Interface Instance
12-19
5. Use the port-channel command to select the criteria used to determine which link is
selected for a given packet. The port-channel selection is based on either source-
destination IP or source destination MAC
RFS7000(config-if)#port-channel load-balance src-dst-ip
RFS7000(config-if)#
The default port-channel criteria is based on source-destination IP. The port channel
(when configured with
src-dst-ip) does not show up in the running-config. Hence,
this mode is preferred over
src-dst-mac.
How src-dst-mac mode works
When the switch sends a packet out of a SA, it selects the egress port as a function of the
packet's source MAC, destination MAC, and the set of ports in the SA which are running.
It XORs the bottom bits of the two MACs and indexes it into a table of the running ports.
How src-dst-ip mode works
When the switch sends an IP packet, the egress port is chosen as a function of the packet's
source IP, destination IP and the set of running ports. It XORs the bottom byte of the two
IP addresses and indexes then into the same table of running ports that
src-dst-mac
mode uses.
If the packet is NOT an IP packet, it uses the same calculation as src-dst-mac mode.
Why is src-dst-ip mode preferred
src-dst-ip mode distributes packets better when most packets, going through the gateway,
are IP packets. In the presence of an IP gateway, the IP packets forwarded from one MU
to hosts that is beyond the gateway all have the same MAC pair <MU MAC, Gateway
NOTE: When a port (GE) is aggregated into a Static Aggregation (SA),
it temporarily takes on the port configuration of the SA.
For example, If GE 1 (previously configured as trunk vlan 1-10) and GE 2
(previously configured as trunk vlan 11-20) are now aggregated as SA 1
and SA 1 is configured as trunk vlan 100-200, then SA 1’s configuration
applies to both GE 1 and GE 2. This new configuration like VLAN, speed,
duplex, MST is now applicable on the ports as long as they are part of
the SA. The ports revert back to the original configuration once they are
removed from the SA.
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