Re: Ether Channel Query!!

  That's the trick. Both ports are NOT forwarding. The port-channel IS.
The port-channel is what STP monitors and places in a forwarding state.
It is unaware of the individual ports. On the other side of the cables,
the receiving switch is receiving STP on the port-channel. Not on an
individual port associated with it. So the STP merely hands instructions
to the port-channel interface to send out BPDUs. It doesn't care how
they get there. The Port-channel interface (and associated PAGP/LACP
protocol) are responsible for getting the BPDU across the wire. STP does
not see both ports in a forwarding state.

--Hammer--

On 9/27/2010 11:36 AM, HEMANTH RAJ wrote:
> hey Hameer i m asking about loop avoiding mechanism .If both the ports
> are forwarding and STP is not aware of the both the ports,then thee
> will be a chance of loop forming on that particular channel
>
> On Mon, Sep 27, 2010 at 10:01 PM, --Hammer-- <bhmccie_at_gmail.com
> <mailto:bhmccie_at_gmail.com>> wrote:
>
> Someone step in if I mis-quote something.
>
> You're statement is a bit off. STP is not forwarding on both
> ports. STP is forwarding on the port-channel. STP is no longer
> aware of the individual ports. How the channel handles STP traffic
> is a different matter. I don't think STP sends traffic on both
> ports in a LACP or PAGP channel. I think the L2 protos (STP, CDP,
> DTP, etc) are just passed on the primary link. I'm not where I can
> google this to confirm it. Anyone?
>
> --Hammer--
>
>
> On 9/27/2010 11:25 AM, HEMANTH RAJ wrote:
>> Hey If STP has forwarding both ports, then there will be chance
>> of loop formation
>> wat is the actual mechanism
>> how does it prevent loops at the same time it makes all the ports
>> forwarding
>>
>> can anyone explain me?
>>
>>
>> On Mon, Sep 27, 2010 at 8:39 PM, --Hammer-- <bhmccie_at_gmail.com
>> <mailto:bhmccie_at_gmail.com>> wrote:
>>
>> Thanks Saulat for the quick lab up....
>>
>> --Hammer--
>>
>>
>>
>> On 9/27/2010 9:51 AM, Saulat Ali wrote:
>>
>> The bundled ports wont show up in the sh spantree command
>> unless you
>> type in sh span int<physical port> which will show them
>> in forwarding
>> state. As mentioned by Hammer as soon as you put the
>> physical port into
>> an ether channel spanning tree process only shows the
>> logical port in
>> the sh span tree.
>>
>> See below e.g .. port 1/0/52 and 2/0/52 wont show up in
>> the span tree
>> process but you can view their status by entering sh
>> span<vlan> int gig
>> 1/0/52<detail> command,
>>
>> #sh etherchannel summ
>>
>> Group Port-channel Protocol Ports
>> ------+-------------+-----------+---------------------------------------
>> --------
>> 1 Po1(SU) LACP Gi1/0/52(P) Gi2/0/52(P)
>>
>> #sh run int gig 1/0/52
>> Building configuration...
>>
>> Current configuration : 181 bytes
>> !
>> interface GigabitEthernet1/0/52
>> switchport trunk encapsulation dot1q
>> switchport mode trunk
>> switchport nonegotiate
>> channel-group 1 mode active
>> end
>>
>> #sh run int gig 2/0/52
>> Building configuration...
>>
>> Current configuration : 181 bytes
>> !
>> interface GigabitEthernet2/0/52
>> switchport trunk encapsulation dot1q
>> switchport mode trunk
>> switchport nonegotiate
>> channel-group 1 mode active
>> end
>>
>> #sh run int po1
>> Building configuration...
>>
>> Current configuration : 144 bytes
>> !
>> interface Port-channel1
>> switchport trunk encapsulation dot1q
>> switchport mode trunk
>> switchport nonegotiate
>> end
>>
>>
>> #sh span vlan 2
>> VLAN0002
>> Spanning tree enabled protocol rstp
>> Root ID Priority 24578
>> Address 0022.be9f.ab80
>> This bridge is the root
>> Hello Time 2 sec Max Age 20 sec Forward
>> Delay 15 sec
>>
>> Bridge ID Priority 24578 (priority 24576 sys-id-ext 2)
>> Address 0022.be9f.ab80
>> Hello Time 2 sec Max Age 20 sec Forward
>> Delay 15 sec
>> Aging Time 300
>>
>> Interface Role Sts Cost Prio.Nbr Type
>> ---------------- ---- --- --------- --------
>> --------------------------------
>> Po1 Desg FWD 3 128.616 P2p
>>
>>
>> #sh spanning-tree vlan 2 int gi2/0/52 de
>> Port 616 (Port-channel1) of VLAN0002 is designated
>> forwarding
>> Port path cost 3, Port priority 128, Port Identifier
>> 128.616.
>> Designated root has priority 24578, address 0022.be9f.ab80
>> Designated bridge has priority 24578, address
>> 0022.be9f.ab80
>> Designated port id is 128.616, designated path cost 0
>> Timers: message age 0, forward delay 0, hold 0
>> Number of transitions to forwarding state: 1
>> Link type is point-to-point by default
>> BPDU: sent 25045070, received 73
>>
>> #sh spanning-tree vlan 2 int gig1/0/52 de
>> Port 616 (Port-channel1) of VLAN0002 is designated
>> forwarding
>> Port path cost 3, Port priority 128, Port Identifier
>> 128.616.
>> Designated root has priority 24578, address 0022.be9f.ab80
>> Designated bridge has priority 24578, address
>> 0022.be9f.ab80
>> Designated port id is 128.616, designated path cost 0
>> Timers: message age 0, forward delay 0, hold 0
>> Number of transitions to forwarding state: 1
>> Link type is point-to-point by default
>> BPDU: sent 25045075, received 73
>>
>> #sh spanning-tree vlan 2 int po1 de
>> Port 616 (Port-channel1) of VLAN0002 is designated
>> forwarding
>> Port path cost 3, Port priority 128, Port Identifier
>> 128.616.
>> Designated root has priority 24578, address 0022.be9f.ab80
>> Designated bridge has priority 24578, address
>> 0022.be9f.ab80
>> Designated port id is 128.616, designated path cost 0
>> Timers: message age 0, forward delay 0, hold 0
>> Number of transitions to forwarding state: 1
>> Link type is point-to-point by default
>> BPDU: sent 25045080, received 73
>>
>> -----Original Message-----
>> From: nobody_at_groupstudy.com
>> <mailto:nobody_at_groupstudy.com>
>> [mailto:nobody_at_groupstudy.com
>> <mailto:nobody_at_groupstudy.com>] On Behalf Of
>> CCIE KID
>> Sent: 27 September 2010 15:29
>> To: --Hammer--
>> Cc: ccielab_at_groupstudy.com <mailto:ccielab_at_groupstudy.com>
>> Subject: Re: Ether Channel Query!!
>>
>> Hey can u explain me the process and what r the packets
>> exchanged so
>> that
>> how does STP come to know that that the particular port
>> is bundled
>>
>> What will be in the sh spanning-tree detail for that
>> particular port
>> which
>> is been blocking
>> Whether it will be of forwarding state
>>
>> That bundled link will be in which state in forwarding
>> state in STP ah??
>> pls brief me about that??
>>
>> On Mon, Sep 27, 2010 at 7:51 PM,
>> --Hammer--<bhmccie_at_gmail.com <mailto:bhmccie_at_gmail.com>>
>> wrote:
>>
>> CCIE KID,
>> When you "bond" the two physical interfaces into a
>> logical port
>>
>> channel,
>>
>> you will pass traffic over both Fa0/1 and Fa0/2. STP
>> treats the entire
>> collection of physical interfaces as a single logical
>> port. This is
>>
>> all
>>
>> negotiated between the endpoints. Does that help?
>>
>> --Hammer--
>>
>>
>>
>> On 9/27/2010 9:17 AM, CCIE KID wrote:
>>
>> I have a doubt in ether Channel
>>
>> This is my scenario
>>
>> SW1
>> fa0/1-------------------------------------------fa 0/1
>> SW2
>>
>> fa0/2-------------------------------------------fa 0/2
>>
>> In STP SW1 is the root bridge and SW2 is the non
>> root bridge , In SW2
>>
>> fa
>>
>> 0/1
>> is in forwarding state and fa 0/2 is in blocking
>> state .
>> So in Ether channel, if we bundle fa0/1 and fa
>> 0/2 ,traffic cannot be
>> passed
>> through fa 0/2 .
>> How Ether Channel informs STP about the bundling
>> and makes the fa 0/2
>>
>> into
>>
>> forwarding
>> Can anyone explain me the process
>> I am expecting the experts to explain
>>
>>
>>
>> With Warmest Regards,
>>
>> CCIE KID
>> IN PURSUIT OF CCIE
>>
>>
>> Blogs and organic groups at http://www.ccie.net
>>
>>
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>>
>>
>>
>>
>>
>>
>>
>>
>> --
>> Problems arise Bcoz we talk,prblms r not solve bcoz we dont talk
>> So gud r bad talk to ur affectionate one's freely
>>
>> Urs Friendly,
>> HP HEMANTH RAJ
>
>
>
>
> --
> Problems arise Bcoz we talk,prblms r not solve bcoz we dont talk So
> gud r bad talk to ur affectionate one's freely
>
> Urs Friendly,
> HP HEMANTH RAJ

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Received on Mon Sep 27 2010 - 11:42:12 ART