From: hadek.el-ayachi@nsn.com
Date: Wed Oct 17 2007 - 08:14:51 ART
There were a lot of discussion aboutsuch an issue, there were no exact,
clear and tested answer.
This question had two answers:
- take 20second timer into consideration in port startup
- ignore it and consider lst&fwd-delay only
Tests show that the 20second timer is not used for access ports. So, I
ll use the second option in case I ll have this in my next attempt :-).
-----Original Message-----
From: ext Joseph Brunner [mailto:joe@affirmedsystems.com]
Sent: mardi 16 octobre 2007 19:08
To: 'Scott Morris'; El Ayachi Hadek (NSN - MA/Rabat);
ccielab@groupstudy.com
Subject: RE: IE lab40
Cleary Scott, this is only on ports that were previously blocked because
of receipt of an inferior BPDU, correct? So you're specifically
describing the max-age HOLD TIME used to block alternate root paths with
802.1d?
I'm asking because if I...
do fwd delay = 7 seconds on ports where users connect and they go from
down to FWD in 14 seconds ONLY (this in lieu of portfast, etc). Notice
no 20 second delay...
watch this test... (and pay attention to the log timestamps, 14 seconds
from no shut -> FWD on a port which previously was not holding a bpdu
for max age
rack1sw1(config)#vlan 10
rack1sw1(config-vlan)#exit
rack1sw1(config)#sp
rack1sw1(config)#spanning-tree vlan 10 for
rack1sw1(config)#spanning-tree vlan 10 forward-time 7
rack1sw1(config)#int g0/1 rack1sw1(config-if)#sw
rack1sw1(config-if)#switchport mode access rack1sw1(config-if)#sw
rack1sw1(config-if)#switchport access vlan 10 rack1sw1(config-if)#int
g0/1 rack1sw1(config-if)#shut rack1sw1(config-if)#^Z rack1sw1#debug sp
rack1sw1#debug spanning-tree event Spanning Tree event debugging is on
rack1sw1#conf t Enter configuration commands, one per line. End with
CNTL/Z.
rack1sw1(config)#logg con
rack1sw1(config)#int g0/1
rack1sw1(config-if)#no shut
rack1sw1(config-if)#^Z
rack1sw1#
*Mar 1 19:46:51: %SYS-5-CONFIG_I: Configured from console by console
rack1sw1# *Mar 1 19:46:52: setting bridge id (which=3) prio 32778 prio
cfg 32768 sysid 10 (on) id 800A.0015.2b2c.7e80 *Mar 1 19:46:52: set
portid: VLAN0010 Gi0/1: new port id 8001 *Mar 1 19:46:52: STP: VLAN0010
Gi0/1 -> listening rack1sw1# *Mar 1 19:46:53: %LINK-3-UPDOWN: Interface
GigabitEthernet0/1, changed state to up rack1sw1# *Mar 1 19:46:54:
%LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/1,
changed state to up rack1sw1# *Mar 1 19:46:59: STP: VLAN0010 Gi0/1 ->
learning rack1sw1# *Mar 1 19:47:06: STP: VLAN0010 Gi0/1 -> forwarding
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Scott Morris
Sent: Tuesday, October 16, 2007 1:16 PM
To: hadek.el-ayachi@nsn.com; ccielab@groupstudy.com
Subject: RE: IE lab40
Max age is how long you wait after receiving the last BPDU before
recalculating things (like a dead timer).
When a port comes up, you block for 20 seconds initially. (first plug
in) That 20 seconds is not a changeable timer. Then you listen/learn
for 15 seconds each. That's the "normal" 50 seconds.
If you want the whole thing to take 34 seconds, subtract 20 first.
Since you can't change that. So now we have 14 seconds for listening
and learning. These timers must be the same per spec, so divide by two
(7) and that's your forward-timer.
HTH,
Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713,
JNCIE-M #153, CISSP, et al.
CCSI/JNCI-M/JNCI-ER
VP - Technical Training - IPexpert, Inc.
IPexpert Sr. Technical Instructor
A Cisco Learning Partner - We Accept Learning Credits!
smorris@ipexpert.com
Telephone: +1.810.326.1444
Fax: +1.810.454.0130
http://www.ipexpert.com
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
hadek.el-ayachi@nsn.com
Sent: Tuesday, October 16, 2007 11:39 AM
To: ccielab@groupstudy.com
Subject: IE lab40
Hi experts,
In Lab40, the question said: access ports should take 34 seconds to come
online.
I was expecting the answer: spanning-tree forward-time 17. I checked
this
answer using sh and no sh in one access port.
However the answer is spanning-tree forward 7???????????????? It takes
into
consideration max-age:( Any comment please
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