Velocity Reviews - Computer Hardware Reviews

Velocity Reviews > Newsgroups > Computing > Cisco > Autonegotiation, DTP, PAgP, and STP steps a port moves through

Reply
Thread Tools

Autonegotiation, DTP, PAgP, and STP steps a port moves through

 
 
John Sasso
Guest
Posts: n/a
 
      08-13-2004
I finished reading a paper from Cisco, "Monitoring PIX Performance," and
p.2-3 describes the impact that autonegotiation, portfast, etherchanneling
(PAgP), and dynamic trunking protocol (DTP) have on a port or interface
coming up to the point where it can starting passing traffic normally.

My question is: assuming an end device (e.g., PIX) is connected to a
Catalyst switch port that itself has channeling set to auto, trunking set to
auto, portfast disabled, and speed/duplex set to auto, what are the phases
the switch port goes through before finally getting to the state where it
starts passing data traffic normally. For example, is it:

Speed/Duplex Negotiated -> Channeling negotiated -> Trunking
negotiated -> Spanning Tree phases -> Port starts processing data traffic

Cisco's paper is interesting, in that it notes that PAgP frames can be
impacted by speed/duplex negotiation, and incur a delay of 3 sec prior to
port forwarding traffic. If portfast is disabled, then there's a delay of
30 sec. If DTP is enabled, then a delay of 15 sec is incurred. Thus, I
ponder if the total delay (from the point a device is powered on or
connected to the switch port) would be 3 + 30 + 15 = 48 sec before the
device can start effectively passing data traffic with the switch.

So, 2 questions here. Any insight would be greatly appreciated!

--john


 
Reply With Quote
 
 
 
 
joe
Guest
Posts: n/a
 
      08-14-2004
Any router or pix should be a "host port" to a switch...

this means all switch to switch protocols disabled... a layer 3 device
or workstation should have no use for these protocols..

set port host


"John Sasso" <(E-Mail Removed)> wrote in message news:<DkWSc.122176$(E-Mail Removed)> ...
> I finished reading a paper from Cisco, "Monitoring PIX Performance," and
> p.2-3 describes the impact that autonegotiation, portfast, etherchanneling
> (PAgP), and dynamic trunking protocol (DTP) have on a port or interface
> coming up to the point where it can starting passing traffic normally.
>
> My question is: assuming an end device (e.g., PIX) is connected to a
> Catalyst switch port that itself has channeling set to auto, trunking set to
> auto, portfast disabled, and speed/duplex set to auto, what are the phases
> the switch port goes through before finally getting to the state where it
> starts passing data traffic normally. For example, is it:
>
> Speed/Duplex Negotiated -> Channeling negotiated -> Trunking
> negotiated -> Spanning Tree phases -> Port starts processing data traffic
>
> Cisco's paper is interesting, in that it notes that PAgP frames can be
> impacted by speed/duplex negotiation, and incur a delay of 3 sec prior to
> port forwarding traffic. If portfast is disabled, then there's a delay of
> 30 sec. If DTP is enabled, then a delay of 15 sec is incurred. Thus, I
> ponder if the total delay (from the point a device is powered on or
> connected to the switch port) would be 3 + 30 + 15 = 48 sec before the
> device can start effectively passing data traffic with the switch.
>
> So, 2 questions here. Any insight would be greatly appreciated!
>
> --john

 
Reply With Quote
 
 
 
 
John Sasso
Guest
Posts: n/a
 
      08-14-2004
That does not answer my question. Yes, I've understood long ago about
disabling DTP, PAgP, and enabling portfast on such ports.

My question is what steps does a port go through before finally passing
data traffic normally, assuming the port had DTP and channeling set to
auto, no portfast, and had speed/duplex set to auto. For example, would
it first do Speed/Duplex Negotiation, followed by Channeling
negotiation, followed by Trunking negotiation, followed by Spanning Tree
phases? Thats all.

Thanks

--john

joe wrote:
> Any router or pix should be a "host port" to a switch...
>
> this means all switch to switch protocols disabled... a layer 3 device
> or workstation should have no use for these protocols..
>
> set port host
>
>
> "John Sasso" <(E-Mail Removed)> wrote in message news:<DkWSc.122176$(E-Mail Removed)> ...
>
>>I finished reading a paper from Cisco, "Monitoring PIX Performance," and
>>p.2-3 describes the impact that autonegotiation, portfast, etherchanneling
>>(PAgP), and dynamic trunking protocol (DTP) have on a port or interface
>>coming up to the point where it can starting passing traffic normally.
>>
>>My question is: assuming an end device (e.g., PIX) is connected to a
>>Catalyst switch port that itself has channeling set to auto, trunking set to
>>auto, portfast disabled, and speed/duplex set to auto, what are the phases
>>the switch port goes through before finally getting to the state where it
>>starts passing data traffic normally. For example, is it:
>>
>> Speed/Duplex Negotiated -> Channeling negotiated -> Trunking
>>negotiated -> Spanning Tree phases -> Port starts processing data traffic
>>
>>Cisco's paper is interesting, in that it notes that PAgP frames can be
>>impacted by speed/duplex negotiation, and incur a delay of 3 sec prior to
>>port forwarding traffic. If portfast is disabled, then there's a delay of
>>30 sec. If DTP is enabled, then a delay of 15 sec is incurred. Thus, I
>>ponder if the total delay (from the point a device is powered on or
>>connected to the switch port) would be 3 + 30 + 15 = 48 sec before the
>>device can start effectively passing data traffic with the switch.
>>
>>So, 2 questions here. Any insight would be greatly appreciated!
>>
>>--john

 
Reply With Quote
 
 
 
Reply

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
strange STP behaviour : stack port in "sh spanning-tree" output Giuseppe Cisco 4 02-06-2008 02:34 PM
Who i can Disabiling STP on a single Port? Oliver Cisco 3 01-19-2007 07:17 AM
STP port inconsistent m.mazurek@netsync.pl Cisco 0 04-10-2006 09:19 PM
STP reconverges unless etherchannel port cost set Chris Buzby Cisco 0 10-27-2004 03:12 PM
Help, mouse moves, sticks for a few seconds, then moves... what's up? unbroken Computer Information 8 01-19-2004 04:18 AM



Advertisments