I have had plenty of experience with this problem when I updated a token ring
network to a fully switched ethernet network.
CISCO has a document on spanning tree and these types of problems.
Enabling portfast still means that it takes 15-30sec for the port on a switch
to come up. If you workstation needs to attach to a server (as with the
Novell
Client) by sending GetNearestServer (or the like packets) and it needs a
reply
to attach during that 15 - 30 sec then it will fail to connect. There may be
other problems with the Mac's -???
I would read the document on the CISCO site and then if that doesn't help let
us know what is the nature of the problem.
>>> "Jason Roysdon" 2/05/01 13:30:21 >>>
This message has been scanned by MAILSweeper.
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The customer claims that even with portfast enabled the Macs won't function
due to Spanning tree. Has anyone else heard any such rumors about this? My
guess, as you suggested, is that portfast would solve it, but supposedly it
was tried before disabling spanning tree.
--
Jason Roysdon, CCNP+Security/CCDP, MCSE, CNA, Network+, A+
List email: [EMAIL PROTECTED]
Homepage: http://jason.artoo.net/
""Leigh Anne Chisholm"" wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
> It's a symptom of the problem I wrote about earlier in this thread. When
a
> MAC becomes active on the network, the computer isn't able to communicate
for
> the first 50 seconds the port detects the end-system is active. The port
> begins in blocking mode, then transitions to listening, then learning.
> Finally, once STP determines that a looped topology hasn't occurred, the
port
> is set to forwarding mode. This creates havoc with any end-system that
> expects to receive over-the-network information within the first 50
seconds.
> IP, IPX, AppleTalk - all face the same issue.
>
> The simple solution isn't to kill Spanning Tree on all switches - that's
the
> "I don't understand the problem so I'll do whatever works and create a
bigger
> problem" solution. The real solution is to enable portfast on all switch
> ports that have end-systems directly connected. The caveat to this is to
> ensure none of the end-systems are capable as acting as a bridge,
forwarding
> packets between LAN segments. Enabling portfast essentially disables
> Spanning
> Tree on a port - and Spanning Tree is used to ensure a loop-free
environment.
>
>
> -- Leigh Anne
>
> > -----Original Message-----
> > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]
> > Sent: April 30, 2001 7:15 PM
> > To: [EMAIL PROTECTED]
> > Subject: Re: Spanning Tree Protocol [7:2564]
> >
> >
> > Oh, speaking of AppleTalk. We've got a customer (not mine, but one of
the
> > engineers working the account bounced this off me): They claim their
new
> > Macs can't access the network if Spanning Tree is enabled. Supposedly
this
> > has been verified by Apple and TAC (but we've never had a customer lie
to
> > us, so that must be gospel, right. Heh, not). I don't know what
exactly
> > the details are, but basically it just doesn't function. The simple
> > solution is to kill spanning-tree on all the switches, but this is at a
> > number of public schools, and I can't wait to hear about a kid bringing
in
> > his Linksys 8 port 10/100 switch and melting their network.
> >
> > Anyone else hear such rumors?
> >
> > --
> > Jason Roysdon, CCNP+Security/CCDP, MCSE, CNA, Network+, A+
> > List email: [EMAIL PROTECTED]
> > Homepage: http://jason.artoo.net/
> >
> >
> >
> > ""Priscilla Oppenheimer"" wrote in message
> > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
> > > At 11:08 AM 4/30/01, Phil Barker wrote:
> > > >Strongly in favour,
> > > >
> > > >A similar problem occurs in an IPX environment.
> > > >Make sure all Servers/Clients are 'portfast' and
> > > >switch/switch disable 'portfast'.
> > >
> > > A similar problem happens with AppleTalk too. That's what we get for
> > > expecting switches to replace hubs in a topology. ;-) They were
designed
> > as
> > > bridges and to talk to other bridges. Despite switches being the
> > > new-fangled thing (well, sort of new), a lot of their functionality is
> > > vintage 1980s.
> > >
> > > Priscilla
> > >
> > >
> > > >Regards,
> > > >
> > > >Phil.
> > > >--- John Gotti wrote: > Hey
> > > >all...we are having a problem where workstations
> > > > > sporatically will not
> > > > > be able to obtain an IP address from our DHCP
> > > > > server. After about 4 minutes,
> > > > > you can perform a manual renew from WINIPCFG and you
> > > > > get your IP address.
> > > > > This has baffled me for quite some time and I have
> > > > > recently been told it is
> > > > > our Cisco 2924 Switch to blame. The story I was told
> > > > > is below. I welcome any
> > > > > comments for or against this opinion. Thank you for
> > > > > your time.
> > > > >
> > > > >
> > > > > "It appears the problem is connected to the
> > > > > spanning tree algorithm used
> > > > > by the CISCO switches. By default, ports on the
> > > > > switch block as they are
> > > > > initialised; during this phase the port is in its
> > > > > spanning tree algorithm
> > > > > learning and listening state - it is not
> > > > > forwarding. This is specifically
> > > > > aimed at ports that will be used to connect to other
> > > > > switches/routers in a
> > > > > stack. After a default time (4 mins?) they switch to
> > > > > the standard forwarding
> > > > > mode and everything seems normal, the problem is
> > > > > that you have missed all
> > > > > the important DHCP broadcast and acknowledgment from
> > > > > client to DHCP server
> > > > > during this period.
> > > > >
> > > > > You can change this default state by changing the
> > > > > PORT-FAST setting on
> > > > > each port. The port is then immediately in the
> > > > > FORWARDING mode as it is
> > > > > initialised. By default this setting is DISABLED,
> > > > > I have ENABLED all
> > > > > ports except the ports doing the linking to other
> > > > > switches"
> > > > >
> > > >_________________________________________________________________
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> > >
> > > ________________________
> > >
> > > Priscilla Oppenheimer
> > > http://www.priscilla.com
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