[c-nsp] Fast Uplink and 802.1w [7:91080]

[Tim Stevenson]

Inline:

At 09:00 AM 7/26/2004, cisco-nsp-request at puck.nether.net opined:
>Message: 1
>Date: Sun, 25 Jul 2004 16:40:29 -0400
>From: "Howard C. Berkowitz" <hcb at gettcomm.com>
>Subject: [c-nsp] Fast Uplink and 802.1w [7:91080]
>To: cisco-nsp at puck.nether.net
>Message-ID: <p05100317bd29cb13f8a8@[192.168.0.2]>
>Content-Type: text/plain; charset="us-ascii" ; format="flowed"
>
>I've been hunting through CCO documentation, and the guide
>"Configuring MST/RSTP on Cat Series Switches Running CatOS" seems
>incomplete. It seems to focus on MST much more than RSTP (802.1w).
>
>   From the standard, my understanding is that 802.1w has the built-in
>capability of doing things functionally equivalent to FastUplink,
>BackboneFast, and BPDU Guard.  I can't seem to find CatOS commands to
>configure these, although it's easy enough to find the commands for
>doing them with Cisco STP.

ULF, BBF are built into the RST protocol, you do not need to configure them 
separately. Note that we have both RST with MST, and PVRST (which is just 
like PVST but with .1w instead of .1d). PVRST is typically easiest to 
configure since when you enable RST it "just happens" (no having to map 
vlans to instances etc), same as with PVST.

>Does Cisco's CatOS implementation of 802.1w have these features and
>I'm just not finding the right documentation?

PortFast & BDPU guard/filter are separately configured just as they are in 
PVST. set spant portfast and set spantre bpdu-guard/bpdu-filter.


>Do they exist, as part of the 802.1w implementation, only in the IOS
>switching release for the 6500?
>
>Are they not implemented in either, implying I must run CatOS Cisco
>STP (PVST, etc.) to get the functionality along with flexibility in
>assigning VLANs to a smaller set of spanning trees?


So here we come back to MST. In my opinion, MST does not buy you much with 
today's network designs, where there are one/few spantrees per closet and 
the spantree domains are very small. In most typical cases, PVRST will work 
fine and gets you the benefits of RST without the additional complexity of MST.


Tim


>--
>
>Howard C. Berkowitz
>Chief Technology Officer
>Gett Communications
>5012 25th Street South
>Arlington VA 22206
>
>(703)998-5819 voice
>(703)998-5058  fax (alas, sometimes poorly operated by "helpful" cat)
>



Tim Stevenson, tstevens at cisco.com
Routing & Switching CCIE #5561
Technical Marketing Engineer, Catalyst 6500
Cisco Systems, http://www.cisco.com
IP Phone: 408-526-6759
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