rstp mstp marvin
DESCRIPTION
RSTPTRANSCRIPT
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Rapid Spanning Tree ProtocolPer VLAN Spanning Tree
Multiple Spanning Tree Protocol
RSTP and MSTP
Marvin Rambhadjan
UvA
February 25, 2010
Marvin Rambhadjan RSTP and MSTP
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Rapid Spanning Tree ProtocolPer VLAN Spanning Tree
Multiple Spanning Tree Protocol
Overview
Rapid Spanning Tree Protocol
Per VLAN Spanning Tree
Multiple Spanning Tree Protocol
Marvin Rambhadjan RSTP and MSTP
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Rapid Spanning Tree ProtocolPer VLAN Spanning Tree
Multiple Spanning Tree Protocol
Rapid Spanning Tree Protocol
IEEE 802.1w 1998
Underlying protocol MSTP
I Similarities with STPI Calculate the same spanning tree topology with the same
configuration
I Differences with STPI Faster conversion timesI Different port states and new port rolesI Different definition topology changeI BPDUs used for Hello mechamism
Marvin Rambhadjan RSTP and MSTP
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Rapid Spanning Tree ProtocolPer VLAN Spanning Tree
Multiple Spanning Tree Protocol
RSTP Port States and Roles
I Port States
Forwarding MAC LearningForwarding traffic
Learning MAC LearningNo forwarding traffic
Disabled No MAC learningNo forwarding traffic
I Port Roles
Root Port Port to higher segments (to the Root Bridge)Designated Port Port to lower segmentsAlternate Port Backup Root PortBackup Port Backup Designated PortDisabled Port Not participating in RSTP
Marvin Rambhadjan RSTP and MSTP
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Rapid Spanning Tree ProtocolPer VLAN Spanning Tree
Multiple Spanning Tree Protocol
Port Roles
Marvin Rambhadjan RSTP and MSTP
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Rapid Spanning Tree ProtocolPer VLAN Spanning Tree
Multiple Spanning Tree Protocol
Definition Topology Change
I STPI A Forwarding or Listening state port that transits to Blocking (lost
connection)I A port that transits in Forwarding state, while the switch already has
a Designated port (new connection)
I RSTPI Non-Edge port that transits in Forwarding (new connection)
Marvin Rambhadjan RSTP and MSTP
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Rapid Spanning Tree ProtocolPer VLAN Spanning Tree
Multiple Spanning Tree Protocol
Rapid transit to Forwarding
I Edge PortsI End stationsI Not part of spanning tree process
I Point to PointI Connection between switchesI Proposal and Agreement mechanism
Marvin Rambhadjan RSTP and MSTP
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Rapid Spanning Tree ProtocolPer VLAN Spanning Tree
Multiple Spanning Tree Protocol
Proposal and Agreement Mechanism
If a designated port wants to transits into a non-discarding state, theupstream switch will do the following in order to agree with thedownstream switch.
1. Upstream Bridge sends proposal on Designated Port
2. Downstream Bridge receives proposalI If it agrees on port role, it starts synchronization.I If it not agree on the proposal, it will send is own proposal
3. Downstream Bridge blocks all non-edge Designated Ports and sendAgreement to upstream bridge
4. Synchronization is needed to make sure there are no loops in thetopology when when the upstream bridge unblocks its DesignatedPort
Marvin Rambhadjan RSTP and MSTP
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Rapid Spanning Tree ProtocolPer VLAN Spanning Tree
Multiple Spanning Tree Protocol
Proposal and Agreement
www.cisco.com
Marvin Rambhadjan RSTP and MSTP
-
Rapid Spanning Tree ProtocolPer VLAN Spanning Tree
Multiple Spanning Tree Protocol
Proposal and Agreement
www.cisco.com
Marvin Rambhadjan RSTP and MSTP
-
Rapid Spanning Tree ProtocolPer VLAN Spanning Tree
Multiple Spanning Tree Protocol
Proposal Agreement
www.cisco.com
Marvin Rambhadjan RSTP and MSTP
-
Rapid Spanning Tree ProtocolPer VLAN Spanning Tree
Multiple Spanning Tree Protocol
Proposal Agreement
www.cisco.com
Marvin Rambhadjan RSTP and MSTP
-
Rapid Spanning Tree ProtocolPer VLAN Spanning Tree
Multiple Spanning Tree Protocol
Proposal Agreement
www.cisco.com
Marvin Rambhadjan RSTP and MSTP
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Rapid Spanning Tree ProtocolPer VLAN Spanning Tree
Multiple Spanning Tree Protocol
Topology Changes
TC DetectionI Start TC While timer (2x Hello-Time) on all Non-Edge designated
and root portsI Flush all MAC addresses on these portsI Sends BPDUs with TC bit set, while TC While timer has not expired
TC PropagationI Flush all MAC addresses on all ports except receiving portI Start TC While timer and sends BPDUs with TC bit set on all
Designated and Root portsI TCN not longer used
Marvin Rambhadjan RSTP and MSTP
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Rapid Spanning Tree ProtocolPer VLAN Spanning Tree
Multiple Spanning Tree Protocol
Per VLAN Spanning Tree
I Many different variantsI ProprietaryI For both STP and RSTP
I Load BalancingI Create independent spanning tree instances
Marvin Rambhadjan RSTP and MSTP
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Rapid Spanning Tree ProtocolPer VLAN Spanning Tree
Multiple Spanning Tree Protocol
Single Spanning Tree
I Not all connections are used
Marvin Rambhadjan RSTP and MSTP
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Rapid Spanning Tree ProtocolPer VLAN Spanning Tree
Multiple Spanning Tree Protocol
Per VLAN Spanning Tree
I 10 Root BridgesI 10 BPDUsI 10 Spanning Tree calculations
Marvin Rambhadjan RSTP and MSTP
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Rapid Spanning Tree ProtocolPer VLAN Spanning Tree
Multiple Spanning Tree Protocol
Multiple Spanning Tree Protocol
IEEE 802.1s 2003
Built on RSTP
I MSTP vs (R)STPI Use all links
I MSTP vs PVSTI Minimize overhead
I Introduction RegionsI Two-Level HierarchyI Multiple independent Spanning Tree Instances
Marvin Rambhadjan RSTP and MSTP
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Rapid Spanning Tree ProtocolPer VLAN Spanning Tree
Multiple Spanning Tree Protocol
MSTP Terminology
I CIST Common Internal Spanning TreeI Topology of all switches in all regions
I CST Common Spanning TreeI Topology of all pseudo bridges
I IST (MSTI0) Internal Spanning TreeI Spanning Tree within a regionI Can communicate with other regionsI Root Bridge election first based on External Path Cost
I MSTIn Multiple Spanning Tree Instance nI Spanning Tree within a regionI Cannot communicate with other regions
Marvin Rambhadjan RSTP and MSTP
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Rapid Spanning Tree ProtocolPer VLAN Spanning Tree
Multiple Spanning Tree Protocol
MSTP parameters
I MSTP Region parametersI VLAN-to-instance mappingI Configuration NameI Configuration Revision
I Root Priority per MSTII Path cost per MSTII Port Priority per MSTI
Marvin Rambhadjan RSTP and MSTP
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Rapid Spanning Tree ProtocolPer VLAN Spanning Tree
Multiple Spanning Tree Protocol
Example IST
Marvin Rambhadjan RSTP and MSTP
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Rapid Spanning Tree ProtocolPer VLAN Spanning Tree
Multiple Spanning Tree Protocol
Example MSTIs
Marvin Rambhadjan RSTP and MSTP
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Rapid Spanning Tree ProtocolPer VLAN Spanning Tree
Multiple Spanning Tree Protocol
MSTP Multi Region
I Every region becomes a pseudo-bridgeI Topology of pseudo-bridges is called CSTI CST has no idea of internal MSTP regions
Hierarchy
I First LayerI Common Internal Spanning Tree (CIST)I Collection of Internal Spanning Tree (IST)
I Second LayerI Internal Spanning Tree (IST)I Multiple Spanning Tree Instance(s) (MSTI)
Marvin Rambhadjan RSTP and MSTP
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Rapid Spanning Tree ProtocolPer VLAN Spanning Tree
Multiple Spanning Tree Protocol
Example MSTP Multi Region Topology
Marvin Rambhadjan RSTP and MSTP
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Rapid Spanning Tree ProtocolPer VLAN Spanning Tree
Multiple Spanning Tree Protocol
Example MSTP Multi Region Root Ports
Marvin Rambhadjan RSTP and MSTP
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Rapid Spanning Tree ProtocolPer VLAN Spanning Tree
Multiple Spanning Tree Protocol
Example MSTP Multi Region Designated Ports
Marvin Rambhadjan RSTP and MSTP
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Rapid Spanning Tree ProtocolPer VLAN Spanning Tree
Multiple Spanning Tree Protocol
Example MSTP Multi Region CIST
Marvin Rambhadjan RSTP and MSTP
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Rapid Spanning Tree ProtocolPer VLAN Spanning Tree
Multiple Spanning Tree Protocol
Example MSTP Pseudo-Bridges CST
Marvin Rambhadjan RSTP and MSTP
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Rapid Spanning Tree ProtocolPer VLAN Spanning Tree
Multiple Spanning Tree Protocol
Example MSTP Within a Region
Marvin Rambhadjan RSTP and MSTP
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Rapid Spanning Tree ProtocolPer VLAN Spanning Tree
Multiple Spanning Tree Protocol
Example MSTP Within a Region
Marvin Rambhadjan RSTP and MSTP
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Rapid Spanning Tree ProtocolPer VLAN Spanning Tree
Multiple Spanning Tree Protocol
Bridge Protocol Data Unit
Octet BPDU Content
1 - 2 Protocol Identifier Spanning Tree Protocol 0x0000
3 Protocol Version Identifier Multiple Spanning Tree 3
4 BPDU Type Rapid/Multiple Spanning Tree (0x02)
5 CIST Flags
6 - 13 CIST Root Identifier
14 - 17 CIST External Path Cost
18 - 25 CIST Regional Root Iden-tifier
26 - 27 CIST Port Identifier
28 - 29 Message Age
30 - 31 Max Age
32 - 33 Hello Time
34 - 35 Forward Delay
36 Version 1 Length 0
37 - 38 Version 3 Length Number of octets in MSTP extension64 octets MSTP Extension & 16 octetsper MSTI
39 - 102 MSTP ExtensionMarvin Rambhadjan RSTP and MSTP
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Rapid Spanning Tree ProtocolPer VLAN Spanning Tree
Multiple Spanning Tree Protocol
Bridge Protocol Data Unit
Octet MSTP Extension Content
39 MST Config ID Format Selector 0
40 -71 MST Config Name
72 - 73 MST Revision
74 - 89 MST Config Digest
90 - 93 CIST Internal Path Cost
94 - 101 CIST Bridge Identifier
102 CIST Remaining Hops
MSTIDn MSTI Instances
Octet MSTID instance number Content
1 MSTI Flags
2 - 9 MSTI Regional Root Identifier
10 - 13 MSTI Internal Root Path Cost
14 MSTI Bridge Priority
15 MSTI Port Priority
16 MSTI Remaining Hops
Marvin Rambhadjan RSTP and MSTP
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Rapid Spanning Tree ProtocolPer VLAN Spanning Tree
Multiple Spanning Tree Protocol
Flags
Bits Description1 Topology Change Acknowledgement1 Agreement1 Forwarding1 Learning2 Port Role1 Proposal1 Topology Change
Marvin Rambhadjan RSTP and MSTP
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Rapid Spanning Tree ProtocolPer VLAN Spanning Tree
Multiple Spanning Tree Protocol
Questions?
Marvin Rambhadjan RSTP and MSTP
Rapid Spanning Tree ProtocolPer VLAN Spanning TreeMultiple Spanning Tree Protocol