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Spanning Tree - Backbone Fast

Posted by markmark1983 , 16 August 2013 - - - - - - · 2,448 views

Cuurently login on a switch with a BLK port.

Interface Role Sts Cost   Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa0/12    Desg FWD 19 128.14   Edge P2p
Fa0/15    Root FWD 19 128.17   P2p
Fa0/18    Altn BLK 19 128.20   P2p


Assuming the upstream switch where the BLK port is connected, has lost its...


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Spanning Tree - Uplink Fast:

Posted by markmark1983 , 15 August 2013 - - - - - - · 1,248 views

Note: UplinkFast only works when the switch has blocked ports. The feature is typically designed for an
access switch that has redundant blocked uplinks. When you enable UplinkFast, it is enabled for the entire
switch and cannot be enabled for individual VLANs


CAM Table Update
Once UplinkFast has achieved a fast−switchover between two uplinks, the...


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Spanning Tree Portfast:

Posted by markmark1983 , 14 August 2013 - - - - - - · 1,040 views

Normal port connected to a PC is set to access , the spanning tree state is FWD.
If the interface goes down, the switch will generate a TCN - topology change notice, informing the root.

The root will in turn max age all mac address associated to all spanning tree domain. All switches will flush out the mac-address.

When the port comes up, the port will...


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Spanning Tree Events

Posted by markmark1983 , 14 August 2013 - - - - - - · 799 views

tsc_lab_sw4(config-if)#
*Mar  4 23:08:57: STP: VLAN0020 new root port Fa0/18, cost 38
*Mar  4 23:08:57: STP: VLAN0020 Fa0/18 -> listening
*Mar  4 23:08:59: %LINK-5-CHANGED: Interface FastEthernet0/15, changed state to administratively down
*Mar  4 23:08:59: STP: VLAN0020 sent Topology Change Notice on Fa0/18
*Mar  4 23:09:00: %LINEPROTO-5-UPDOWN: Line...


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STP loop from carrier

Posted by markmark1983 , 14 August 2013 - - - - - - · 851 views

NOTE THE SPANNING TREE STATES IN THE VLAN UNDER THE INTERFACE. THEY ALL TRANSITIONED TO BLK STATES.
THIS IS JUST A SINGLE L2 PATH , REASON IS THAT THE MAC ADDRESS I LEARNED FROM THE INTERFACES WAS ALSO RECEIVED FROM THE SAME SWITCH.

DEVICE 0 SWITCH - CARRIER - SWITCH - DEVICE


It seems there was a loop in the carrier network as we are seeing mac address...


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Native Vlans

Posted by markmark1983 , 07 August 2013 - - - - - - · 291 views

native vlans , are vlans sent across the trunk that are untagged. (meaning, it is not taqgged or encapsulated with a 802.1q header).

Example of this:

Connect a router on a switch.
Configure vlans 10, 20, .
Configure another vlan 13 - to be used as a native:

trunk the switch to router: (note of the native statement under the interface)

interface...


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Resetvlan info / vtp info

Posted by markmark1983 , 07 August 2013 - - - - - - · 309 views

To reset vlan / vtp info, delete the vlan.dat file in flash, and reload the switch


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Etherchannel L2 - L3

Posted by markmark1983 , 07 August 2013 - - - - - - · 363 views

Etherchannel for L2 is pertty straightforward:

However for L3, there must be some operational order:

If you configured the channel - group in the interface befre applying the " no switchport" command, the port channel that will be generated is a L2, and will cause the status of the port channel to be down.

The correct way is to issue  the...


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Static nat statement

Posted by markmark1983 , 01 August 2013 - - - - - - · 274 views

Failure to modify static nat replacement:

Systems says " nat busy " or something related to that:

Need to perform either one or all of the following:

1. Remove ip nat " inside and outside " staements on the interface
2. clear ip nat tables
3. shutdown any snat  and lan interfaces using hsrp
4. shutdown any interconnection between two...


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SPAN and RSPAN

Posted by markmark1983 , 26 April 2013 - - - - - - · 308 views

SPAN commands using filter.

monitor session 1 source interface Fa0/5
monitor session 1 filter vlan 229
monitor session 1 destination interface Fa0/19




no monitor session 61
monitor session 61 source interface Fa0/1
monitor session 61 filter vlan 71 , 3405
monitor session 61 destination interface Fa0/3

no monitor session 62
monitor session 62 source...






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