MLPPP drop packet

Unanswered Question

I am experiencing many packets drop when I configure interface Multilink with only one physical link.The hardware is 7606 with SUP32 and IOS version 12.2(18)SXF9.I don?t have packet drop when configure IP Address in the physical link (no MLPPP in use).In the output below, you can see that the drops occur in the Multilink interface, in the physical interface I don?t have drops.


The drops occur in the input direction. In the other end has no drops.


A#ping 1.1.1.2 repeat 100


Type escape sequence to abort.

Sending 100, 100-byte ICMP Echos to 1.1.1.2, timeout is 2 seconds:

!!!!!.!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!

.!!!!!!!!!!!!!!!!!.!!!!!!!!!!!

Success rate is 94 percent (94/100), round-trip min/avg/max = 4/13/216 ms

!

!

!

A#sh int mu1

Multilink1 is up, line protocol is up

Hardware is multilink group interface

Internet address is 1.1.1.1/30

MTU 1500 bytes, BW 155000 Kbit, DLY 100000 usec,

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

Encapsulation PPP, loopback not set

Keepalive set (10 sec)

DTR is pulsed for 2 seconds on reset

LCP Open, multilink Open

Open: IPCP

Last input 00:00:25, output never, output hang never

Last clearing of "show interface" counters 00:01:47

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 0 bits/sec, 0 packets/sec

5 minute output rate 0 bits/sec, 0 packets/sec

94 packets input, 9776 bytes, 0 no buffer

Received 0 broadcasts (0 IP multicasts)

0 runts, 0 giants, 0 throttles

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

100 packets output, 10400 bytes, 0 underruns

0 output errors, 0 collisions, 0 interface resets

0 output buffer failures, 0 output buffers swapped out

0 carrier transitions

!

POS2/1/0 is up, line protocol is up

Hardware is Packet over Sonet

Description: Backbone: <removed>

MTU 1500 bytes, BW 155000 Kbit, DLY 100 usec,

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

Encapsulation PPP, crc 32, loopback not set

Keepalive set (10 sec)

Scramble disabled

LCP Open, multilink Open

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

Last clearing of "show interface" counters 00:01:38

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 0 bits/sec, 0 packets/sec

5 minute output rate 0 bits/sec, 0 packets/sec

113 packets input, 10608 bytes, 0 no buffer

Received 0 broadcasts (0 IP multicasts)

0 runts, 0 giants, 0 throttles

0 parity

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

113 packets output, 10608 bytes, 0 underruns

0 output errors, 0 applique, 0 interface resets

0 output buffer failures, 0 output buffers swapped out

0 carrier transitions


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Cont.


B#sh int mu 1

Multilink1 is up, line protocol is up

Hardware is multilink group interface

Internet address is 1.1.1.2/30

MTU 1500 bytes, BW 155000 Kbit, DLY 100000 usec,

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

Encapsulation PPP, loopback not set

Keepalive set (10 sec)

DTR is pulsed for 2 seconds on reset

LCP Open, multilink Open

Open: IPCP

Last input 00:01:12, output never, output hang never

Last clearing of "show interface" counters 00:01:44

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 0 bits/sec, 0 packets/sec

5 minute output rate 0 bits/sec, 0 packets/sec

100 packets input, 10400 bytes, 0 no buffer

Received 0 broadcasts (0 IP multicasts)

0 runts, 0 giants, 0 throttles

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

100 packets output, 10400 bytes, 0 underruns

0 output errors, 0 collisions, 0 interface resets

0 output buffer failures, 0 output buffers swapped out

0 carrier transitions

!

!

!

POS2/0/0 is up, line protocol is up

Hardware is Packet over Sonet

Description: Backbone :

MTU 1500 bytes, BW 155000 Kbit, DLY 100 usec,

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

Encapsulation PPP, crc 32, loopback not set

Keepalive set (10 sec)

Scramble disabled

LCP Open, multilink Open

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

Last clearing of "show interface" counters 00:02:12

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 0 bits/sec, 0 packets/sec

5 minute output rate 0 bits/sec, 0 packets/sec

121 packets input, 10736 bytes, 0 no buffer

Received 0 broadcasts (0 IP multicasts)

0 runts, 0 giants, 0 throttles

0 parity

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

121 packets output, 10736 bytes, 0 underruns

0 output errors, 0 applique, 0 interface resets

0 output buffer failures, 0 output buffers swapped out

0 carrier transitions


paolo bevilacqua Mon, 06/25/2007 - 14:37
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Hello,


can you execute the same diagnostics on the other ends? The fact that you are not receiving the ping reply may mean that the remote has not received the request.

Also I would try a ping "across" the devices to see if it happens with locally generated packets only, or with carried traffic as well.

Hello,


Yes, I executed the same diagnostics on the other end and occur the same behavior.


However, when I used two physical interfaces, the problem did not occur.


B#ping 1.1.1.1 repeat 100


Type escape sequence to abort.

Sending 100, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Success rate is 100 percent (100/100), round-trip min/avg/max = 4/6/24 ms




B#sh ppp mu


Multilink1, bundle name is

Bundle up for 00:08:16

0 lost fragments, 0 reordered, 0 unassigned

0 discarded, 0 lost received, 1/255 load

0x64 received sequence, 0x64 sent sequence

Member links: 2 active, 0 inactive (max not set, min not set)

PO2/0/1, since 00:08:16, last rcvd seq 000062

PO2/0/0, since 00:00:16, last rcvd seq 000063



paolo bevilacqua Tue, 06/26/2007 - 05:02
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Hello,


have you tried if if happens only when pinging from router to router, or also to devices connected to the routers, pinging each other ?

paolo bevilacqua Tue, 06/26/2007 - 05:19
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The thing is that even is possible that pings locally source from router to router can have an anomaly like these drops, that doesn't necessarily means the traffic carried across does suffer of the same problem.

So you should execute a test with external devices end-to-end to see if it happens as well.

In any case, even if you don't configure MLPPP, the router will lad balance over the two circuits and you should have no issues.


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