RE: covergence in RSTP

Hi Shekhar,

It's technically not portfast, its configuring the link as an edge port. In Catalyst IOS when you're running RSTP the links don't run as edge ports automatically. Instead of adding a "spanning-tree edge" or similar command, they simply made the "spanning-tree portfast" command do the same thing. The idea is that if you're migrating from legacy PVST to Rapid PVST or to MST, your ports that used to be portfast ports now become edge ports. They basically do the same thing, but in RSTP they're called edge ports instead of portfast ports.

HTH,

Brian McGahan, CCIE #8593 (R&S/SP/Security)
bmcgahan_at_INE.com
 
Internetwork Expert, Inc.
http://www.INE.com

-----Original Message-----
From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of Bruno Silva
Sent: Monday, June 25, 2012 9:36 AM
To: shekhar sharma
Cc: Cisco certification
Subject: Re: covergence in RSTP

you will still have to use portfast even with RSTP due to standard specifications.

On Mon, Jun 25, 2012 at 9:49 AM, shekhar sharma
<shekhar.sharma21_at_gmail.com>wrote:

> Hi Experts ,
>
> I know RSTP is mush faster than legacy STP or PVST because of its
> alternate ,,,back ports & a different algorithm to achive faster
> convergence in the interswitch links & uplinks.
>
> But I am little confused about its behaviour for edge ports i.e access
> ports.
>
> Yesterday I have done some tests ,,,.Observation is without enablings
> portfast on acess ports ,if I am doing shut/noshut on that accessport
> interface. convergence is slow and I am getting 10 packet drops b/w
> the pings.
>
> But with portfast enabled , convergence is faster and my gettig 2-3
> packet drop.
>
> So, the question is if portfast is still required in RSTP ,then how
> will we utilize its use in non-cisco environment .since portfast is
> cisco propriteiry.....
>
> Thanks,
> Shekhar
>
>
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Received on Mon Jun 25 2012 - 09:54:06 ART