[c-nsp] GSR 12008 physical loop ping problem?

[Sorin CONSTANTINESCU]

Hello, all.

I'm bothering you with another possible problem i've discovered today,
while trying to test this router and some linecards before i put them
to work ;)

So... i looped an STM-1 interface with a Fiber patch, the line
protocol went up, and i could ping the interface (HDLC encapsulation),
but, see below:

=== cut here ===
Router#sh run int p2/0
Building configuration...

Current configuration : 95 bytes
!
interface POS2/0
 ip address 10.0.0.1 255.255.255.252
 no ip directed-broadcast
 crc 32
end

Router#show int p2/0
POS2/0 is up, line protocol is up (looped)
  Hardware is Packet over SONET
  Internet address is 10.0.0.1/30
  MTU 4470 bytes, BW 155000 Kbit, DLY 100 usec, rely 255/255, load 1/255
  Encapsulation HDLC, crc 32, loopback not set
  Keepalive set (10 sec)
  Scramble disabled
  Last input 00:00:07, output 00:00:07, output hang never
  Last clearing of "show interface" counters never
  Queueing strategy: fifo
  Output queue 0/40, 0 drops; input queue 0/75, 0 drops
  5 minute input rate 0 bits/sec, 0 packets/sec
  5 minute output rate 0 bits/sec, 0 packets/sec
     371 packets input, 133608 bytes, 0 no buffer
     Received 0 broadcasts, 8 runts, 0 giants, 0 throttles
              0 parity
     89 input errors, 80 CRC, 0 frame, 0 overrun, 0 ignored, 1 abort
     389 packets output, 160680 bytes, 0 underruns
     0 output errors, 0 applique, 1 interface resets
     0 output buffer failures, 0 output buffers swapped out
     4 carrier transitions
Router#
Router#
Router#
Router#p
Protocol [ip]: 
Target IP address: 10.0.0.1
Repeat count [5]: 100
Datagram size [100]: 4470
Timeout in seconds [2]: 
Extended commands [n]: y
Source address or interface: 
Type of service [0]: 
Set DF bit in IP header? [no]: y
Validate reply data? [no]: 
Data pattern [0xABCD]: 
Loose, Strict, Record, Timestamp, Verbose[none]: 
Sweep range of sizes [n]: 
Type escape sequence to abort.
Sending 100, 4470-byte ICMP Echos to 10.0.0.1, timeout is 2 seconds:
!.!.!.!.!.!.!.!.!.!.
Success rate is 50 percent (10/20), round-trip min/avg/max = 1/1/4 ms
Router#p
Protocol [ip]: 
Target IP address: 10.0.0.1
Repeat count [5]: 100
Datagram size [100]: 1500
Timeout in seconds [2]: 
Extended commands [n]: y
Source address or interface: 
Type of service [0]: 
Set DF bit in IP header? [no]: y
Validate reply data? [no]: 
Data pattern [0xABCD]: 
Loose, Strict, Record, Timestamp, Verbose[none]: 
Sweep range of sizes [n]: 
Type escape sequence to abort.
Sending 100, 1500-byte ICMP Echos to 10.0.0.1, timeout is 2 seconds:
!!.!!.!!.!!.!!.!!.!!.!!.
Success rate is 66 percent (16/24), round-trip min/avg/max = 1/1/4 ms
Router#p
Protocol [ip]: 
Target IP address: 10.0.0.1
Repeat count [5]: 100
Datagram size [100]: 750
Timeout in seconds [2]: 
Extended commands [n]: 
Sweep range of sizes [n]: 
Type escape sequence to abort.
Sending 100, 750-byte ICMP Echos to 10.0.0.1, timeout is 2 seconds:
!!!!!!!.!!!!!!!.!!!!!!!.!!!!!!!.!!!!!!!.!!!!!!!.!!!!!!!.!!!!!!!.!!!!!!
!!.!!!!!!!!.!!!!!!!!.!!!!!!!!.
Success rate is 88 percent (88/100), round-trip min/avg/max = 1/1/4 ms
Router#p
Protocol [ip]: 
Target IP address: 10.0.0.1
Repeat count [5]: 100
Datagram size [100]: 375
Timeout in seconds [2]: 
Extended commands [n]: 
Sweep range of sizes [n]: 
Type escape sequence to abort.
Sending 100, 375-byte ICMP Echos to 10.0.0.1, timeout is 2 seconds:
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Success rate is 100 percent (100/100), round-trip min/avg/max = 1/1/4 ms
Router#
=== and here ===

Only if i ping with small packets, i don't have packet loss.

The STM-1 port isn't broken. I connected it into another router, and
it works fine with 4470 bytes pachets with DF set.

Should this happen?

TIA
-- 
Sorin CONSTANTINESCU
consta at gmail.com
Linux Registered User #222086