From: Scott Morris (smorris@ipexpert.com)
Date: Sun Sep 16 2007 - 18:52:52 ART
Actually path cost comes first. One would assume that if you received two
BPDUs from the same bridge id (two connections to same switch) that the
cumulative path cost SHOULD be the same between each, at least pending any
manual overrides on your device!
So you can manipulate either. But I'd suggest playing around with different
manipulations and see what "show spanning-tree" does and whether it's what
you expect or not!
Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713, JNCIE
#153, CISSP, et al.
CCSI/JNCI-M/JNCI-J
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 NET
HE
Sent: Sunday, September 16, 2007 4:14 PM
To: Gregory Gombas; Keith Bizzell
Cc: slevin kremera; Cisco certification
Subject: RE: Spanning-tree port priority versus port-cost
I agree with Gregory.
Root port selection processes as below if a switch receives multiple BPDU
hellos at multiple ports:
1)lowest bridge-id of neighboring switches
2)if equal, in other words, all BPDUs are from same switch, lowest
accumulative cost to root bridge (accumulative cost = port cost in BPDU
message + local port cost)
3)if equal, lowest port priority in BPDU message from upstream switch, the
upstream switch uses it to influence downstream switch root port selection
4)if equal, lowest port number at local switchBest Regards,Net (Xin) He
> Date: Sun, 16 Sep 2007 12:52:20 -0400> From: ggombas@gmail.com> To:
mkbcoolman@gmail.com> Subject: Re: Spanning-tree port priority versus
port-cost> CC: slevin.kremera@gmail.com; ccielab@groupstudy.com> >
port-cost> Correct me
if I'm wrong, but I don't believe port priority is used to> affect the local
switch, it is used for influencing the downstream> switche's path
selection.>
> In this simple case:> > SW1> | |> SW2> > If SW1 is the root you use
configure port priority on SW1 to influence> which port will be SW2's root
port and which port will be blocking. If> the configuration states you must
do the configuration on SW2, then> configure cost on SW2.> > Also port
priority is only useful when you have multiple connections> between two
switches.> >
HTH> > On 9/16/07, Keith Bizzell <mkbcoolman@gmail.com> wrote:> > It
HTH> > depends
on the direction. Port cost will affect spanning tree> > down-stream, but
port-priority will affect the local switch. And yes,> > wording has
everything to do with it. For instance, 'Configre S1 so that it> > prefers
fa0/23 for all vlan 10 traffic' would point you to port priority.> >
'Configure S2 so that S1 prefers fa0/23 for all vlan 10 traffic' would> >
require cost. Subtle...so be careful.> >> >> >> > On 9/16/07, slevin kremera
<slevin.kremera@gmail.com> wrote:> > >> > > Hi experts> > >> > > when does
one use port-priority and port-cost.wud that depend on how the> > > question
is worded in the exam..can someone gimme some examples> > >> > >> > > thks>
> > SK> > >> > >
This archive was generated by hypermail 2.1.4 : Sat Oct 06 2007 - 12:01:12 ART