[mrtg-developers] MRTG fails to handle different Request Id sizes

Vann H. Walke walkev at presearch.com
Wed Sep 11 16:35:02 MEST 2002


I'm attempting to use MRTG on Dell 5012 10-port 1GB switches.  On some
runs MRTG completes successfully, other times it fails.

On failure, the following message is repeated for each port (followed by
other error messages):

-------------------------------------------------------------------

stda-bluto 65% ~/mrtg-2.9.22/bin/mrtg ~/mrtg201.cfg
SNMP Error:
no response received
SNMPv1_Session (remote host: "192.168.2.201" [192.168.2.201].161)
                  community: "public"
                 request ID: -1928061565
                PDU bufsize: 8000 bytes
                    timeout: 2s
                    retries: 5
                    backoff: 1)
 at /imat/people/vwalke/mrtg-2.9.22/bin/../lib/mrtg2/SNMP_util.pm line
458
SNMPGET Problem for ifInOctets.1 ifOutOctets.1 sysUptime sysName on
public at 192.168.2.201:
 at /imat/people/vwalke/mrtg-2.9.22/bin/mrtg line 1607
WARNING: skipping because at least the query for ifInOctets.1 on 
192.168.2.201 did not succeed

---------------------------------------------------

I think I have localized the problem to the way in which the Dell switch
encodes the Request Id.  When mrtg completes successfully, the Request
ID is sent as
   02 04 XX XX XX XX
where 02 indicates integer, 
      04 indicates the length 
and   XX XX XX XX is the request ID.

For some reason the Dell switch sometimes encodes the Request ID as
   02 05 XX XX XX XX XX
using 5 bytes for the request ID.  This seems odd, but I can't find
anything reporting it as "illegal" in the RFC.

The ucdsnmp tools (snmpwalk, snmpget etc..) handle the response.

Complete packet captures of a successful (frames 1 and 2) and
unsuccessful (frames 41 and 42) transaction follow:

------------------------------------------------

Frame 1 (131 on wire, 131 captured)
    Arrival Time: Sep 11, 2002 10:33:42.313115000
    Time delta from previous packet: 0.000000000 seconds
    Time relative to first packet: 0.000000000 seconds
    Frame Number: 1
    Packet Length: 131 bytes
    Capture Length: 131 bytes
Ethernet II
    Destination: 00:30:1e:68:39:40 (3COM_68:39:40)
    Source: 00:06:5b:84:77:90 (Dell_84:77:90)
    Type: IP (0x0800)
Internet Protocol, Src Addr: stda-bluto.imat (192.26.8.8), Dst Addr:
set201.rack2.imat (192.168.2.201)
    Version: 4
    Header length: 20 bytes
    Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00)
        0000 00.. = Differentiated Services Codepoint: Default (0x00)
        .... ..0. = ECN-Capable Transport (ECT): 0
        .... ...0 = ECN-CE: 0
    Total Length: 117
    Identification: 0x0000
    Flags: 0x04
        .1.. = Don't fragment: Set
        ..0. = More fragments: Not set
    Fragment offset: 0
    Time to live: 64
    Protocol: UDP (0x11)
    Header checksum: 0xaee4 (correct)
    Source: stda-bluto.imat (192.26.8.8)
    Destination: set201.rack2.imat (192.168.2.201)
User Datagram Protocol, Src Port: 33277 (33277), Dst Port: snmp (161)
    Source port: 33277 (33277)
    Destination port: snmp (161)
    Length: 97
    Checksum: 0x80ca (correct)
Simple Network Management Protocol
    Version: 1
    Community: public
    PDU type: GET
    Request Id: 0x4c3eaea2
    Error Status: NO ERROR
    Error Index: 0
    Object identifier 1: 1.3.6.1.2.1.2.2.1.10.1 (IF-MIB::ifInOctets.1)
    Value: NULL
    Object identifier 2: 1.3.6.1.2.1.2.2.1.16.1 (IF-MIB::ifOutOctets.1)
    Value: NULL
    Object identifier 3: 1.3.6.1.2.1.1.3.0 (SNMPv2-MIB::sysUpTime.0)
    Value: NULL
    Object identifier 4: 1.3.6.1.2.1.1.5.0 (SNMPv2-MIB::sysName.0)
    Value: NULL

0000  00 30 1e 68 39 40 00 06 5b 84 77 90 08 00 45 00   .0.h9 at ..[.w...E.
0010  00 75 00 00 40 00 40 11 ae e4 c0 1a 08 08 c0 a8   .u.. at .@.........
0020  02 c9 81 fd 00 a1 00 61 80 ca 30 57 02 01 00 04   .......a..0W....
0030  06 70 75 62 6c 69 63 a0 4a 02 04 4c 3e ae a2 02   .public.J..L>...
0040  01 00 02 01 00 30 3c 30 0e 06 0a 2b 06 01 02 01   .....0<0...+....
0050  02 02 01 0a 01 05 00 30 0e 06 0a 2b 06 01 02 01   .......0...+....
0060  02 02 01 10 01 05 00 30 0c 06 08 2b 06 01 02 01   .......0...+....
0070  01 03 00 05 00 30 0c 06 08 2b 06 01 02 01 01 05   .....0...+......
0080  00 05 00                                          ...

Frame 2 (159 on wire, 159 captured)
    Arrival Time: Sep 11, 2002 10:33:42.316017000
    Time delta from previous packet: 0.002902000 seconds
    Time relative to first packet: 0.002902000 seconds
    Frame Number: 2
    Packet Length: 159 bytes
    Capture Length: 159 bytes
Ethernet II
    Destination: 00:06:5b:84:77:90 (Dell_84:77:90)
    Source: 00:30:1e:68:39:40 (3COM_68:39:40)
    Type: IP (0x0800)
Internet Protocol, Src Addr: set201.rack2.imat (192.168.2.201), Dst
Addr: stda-bluto.imat (192.26.8.8)
    Version: 4
    Header length: 20 bytes
    Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00)
        0000 00.. = Differentiated Services Codepoint: Default (0x00)
        .... ..0. = ECN-Capable Transport (ECT): 0
        .... ...0 = ECN-CE: 0
    Total Length: 145
    Identification: 0xd211
    Flags: 0x00
        .0.. = Don't fragment: Not set
        ..0. = More fragments: Not set
    Fragment offset: 0
    Time to live: 63
    Protocol: UDP (0x11)
    Header checksum: 0x1db7 (correct)
    Source: set201.rack2.imat (192.168.2.201)
    Destination: stda-bluto.imat (192.26.8.8)
User Datagram Protocol, Src Port: snmp (161), Dst Port: 33277 (33277)
    Source port: snmp (161)
    Destination port: 33277 (33277)
    Length: 125
    Checksum: 0xb7f9 (correct)
Simple Network Management Protocol
    Version: 1
    Community: public
    PDU type: RESPONSE
    Request Id: 0x4c3eaea2
    Error Status: NO ERROR
    Error Index: 0
    Object identifier 1: 1.3.6.1.2.1.2.2.1.10.1 (IF-MIB::ifInOctets.1)
    Value: Counter32: 18054556
    Object identifier 2: 1.3.6.1.2.1.2.2.1.16.1 (IF-MIB::ifOutOctets.1)
    Value: Counter32: 2166950052
    Object identifier 3: 1.3.6.1.2.1.1.3.0 (SNMPv2-MIB::sysUpTime.0)
    Value: Timeticks: (49933300) 5 days, 18:42:13.00
    Object identifier 4: 1.3.6.1.2.1.1.5.0 (SNMPv2-MIB::sysName.0)
    Value: Rack 2 Switch 1

0000  00 06 5b 84 77 90 00 30 1e 68 39 40 08 00 45 00   ..[.w..0.h9 at ..E.
0010  00 91 d2 11 00 00 3f 11 1d b7 c0 a8 02 c9 c0 1a   ......?.........
0020  08 08 00 a1 81 fd 00 7d b7 f9 30 73 02 01 00 04   .......}..0s....
0030  06 70 75 62 6c 69 63 a2 66 02 04 4c 3e ae a2 02   .public.f..L>...
0040  01 00 02 01 00 30 58 30 12 06 0a 2b 06 01 02 01   .....0X0...+....
0050  02 02 01 0a 01 41 04 01 13 7d 9c 30 13 06 0a 2b   .....A...}.0...+
0060  06 01 02 01 02 02 01 10 01 41 05 00 81 29 08 a4   .........A...)..
0070  30 10 06 08 2b 06 01 02 01 01 03 00 43 04 02 f9   0...+.......C...
0080  eb f4 30 1b 06 08 2b 06 01 02 01 01 05 00 04 0f   ..0...+.........
0090  52 61 63 6b 20 32 20 53 77 69 74 63 68 20 31      Rack 2 Switch 1

********************************************************************************

Frame 41 (131 on wire, 131 captured)
    Arrival Time: Sep 11, 2002 10:33:49.692392000
    Time delta from previous packet: 2.638554000 seconds
    Time relative to first packet: 7.379277000 seconds
    Frame Number: 41
    Packet Length: 131 bytes
    Capture Length: 131 bytes
Ethernet II
    Destination: 00:30:1e:68:39:40 (3COM_68:39:40)
    Source: 00:06:5b:84:77:90 (Dell_84:77:90)
    Type: IP (0x0800)
Internet Protocol, Src Addr: stda-bluto.imat (192.26.8.8), Dst Addr:
set201.rack2.imat (192.168.2.201)
    Version: 4
    Header length: 20 bytes
    Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00)
        0000 00.. = Differentiated Services Codepoint: Default (0x00)
        .... ..0. = ECN-Capable Transport (ECT): 0
        .... ...0 = ECN-CE: 0
    Total Length: 117
    Identification: 0x0000
    Flags: 0x04
        .1.. = Don't fragment: Set
        ..0. = More fragments: Not set
    Fragment offset: 0
    Time to live: 64
    Protocol: UDP (0x11)
    Header checksum: 0xaee4 (correct)
    Source: stda-bluto.imat (192.26.8.8)
    Destination: set201.rack2.imat (192.168.2.201)
User Datagram Protocol, Src Port: 33277 (33277), Dst Port: snmp (161)
    Source port: 33277 (33277)
    Destination port: snmp (161)
    Length: 97
    Checksum: 0xca1a (correct)
Simple Network Management Protocol
    Version: 1
    Community: public
    PDU type: GET
    Request Id: 0x8d141d83
    Error Status: NO ERROR
    Error Index: 0
    Object identifier 1: 1.3.6.1.2.1.2.2.1.10.1 (IF-MIB::ifInOctets.1)
    Value: NULL
    Object identifier 2: 1.3.6.1.2.1.2.2.1.16.1 (IF-MIB::ifOutOctets.1)
    Value: NULL
    Object identifier 3: 1.3.6.1.2.1.1.3.0 (SNMPv2-MIB::sysUpTime.0)
    Value: NULL
    Object identifier 4: 1.3.6.1.2.1.1.5.0 (SNMPv2-MIB::sysName.0)
    Value: NULL

0000  00 30 1e 68 39 40 00 06 5b 84 77 90 08 00 45 00   .0.h9 at ..[.w...E.
0010  00 75 00 00 40 00 40 11 ae e4 c0 1a 08 08 c0 a8   .u.. at .@.........
0020  02 c9 81 fd 00 a1 00 61 ca 1a 30 57 02 01 00 04   .......a..0W....
0030  06 70 75 62 6c 69 63 a0 4a 02 04 8d 14 1d 83 02   .public.J.......
0040  01 00 02 01 00 30 3c 30 0e 06 0a 2b 06 01 02 01   .....0<0...+....
0050  02 02 01 0a 01 05 00 30 0e 06 0a 2b 06 01 02 01   .......0...+....
0060  02 02 01 10 01 05 00 30 0c 06 08 2b 06 01 02 01   .......0...+....
0070  01 03 00 05 00 30 0c 06 08 2b 06 01 02 01 01 05   .....0...+......
0080  00 05 00                                          ...

Frame 42 (160 on wire, 160 captured)
    Arrival Time: Sep 11, 2002 10:33:49.695036000
    Time delta from previous packet: 0.002644000 seconds
    Time relative to first packet: 7.381921000 seconds
    Frame Number: 42
    Packet Length: 160 bytes
    Capture Length: 160 bytes
Ethernet II
    Destination: 00:06:5b:84:77:90 (Dell_84:77:90)
    Source: 00:30:1e:68:39:40 (3COM_68:39:40)
    Type: IP (0x0800)
Internet Protocol, Src Addr: set201.rack2.imat (192.168.2.201), Dst
Addr: stda-bluto.imat (192.26.8.8)
    Version: 4
    Header length: 20 bytes
    Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00)
        0000 00.. = Differentiated Services Codepoint: Default (0x00)
        .... ..0. = ECN-Capable Transport (ECT): 0
        .... ...0 = ECN-CE: 0
    Total Length: 146
    Identification: 0xd226
    Flags: 0x00
        .0.. = Don't fragment: Not set
        ..0. = More fragments: Not set
    Fragment offset: 0
    Time to live: 63
    Protocol: UDP (0x11)
    Header checksum: 0x1da1 (correct)
    Source: set201.rack2.imat (192.168.2.201)
    Destination: stda-bluto.imat (192.26.8.8)
User Datagram Protocol, Src Port: snmp (161), Dst Port: 33277 (33277)
    Source port: snmp (161)
    Destination port: 33277 (33277)
    Length: 126
    Checksum: 0x013e (correct)
Simple Network Management Protocol
    Version: 1
    Community: public
    PDU type: RESPONSE
    Request Id: 0x8d141d83
    Error Status: NO ERROR
    Error Index: 0
    Object identifier 1: 1.3.6.1.2.1.2.2.1.10.1 (IF-MIB::ifInOctets.1)
    Value: Counter32: 18054804
    Object identifier 2: 1.3.6.1.2.1.2.2.1.16.1 (IF-MIB::ifOutOctets.1)
    Value: Counter32: 2166959721
    Object identifier 3: 1.3.6.1.2.1.1.3.0 (SNMPv2-MIB::sysUpTime.0)
    Value: Timeticks: (49934100) 5 days, 18:42:21.00
    Object identifier 4: 1.3.6.1.2.1.1.5.0 (SNMPv2-MIB::sysName.0)
    Value: Rack 2 Switch 1

0000  00 06 5b 84 77 90 00 30 1e 68 39 40 08 00 45 00   ..[.w..0.h9 at ..E.
0010  00 92 d2 26 00 00 3f 11 1d a1 c0 a8 02 c9 c0 1a   ...&..?.........
0020  08 08 00 a1 81 fd 00 7e 01 3e 30 74 02 01 00 04   .......~.>0t....
0030  06 70 75 62 6c 69 63 a2 67 02 05 00 8d 14 1d 83   .public.g.......
0040  02 01 00 02 01 00 30 58 30 12 06 0a 2b 06 01 02   ......0X0...+...
0050  01 02 02 01 0a 01 41 04 01 13 7e 94 30 13 06 0a   ......A...~.0...
0060  2b 06 01 02 01 02 02 01 10 01 41 05 00 81 29 2e   +.........A...).
0070  69 30 10 06 08 2b 06 01 02 01 01 03 00 43 04 02   i0...+.......C..
0080  f9 ef 14 30 1b 06 08 2b 06 01 02 01 01 05 00 04   ...0...+........
0090  0f 52 61 63 6b 20 32 20 53 77 69 74 63 68 20 31   .Rack 2 Switch 1






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