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Beschreibung
Mindmap von Irakli Goksadze, aktualisiert more than 1 year ago
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Erstellt von Irakli Goksadze
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Spanning Tree Protocol
- Versions
- IEEE 802.1D
- IEEE 802.1D
- What Problem(s) can happen without STP
- LOOP///// Some Ethernet frames would loop around the
network for a long time (hours, days, literally forever if the
LAN devices and links never failed).
- unknown-destination unicast frames
- broadcast frames
- Broadcast Storm
- MAC table instability
- Multiple frames received to host
- MAC table instability
- Broadcast Storm
- multicast frames
- STP prevents loops by placing
each switch port in either:
- Blocking State
- do not process any frames except STP messages
(and some other overhead messages). Interfaces
that block do not forward user frames, do not
learn MAC addresses of received frames, and do
not process received user frames.
- do not process any frames except STP messages
(and some other overhead messages). Interfaces
that block do not forward user frames, do not
learn MAC addresses of received frames, and do
not process received user frames.
- Forwarding State
- act as normal, forwarding and receiving frames.
- act as normal, forwarding and receiving frames.
- Blocking State
- unknown-destination unicast frames
- LOOP///// Some Ethernet frames would loop around the
network for a long time (hours, days, literally forever if the
LAN devices and links never failed).
- STP convergence
- process by which the switches collectively
realize that something has changed in the
LAN topology and determine whether
they need to change which ports block
and which ports forward.
- process by which the switches collectively
realize that something has changed in the
LAN topology and determine whether
they need to change which ports block
and which ports forward.
- How STP works
- STP uses 3 criteria to choose whether
to put an interface in forwarding state:
- 3. The switch with the lowest root cost, as compared with the other switches attached to the same link,
is placed in forwarding state.
- That switch is the designated switch, and that switch’s interface, attached to that
segment, is called the designated port (DP).
- That switch is the designated switch, and that switch’s interface, attached to that
segment, is called the designated port (DP).
- 2. Non-root switches select one of its ports as root port.
- Root port (RP) means that it has lowest cost (or nearest path) back to the Root bridge
- root port (RP) is in forwarding state.
- Root port (RP) means that it has lowest cost (or nearest path) back to the Root bridge
- 1. Select Root switch and put all its working ports in forwarding state
- 3. The switch with the lowest root cost, as compared with the other switches attached to the same link,
is placed in forwarding state.
- STP uses 3 criteria to choose whether
to put an interface in forwarding state:
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