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اتمنى كتابت الموضوع في القسم المناسب
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STP هي ال CSTP ودي العاديه 802.1d
RSTP ودي القللنا فيها الوقت
PVST ودي العملنا ال STP على كل VLAN
Rapid-PVST ودي العملنا RSTP على كل VLAN
+ يعني بتدعم ال 802.1q
واتفضل الملخص ده من اعدادي
انشاء الله يفيدك
واي سؤال انا تحت امرك
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Spanning Tree
-802.1D
Broadcast storm: loop until shut the path.
Flooding: Forward broadcasts and multicasts out all ports except the one in which send it.
STP must select:
- one root bridge
- one root port per non root bridge
- one designated port per network segment
Root Bridge
- Lowest Bridge ID (BID): priority and MAC address
Root Port
- Lowest path cost to the root bridge.
- Lowest bridge ID (BID).
- Lowest sender port ID (PID): f 0/1 best f 0/2 (NOTE: SENDER)
Remember:
- Bridge Priority: 2 byte 0-->65,535 by default 32,768
(or 32,768 plus the VLAN ID, if the extended system ID is enabled
4-bit priority, plus a 12-bit VLAN ID, system ID value= VID)
config)# spanning-tree extend system-id
- Port priority
- Path cost: between the bridge to root
STP Costs:
10 Mb/s Ethernet --> 100
100 Mb/s Fast Ethernet --> 19+
1 Gbps Giga Ethernet --> 4
10 Gbps 10 Giga Ethernet --> 2
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Bridge Protocol Data Units (BPDU)
TCN (Topology Change Notification)
There are 2 types of BPDU:
- (Configuration BPDU) send every 2 seconds from the root toward the downstream switches
* During election.
* Maintain connectivity between switches.
* Send timer information from the root.
- (TCN BPDU) send from downstream to root switch when:
* Link failure.
* A port starts forwarding.
* The switch receives TCN from neighbor.
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Per-VLAN Spanning-Tree (PVST+) or RPVST+
-it’s enabling by default in Cisco’s switch (only Cisco)
- Each vlan has BID, root bridge, root port and so on ……..
- Support 802.1q but the pvst don’t
- Work with RSTP but the PVST work individual(CSTP)
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Configuration Spanning Tree
config)# spanning-tree vlan 5,100-200 priority 100
config)# spanning-tree vlan 5 root primary | secondary
-if)# spanning-tree cost 1 ( Access port)
-if)# spanning-tree vlan 7 cost 10 (Trunk port)
CONFIG)#SPANNING-TREE MODE PVST
Verification
show spanning-tree
show spanning-tree vlan 9 (special vlan)
show spanning-tree interface fa 0/1 ( special interface)
show spanning-tree bridge brief
show interface trunk (witch vlans are allowed and passes)
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RSTP (Rapid STP)
- 802.1w--> after 2004 802.1D ( in exam is stilling 802.1w)
- Discarding= Blocking, Disabled and listening.
- Discarding to forwarding if not receive 3 BPDU
- Alternate port= Backup to the root port.
- Backup port= Backup to designated port.
- Edge port= connected to end user
- Disabled port= not used in Rapid STP
- BPDU: each switches originates BPDU.
- RSTP similar BackboneFast: accept BPDU if there another path to root it become alternative path.
- Edge port: same as Portfast ports (automatically)--> if receive BPDU the switch will send TCN BPDU
- Backup and Alternate ports: similar UplinkFast ports is forwarding if not received BPDU from neighbor.
- config)# spanning-tree mode rapid-pvst
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Multiple Spanning Tree (MST)
-802.1S
-Root for group of VLANs
-stop pvst+ or rpvst+
- all switch belong the same region must apply MST
config)#spanning-tree mode mst
config)#spanning-tree mst configuration
-mst)#name AHMED (same region)
-mst)#revision 1 (same)
-mst)#instance 3 vlan 1-100
config)#spanning-tree mst 3 priority 200
show spanning-tree mst
NOW this switch work with multi-vlan as one vlan
and the vlan 1 to 100 have priority 200
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STP to Protected the network
PortFast (benefit in CST and RSTP)
-Cisco-proprietary, Speed up network, Access port.
- STP not block --> shut to on is forwarding immediately.
config)# spanning-tree portfast default
then
-if)# no spanning-tree portfast ( in trunk port)
OR
-if)# spanning-tree portfast (in access port)
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UplinkFast (benefit in CST)
- Identify backup ports for root port (direct switch)
-called uplink group
- if root fails one of group be unblock
-bypass listing and learning stages
config)#spanning-tree uplinkfast
-------------------------------------------------------------------
BackboneFast (benefit in CST)
- detect alternative path to root (indirect switch)
- Inferior BPDUs are sent from a designated bridge that has lost its connection to the root.
- Normally the switch wait MAX age but with BackboneFast If the inferior BPDU was received on
* Blocked port, the root port and blocked ports are considered alternate.
* Root port, all blocked ports are considered alternates.
* Root port and there are no blocked ports, the switch assumes it has lost
connectivity with the root and advertises itself as root.
config)# spanning-tree backbonefast
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BPDU Guard
- prevents loops if another switch attached to portfast port.
- error-disabled if received BPDU.
config)# spanning-tree portfast bpduguard default (all portfast interfaces)
- if)# spanning-tree bpduguard enable
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BPDU Filtering
- prevent loops if another switch attached to portfast port.
-don’t send or receive bpdu if receive it, disable portfast and work normally STP
config)# spanning-tree portfast bpdufilter default
-if)# spanning-tree bpdufilter enable
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Root Guard
- prevent other switch to be root.
- root-inconsistent state meant receive BPDU and not pass traffic
-if)# spanning-tree guard root
show spanning-tree inconsistent
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Unidirectional--> that link can be send data but not receive it.
UDLD (Unidirectional Link Detection)
- if Physical connection broken (benefit)
- send hello out to interface (ping)
- Two Models: normal and aggressive.
-Normal: is undetermined state if hellos are not return.
-Aggressive: is error-disabled if unidirectional link.
- specific fiber interface
config)# udld enable | aggressive ( for all fiber interface) recommend
-if)# udld port aggressive
#udld reset (to re-enable all interface shutdown by udld)
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Loop Guard
- if link not receive BPDU.
- state is loop inconsistent.
- more effective with udld
config)# spanning-tree loopguard default
-if)# spanning-tree guard loop
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This process of forwarding a single frame around and around between two switches is
known as a bridging loop.
.
المشاركة الأصلية كتبت بواسطة Eng.AhmedAmin
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