Link down due to STP
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Posted by Andreas Heinzelmann on June 18, 2008, 4:05 am
Please log in for more thread options I have a basic question. When STP is putting a port in Blocking mode is the physical connection to the port down as well? I had the problem that on one port the link to a server was down right after the port was in STP blocking state. Maybe one could give me an explaination on this. Thanks...Andy | |||||||||||||||||||||||||||||||
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Posted by Sam Wilson on June 18, 2008, 5:30 am
Please log in for more thread options No. The port has to stay up to keep receiving STP BPDUs even though it doesn't forward any traffic. > I had the problem that on one port the link to a server was down right after
> the port was in STP blocking state. > > Maybe one could give me an explaination on this. Dunno - sorry. Sam | |||||||||||||||||||||||||||||||
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Posted by Andreas Heinzelmann on June 18, 2008, 7:29 am
Please log in for more thread options
>
>> I have a basic question. When STP is putting a port in Blocking mode is
>> the >> physical connection to the port down as well? >
> No. The port has to stay up to keep receiving STP BPDUs even though it > doesn't forward any traffic. So a host on the port should not notice it at all, right? >> I had the problem that on one port the link to a server was down right
>> after >> the port was in STP blocking state. >> >> Maybe one could give me an explaination on this. >
> Dunno - sorry. > > Sam | |||||||||||||||||||||||||||||||
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Posted by Sam Wilson on June 18, 2008, 9:49 am
Please log in for more thread options
> >
> >> I have a basic question. When STP is putting a port in Blocking mode is
> >> the > >> physical connection to the port down as well? > >
> > No. The port has to stay up to keep receiving STP BPDUs even though it > > doesn't forward any traffic. >
> So a host on the port should not notice it at all, right? Err... no, but why would a switch block a port that a host was attached to? Sam | |||||||||||||||||||||||||||||||
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Posted by Stephen on June 18, 2008, 5:41 pm
Please log in for more thread options wrote:
>
>> >
>> >> I have a basic question. When STP is putting a port in Blocking mode is >> >> the >> >> physical connection to the port down as well? >> > >> > No. The port has to stay up to keep receiving STP BPDUs even though it >> > doesn't forward any traffic. >>
>> So a host on the port should not notice it at all, right? >
>Err... no, but why would a switch block a port that a host was attached >to? 1. because someone turned on bridging in the host, and spanning tree is doing exactly what it should as this is a loop bridging in windows XP sometimes gives this kind of hassle, but shouldnt be on a server.... 2. the host has the same MAC address on all ports and the switch got confused and put 1 port in err-disable (used to be common on a Sun box) 3. 1 of the wierd mix ups that sometimes happen with link aggregation - not setting it up on both ends, or mixing 802.1ad with cisco port aggregation.... any more? slightly related - latest one i seem to get is Ethernet WAN links that reflect packets when there is an error (or when the transmission engineers are testing - they insist on looping circuits). cisco routers dont seem to mind too much, but a Catalyst will err disable the port very quickly - and they dont auto recover by default.... >
--
>Sam Regards stephen_hope@xyzworld.com - replace xyz with ntl | |||||||||||||||||||||||||||||||
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> physical connection to the port down as well?