ajout Etherchannel
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shango-wk
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[[PortFast (STP Toolkit)]]
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[[PortFast (STP Toolkit)]]
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[[BPDU Guard & BPDU Filter (STP Toolkit)]]
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[[BPDU Guard & BPDU Filter (STP Toolkit)]]
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[[Root Guard (STP Toolkit)]]
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[[Root Guard (STP Toolkit)]]
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[[Rapid Spanning Tree Protocol]]
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[[EtherChannel]]
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185
22 Rapid Spanning Tree Protocol.md
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22 Rapid Spanning Tree Protocol.md
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---
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id: 22 Rapid Spanning Tree Protocol
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aliases: []
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tags:
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- CCNA
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---
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# Rapid Spanning Tree Protocol
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## Spanning Tree Version
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### Industry standards (IEEE)
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Spanning Tree Protocol (802.1D)
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- The original STP
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- ALl VLANs share one STP instance.
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- Therefore, cannot load balance.
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Rapid spanning Tree Protocol (802.1w)
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- Much faster at converging/adaptating to network changes than 802.1D
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- All VLANs share one STP instance.
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- Therefore, cannot load balance
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Multiple Spanning Tree Protocol (802.1s)
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- Uses modified RSTP mechanics.
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- Can group multiple VLANs into different instacnces (ie. VLANs 1-5 instance 1, VLANs 6-10 in instance
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2 ) to perform load balancing
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### CISCO Versions
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Per-VLAN Spanning Tree Plus (PVST+)
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- Cisco's upgrade to 802.1D
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- Each VLAN has its own STP instance.
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- Can load balance by blocking different ports in each VLAN.
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Rapid Per-VLAN Spanning Tree Plus (Rapid PVST+)
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- Cisco's upgrade to 802.1w
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- Each VLAN has its own STP instance
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- Can load balance by blocking different ports in each VLAN
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## Rapid spanning Tree Protocol
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Cisco's summary:
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"RSTP is not a timer-based spanning tree algorithm like 802.1D. therefore, RSTP offers an improvement
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over the 30 seconds or more that 902.1d takes to move a link to forwarding. the heart of
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the protocol is new bridge-bridge handshake mechanism, which allows ports to move directly to forwarding."
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### Similarities between STP and RSTP:
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RSTP serves the same purpoe as STP, blocking specific ports to prevent Layer2 loops.
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- RSTP elect a root bridge with same rules as STP
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- RSTP elects root ports with the same rules as STP.
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- RSTP elects designated ports with the same rules as STP
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### Differences
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#### COST
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| speed | STP COST | STP COST |
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| -------------- | --------------- | --------------- |
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| 10 Mbps | 100 | 2,000,000 |
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| 100 Mbps | 19 | 200,000 |
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| 1 Gbps | 4 | 20,000 |
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| 10 Gbps | 2 | 2,000 |
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| 100 Gbps | x | 200 |
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| 1 Tbps | x | 20 |
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#### Port State
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| STP Port State | Send/Receive BPDUs | Frame Forwarding | MAC Learning | Stable/Transitional |
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| ------------- | -------------- | -------------- | -------------- | -------------- |
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| Discarding | NO/YES | NO | NO | Stable |
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| Learing | YES/YES | NO | YES | Tranisitional |
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| Forwarding | YES/YES | YES | YES | Stable |
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- if a port is administratively disabled (shutdown command) = discarding state
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- if a port is enabled but blocking traffic to prevent Layer 2 loops = discarding state
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#### Port Roles
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*The root port role remains unchanged in RSTP.*
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- The port wthat is closet to the root bridge becomes the root port for the switch.
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- The root bridge is the only switch that doesn't have a root port.
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*The designated port role remains unchanged in RSTP.*
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- The port on a segment (collision domain) that sends the best BPDU is that
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segment's designated port (only one per segment)
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- *The non designated port role is split into two separate roles in RSTP*:
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- The alternate port role
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- the backup port role
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##### Alternate port Role
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The RSTP alternate port role is discarding port that receives a superior BPDU from another switch.
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- This is the same as what you've learned about *blocking* ports in classic STP.
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- Functions as a backup to the root port.
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- If the root port fails, the switch can immediately move its best alternate port to forwarding
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This immediate move to fowarding state functions like a classic STP optional feature called
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UplinkFast. Because it is built into RSTP, you do not need to activate UplinkFast when using
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RSTP/Rapid PVST+
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One more STP optional feature that was built into RSTP is BackboneFast.
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Backbone Fast allows SW3 to expire the made age timers on its interface and rapidly forward the superior
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BPDUs to SW2.
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This functionality is built into RSTP, so it does not need to be configured
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##### Backup port role
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The RSTP backup port role is a discarding port that receives a superior BPDU from another
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interface on the same switch.
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- This only happnes when two interfaces are connected to the same collision domain (via a hub)
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- Hubs are not used in modern networks, so you will probably not encounter an RSTP backup port.
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- Function as backup for a designated port
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- The interface with the lowest port ID will be selected as the designated port and the other will be the
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backup port
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### BPDU
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In classic [[STP]], only the root bridge originated BPDUs, and other switches just forwarded the BPDUs
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they received.
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In Rapid STP, all Switches originate and send their own BPDUs from their designated ports
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All switches running Rapid STP send their own BPDUs every hello time (2 seconds).
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- Switches 'age' the BPDU information much more quickly, in classic STP a switch waits 10 hello intervales
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(20 seconds). In rapid STP, a switch considers a neighbor lost if it misses 3 BPDUs (6 seconds)
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It will the 'Flush' All MAV addresses learned on that interface
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## RSTP Link Types
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RSTP distiguishes between three different 'link types'
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- Edge: a port that is connected to an end host. Moves directly to forwarding without negotiation.
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- Point-to-point: a direct connection between two switches
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- Shared a connection to a [[hub]]. Must operate in half-duplex mode.
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### Edge
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Edge ports are connected to end hosts.
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- Because ther is no risk of creating a loop, they can move stright to the forwarding state without the
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negotiation process.
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- They function like a classic STP port with PortFast enabled
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```Cisco
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SW1(config-if)# spanning-tree portfast
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```
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### Point-to-Point
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Point-to-point ports connect directly to another switch
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- They function in full-duplex
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- you don't need to configure the interface as point-to-point (it should be detected)
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```Cisco
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SW1(config-if)# spanning-tree link-type point-to-point
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```
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### Shared
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shared Ports connect to another switch (or switches) via a hub.
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- They function in half-duplex
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- You don't need to configure the interface as shared (it should be detected)
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```Cisco
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SW1(config-if)# spanning-tree link-type shared
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```
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### Configuration
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```Cisco
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SW3(config)# spanning-tree mode rapid-pvst
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SW3(config)# do show spanning-tree
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```
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## Review
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Comparison of [[STP]] versions (standard vs [[Cisco]])
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Rapid PVST+
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128
23. EtherChannel.md
Normal file
128
23. EtherChannel.md
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@@ -0,0 +1,128 @@
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---
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id: 23. EtherChannel
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aliases: []
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tags: []
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---
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# EtherChannel
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multiple host -- ASW1 -- DSW1
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ASW = Access layer Switch, a switch that end hosts connect to
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DSW = Distribution layer switch, a switch that access layer switches connect to
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When the bandwith of the interfaces connected to end hosts is greater than the bandwidth of the
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connection to the distribution switch(es), this is called *oversubscription*.
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Some oversubscription is acceptable, but too much will cause congestion.
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- if you connect two switchs together with multiple links, all except one will be disabled by
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[[spanning tree]]
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- if all of ASW1's interfaces were forwarding, Layer 2 loops would form between ASW1 and DSW1,
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leading to [[broadcast storms]].
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- Other links will be unused unless the active link fails. in that case one of the inactive
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links will start forwarding
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- EtherChannel groups multiple interfaces together to act as a single interface.
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- STP will treat this group as a single interface
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Traffic using the EtherChannel wil be load balanced among the physical interfaces in the group.
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An [[algorithm]] is used to determine which traffic will use which physical interface.
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Some other names for an EtherChannel are:
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- Port Channel
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- LAG (Link aggregaton Group)
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## Load Balancing
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- EtherChannel load balances based on flows
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- A flow is a communication between two nodes in the network
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- Frames in the same flow will be forwarded using the same physicial interface.
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- If frames in the same flow were forwarded using different physical interfaces, some frames
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may arrive at the destination out of order, which can cause problems
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- You can change the inputs used in the interface selection calculation.
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- Inputs that can be used:
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- Source [[MAC]]
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- Destination MAC
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- Source and Destination MAC
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- Source [[IP]]
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- Destination IP
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- Source and Destination IP
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### Commands
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see current configuration
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```Cisco
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ASW1#show etherchannel load-balance
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### default will be set to src-dst-ip
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```
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for configuring load balance configuration
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```Cisco
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ASW1(config)#port-channel load-balance src-dst-mac
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## to see other method
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ASW1(config)#port-channel load-balance ?
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```
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## EtherChannel Configuration
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There are three methods of EtherChannel configuration on Cisco switches:
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- PAgP (Port Aggregation Protocol)
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- Cisco proprietary protocol
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- Dynamically negotiates the creation/maintenance of the EtherChannel.
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(like DTP does for trunks)
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- LACP (Link Aggregation Control Protocol)
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- Industry standard protocol (IEEE 802.3ad)
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- Dynamically negotiate the creation/maintenance of the EtherChannel.
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(like DTP does for trunks)
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- Static EtherChannel
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- A protocol isn't used to determine if an EtherChannel should be formed.
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- Interfaces are statically configured to form an EtherChannel
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Up to *8 interfaces* can be formed into a single EtherChannel (LACP allows up to 16, but only
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8 will be active, the other 8 will be in standby mode, waiting for an active interface to fail)
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```Cisco
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ASW1(config)#inteface range g0/0 - 3
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## to see all methods
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ASW1(config-if-range)#channel-group 1 mode ?
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## for PAgP
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ASW1(config-if-range)#channel-group 1 mode desirable
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```
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note: The channel-group number has to match for member interfaces on the same switch.
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However, it doesn't have to match the channel-group number on the other switch.
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(channel-group 1 on ASW1 can form an EhterChannel with channel-group 2 on DSW1)
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Member intefaces must have matching configurations.
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- Same duplex (full/half)
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- Same speed
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- Same switchport mode (access/trunk)
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- Same allowed VLANs/native VLAN (for trunk interfaces)
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If an interface's configurations do not match the others, it will be excluded from the EtherChannel
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to see running configuration of the EtherChannel
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```Cisco
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ASW1#show etherchannel summary
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## less utilise command
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ASW1#show etherchannel port-channel
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```
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## Layer 3 EtherChannel
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```Cisco
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ASW1(config)#int range g0/0 - 3
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ASW1(config-if-range)#no switchport
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ASW1(config-if-range)#channel-group 1 mode active
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ASW1(config-if-range)#int po1
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ASW1(config-if)#ip address 10.0.0.1 255.255.255.252
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```
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## Review
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- What is EtherChannel? what problems does it solve?
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- Configuring Layer 2/Layer 3 EtherChannel
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Reference in New Issue
Block a user