Cisco 4451 - Drops

[CAMPE]

I have a problem because the drops appear in the fisical interface but not in the policy-map

Router1#sh int Gi0/0/3 | inc drops
Input queue: 0/375/0/0 (size/max/drops/flushes); Total output drops: 236462
0 unknown protocol drops

Router1#sh policy-map interface | inc drops
(queue depth/total drops/no-buffer drops) 0/0/0
(queue depth/total drops/no-buffer drops) 0/0/0
Priority: Strict, b/w exceed drops: 0
(queue depth/total drops/no-buffer drops) 0/0/0
(queue depth/total drops/no-buffer drops) 0/0/0
(queue depth/total drops/no-buffer drops) 0/0/0
(queue depth/total drops/no-buffer drops) 0/0/0
Priority: Strict, b/w exceed drops: 0
(queue depth/total drops/no-buffer drops) 0/0/0
(queue depth/total drops/no-buffer drops) 0/0/0
(queue depth/total drops/no-buffer drops) 0/0/0
(queue depth/total drops/no-buffer drops) 0/0/0
Priority: Strict, b/w exceed drops: 0
(queue depth/total drops/no-buffer drops) 0/0/0
(queue depth/total drops/no-buffer drops) 0/0/0
(queue depth/total drops/no-buffer drops) 0/0/0
(queue depth/total drops/no-buffer drops) 0/0/0
Priority: Strict, b/w exceed drops: 0
(queue depth/total drops/no-buffer drops) 0/0/0
(queue depth/total drops/no-buffer drops) 0/0/0
(queue depth/total drops/no-buffer drops) 0/0/0
(queue depth/total drops/no-buffer drops) 0/0/0
Priority: Strict, b/w exceed drops: 0
(queue depth/total drops/no-buffer drops) 0/0/0
(queue depth/total drops/no-buffer drops) 0/0/0
(queue depth/total drops/no-buffer drops) 0/0/0
(queue depth/total drops/no-buffer drops) 0/0/0
Priority: Strict, b/w exceed drops: 0
(queue depth/total drops/no-buffer drops) 0/0/0
(queue depth/total drops/no-buffer drops) 0/0/0

NAME: "Chassis", DESCR: "Cisco ISR4451 Chassis"
PID: ISR4451-X/K9

System image file is "bootflash:isr4400-universalk9.16.05.01b.SPA.bin"

Any solution?

[Giuseppe Larosa]

Hello CAMPE,

can you post a whole

show interface type x/y

and

show policy-map interface type x/y

for the same interface so that we can see all the different counters.

Hope to help

Giuseppe

[CAMPE]

Hi, 

With command show interface type x/y you see total drops, whit the other command you see subinterface counters but de drops are zero, my router have almost 20 subinterfaces.

Router1#sh interfaces gigabitEthernet 0/0/3
GigabitEthernet0/0/3 is up, line protocol is up
Hardware is ISR4451-X-4x1GE, address is 7069.5a58.6743 (bia 7069.5a58.6743)
Description: WAN
MTU 1500 bytes, BW 1000000 Kbit/sec, DLY 10 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation 802.1Q Virtual LAN, Vlan ID 1., loopback not set
Keepalive not supported
Full Duplex, 1000Mbps, link type is force-up, media type is LX
output flow-control is on, input flow-control is on
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:00, output 00:00:07, output hang never
Last clearing of "show interface" counters 5w3d
Input queue: 0/375/0/0 (size/max/drops/flushes); Total output drops: 237750
Queueing strategy: Class-based queueing
Output queue: 0/40 (size/max)
30 second input rate 5118000 bits/sec, 5243 packets/sec
30 second output rate 3881000 bits/sec, 5068 packets/sec
31664084465 packets input, 3181771920648 bytes, 0 no buffer
Received 163584994 broadcasts (0 IP multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 124420684 multicast, 0 pause input
31638686419 packets output, 2999692209140 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 unknown protocol drops
0 babbles, 0 late collision, 0 deferred
3230 lost carrier, 0 no carrier, 0 pause output
0 output buffer failures, 0 output buffers swapped out

Two subinterfaces for example:

Router1#sh policy-map interface
GigabitEthernet0/0/3.107

Service-policy output: shaping_vpn_1

Class-map: class-default (match-any)
101890573 packets, 7291420247 bytes
30 second offered rate 3000 bps, drop rate 0000 bps
Match: any
Queueing
queue limit 64 packets
(queue depth/total drops/no-buffer drops) 0/0/0
(pkts output/bytes output) 101890573/7291420247
shape (average) cir 15000000, bc 60000, be 60000
target shape rate 15000000

Service-policy : QoS_Out_vpn_1

queue stats for all priority classes:
Queueing
queue limit 512 packets
(queue depth/total drops/no-buffer drops) 0/0/0
(pkts output/bytes output) 100319811/7177644691

Class-map: Clase_Voz_o_vpn_1 (match-all)
100319811 packets, 7177644691 bytes
30 second offered rate 2000 bps, drop rate 0000 bps
Match: ip precedence 5
Priority: Strict, b/w exceed drops: 0

QoS Set
cos 5
Packets marked 100319811
police:
cir 10000000 bps, bc 312500 bytes
conformed 100319811 packets, 7177644691 bytes; actions:
set-prec-transmit 5
exceeded 0 packets, 0 bytes; actions:
drop
conformed 2000 bps, exceeded 0000 bps

Class-map: Clase_Plata_o_vpn_1 (match-all)
182471 packets, 19805594 bytes
30 second offered rate 0000 bps, drop rate 0000 bps
Match: ip precedence 1
Queueing
queue limit 64 packets
(queue depth/total drops/no-buffer drops) 0/0/0
(pkts output/bytes output) 182471/19805594
bandwidth 4983 kbps
QoS Set
cos 1
Packets marked 182471

Class-map: Clase_Gestion_vpn_1 (match-all)
0 packets, 0 bytes
30 second offered rate 0000 bps, drop rate 0000 bps
Match: ip precedence 7
QoS Set
cos 7
Packets marked 0

Class-map: class-default (match-any)
1388291 packets, 93969962 bytes
30 second offered rate 0000 bps, drop rate 0000 bps
Match: any

queue limit 64 packets
(queue depth/total drops/no-buffer drops) 0/0/0
(pkts output/bytes output) 1388291/93969962

GigabitEthernet0/0/3.128

Service-policy output: shaping_vpn_secretaria

Class-map: class-default (match-any)
5826633917 packets, 464756363673 bytes
30 second offered rate 343000 bps, drop rate 0000 bps
Match: any
Queueing
queue limit 104 packets
(queue depth/total drops/no-buffer drops) 0/0/0
(pkts output/bytes output) 5826617948/464740040354
shape (average) cir 25000000, bc 100000, be 100000
target shape rate 25000000

Service-policy : QoS_Out_vpn_2

queue stats for all priority classes:
Queueing
queue limit 512 packets
(queue depth/total drops/no-buffer drops) 0/0/0
(pkts output/bytes output) 5818162116/463909541254

Class-map: Clase_Voz_o_vpn_2 (match-all)
5818178087 packets, 463925864729 bytes
30 second offered rate 340000 bps, drop rate 0000 bps
Match: ip precedence 5
Priority: Strict, b/w exceed drops: 0

QoS Set
cos 5
Packets marked 5818184542
police:
cir 20000000 bps, bc 625000 bytes
conformed 5818168571 packets, 463909999742 bytes; actions:
set-prec-transmit 5
exceeded 15971 packets, 16323475 bytes; actions:
drop
conformed 340000 bps, exceeded 0000 bps

Class-map: Clase_Plata_o_vpn_2 (match-all)
5816966 packets, 641475830 bytes
30 second offered rate 2000 bps, drop rate 0000 bps
Match: ip precedence 1
Queueing
queue limit 64 packets
(queue depth/total drops/no-buffer drops) 0/0/0
(pkts output/bytes output) 5816966/641475830
bandwidth 4983 kbps
QoS Set
cos 1
Packets marked 5816988

Class-map: Clase_Gestion_vpn_2 (match-all)
400 packets, 51540 bytes
30 second offered rate 0000 bps, drop rate 0000 bps
Match: ip precedence 7
QoS Set
cos 7
Packets marked 400

Class-map: class-default (match-any)
2638466 packets, 188971730 bytes
30 second offered rate 0000 bps, drop rate 0000 bps
Match: any

queue limit 104 packets
(queue depth/total drops/no-buffer drops) 0/0/0
(pkts output/bytes output) 2638866/189023270

[Giuseppe Larosa · Accepted solution]

Hello CAMPE,

you have output drops at physical interface level not a lot compared to total output packets.

>> Input queue: 0/375/0/0 (size/max/drops/flushes); Total output drops: 237750

>> 31638686419 packets output, 2999692209140 bytes, 0 underruns

loss ratio is : 237750 / (237750+ 31638686419 ) = 7,5144780122754242819842197018036e-6‬

However, there are drops caused by policer in the policy-map applied to the second subinterface you have reported:

>> QoS Set
cos 5
Packets marked 5818184542
police:
cir 20000000 bps, bc 625000 bytes
conformed 5818168571 packets, 463909999742 bytes; actions:
set-prec-transmit 5
>>>exceeded 15971 packets, 16323475 bytes; actions:
>>>drop
conformed 340000 bps, exceeded 0000 bps

Verify all the policy-maps applied to the 20 subinterfaces it is likely that the sum of drops caused by policer on the real time class is the same as the output drops listed in main interface.

Here we have 15971 packets dropped by policer.

Hope to help

Giuseppe

[CAMPE]

Hi, you're right.

The total number is very similar:

exceeded 27 packets, 39906 bytes; actions:
exceeded 270 packets, 376415 bytes; actions:
exceeded 6450 packets, 9498756 bytes; actions:
exceeded 6780 packets, 9710322 bytes; actions:
exceeded 9252 packets, 13674456 bytes; actions:
exceeded 15971 packets, 16323475 bytes; actions:
exceeded 81482 packets, 117015097 bytes; actions:
exceeded 117575 packets, 160560489 bytes; actions:

Total: 237807

genev-picq#sh interfaces g0/0/3 | include drops
Input queue: 0/375/0/0 (size/max/drops/flushes); Total output drops: 237821

And now the question is how can I mitigate these discards?

Thanks!

[Georg Pauwen]

Hello,

try and replace the policers with the shapers as suggested...

[Georg Pauwen]

Hello,

try and replace the policers with the shapers as suggested...

[CAMPE]

Hi, 

In my company they don't allow me to use shapers, we must use policers.

We have decided to increase the flow and now it seems that it does not discard

Thank you very much for the help!

[Joseph W. Doherty]

If you're company doesn't allow the usage of shapers, you might ask whether you can adjust the policer's Bc. Often the default is sized such that a policer drops prematurely compared to a like bandwidth physical interface.

[Georg Pauwen]

Hello,

on a side note, you want to avoid policing as much as possible. Try and replace 'police cir' with 'shape average' in your classes...