From: Scott Morris (smorris@ipexpert.com)
Date: Mon Oct 29 2007 - 11:30:37 ART
"Convergence" is different. With convergence, it means you first have to
detect a failure (your max-age sets this as your dead timer). Then you need
to go through listening/learning again per spec. And in your example this
is set to 4 seconds each (8 seconds).
So 6 seconds to detect the failure and then 8 seconds to converge will add
up to 14 seconds but that's a detect + convergence time, not just a topology
convergence.
HTH,
Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713, JNCIE-M
#153, JNCIS-ER, CISSP, et al.
CCSI/JNCI-M/JNCI-ER
VP - Technical Training - IPexpert, Inc.
IPexpert Sr. Technical Instructor
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smorris@ipexpert.com
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-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Henrique Reis
Sent: Monday, October 29, 2007 8:42 AM
To: kuldip singh
Cc: nicky noname; Cisco certification
Subject: Re: setting spanning-tree timers
This is strange because according to Cisco webpage you need to change the
following fields:
To speed up convergence, we use nondefault parameters valuespermitted by the
IEEE 802.1D standard. Non-default parameters to set for a reconvergence of
14 seconds are as follows:
Hello Time
2 seconds
Forward Delay Timer
4 seconds
Maximum Age Timer
6 seconds
On 10/27/07, kuldip singh <dipa.singh@gmail.com> wrote:
>
> Hi Nicky,
>
>
> I have just changed the forward delay timer (4 secs) for
> vlan 80 on the root bridge and shut/unshut the root port on the
> neighbor switch , and you can see in the log messages below it take 8
> seconds for the port to go from listening mode to forwarding
> state.Note forwarding delay timer = (listening + learning time).
>
> 02:47:58: STP: VLAN0080 Fa0/19 -> listening
> 02:48:00: STP: VLAN0080 new root port Fa0/19, cost 19
> 02:48:02: STP: VLAN0080 Fa0/19 -> learning
> 02:48:06: STP: VLAN0080 sent Topology Change Notice on Fa0/19
> 02:48:06: STP: VLAN0080 Fa0/19 -> forwarding
>
>
>
> On 10/27/07, nicky noname <cisco2study@gmail.com> wrote:
> >
> > Hello,
> >
> > I have two conflicting methods of making a vlan converge asap.
> >
> > The first is:
> > spanning-tree vlan 36 root primary diameter 3 hello-time 1 { this
> > will calculate a forward time of 5 and max age of 7......adding
> to
> > a
> > convergence time of 17 sec. But I think this may be the accepted answer?
> }
> > {
> > see output below}
> >
> >
> > The second is:
> > Rack8SW3(config)# spanning-tree vlan 36 forward-time 4
> > Rack8SW3(config)# spanning-tree vlan 36 max-age 6 { These commands
> > will give a convergence time of 14 seconds.} {see
> output
> > below}
> >
> > I would really appreciate an experienced opinion on this. ( in
> > relation
> to
> > the question)
> >
> > Thanks
> > Nic
> >
> >
> >
> > ##############################################
> > Rack8SW3(config)#spanning-tree vlan 36 root primary diameter 3
> hello-time
> > 1
> >
> > Rack8SW3(config)#do sh span vlan 36
> >
> > VLAN0036
> > Spanning tree enabled protocol ieee
> > Root ID Priority 24612
> > Address 0009.e8e2.fc00
> > This bridge is the root
> > Hello Time 1 sec Max Age 7 sec Forward Delay 5 sec
> >
> > Bridge ID Priority 24612 (priority 24576 sys-id-ext 36)
> > Address 0009.e8e2.fc00
> > Hello Time 1 sec Max Age 7 sec Forward Delay 5 sec
> > Aging Time 15
> >
> > Interface Role Sts Cost Prio.Nbr Type
> > ---------------- ---- --- --------- --------
> > --------------------------------
> > Fa0/3 Desg FWD 19 128.3 P2p
> > Fa0/16 Desg FWD 19 128.16 P2p
> > Fa0/17 Desg FWD 19 128.17 P2p
> > Fa0/18 Desg FWD 19 128.18 P2p
> > Fa0/19 Desg FWD 19 128.19 P2p
> > Fa0/20 Desg FWD 19 128.20 P2p
> > Fa0/21 Desg FWD 19 128.21 P2p
> > ###################################################
> > Rack8SW3(config)# spanning-tree vlan 36 forward-time ?
> > <4-30> number of seconds for the forward delay timer
> >
> > Rack8SW3(config)# spanning-tree vlan 36 forward-time 4
> > Rack8SW3(config)# spanning-tree vlan 36 max Rack8SW3(config)#
> > spanning-tree vlan 36 max-age ?
> > <6-40> maximum number of seconds the information in a BPDU is valid
> >
> > Rack8SW3(config)# spanning-tree vlan 36 max-age 6
> > Rack8SW3(config)#do sh span vlan 36
> >
> > VLAN0036
> > Spanning tree enabled protocol ieee
> > Root ID Priority 24612
> > Address 0009.e8e2.fc00
> > This bridge is the root
> > Hello Time 2 sec Max Age 6 sec Forward Delay 4 sec
> >
> > Bridge ID Priority 24612 (priority 24576 sys-id-ext 36)
> > Address 0009.e8e2.fc00
> > Hello Time 2 sec Max Age 6 sec Forward Delay 4 sec
> > Aging Time 15
> >
> > Interface Role Sts Cost Prio.Nbr Type
> > ---------------- ---- --- --------- --------
> > --------------------------------
> > Fa0/3 Desg FWD 19 128.3 P2p
> > Fa0/16 Desg FWD 19 128.16 P2p
> > Fa0/17 Desg FWD 19 128.17 P2p
> > Fa0/18 Desg FWD 19 128.18 P2p
> > Fa0/19 Desg FWD 19 128.19 P2p
> > Fa0/20 Desg FWD 19 128.20 P2p
> > Fa0/21 Desg FWD 19 128.21 P2p
> > #########################################################
> >
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