Cisco WS-X6K-SUP1A-PFC= Software Guide - Page 99

Understanding Frame Distribution

Page 99 highlights

Chapter 6 Configuring EtherChannel Understanding How EtherChannel Works Table 6-1 describes EtherChannel modes. Table 6-1 EtherChannel Modes Mode Description on Mode that forces the port to channel without PAgP. With the on mode, a usable EtherChannel exists only when a port group in on mode is connected to another port group in on mode. off Mode that prevents the port from channeling. auto PAgP mode that places a port into a passive negotiating state, in which the port responds to PAgP packets it receives but does not initiate PAgP packet negotiation. (Default) desirable PAgP mode that places a port into an active negotiating state, in which the port initiates negotiations with other ports by sending PAgP packets. silent Keyword that is used with the auto or desirable mode when no traffic is expected from the other device to prevent the link from being reported to the Spanning Tree Protocol as down. (Default) non-silent Keyword that is used with the auto or desirable mode when traffic is expected from the other device. Both the auto and desirable modes allow ports to negotiate with connected ports to determine if they can form an EtherChannel, based on criteria such as port speed, trunking state, and VLAN numbers. Ports can form an EtherChannel when they are in different PAgP modes as long as the modes are compatible: • A port in desirable mode can form an EtherChannel successfully with another port that is in desirable or auto mode. • A port in auto mode can form an EtherChannel with another port in desirable mode. • A port in auto mode cannot form an EtherChannel with another port that is also in auto mode, because neither port will initiate negotiation. Understanding Frame Distribution EtherChannel distributes frames across the links in a channel by reducing part of the binary pattern formed from the addresses in the frame to a numerical value that selects one of the links in the channel. Enter the show module command for the supervisor engine to determine if EtherChannel frame distribution is configurable on your switch: • If the display shows the "Sub-Type" to be "L2 Switching Engine I WS-F6020," then EtherChannel frame distribution is not configurable on your switch; it uses source and destination Media Access Control (MAC) addresses. • EtherChannel frame distribution is configurable with all other switching engines. The default is to use source and destination IP addresses. 78-13315-02 Catalyst 6000 Family Software Configuration Guide-Releases 6.3 and 6.4 6-3

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6-3
Catalyst 6000 Family Software Configuration Guide—Releases 6.3 and 6.4
78-13315-02
Chapter 6
Configuring EtherChannel
Understanding How EtherChannel Works
Table 6-1
describes EtherChannel modes.
Both the
auto
and
desirable
modes allow ports to negotiate with connected ports to determine if they
can form an EtherChannel, based on criteria such as port speed, trunking state, and VLAN numbers.
Ports can form an EtherChannel when they are in different PAgP modes as long as the modes are
compatible:
A port in
desirable
mode can form an EtherChannel successfully with another port that is in
desirable
or
auto
mode.
A port in
auto
mode can form an EtherChannel with another port in
desirable
mode.
A port in
auto
mode cannot form an EtherChannel with another port that is also in
auto
mode,
because neither port will initiate negotiation.
Understanding Frame Distribution
EtherChannel distributes frames across the links in a channel by reducing part of the binary pattern
formed from the addresses in the frame to a numerical value that selects one of the links in the channel.
Enter the
show module
command for the supervisor engine to determine if EtherChannel frame
distribution is configurable on your switch:
If the display shows the “Sub-Type” to be “L2 Switching Engine I WS-F6020,” then EtherChannel
frame distribution is not configurable on your switch; it uses source and destination Media Access
Control (MAC) addresses.
EtherChannel frame distribution is configurable with all other switching engines. The default is to
use source and destination IP addresses.
Table 6-1
EtherChannel Modes
Mode
Description
on
Mode that forces the port to channel without PAgP. With the
on
mode, a usable
EtherChannel exists only when a port group in
on
mode is connected to another port group
in
on
mode.
off
Mode that prevents the port from channeling.
auto
PAgP mode that places a port into a passive negotiating state, in which the port responds
to PAgP packets it receives but does not initiate PAgP packet negotiation. (Default)
desirable
PAgP mode that places a port into an active negotiating state, in which the port initiates
negotiations with other ports by sending PAgP packets.
silent
Keyword that is used with the
auto
or
desirable
mode when no traffic is expected from
the other device to prevent the link from being reported to the Spanning Tree Protocol as
down. (Default)
non-silent
Keyword that is used with the
auto
or
desirable
mode when traffic is expected from the
other device.