May 12, 2013

Aggregated Ports (Notes)

Load Balancing
switch(config)# port-channel load-balance {src-ip|dst-ip|src-dst-ip|src-mac|dst-mac|src-dst-mac|src-port|dst-port|src-dst-port}
Method Hash Operation Switches
src-ip bits All Models
dst-ip bits All Models
src-dst-ip XOR All Models
src-mac bits All Models
dst-mac bits All Models
src-dst-mac XOR All Models
src-port bits 4500, 6500
dst-port bits 4500, 6500
src-dst-port XOR 4500, 6500
For 2 links last one bit of the address will be chosen for hash operation
For 3-4 links last two bits will be choosen
For 5-8 links last three bits will be choosen
EtherChannel Negotiation Protocols
To provide some dynamic link configuration
PAgP Cisco proprietary
Modes on|auto|desirable
on - all ports channeling, no pagp packets will be exchanged
auto - waits to channel until asked
desirable - actively asks for 
PAgP forms EtherChannel only on ports that are configured for identical static vlans or trunk
PAgP also modifies dynamically modifies parameters of EtherChannel if one of the bundled ports is modified
LACP Standard 802.3ad
Modes on|passive|active
on - all ports channeling, no lacp packets will be exchanged
passive - waits to channel until asked
active - actively asks for 
In addition to learning neighbor's port group capabilities and comparing with local port capabilities, LACP also assigns roles to EtherChannel endpoints.
Switch with lowest system priority (2byte priority + 6byte MAC address) is allowed to make decisions on which ports actively are participating in EtherChannel at a given point of time
In LACP upto 16 ports can be configured as members, with 8 being active at a time and rest being on standby. Should an active port go down, one of the standby ports become active.
Active ports are selected based on port priority (2byte priority + 2byte port number) by the switch with lowest system priority.
Lower value indicates high priority.
switch(config-if)# channel-protocol {lacp|pagp}
switch(config)# lacp system-priority <0-65535>
switch(config-if)# channel-group <no.> mode {on|desirable|auto|active|passive}
switch(config-if)# lacp port-priority <0-65535>
show etherchannel <no.>
show etherchannel load-balance
show etherchannel protocol
show ethterchannel {detail|summary}