Essay About Root Port And Alternate Port

Ethernet Case
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STP (802.1d)
Prevent L2 loops and provide redundancy
Port stats:
Blocking
RX PBDU, No MAC table building, No data
Listening
RX & TX PBDUs (Participate in election) 15 sec forward delay , No MAC table no data
Learning
RX PBDU, TX PBDU, MAC table
Forwarding
RX PBDU, TX PBDU, MAC table, data transfer
Root bridge ID (64 Bytes): Bridge Priority (2 Bytes)+MAC address (6 BYTEs) lowest is the choice default is 32768
BPDU are of 2 types, configuration (used for root bridge election) and TCN (Topology change notification)
Port Roles
RSTP (IEEE 802.1w)
Root Port: Receive best BPDU (generated by Root bridge)
Designated Port: Transmit best BPDU
Alternate Port: Recive better BPDU from another bridge
Backup port: receive better PBDU From the local bridge
Ports states: discarding, learning and forwarding
Port Roles: Root Port, Designated Port, Blocked port, Alternate Port and Backup port
Enhancements:
Non-root bridge generate PBDUs – HELLO packets in 2 secs.(helps in fast aging)
Fast Aging
Backbone FAST
PSEDO PORT FAST
Edge port (skip listening and learning statessaves 30 secs.)
If you have pt. to pt link skip listening and learning statessaves 30 secs
Any link that is in Full duplexit counts it as pt to pt link
SYNC Operation (Proposal PBDU, Agreement PBDU). Fast backbone convergence
Ethernchannel
Technology that combines the BW of multiple physical links into a single logical channel
Three types: FAST, GIGABIT
Channel range: 2-8
Link requirements to be in etherchannel: Same speed, same duplex, same VLAN, Port contiguous (depending about platform)
Benefits:
Increased BW, load balancing, Fault tolerance (with in one second, while in normal STP it took 30 secs and at UPLINK FAST it took 1-5 secs.)
Port aggregation protocol (PAgP) – etherchannel either ON or