Re: Ether Channel Query!!

Should have attached the below, as you see, the frame wasn't seen coming
from port 13, 14 or 15, it was seen coming from the port-channel.

SW2#sh mac-address-table
           Mac Address Table
-------------------------------------------

Vlan Mac Address Type Ports
---- ----------- -------- -----

    1 000e.83cd.a88e DYNAMIC Po10

SW2#sh etherchannel summary
Flags: D - down P - in port-channel
         I - stand-alone s - suspended
         H - Hot-standby (LACP only)
         R - Layer3 S - Layer2
         U - in use f - failed to allocate aggregator
         u - unsuitable for bundling
         w - waiting to be aggregated
         d - default port

Number of channel-groups in use: 1
Number of aggregators: 1

Group Port-channel Protocol Ports
------+-------------+-----------+-----------------------------------------------
10 Po10(SU) - Fa0/13(P) Fa0/14(P) Fa0/15(P)

On 27/09/2010 18:06, Paul Cocker wrote:
> If a switch doesn't have an entry in its mac-address-table for a
> particular destination, it forwards the frame out of all ports
> (including port channels) EXCEPT the port it was received on. When there
> are loops in the topology, this can cause a storm, as it can keep coming
> back around.
>
> Are we agreed so far?
>
> In your case, the frame is received on a port-channel. So, if the switch
> doesn't know the destination mac, it will be forwarded out all ports in
> that vlan (including other port channels), except the port-channel that
> it was received on.
>
> Hey presto, no switching loop.
>
> Regards,
> Paul
>
>
> On 27/09/2010 17:47, HEMANTH RAJ wrote:
>> yeah Hammer u right ,But my question is how that LACP/PagP protocols
>> handle
>> and sends the traffic to the destination without any formation of loop
>>
>> In reality if there are two ports which is forwarding and there will be a
>> formation of loop,MAC table instability which results in a broadcast
>> storm
>> how does it is not happening?
>>
>>
>>
>> On Mon, Sep 27, 2010 at 10:12 PM, --Hammer--<bhmccie_at_gmail.com> wrote:
>>
>>> 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> 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> 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] On
>>>>>> Behalf Of
>>>>>> CCIE KID
>>>>>> Sent: 27 September 2010 15:29
>>>>>> To: --Hammer--
>>>>>> Cc: 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> 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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>>>>>>>
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>>>>>>>
>>>>>>
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>>>>>>>
>>>>>>
>>>>>
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>>>>>
>>>>> _______________________________________________________________________
>>>>>
>>>>> Subscription information may be found at:
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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 - 18:15:41 ART