EtherChannel mode ON ? Any catch?

Hi GS,

LACP takes some time to negotiate, while mode ON does not require it,
and hence gives a better convergence time. I am not sure if there's
any issue with using EtherChannel mode ON, instead of LACP (apart from
user-misconfig issues). This is not clear in the DOC CD configuration
guide.

More specifically, if we have two Cisco switches, and need to
configure ether-channel between them, would you recommend mode ON or
LACP (open standard). E.g. issue with mode ON such as one link is
recognised as UP at one end, but as DOWN by the switch at the other
end.

Appreciate your feedbacks.

http://www.cisco.com/en/US/docs/switches/lan/catalyst3560/software/release/12.2_44_se/configuration/guide/swethchl.html#wp1275503

Understanding EtherChannels
These sections describe how EtherChannels work:

EtherChannel Overview

Port-Channel Interfaces

Port Aggregation Protocol

Link Aggregation Control Protocol

EtherChannel On Mode

Load Balancing and Forwarding Methods

EtherChannel Overview
An EtherChannel consists of individual Fast Ethernet or Gigabit
Ethernet links bundled into a single logical link as shown in Figure
34-1.

Figure 34-1 Typical EtherChannel Configuration

The EtherChannel provides full-duplex bandwidth up to 800 Mb/s (Fast
EtherChannel) or 8 Gb/s (Gigabit EtherChannel) between your switch and
another switch or host.

Each EtherChannel can consist of up to eight compatibly configured
Ethernet ports. All ports in each EtherChannel must be configured as
either Layer 2 or Layer 3 ports. The number of EtherChannels is
limited to 48. For more information, see the "EtherChannel
Configuration Guidelines" section. The EtherChannel Layer 3 ports are
made up of routed ports. Routed ports are physical ports configured to
be in Layer 3 mode by using the no switchport interface configuration
command. For more information, see the Chapter 10, "Configuring
Interface Characteristics."

You can configure an EtherChannel in one of these modes: Port
Aggregation Protocol (PAgP), Link Aggregation Control Protocol (LACP),
or On. Configure both ends of the EtherChannel in the same mode:

When you configure one end of an EtherChannel in either PAgP or LACP
mode, the system negotiates with the other end of the channel to
determine which ports should become active. Incompatible ports are
suspended. Beginning with Cisco IOS Release 12.2(35)SE, instead of a
suspended state, the local port is put into an independent state and
continues to carry data traffic as would any other single link. The
port configuration does not change, but the port does not participate
in the EtherChannel.

When you configure an EtherChannel in the on mode, no negotiations
take place. The switch forces all compatible ports to become active in
the EtherChannel. The other end of the channel (on the other switch)
must also be configured in the on mode; otherwise, packet loss can
occur.

If a link within an EtherChannel fails, traffic previously carried
over that failed link moves to the remaining links within the
EtherChannel. If traps are enabled on the switch, a trap is sent for a
failure that identifies the switch, the EtherChannel, and the failed
link. Inbound broadcast and multicast packets on one link in an
EtherChannel are blocked from returning on any other link of the
EtherChannel.

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Received on Wed Oct 06 2010 - 10:35:48 ART