The actual fix is to add the parameter "fake_ll=1" to the appropriate
place so that when the qeth module loads it creates a fake link level
header. This is only necessary when going straight to the OSA adapter, and
only when using protocol analyzers (nmap, tcpdump) or daemons (DHCP) that
expect there to be an LL header in the packet.

In SLES9, this goes in the
/etc/sysconfig/hardware/hwcfg-qeth-bus-ccw-0.0.xxxx (where xxxx is the OSA
unit address) as in the following:

/etc/sysconfig/hardware/hwcfg-qeth-bus-ccw-0.0.a000:
CCW_CHAN_IDS='0.0.a000 0.0.a001 0.0.a002'
CCW_CHAN_MODE='OSAPORT'
CCW_CHAN_NUM='3'
MODULE='qeth'
MODULE_OPTIONS=''
SCRIPTDOWN='hwdown-ccw'
SCRIPTUP='hwup-ccw'
SCRIPTUP_ccw='hwup-ccw'
SCRIPTUP_ccwgroup='hwup-qeth'
STARTMODE='auto'
QETH_OPTIONS='fake_ll=1'

In SLES8 it goes in /etc/chandev.conf as:

/etc/chandev.conf:
qeth0,0xa000,0xa001,0xa002
add_parms,0x10,0xa000,0xa002,fake_ll:1

In RHEL4 you add an OPTIONS line in
/etc/sysconfig/network-scripts/ifcfg-ethx (eth0, 1, whatever):

/etc/sysconfig/network-scripts/ifcfg-eth0:
DEVICE=eth0
BOOTPROTO=static
NETTYPE=qeth
ONBOOT=yes
SUBCHANNELS=0.0.4000,0.0.4001,0.0.4002
TYPE=Ethernet
OPTIONS="fake_ll=1"

The device drivers manual describes the parameter and is available on the
IBM DeveloperWorks Linux website.

Paul Giordano
Technical Sales Specialist - Linux zSeries
e-business Solutions Technical Sales, Americas
(312) 529-1347
(630) 207-9435 (cell)

email: [EMAIL PROTECTED]

Check http://www.ibm.com/linux for the latest in Linux news and
information



Alan Altmark/Endicott/[EMAIL PROTECTED]
Sent by: Linux on 390 Port <[email protected]>
08/07/2006 02:38 PM
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Linux on 390 Port <[email protected]>


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Subject
Re: NMAP






Another couple of things about Layer 2 (TYPE ETHERNET) VSWITCHes:

1. Don't forget to change the NICDEF / DEFINE NIC to have a TYPE ETHERNET
also.

2. A layer 2 VSWITCH surfaces the virtual MAC address of a virtual NIC to
the physical network.  (I guess maybe it isn't so virtual any more!)  If
you have two z/VM systems in the same LAN segment, be sure to configure
VMLAN MACPREFIX in the SYSTEM CONFIG file.  Each VM system needs a unique
value to ensure that you don't get two guests with the same MAC address.
Duplicate MAC addresses, like duplicate IP addresses, can be deadly.  You
will have to re-IPL after changing the MACPREFIX.

Regards,
      Alan

Alan Altmark
Sr. Software Engineer
IBM z/VM Development

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