[nsp] Packet loss on MLPPP

[Vincent De Keyzer]

Hi,
 
I have some packet loss on a PPP multilink, and I am wondering what it could
be caused by. I get 0.4% packet loss, with no errors at the E1 level.
 
Could it be a software problem? When a ping packet fails, 'debug ppp
multilink fragments' produces:
 
Nov 21 12:39:40.111 CET: Mu1 MLP: Lost fragment DF0835 in 'EBIC00101r' (all
links have rcvd higher seq#)
Nov 21 12:39:43.091 CET: Mu1 MLP: Lost fragment DF0BE1 in 'EBIC00101r' (all
links have rcvd higher seq#)
Nov 21 12:39:46.095 CET: Mu1 MLP: Lost fragment DF0F1B in 'EBIC00101r' (all
links have rcvd higher seq#)
Nov 21 12:40:47.373 CET: Mu1 MLP: Lost fragment DF2FF1 in 'EBIC00101r' (all
links have rcvd higher seq#)
Nov 21 12:40:59.281 CET: Mu1 MLP: Lost fragment DF383F in 'EBIC00101r' (all
links have rcvd higher seq#)
Nov 21 12:43:33.136 CET: Mu1 MLP: Lost fragment DF706D in 'EBIC00101r' (all
links have rcvd higher seq#)
Nov 21 12:44:22.437 CET: Mu1 MLP: Lost fragment DF83FB in 'EBIC00101r' (all
links have rcvd higher seq#)
Nov 21 12:44:50.877 CET: Mu1 MLP: Lost fragment DF9185 in 'EBIC00101r' (all
links have rcvd higher seq#)
Nov 21 12:45:17.702 CET: Mu1 MLP: Lost fragment DFA15D in 'EBIC00101r' (all
links have rcvd higher seq#)
Nov 21 12:47:29.148 CET: Mu1 MLP: Lost fragment DFDD1B in 'EBIC00101r' (all
links have rcvd higher seq#)

Any idea what this means?
 
Thanks for any help (details below if required)
 
Vincent
 
______
 
The setup is as follows:
 
PoP side, a 2621 running "IOS (tm) C2600 Software (C2600-JS-M), Version
12.2(5), RELEASE SOFTWARE (fc1)"
Customer side, a 2610 running "IOS (tm) C2600 Software (C2600-I-M), Version
12.1(5)T5,  RELEASE SOFTWARE (fc1)"
 
Both are equipped with VWIC-2MFT-E1, and the config looks like this:
 
interface Serial0/1:0
 description First E1
 no ip address
 encapsulation ppp
 load-interval 30
 ppp multilink
 multilink-group 1

interface Serial1/2:0
 description Second E1
 no ip address
 encapsulation ppp
 load-interval 30
 ppp multilink
 multilink-group 1

interface Multilink1
 description #customer: XXXX
 ip address a.b.c.d 255.255.255.252
 no ip redirects
 no ip proxy-arp
 load-interval 30
 ntp broadcast
 ppp multilink
 multilink-group 1
 
The controllers are perfect for the last 24 hours (specifically, no slips,
so not a clocking problem?): 
 
E1 1/2 is up.
  Applique type is Channelized E1 - balanced
  No alarms detected.
  alarm-trigger is not set
  Version info Firmware: 20010805, FPGA: 15
  Framing is CRC4, Line Code is HDB3, Clock Source is Internal.
   Current port master clock: recovered from controller 1/1
  Total Data (last 24 hours)
     0 Line Code Violations, 0 Path Code Violations,
     0 Slip Secs, 0 Fr Loss Secs, 0 Line Err Secs, 0 Degraded Mins,
     0 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 0 Unavail Secs

E1 0/1 is up.
  Applique type is Channelized E1 - balanced
  No alarms detected.
  alarm-trigger is not set
  Version info Firmware: 20010805, FPGA: 15
  Framing is CRC4, Line Code is HDB3, Clock Source is Line.
  Total Data (last 24 hours)
     0 Line Code Violations, 0 Path Code Violations,
     0 Slip Secs, 0 Fr Loss Secs, 0 Line Err Secs, 0 Degraded Mins,
     0 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 0 Unavail Secs

pedro#ping ip
Target IP address: ebic02
Repeat count [5]: 1000
Datagram size [100]: 1500
Timeout in seconds [2]:
Extended commands [n]:
Sweep range of sizes [n]:
Type escape sequence to abort.
Sending 1000, 1500-byte ICMP Echos to 217.64.241.42, timeout is 2 seconds:
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Nov 21 12:54:27.444 CET: Mu1 MLP: Lost fragment E055B9 in 'EBIC00101r' (all
links have rcvd higher seq#).!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!
!!!!!!!!!!!!!!!!!!!!
Success rate is 99 percent (996/1000), round-trip min/avg/max = 8/12/80 ms
pedro#