[nsp] 802.1Q Incompatibility Cisco-3Com

[Bernardo Castilho Pinto]

   Recently we buy a 3750 with 12.1(14)EA1. Now we are trying to estabilish a
connection with the switch 3com cb4007. This link is being made by SFP port with
GLC-SX-MM (LC conector, SX transceiver) in the cisco side and in the 3com side a
1000Base-SX port with SC conector.

  The problem is that if i configure the both ports to be a unique vlan,
everything works fine. The port and the vlan came up with no erros. However when
i try to configure this link to be a trunk the interface goes up, but when
802.1Q starts the  link fail and the vlan came down. Looking at int the sh int,
i verified that at this moment it starts to increase input error (runts). We
have the same configuration with a 3550 and works like a charm.

  Any ideas to solve this ?  This is a incompatibility or ... ?

  This is the very simple configuration and some commands ....


##################################

vtp mode transparent
!
!
spanning-tree mode pvst
no spanning-tree optimize bpdu transmission
spanning-tree extend system-id
spanning-tree vlan 1-20 priority 40960
!
!
vlan 6
 name Site1
!
vlan 19
 name Site2

interface GigabitEthernet1/0/25
 switchport access vlan 19           -------------> Works fine
 bandwidth 10000000
 speed nonegotiate
!
interface GigabitEthernet1/0/26
 switchport trunk encapsulation dot1q  -----------> In the 3com side we set
802.1Q
 switchport mode trunk
 switchport nonegotiate
 bandwidth 10000000
 speed nonegotiate

interface GigabitEthernet1/0/27
!
interface GigabitEthernet1/0/28
!
interface Vlan1
 no ip address
 shutdown
!
interface Vlan6
 ip address 192.168.9.50 255.255.255.0

!
interface Vlan19
 ip address 192.168.2.50 255.255.255.0

#############################
   Sh int
###########################3
GigabitEthernet1/0/25 is up, line protocol is up (connected)
  Hardware is Gigabit Ethernet, address is 000f.23e5.0399 (bia 000f.23e5.0399)
  MTU 1500 bytes, BW 10000000 Kbit, DLY 10 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation ARPA, loopback not set
  Keepalive set (10 sec)
  Full-duplex, 1000Mb/s, link type is force-up, media type is SX
  output flow-control is off, input flow-control is off
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 00:00:01, output 00:00:03, output hang never
  Last clearing of "show interface" counters 17:44:51
  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 8000 bits/sec, 7 packets/sec
  5 minute output rate 1000 bits/sec, 1 packets/sec
     179517 packets input, 57039451 bytes, 0 no buffer
     Received 143838 broadcasts (0 multicast)
     0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 94630 multicast, 0 pause input
     0 input packets with dribble condition detected
     12373 packets output, 1239139 bytes, 0 underruns
     0 output errors, 0 collisions, 0 interface resets
     0 babbles, 0 late collision, 0 deferred
     0 lost carrier, 0 no carrier, 0 PAUSE output
     0 output buffer failures, 0 output buffers swapped out

GigabitEthernet1/0/26 is down, line protocol is down (notconnect)
  Hardware is Gigabit Ethernet, address is 000f.23e5.039a (bia 000f.23e5.039a)
  MTU 1500 bytes, BW 10000000 Kbit, DLY 10 usec,
     reliability 230/255, txload 1/255, rxload 1/255
  Encapsulation ARPA, loopback not set
  Keepalive set (10 sec)
  Auto-duplex, Auto-speed
  input flow-control is off, output flow-control is off
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 16:41:29, output 16:41:28, output hang never
  Last clearing of "show interface" counters 17:46:05
  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
     145 packets input, 81535 bytes, 0 no buffer
     Received 91 broadcasts (0 multicast)
     107 runts, 0 giants, 0 throttles
     107 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 80 multicast, 0 pause input
     0 input packets with dribble condition detected
     74 packets output, 5883 bytes, 0 underruns
     0 output errors, 0 collisions, 0 interface resets
     0 babbles, 0 late collision, 0 deferred
     0 lost carrier, 0 no carrier, 0 PAUSE output
     0 output buffer failures, 0 output buffers swapped out

###########################################
##sh interfaces switchport
#######################

  Appliance trust: none
Name: Gi1/0/25
Switchport: Enabled
Administrative Mode: dynamic auto
Operational Mode: static access
Administrative Trunking Encapsulation: negotiate
Operational Trunking Encapsulation: native
Negotiation of Trunking: On
Access Mode VLAN: 19 (Site2)
Trunking Native Mode VLAN: 1 (default)
Voice VLAN: none
Administrative private-vlan host-association: none
Administrative private-vlan mapping: none
Administrative private-vlan trunk native VLAN: none
Administrative private-vlan trunk encapsulation: dot1q
Administrative private-vlan trunk normal VLANs: none
Administrative private-vlan trunk private VLANs: none
Operational private-vlan: none
Trunking VLANs Enabled: ALL
Pruning VLANs Enabled: 2-1001
Capture Mode Disabled
Capture VLANs Allowed: ALL
Protected: false
Unknown unicast blocked: disabled
Unknown multicast blocked: disabled
Appliance trust: none

Name: Gi1/0/26
Switchport: Enabled
Administrative Mode: trunk
Operational Mode: down
Administrative Trunking Encapsulation: dot1q
Negotiation of Trunking: Off
Access Mode VLAN: 1 (default)
Trunking Native Mode VLAN: 1 (default)
Voice VLAN: none
Administrative private-vlan host-association: none
Administrative private-vlan mapping: none
Administrative private-vlan trunk native VLAN: none
Administrative private-vlan trunk encapsulation: dot1q
Administrative private-vlan trunk normal VLANs: none
Administrative private-vlan trunk private VLANs: none
Operational private-vlan: none
Trunking VLANs Enabled: ALL
Pruning VLANs Enabled: 2-1001
Capture Mode Disabled
Capture VLANs Allowed: ALL
Protected: false
Unknown unicast blocked: disabled
Unknown multicast blocked: disabled
########################################
########################

 3750#sh ver
Cisco Internetwork Operating System Software
IOS (tm) C3750 Software (C3750-I5-M), Version 12.1(14)EA1a, RELEASE SOFTWARE (f)
Copyright (c) 1986-2003 by cisco Systems, Inc.
Compiled Tue 02-Sep-03 04:39 by antonino
Image text-base: 0x00003000, data-base: 0x008F14A0
ROM: Bootstrap program is C3750 boot loader
BOOTLDR: C3750 Boot Loader (C3750-HBOOT-M) Version 12.1(11r)AX, RELEASE SOFTWAR)
3750 uptime is 23 hours, 39 minutes
System returned to ROM by power-on
System image file is "flash:c3750-i5-mz.121.14-EA1a/c3750-i5-mz.121.14-EA1a.bin"
cisco WS-C3750G-24TS (PowerPC405) processor (revision C0) with 118774K/12288K b.
Processor board ID CAT0803R22Y
Last reset from power-on
Bridging software.
3 Virtual Ethernet/IEEE 802.3  interface(s)
28 Gigabit Ethernet/IEEE 802.3 interface(s)
The password-recovery mechanism is enabled.

512K bytes of flash-simulated non-volatile configuration memory.
Base ethernet MAC Address       : 00:0F:23:E5:03:80
Motherboard assembly number     : 73-7058-09
Power supply part number        : 341-0045-01
Motherboard serial number       : CAT08030QB0
Power supply serial number      : LIT0749063M
Model revision number           : C0
Motherboard revision number     : A0
Model number                    : WS-C3750G-24TS-E
System serial number            : CAT0803R22Y


Switch   Ports  Model              SW Version              SW Image
------   -----  -----              ----------              ----------
*    1   28     WS-C3750G-24TS     12.1(14)EA1a            C3750-I5-M


Configuration register is 0xF