At 06:12 PM 5/2/01, Jason Roysdon wrote:
>True about that being a long time, but I think that's just a matter of how
>fast did I plug it in, and how long did it take for my NIC to see it (and
>which is a good 1 second delay from when I plug it in and when the NIC LED
>goes green).
Yes, I see what you're saying. I think as long as portfast is enabled,
AppleTalk devices should be OK. That's the bottom line. Thanks for all your
testing!
Priscilla
>The one thing I forgot to test was without spanning tree enabled. I tested
>the switch with 'no spanning-tree' for 10 times, and 10 times with it
>optimally configured with spanning tree on (portfast, full duplex, 100mbit,
>power inline never). The hardest thing to test is that Win2k will generate
>"Destination host unreachable." when no TCP/IP interfaces are up. It seemed
>that if instead of letting a constant ping run and watch pagefulls of those
>messages go by, I would instead hit enter as soon as I saw the NIC LED go
>green. This definately produces faster results (since the stack isn't being
>accessed, perhaps it initilizes faster?).
>
>Anyway, at first I forgot I had DHCP running and was wondering why it was
>taking so long (5-7 seconds). It acted the same with spanning tree
>disabled, and optimized as stated above. When I configured a static
>address, it dropped to 3-4 seconds for both, just as before.
>
>Of course, this isn't scientific, and Win2k doesn't really let you test the
>way you could with Win9x or even NT4 (where you could leave it pinging, and
>it would just sit there and respond with normal timeouts). Oh, growl, I
>just remembered I have Win98SE on this laptop. I'll save this post and go
>try it out.
>
>Ok, so I just rebooted to Win98. I must say, it handles lose of
>connectivity much better than Win2k, IMHO. I guess it all depends on what
>you want it to do: If it's a server/router, then you want the IP stack to
>know right away when there is a lost connection and drop it; if it's a
>desktop, you don't want to concern the user too fast (so long as the NIC
>gets plugged back in rather fast, or they're not generating IP traffic, no
>big deal).
>
>What I dislike on Win2k is that the second you lose your connection, you
>lose your DHCP lease (it remembers it and will try to renegotiate for it,
>but that IP/NIC is gone from the stack). With Win98, you still have it, so
>no need to re-negotiate for it when your connection comes back. That
>explains why DHCP was taking 2 extra seconds with Win2k (my DHCP server
>pings twice to make sure it's not in use before giving it back out). Win98
>never checks the DHCP lease due to cable loss, so long as the lease is still
>valid.
>
>Anyway, the results seemed to show no discernable different between
>optimized spanning tree, and diabled spanning tree. I also tested with
>using 'shutdown' and 'no shutdown' instead of physically removing the cable.
>Much easier, but the results were the same (my NIC couldn't tell the
>difference). 3-4 seconds after bringing the the switch interface up,
>pinging would start. The biggest thing I ran into with Win98 is that I
>couldn't shut/no shut or unplug/plug too fast, or it would never bring the
>stack back up no matter how long I left it (even though the NIC LED was on).
>I needed to let it have a good 1-2 seconds of disconnect for it to work.
>
>Perhaps Apple can tell the difference, but 3-4 seconds seemed constant with
>or without spanning tree. Perhaps some of the other Cisco switches or OS
>bases do things differently, but I don't have access to anything else at the
>moment. Anyone else want to post some results with other gear? I was using
>'debug spanning events' and 'debug interface f0/6' to see the original
>content I was posting.
>
>--
>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]...
> > Thanks for the testing! I have bad news for you. ;-) Three or 4 seconds
is
> > a lot of time.
> >
> > An AppleTalk device sends its AARP frame to see if its address is unique
>10
> > times, with only 1/5 of a second between tries. Then it sends a
> > ZIPGetNetInfo. It tries that 3 times, I think with the same timeout. This
> > could happen before the switch is forwarding, even with portfast enabled
>it
> > seems. (These timeout values may be dated. I haven't looked at AppleTalk
>in
> > a while! But I bet it's still really fast, perhaps even faster on a G4?
>;-)
> >
> > My guess is that IPX and DHCP are really fast too. ARGH.
> >
> > Priscilla
> >
> > At 03:15 PM 5/2/01, Jason Roysdon wrote:
> > >I wonder what switch and software version you were running at the time?
>I'm
> > >trying this on a Catalyst 3524 XL Inline Power running 12.0(5.2)XU (I
> > >haven't upgraded it, so that's whatever it shipped with).
> > >
> > >I did a number of tests (but not enough samples to make it 100% accurate
>on
> > >the timing, but a general idea +/- 2 seconds). The digits "00:16:47,"
>are
> > >time since boot, while the dated timestamps are accurate GMT. For each
>of
> > >my tests, I would attempt to physically plug in the patch cable at :00
> > >seconds based on the clock on my laptop, and both the laptop and switch
>are
> > >accurate from ntp (the log is not timestamped at :00 seconds, but just
>for
> > >your reference).
> > >
> > >The first with the port in the "out of the box" state with it left at
> > >defaults:
> > >00:16:54: ST: FastEthernet0/6 vlan 1 -> listening
> > >May 2 11:33:02.985 PDT: %LINK-3-UPDOWN: Interface FastEthernet0/6,
>changed
> > >state to up
> > >May 2 11:33:03.986 PDT: %LINEPROTO-5-UPDOWN: Line protocol on Interface
> > >FastEthernet0/6,
> > >changed state to up
> > >00:17:09: ST: FastEthernet0/6 vlan 1 -> learning
> > >00:17:24: ST: sent Topology Change Notice on Port Group 1 vlan 1
> > >00:17:24: ST: FastEthernet0/6 vlan 1 -> forwarding
> > >! 32 seconds
> > >
> > >At 32 seconds I had ping replies at my desktop (using a static address,
>as
> > >DHCP wouldn't be accurate to see how fast it comes up).
> > >
> > >Next, I wanted to see if the inline power slowed bringing the power up.
>It
> > >doesn't appear to (of course, thinking about it, the only time it
applies
> > >power is if it sees a certain loop/load between a pair of wires, the
>details
> > >I don't recall):
> > >
> > >Cat3524(config-if)#power inline never
> > >00:18:54: ST: FastEthernet0/6 vlan 1 -> listening
> > >May 2 11:35:02.497 PDT: %LINK-3-UPDOWN: Interface FastEthernet0/6,
>changed
> > >state to up
> > >May 2 11:35:03.498 PDT: %LINEPROTO-5-UPDOWN: Line protocol on Interface
> > >FastEthernet0/6,
> > >changed state to up
> > >00:19:09: ST: FastEthernet0/6 vlan 1 -> learning
> > >00:19:24: ST: sent Topology Change Notice on Port Group 1 vlan 1
> > >00:19:24: ST: FastEthernet0/6 vlan 1 -> forwarding
> > >!32 seconds
> > >
> > >Again, 32 seconds with spanning tree left to the defaults. 30 seconds
as
> > >far as the switch was concerned.
> > >
> > >Now lets enable portfast:
> > >
> > >Cat3524(config-if)#span portfast
> > >00:20:54: ST: FastEthernet0/6 vlan 1 ->jump to forwarding from blocking
> > >May 2 11:37:02.483 PDT: %LINK-3-UPDOWN: Interface FastEthernet0/6,
>changed
> > >state to up
> > >May 2 11:37:03.485 PDT: %LINEPROTO-5-UPDOWN: Line protocol on Interface
> > >FastEthernet0/6,
> > >changed state to up
> > >! 3 seconds
> > >
> > >In 3 seconds my PC was pinging with portfast set.
> > >
> > >My final test, I wanted to see if locking to speed and duplex would
>increase
> > >the time at all:
> > >
> > >interface FastEthernet0/6
> > > duplex full
> > > speed 100
> > > power inline never
> > > spanning-tree portfast
> > >
> > >Cat3524#
> > >00:22:54: ST: FastEthernet0/6 vlan 1 ->jump to forwarding from blocking
> > >May 2 11:39:03.165 PDT: %LINK-3-UPDOWN: Interface FastEthernet0/6,
>changed
> > >state to up
> > >May 2 11:39:04.166 PDT: %LINEPROTO-5-UPDOWN: Line protocol on Interface
> > >FastEthernet0/6,
> > >changed state to up
> > >May 2 11:39:06.622 PDT: %RTD-1-LINK_FLAP: FastEthernet0/6 link down/up
5
> > >times per minsh
> > >int
> > >
> > >Oops, the switch doesn't like all the flapping of my tests and left it
in
>an
> > >down/up state (good thing to know though!).
> > >
> > >Ok, give it a moment without the cable connected and try again:
> > >
> > >Cat3524#
> > >00:26:54: ST: FastEthernet0/6 vlan 1 ->jump to forwarding from blocking
> > >May 2 11:43:03.200 PDT: %LINK-3-UPDOWN: Interface FastEthernet0/6,
>changed
> > >state to up
> > >May 2 11:43:04.201 PDT: %LINEPROTO-5-UPDOWN: Line protocol on Interface
> > >FastEthernet0/6,
> > >changed state to up
> > >!4 seconds
> > >
> > >I think this time I was a little slow getting the cable in, but
basically
> > >the same results, 3-4 seconds and the port is up and pinging from my
> > >connected laptop. That shouldn't be a problem for any network devices,
I
> > >wouldn't think. The only way I could see it affecting is if during boot
>the
> > >NIC is not activated until the drivers load, and then within 1-2 seconds
>the
> > >protocol stack gets access to the NIC before the switch takes the port
> > >up/up, but I don't think this would be any different with or without
> > >spanning-tree enabled.
> > >
> > >
> > >--
> > >Jason Roysdon, CCNP+Security/CCDP, MCSE, CNA, Network+, A+
> > >List email: [EMAIL PROTECTED]
> > >Homepage: http://jason.artoo.net/
> > >
> > >
> > >
> > >""Jim Gillen"" wrote in message
> > >[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
> > > > 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.
> > > > ************************************************************
> > > >
> > > > 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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