RE: [Bridge] Election of root port

RE: [Bridge] Election of root port

[Jeff Gercken]

STP root port selection is based on port priority which, by default, is
based upon the interface speed.  If they're equal I believe the lowest
port address wins.
http://www.hojmark.net/stp-port-cost.html

You're talking switches right?  Why post to a bridge list?  You'd be
better off at http://www.tek-tips.com/threadminder.cfm?pid=558

-Jeff

-----Original Message-----
From: bridge-bounces@lists.osdl.org
[mailto:bridge-bounces@lists.osdl.org] On Behalf Of sameer
Sent: Thursday, August 04, 2005 4:39 AM
To: bridge@lists.osdl.org
Subject: [Bridge] Election of root port

Hi,

I have a situation where in there are 2 switches A and B.

port 0 of A is connected to port 0 of B
port 1 of A is connected to port 1 of B

all the four ports are in auto negotiation and 100mbps

Last byte of MAC of A = 7F
Last byte of MAC of B = 7E
(remaining bytes of the MAC address are identical)

Considering the switch B will be elected as root bridge which port of
switch A will be root port.

Will this configuration work perpetually?

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[Bridge] Designated port Selection

[Prasenjit Manna]

Hi,

I have two questions:

1. br_designated_port_selection() in br_stp.c:
    In this function, the port, which is not DISABLED and
    br_should_become_designated_port, then the port is becoming
    designated port.

    Question: Why the port state(DISABLED) is checking here? According to
              standard, there should not be any checking for disabled.

2. br_stp_set_bridge_priority() in br_stp_if.c:
    In this function also, the same DISABLED checking is done.

    Question: Why the port state(DISABLED) is checking here also for
              updating the bridge priority?


Thanks and Regards,
Prasenjit

Re: [Bridge] Designated port Selection

[Prasenjit Manna]

I am sending this mail once again.
Please have a look and give me some suggestions.

Prasenjit Manna wrote:
> Hi,
> 
> I have two questions:
> 
> 1. br_designated_port_selection() in br_stp.c:
>    In this function, the port, which is not DISABLED and
>    br_should_become_designated_port, then the port is becoming
>    designated port.
> 
>    Question: Why the port state(DISABLED) is checking here? According to
>              standard, there should not be any checking for disabled.
> 
> 2. br_stp_set_bridge_priority() in br_stp_if.c:
>    In this function also, the same DISABLED checking is done.
> 
>    Question: Why the port state(DISABLED) is checking here also for
>              updating the bridge priority?
> 
> 
> Thanks and Regards,
> Prasenjit
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