# spanning-tree backbonefast (enable on all switches) Reduces convergence time from 50s to 30 (no mac-age timer) No longer has to wait max-age timer before acting on inferior bpdus Sets port cost to +3000 to stop it being used by downstream switches.īridge priority set to 49,152. Next lowest cost port put into forwarding Uplinkfast - for direct link failures to the root. # spanning-tree portfast default (all access ports to portfast) # spanning-tree vlan 1 - 4095 root primary diameter 3 (automatically sets above timers properly) # spanning-tree max-age 20 (How long a blocking port will take to go listening) # spanning-tree forward-time 15 (listening & learning timer) if)# spanning-tree port-priority 128 (changes the priority on the downstream remote switch.) if)# spanning-tree vlan 10 cost 2 (changes the value to the root on the local switch) # spanning-tree vlan 1-4095 root primary (uses 24,576 otherwise 4096 if not low enough. # spanning-tree vlan 1 - 4095 priority 4096 Losing root port results in 2x forwarding delay outage (30s) TCN sent to every switch, macs flushed after 15 seconds (forward delay value) instead of 300. Timers changed on root bridge, use network diameter instead of changing individual valuesĪ TCN happens happens when a port goes into forwarding, or from forwarding/learning to blocking. Max age = 20 seconds (time to hold a bpdu without hearing another) Listening state, for sending and receiving BPDUs only. Redundant path = blocking, other side will be designated Topology Change Notification (TCN) - to announce changesĭefault Bridge Priority 32,768.
if) switchport trunk pruning vlan add 100 VTP pruning = offĭomain and version can be learnt from server, as well as VTP pruningįor VTP pruning, a switch tells its neighbors its active vlans.
VTP client with high revision number will update serverīy default: VTP v1, domain = null and is vtp server. If update removes configured vlan, then interface is reset back to VLAN 1 Subset advertisements contain the changes Summary advertisements every 300 seconds and when a change is made Reset by changing domain or by going into transparent then back to server Highest number overwrites previous database. V3 required for 4094 VLANs, MSTP and primary and secondary servers VTP advertisements contain management domain, VTP revision number, known vlans and names Lightweight WiFi traffic uses a CAPWAP tunnel Voice vlan only seen through STP (not show vlan) if)# switchport mode dynamic auto (default otherside needs dynamic desirable or trunk to form) ISL adds 26 byte header + 4 byte trailer to a frameĭot1q adds 4 bytes after ethernet source addressĭTP will form an ISL trunk if both sides support itĭTP still operates on switchport mode trunk VLAN management Policy Server (VMPS) for dynamic allocation Negotiated once powered on.Įxtended VLAN range only allowed in vtp transparent or v3. LLDP MED = Media Endpoint Discovery for notifying the switch of the endpoints network requirements (PoE, QoS)Ĩ02.3at = 30w. Native vlan mismatch detected through CDPv2 or LLDP # errdisable recovery interval 300 (default timeout in seconds)Ĭdp - layer 2 protocol.
Different at layer 1ġ0Gb - full duplex operation only.
# sdm prefer default (reload required if changing)Įthernet uses CSMA/CD when in half duplex modeĮthernet is the same at layer 2. Limited number supported and can be reused. LOU - Logical Operation Unit for port ranges. Switching Database Manager (SDM - TCAM partitioning to optimise for switching/routing performance
Old mac address purged straight away if found on a different interfaceĪCL’s are made up of ACE’s - Access Control Entriesįeature Manager manages ACE’s into the TCAM # mac address-table aging-time 300 (by default) 元 packet rewrite still completed before sent to egress queue I haven't actually read through it so would be good if someone who is currently studying for the exam can correct any spelling mistakes and add additional content they think will help.Ĭore layer - Advanced QoS, 元 only. I did intend to make it fairly comprehensive but more to the point then the books, however sometimes it was a bit tiring writing stuff I already knew well. These were the notes I wrote up the day before my Switch exam.