[c-nsp] drops on Vlan interface - sup720

[Ian Cox]

Work out what is destined to the RP. The input/output queue indicates 
packets that are sent up to the RP in show interface on the Sup720. 
You have a number of flushes which means SPD is kicking in and 
dropping packets that are bound to the ARP. These packets could be 
packets that you don't have a route for, ttl expires, ARP requests, 
routing updates, ... If your running BGP  through this interface then 
the recommendation would be to up the queue size to 2k or 4k entries 
"hold queue ..." You have have a significant number of hosts attached 
to warrant increasing the hold queue size.

The reason why the 2 gig ports in the channel do not see any drops is 
that, they are not a L3 entity as far as the RP is concerned when in 
an etherchannel. The L3 entity where local packets are destined in 
your case is the vlan interface, and that is why you see drops on 
that interface rather than the L2 entities making up the channel.

The input/output queue x/y numbers shows the RP software queues for 
packets, not the hardware queues in the ports ASICs. The drop counter 
in input/output queues gets incremented for packets dropped in 
hardware. "sh counters int gig x/y" shows the counters from what the 
port ASIC persepctive.


Ian


At 11:46 AM 6/22/2005 +0200, Jerome Fleury wrote:
>Hi,
>
>I see drops on a vlan interface on my Sup720. The vlan interface is on a
>2x1G etherchannel
>
>However, the 2 gigabit interfaces of the etherchannel have no queue issue:
>
>SW1.GRE#sh int gi1/23 | inc queue
>   Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 0
>   Output queue: 0/40 (size/max)
>SW1.GRE#sh int gi1/24 | inc queue
>   Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 0
>   Output queue: 0/40 (size/max)
>
>Doe someone have an idea where I should look at first ?
>(details below)
>
>Thanks
>
>
>SW1.GRE#sh int po2
>Port-channel2 is up, line protocol is up (connected)
>   Hardware is EtherChannel, address is 0011.20e7.c98a (bia 0011.20e7.c98a)
>   Description: F=B, E=BB1.GRE, P=ae0
>   MTU 9216 bytes, BW 2000000 Kbit, DLY 10 usec,
>      reliability 255/255, txload 92/255, rxload 19/255
>   Encapsulation ARPA, loopback not set
>   Full-duplex, 1000Mb/s
>   input flow-control is off, output flow-control is unsupported
>   Members in this channel: Gi1/23 Gi1/24
>   ARP type: ARPA, ARP Timeout 04:00:00
>   Last input never, output never, output hang never
>   Last clearing of "show interface" counters never
>   Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 0
>   Queueing strategy: fifo
>   Output queue: 0/40 (size/max)
>   5 minute input rate 152135000 bits/sec, 87647 packets/sec
>   5 minute output rate 725234000 bits/sec, 99372 packets/sec
>      207947216600 packets input, 44631570217877 bytes, 0 no buffer
>      Received 10315102 broadcasts (10310964 multicast)
>      0 runts, 0 giants, 0 throttles
>      0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
>      0 watchdog, 0 multicast, 0 pause input
>      0 input packets with dribble condition detected
>      237075515646 packets output, 219837982247053 bytes, 0 underruns
>      0 output errors, 0 collisions, 1 interface resets
>      0 babbles, 0 late collision, 0 deferred
>      0 lost carrier, 0 no carrier, 0 PAUSE output
>      0 output buffer failures, 0 output buffers swapped out
>
>SW1.GRE#sh int vlan11
>Vlan11 is up, line protocol is up
>   Hardware is EtherSVI, address is 0011.5d6a.dc00 (bia 0011.5d6a.dc00)
>   Description: F=B, E=BB1.GRE, P=ae0.11
>   Internet address is 212.129.1.54/30
>   MTU 4470 bytes, BW 1000000 Kbit, DLY 10 usec,
>      reliability 255/255, txload 176/255, rxload 37/255
>   Encapsulation ARPA, loopback not set
>   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 16:18:30
>   Input queue: 1/75/1040/744 (size/max/drops/flushes); Total output drops: 0
>^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>   Queueing strategy: fifo
>   Output queue: 0/40 (size/max)
>   5 minute input rate 145433000 bits/sec, 86066 packets/sec
>   5 minute output rate 692230000 bits/sec, 95216 packets/sec
>   L2 Switched: ucast: 1494256 pkt, 188596464 bytes - mcast: 113395 pkt,
>33721309 bytes
>   L3 in Switched: ucast: 2494075400 pkt, 528540693373 bytes - mcast: 0 pkt,
>0 bytes mcast
>   L3 out Switched: ucast: 2818177702 pkt, 2576657750171 bytes mcast:
>20736382 pkt, 28242952284 bytes
>      2498290535 packets input, 528949723390 bytes, 0 no buffer
>      Received 118581 broadcasts (0 IP multicast)
>      0 runts, 0 giants, 0 throttles
>      0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
>      2815916776 packets output, 2573848246783 bytes, 0 underruns
>      0 output errors, 0 interface resets
>      0 output buffer failures, 0 output buffers swapped out
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