From: Kirit Bhamre (kirit4144@gmail.com)
Date: Mon Jul 30 2007 - 14:10:43 ART
Guys,
I found some useful info. on ErrDisable state from Cisco website...Thought
this might help to understand this concept.
Cheers,
Kirit
Function of Errdisable
If the configuration shows a port to be enabled, but software on the switch
detects an error situation on the port, the software shuts down that port.
In other words, the port is automatically disabled by the switch operating
system software because of an error condition that is encountered on the
port.
When a port is error disabled, it is effectively shut down and no traffic is
sent or received on that port. The port LED is set to the color orange and,
when you issue the *show interfaces* command, the port status shows
err-disabled. Here is an example of what an error-disabled port looks like
from the command-line interface (CLI) of the switch:
cat6knative#*show interfaces gigabitethernet 4/1 status*
Port Name Status Vlan Duplex Speed Type
Gi4/1 err-disabled 100 full 1000 1000BaseSX
Or, if the interface has been disabled because of an error condition, you
can see messages that are similar to these in both the console and the
syslog:
%SPANTREE-SP-2-BLOCK_BPDUGUARD:
Received BPDU on port GigabitEthernet4/1 with BPDU Guard enabled.
Disabling port.
%PM-SP-4-ERR_DISABLE:
bpduguard error detected on Gi4/1, putting Gi4/1 in err-disable state
This example message displays when a host port receives the bridge protocol
data unit (BPDU). The actual message depends on the reason for the error
condition.
The error disable function serves two purposes:
-
It lets the administrator know when and where there is a port problem.
-
It eliminates the possibility that this port can cause other ports on
the module (or the entire module) to fail.
Such a failure can occur when a bad port monopolizes buffers or port
error messages monopolize interprocess communications on the card, which can
ultimately cause serious network issues. The error disable feature helps
prevent these situations.
Causes of Errdisable
This feature was first implemented to handle special collision situations in
which the switch detected excessive or late collisions on a port. Excessive
collisions occur when a frame is dropped because the switch encounters 16
collisions in a row. Late collisions occur after every device on the wire
should have recognized that the wire was in use. Possible causes of these
types of errors include:
-
A cable that is out of specification (either too long, the wrong type,
or defective)
-
A bad network interface card (NIC) card (with physical problems or
driver problems)
-
A port duplex misconfiguration
A port duplex misconfiguration is a common cause of the errors because
of failures to negotiate the speed and duplex properly between two directly
connected devices (for example, a NIC that connects to a switch). Only
half-duplex connections should ever have collisions in a LAN. Because of the
carrier sense multiple access (CSMA) nature of Ethernet, collisions are
normal for half duplex, as long as the collisions do not exceed a small
percentage of traffic.
There are various reasons for the interface to go into errdisable. The
reason can be:
-
Duplex mismatch
-
Port channel misconfiguration
-
BPDU guard violation
-
UniDirectional Link Detection (UDLD) condition
-
Late-collision detection
-
Link-flap detection
-
Security violation
-
Port Aggregation Protocol (PAgP) flap
-
Layer 2 Tunneling Protocol (L2TP) guard
-
DHCP snooping rate-limit
On 7/29/07, A Murty <a.murty@tcs.com> wrote:
>
> Hi All,
>
> Best thing to do before configuring the port channel is to shut the ports
> and configure on both sides and un shut thereafter.
>
> Beware "Dont forget to unshut after you finish ur configuration"
>
>
> Regards
> Murty
>
>
>
>
> "Mounir Mohamed" <mounir.mohamed@gmail.com>
> Sent by: nobody@groupstudy.com
> 07/30/2007 02:50 AM
> Please respond to
> "Mounir Mohamed" <mounir.mohamed@gmail.com>
>
>
> To
> "Jonny English" <redkidneybeans@gmail.com>
> cc
> "Djerk Geurts" <djerk@djerk.nl>, "Cisco certification"
> <ccielab@groupstudy.com>
> Subject
> Re: Etherchannel & err-disable
>
>
>
>
>
>
> I beleive the interfaces going to err-disable mode when there is only one
> side configured by channel-group X mode on, due to STP issue, when you
> enable ether-channel all Ether-channel members sending traffic which
> casued
> in the err-disable.
>
>
>
> On 7/30/07, Jonny English <redkidneybeans@gmail.com> wrote:
> >
> > Etherchannel in on mode will cause the link to go into err-disable.
> >
> > Like if you have two sides of an etherchannel in on mode and you reload
> > switch A, switch B's etherchannel ports that are in on mode will go into
> > err-disable.
> >
> > This doesn't happen with the other modes.
> >
> > Correct me if I am wrong, but i had this issue when i did an after hours
> > change from work.
> >
> >
> > On 7/29/07, Djerk Geurts <djerk@djerk.nl> wrote:
> > >
> > > I have a 3750 and a 355 and when bringing up an etherchannel I get the
> > > following on the 3550:
> > >
> > > 1d21h: %PM-4-ERR_DISABLE: channel-misconfig error detected on Fa0/23,
> > > putting Fa0/23 in err-disable state
> > >
> > > Same config between a 3550 and 3750 is fine. 3548 - 3750 is fine as
> well
> > > as
> > > is 3548 - 3550. Actually all options between all 4 switches work but
> > this
> > > one.
> > >
> > > Port and eth-chan config:
> > >
> > > interface FastEthernet0/22
> > > description *** C3750-ME F1/0/22 ***
> > > switchport trunk encapsulation isl
> > > switchport mode trunk
> > > channel-group 5 mode on
> > > End
> > >
> > > interface Port-channel5
> > > description *** C3750 Po5 ***
> > > switchport trunk encapsulation isl
> > > switchport mode trunk
> > > end
> > >
> > > Switchport mode has no influence, port-security is off on both sides.
> > What
> > > is casusing this and how can I troubleshoot this? A debug etherchannel
> > > doesn't display anything related at all, other than the message listed
> > > above.
> > >
> > > So far I've seen it happen when one side is configured for
> etherchannel
> > > and
> > > the other side isn't but a shut no-shut helps things along nicely once
> > > both
> > > sides are configured for etherchannel propperly. But this time it
> > > doesn't...
> > >
> > > Any help appreciated.
> > >
> > > Regards,
> > >
> > > --
> > > Djerk Geurts | Senior R&D Engineer | Easynet
> > > T +31 (0)20 798 98 84 | F +31 (0)20 798 98 99 | www.easynet.com
> > > Karspeldreef 14 | 1101 CK Amsterdam | The Netherlands
> > > mailto:djerk.geurts@nl.easynet.net
> > >
> > > Please consider the environment before printing this e-mail.
> > >
> > >
> _______________________________________________________________________
> > > Subscription information may be found at:
> > > http://www.groupstudy.com/list/CCIELab.html
> >
> > _______________________________________________________________________
> > Subscription information may be found at:
> > http://www.groupstudy.com/list/CCIELab.html
> >
>
>
>
> --
> Best Reagrds,
> Mounir Mohamed
>
> _______________________________________________________________________
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