate 2000 bits/sec, 2 packets/sec

108257 packets input, 22583077 bytes

Received 10522 broadcasts, 0 runts, 0 giants, 0 throttles

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored

0 watchdog

0 input packets with dribble condition detected

94558 packets output, 38512505 bytes, 0 underruns

0 output errors, 0 collisions, 0 interface resets

6151 unknown protocol drops

0 babbles, 0 late collision, 0 deferred

0 lost carrier, 0 no carrier

0 output buffer failures, 0 output buffers swapped out

Yudong Wu · ‎04-01-2009

can you post the port configuration on 2900 switch and the output of "sh int fa x/y switchport"