[c-nsp] MACFLAP loop with l2pt

[Erik Klaassen]

Solved by protecting the port with guard loop.
Guard loop for the sudden loss of bpdu's on nondesignated ports.

Weird this is not mentioned in the l2pt docs, very plausible to happen.

Erik



----- Oorspronkelijk bericht -----
Van: "Erik Klaassen" <e.klaassen at fr-ix.nl>
Aan: "Aaron" <aaron1 at gvtc.com>, cisco-nsp at puck.nether.net
Verzonden: Zaterdag 31 augustus 2013 11:58:23
Onderwerp: Re: [c-nsp] MACFLAP loop with l2pt

No port-fast on any port. i am using r-pvst.
Before is goes in fwd it is first learning indeed.

should a port go fwd when its not receiving stp bpdu's? 

Is this a wrong implementation of l2pt for stp?

Erik

----- Oorspronkelijk bericht -----
Van: "Aaron" <aaron1 at gvtc.com>
Aan: "Erik Klaassen" <e.klaassen at fr-ix.nl>, cisco-nsp at puck.nether.net
Verzonden: Vrijdag 30 augustus 2013 17:13:08
Onderwerp: RE: [c-nsp] MACFLAP loop with l2pt

Are you port-fasting that sw2 g0/1 trunk interface ?  I'm wondering why it
goes straight to fwd prior to listening and learning ?  ...i thought it
would blk, list, learn, fwd...

Aaron

-----Original Message-----
From: cisco-nsp [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Erik
Klaassen
Sent: Friday, August 30, 2013 8:36 AM
To: cisco-nsp at puck.nether.net
Subject: [c-nsp] MACFLAP loop with l2pt

Hello,

I have created a l2pt between sw1-gi0/1 and sw2-gi0/1 so both switches are
logical connected.
The te1/1 interface has the lowest cost so gi0/1 in sw2 goes in BLK state.
When the connection between sw4 and the isp swich goes down, the link
between sw2 and sw4 stays up but no bpdu's are received.
gi0/1 in sw then goes in FWD state. So when the link between sw4 and isp
comes up you have loop till some bpdu is received on sw2 gi0/1. 

How can i prevent this interface going in fwd state? What am i missing?

Kind regards
Erik



                     gi0/1 do1q      gi0/1 access vlan 170
                     vlan23          mode dot1q-tun, l2pt stp
      +-----------------+              +-----------+
      |  sw1 root br    +--------------> sw3       |
      |                 |              |           |
      +-+---------------+              +-----+-----+
        | te1/1 vlan 23                      |
        |                                    |
        |                                    |  trunk dot1q vlan 170
        |                                    |
        |                           +--------v---------+
        |                           |   isp l2 network |    non cisco
        |                           +--------^---------+
        |                                    |
        |                                    |
        |                                    |
        |                                    | trunk dot1q vlan 170
        |                                    |
        |te1/1 vlan23                        |
      +-v----------------+            +------+----+
      | sw2              |X           |sw4        |
      |                  +------------>           |
      +------------------+            +-----------+
                   gi0/1 dot1q       gi0/1 access vlan 170
                   vlan 23           mode dot1q-tun, l2pt stp
_______________________________________________
cisco-nsp mailing list  cisco-nsp at puck.nether.net
https://puck.nether.net/mailman/listinfo/cisco-nsp
archive at http://puck.nether.net/pipermail/cisco-nsp/

_______________________________________________
cisco-nsp mailing list  cisco-nsp at puck.nether.net
https://puck.nether.net/mailman/listinfo/cisco-nsp
archive at http://puck.nether.net/pipermail/cisco-nsp/