From: Godswill Oletu (oletu@inbox.lv)
Date: Thu Aug 11 2005 - 10:29:20 GMT-3
Ahmed,
Uplink fast is used to choose a secondary root port, this will speed up
convergence is case the root port fails or the downstream bridge connected
to this root port fails.
Without uplink fast, when your root port/link fails, the switch will have to
transition to an alternative port (from blocking, to listening, to learning
and then forwarding), this will take about 30 - 50 sec - which is by the way
a trillion light years in Networking. But with uplink fast enable, STP, will
choose a secondary root port ahead of time and transition to that port
immediately upon the failure of the root port, thus saving you 30 - 50 sec
network outage.
http://www.cisco.com/warp/public/473/51.html
Backbone fast is used to choose a secondary root bridge, this will also
speed up convergence, if the primary bridge fails.
http://www.cisco.com/en/US/tech/tk389/tk621/technologies_tech_note09186a00800c2548.shtml
As if IEEE anticipated your kind of confusion and to save the rest of us the
headache and confusion, they came out with, Rapid Spanning Tree Protocol
(RSTP, IEEE 802.1w).
With RSTP, root ports, designated root port; root bridge, designated root
bridge are all choosen when the STP runs at the first time, this then saves
us the extral configuration commands and worries, because the switch is now
made to think ahead. So, with RSTP, we really do not care about uplink fast
and backbone fast.
http://www.cisco.com/warp/public/473/146.html
HTH
---- Godswill Oletu----- Original Message ----- From: "Ahmed Ossama" <ahmed_ossama@rayatelecom.net> To: <ccielab@groupstudy.com> Sent: Thursday, August 11, 2005 9:35 AM Subject: uplink fast or backbone fast
> Dear All, > > > > I want to know when can I use the spanning-tree uplink fast command and > when I can use the spanning-tree backbonefast command because I am > confused about the two command and don't know when to use either. > > > > Best regards, > > _______________________________________________________________________ > Subscription information may be found at: > http://www.groupstudy.com/list/CCIELab.html
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