CRS 100G linecard drops - Packet LPQ LP1 Tail Drop

[Konrad Kulikowski]

Hi

I have made test with 100G CRS linecard with traffic generator.

I can not get linerate because there is packets drop.

I have checked in detail and found this counter with big number which probably cause this issue.

How that possible that packets are droped on PLIM itself ?

What does this counter exactly mean ?

# show controllers plim asic statistics interface hundredGigE 0/10/0/0

..

..

Packet LPQ LP1 Tail Drop : 25895875872 Bytes LPQ LP1 Tail Drop : 1657336055808

Konrad

[tkarnani]

Hi,

it could be congestion. can you give us some more information?

packet size? ingress interface speed, egress interface speed. plim/msc types

Thanks

[Konrad Kulikowski]

Hi, all details below :

IOS XR 6.4.2

Tester Packet size : 512
Tester generate 10 streams with different mac addresses
Packets with greater size than 512 works well and give us linerate.
Below 512 size we observed plenty of drops.

Just simple local xconnect for testing purpose.

xconnect group test
p2p test
interface HundredGigE0/9/0/0
interface HundredGigE0/10/0/0

interface HundredGigE0/10/0/0
mtu 9216
l2transport

interface HundredGigE0/9/0/0
mtu 9216
l2transport

Interface : 0/100/CPU0 FP-140G 1-100GbE IOS XR RUN PWR,NSHUT,MON

sh int hu 0/10/0/0
HundredGigE0/10/0/0 is up, line protocol is up
Interface state transitions: 19
Hardware is HundredGigE, address is xxxxxxxxxxxx
Description: test
Layer 2 Transport Mode
MTU 9216 bytes, BW 100000000 Kbit (Max: 100000000 Kbit)
reliability 255/255, txload 224/255, rxload 243/255
Encapsulation ARPA,
Full-duplex, 100000Mb/s, 100GBASE-SR10, link type is force-up
output flow control is off, input flow control is off
loopback not set,
Last link flapped 21:45:16
Last input 00:00:01, output 00:00:01
Last clearing of "show interface" counters 5d02h
30 second input rate 95661105000 bits/sec, 23538658 packets/sec
30 second output rate 87898562000 bits/sec, 21628584 packets/sec
10342634489194 packets input, 5254459054317596 bytes, 0 total input drops
0 drops for unrecognized upper-level protocol
Received 576 broadcast packets, 0 multicast packets
0 runts, 0 giants, 0 throttles, 0 parity
1160 input errors, 6 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
9503493909861 packets output, 4828164585916394 bytes, 1011723 total output drops
Output 576 broadcast packets, 0 multicast packets
0 output errors, 0 underruns, 0 applique, 0 resets
0 output buffer failures, 0 output buffers swapped out
8 carrier transitions

Konrad