05-07-2013 12:42 PM - edited 03-07-2019 01:14 PM
Hi Guys,
I am having a issue where i see huge output drops on trunk .....basically i have a access layer switch which is conected to core , core's trunk is gig \n access layer has 100 meg....instead of seeing errors on 100meg i see it on gig interface....i have host A conected to access layer which polls servers connectwed behind another core switch (say host B) ...every now and then host A idrop packet and send false alert out for unpoll server as down....now i traced path and done ping test from HOST A to HOST B .....from Host A to get to (PING) servers it takes Max 25 ms for 30000 pings ( min is 1ms, avergae is 2msec)...for HIOSt B to get HOST A min 1msec , average 3msec and max 100msec for 1000 pings.....i even traced the path back ( mac to port tracing )and HOST hits one main core switch and then destination and HOST B hits two core switches and then HOST A....i see out put drops on GIG trunk of core...
CORE switch trunk
GigabitEthernet3/37 is up, line protocol is up (connected)
Hardware is C6k 1000Mb 802.3, address is 001e.13dd.e5b4 (bia 001e.13dd.e5b4)
Description: trunk to it area switch
MTU 1500 bytes, BW 100000 Kbit, DLY 10 usec,
reliability 255/255, txload 5/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 100Mb/s
input flow-control is off, output flow-control is off
Clock mode is auto
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:34, output 00:00:50, output hang never
Last clearing of "show interface" counters 1w4d
Input queue: 0/2000/22/0 (size/max/drops/flushes); Total output drops: 318966450
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 124000 bits/sec, 208 packets/sec
5 minute output rate 2335000 bits/sec, 844 packets/sec
423686111 packets input, 75694893840 bytes, 0 no buffer
Received 771518 broadcasts (707699 multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 11 overrun, 0 ignored
0 watchdog, 0 multicast, 0 pause input
0 input packets with dribble condition detected
2977282761 packets output, 2042066847687 bytes, 0 underruns
2 output errors, 0 collisions, 0 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
SHow interface counter error
Port Align-Err FCS-Err Xmit-Err Rcv-Err UnderSize OutDiscards
Gi3/37 0 0 2 0 0 318966450
SHow ip traffic on core
IP statistics:
Rcvd: 154315762 total, 982345507 local destination
107 format errors, 1704 checksum errors, 65838464 bad hop count
0 unknown protocol, 22423094 not a gateway
0 security failures, 0 bad options, 26827831 with options
Opts: 41092 end, 0 nop, 0 basic security, 0 loose source route
0 timestamp, 0 extended security, 8 record route
0 stream ID, 0 strict source route, 26786739 alert, 0 cipso, 0 ump
0 other
Frags: 300 reassembled, 0 timeouts, 0 couldn't reassemble
204750 fragmented, 0 couldn't fragment
Bcast: 565095059 received, 2084899 sent
Mcast: 396305142 received, 326552877 sent
Sent: 304134024 generated, 2119036473 forwarded
Drop: 272133326 encapsulation failed, 0 unresolved, 0 no adjacency
0 no route, 0 unicast RPF, 12466 forced drop
Drop: 81 packets with source IP address zero
ICMP statistics:
Rcvd: 0 format errors, 33700 checksum errors, 2196 redirects, 346621 unreachable
13450588 echo, 8187 echo reply, 0 mask requests, 0 mask replies, 0 quench
0 parameter, 0 timestamp, 0 info request, 0 other
284 irdp solicitations, 0 irdp advertisements
Sent: 23639 redirects, 11737 unreachable, 8383 echo, 13450505 echo reply
0 mask requests, 0 mask replies, 0 quench, 0 timestamp
0 info reply, 2668767 time exceeded, 0 parameter problem
0 irdp solicitations, 0 irdp advertisements
BGP statistics:
Rcvd: 0 total, 0 opens, 0 notifications, 0 updates
0 keepalives, 0 route-refresh, 0 unrecognized
Sent: 0 total, 0 opens, 0 notifications, 0 updates
0 keepalives, 0 route-refresh
PIMv2 statistics: Sent/Received
Total: 55361949/147580009, 0 checksum errors, 0 format errors
Registers: 0/0 (0 non-rp, 0 non-sm-group), Register Stops: 0/0, Hellos: 9646881/9648389
Join/Prunes: 0/0, Asserts: 45715068/137931620, grafts: 0/0
Bootstraps: 0/0, Candidate_RP_Advertisements: 0/0
State-Refresh: 0/0
IGMP statistics: Sent/Received
Total: 4916042/30310848, Format errors: 0/0, Checksum errors: 0/0
Host Queries: 4765648/3, Host Reports: 150394/27250088, Host Leaves: 0/1045333
DVMRP: 0/0, PIM: 0/0
UDP statistics:
Rcvd: 789512758 total, 81 checksum errors, 68072949 no port
Sent: 226593422 total, 1337189545 forwarded broadcasts
TCP statistics:
Rcvd: 1100399 total, 0 checksum errors, 2336 no port
Sent: 1099626 total
OSPF statistics:
Rcvd: 0 total, 0 checksum errors
0 hello, 0 database desc, 0 link state req
0 link state updates, 0 link state acks
Sent: 0 total
EGP statistics:
Rcvd: 0 total, 0 format errors, 0 checksum errors, 0 no listener
Sent: 0 total
Probe statistics:
Rcvd: 0 address requests, 0 address replies
0 proxy name requests, 0 where-is requests, 0 other
Sent: 0 address requests, 0 address replies (0 proxy)
0 proxy name replies, 0 where-is replies
IP-EIGRP statistics:
Rcvd: 0 total
Sent: 0 total
ARP statistics:
Rcvd: 476570723 requests, 31382270 replies, 40485 reverse, 0 other
Sent: 57319280 requests, 80166745 replies (79900818 proxy), 0 reverse
Drop due to input queue full: 179517
Access layer switch ip traffci
IP statistics:
Rcvd: 20444807 total, 9491341 local destination
0 format errors, 0 checksum errors, 10526295 bad hop count
0 unknown protocol, 4422 not a gateway
0 security failures, 0 bad options, 6782252 with options
Opts: 40968 end, 0 nop, 0 basic security, 0 loose source route
0 timestamp, 0 extended security, 0 record route
0 stream ID, 0 strict source route, 6741284 alert, 0 cipso, 0 ump
0 other
Frags: 5998 reassembled, 1 timeouts, 0 couldn't reassemble
0 fragmented, 0 couldn't fragment
Bcast: 1211668 received, 19 sent
Mcast: 0 received, 0 sent
Sent: 7814147 generated, 2 forwarded
Drop: 153 encapsulation failed, 0 unresolved, 0 no adjacency
0 no route, 0 unicast RPF, 0 forced drop
0 options denied, 0 source IP address zero
ICMP statistics:
Rcvd: 0 format errors, 0 checksum errors, 0 redirects, 18470 unreachable
7071061 echo, 128440 echo reply, 0 mask requests, 0 mask replies, 0 quench
0 parameter, 0 timestamp, 0 info request, 0 other
0 irdp solicitations, 0 irdp advertisements
Sent: 0 redirects, 8 unreachable, 128495 echo, 7071061 echo reply
0 mask requests, 0 mask replies, 0 quench, 0 timestamp
0 info reply, 1 time exceeded, 0 parameter problem
0 irdp solicitations, 0 irdp advertisements
TCP statistics:
Rcvd: 442950 total, 0 checksum errors, 844 no port
Sent: 522227 total
UDP statistics:
Rcvd: 1830400 total, 0 checksum errors, 1202334 no port
Sent: 92514 total, 2976 forwarded broadcasts
IP-EIGRP statistics:
Rcvd: 0 total
Sent: 0 total
ARP statistics:
Rcvd: 12419723 requests, 13914426 replies, 0 reverse, 0 other
Sent: 3113 requests, 2782 replies (16 proxy), 0 reverse
Drop due to input queue full: 0
FastEthernet1/0/1 is up, line protocol is up (connected)
Hardware is Fast Ethernet, address is 001f.9d4f.e003 (bia 001f.9d4f.e003)
Description: floorport main
MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,
reliability 255/255, txload 1/255, rxload 6/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 100Mb/s, media type is 10/100BaseTX
input flow-control is off, output flow-control is unsupported
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 1w5d
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 2674000 bits/sec, 897 packets/sec
5 minute output rate 128000 bits/sec, 215 packets/sec
3096311877 packets input, 2122061396037 bytes, 0 no buffer
Received 324515796 broadcasts (0 multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 248145891 multicast, 0 pause input
0 input packets with dribble condition detected
Can any one advise please ....iam think of upgrading from 100 meg to gig but i still should see these errors on 100 trunk not core....and also all the cores got 10gig connection between each other .....
05-07-2013 02:31 PM
Hello
Output drops usually indicate congestion onI the link. however from the readouts you have posted don't show any high utilisation on the interfaces.
I do see you have default mtu of 1500 - possibility this needs to higher to support the multiple vlan tags of the dot1q trunks
Do you have any Qos applied on these switches?
Res
Paul
Sent from Cisco Technical Support iPad App
05-07-2013 02:45 PM
hi paul,
thanks for your reply, yes auto qos has been configured ....as far as utilization is concerned access layer switch has high voulme of traffic during peak hours, mind out put is from ooh.... but y dnt i see any drops on 100 meg trunk? ....
05-07-2013 02:52 PM
Ok, output drops means that your interface is pushing as much data as it can but the remote end device is sending back a PAUSE frame.
So the data that the switch cannot deliver goes into a bucket or buffer. This buffer gets full and this is why you are seeing output drops.
Now, the question is WHERE is the fault.
One easy test is to bring down your interface speed to 10 Mbps and see if the output drops stops incrementing. If it does, then I'd recommend you look at the remote end.
05-07-2013 03:31 PM
thanks leo,
my host A is trying to talk to host B.... host A is connected to access layer switch which connects to core A ... host A DG points to hsrp ip for vlan configured on core A... core a send all traffic to coreB where host B is ... so if i see output drops on core A trunk ( trunk between host A access layer switch and cor A) this means core A sends but all traffic to Core B but due to congestion Core B cant take all frames and core B trunk puts it in buffern then drop... am i right? ... all the three core's have trunks configured two cores areusing hsrp third is datacenter vss ...lately more 48 port gig switches have been added to network n uplinks arenot increased they are only 10 gigs....
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