From: Mark Mahan (mmahan@caprock.com)
Date: Tue Nov 06 2007 - 19:41:00 ART
If you have an x-over cable between the switch and router but are using
auto MDIX to correct the pins, the switch requires speed/duplex to be
set to auto for auto MDIX to work. If it's hard set to 100/full then
auto MDIX is disabled making the cable the wrong type causing the
interface status to go down.
Usage Guidelines
When you enable auto-MDIX on an interface, you must also set the
interface speed and duplex to auto so that the feature operates
correctly.
When auto-MDIX (and autonegotiation of speed and duplex) is enabled on
one or both of connected interfaces, link up occurs, even if the cable
type (straight-through or crossover) is incorrect.
Auto-MDIX is supported on all 10/100 and 10/100/1000 Mbps interfaces and
on 10/100/1000BASE-TX small form-factor pluggable (SFP) module
interfaces. It is not supported on 1000BASE-SX or -LX SFP module
interfaces.
Mark Mahan
Network Engineer
-------------------------------
CapRock Communications
4400 S. Sam Houston Parkway E.
Houston, Texas 77048
Office: 832 668 2528
mmahan@caprock.com
www.caprock.com
--------------------------------------------------------------------------
NOTICE OF CONFIDENTIALITY: This e-mail message may contain confidential
information and is intended only for the person(s) named above. Any review,
use, disclosure or distribution by any other person is prohibited. If you are
not the intended recipient, please contact the sender by e-mail and destroy
all copies of this message.
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Mohammad Saeed
Sent: Tuesday, November 06, 2007 4:08 PM
To: Cisco certification
Subject: Interface config problem
Hello Everybody,
Gigabit Ethernet Interface on 3750 connecting to fa0/0 of 2811, if we
hardcode both ends to 100Mbps and Full Duplex they shall be fine? Am I
right?
OR if we put both end to Speed auto and Duplex Auto, they shall be
able to negotiate maximum like 100 and full duplex, right?
Now in my case, Router's fa0/0 has hardcoded 100 and full duplex and
Switch interface was speed auto and duplex auto and as normal behavior
as other end was hardcoded, switch interface fall back to half duplex
and 100. Now when I hardcoded switch interface, to 100 and Full
duplex, it went to Interface Down, Line protocol Down, I tried shut
and no shut on the interface, but it went to Interface
Administratively down to again same Interface Down, Line protocol
Down. Can any one tell me what could be the problem, here is sample
config:
On Switch
interface vlan9
ip address 1.1.1.1 255.255.255.0
interface gigabitethernet 0/1
switchport access vlan9
speed 100
duplex full
On Router:
interface fa0/0
ip address 1.1.1.2 255.255.255.0
speed 100
duplex full
In the above scenerio as I mentioned above, switch interface will be
interface is down line protocol is down and router interface will be
interface is up and line protocol is down state.
Right now we put router to half duplex and 100 and switch to auto and
its falling to half duplex and 100, so no problems, but we want to
have 100 and full duplex to get better link speed.
Any idea, whats the problem?
Regards,
Mohammad Zahed Saeed
This archive was generated by hypermail 2.1.4 : Sat Dec 01 2007 - 06:37:28 ART