Management and Configuration Guide K/KA/KB.15.15

General operating rules for port trunks
Media: For proper trunk operation, all ports on both ends of a trunk group
must have the same media type and mode (speed and duplex.) (For
the switches, HP Switch recommends leaving the port Mode setting
at Auto or, in networks using Cat 3 cabling, Auto-10.)
Port Configuration The default port configuration is Auto, which enables a port to sense
speed and negotiate duplex with an auto-enabled port on another
device. HP Switch recommends that you use the Auto setting for all
ports you plan to use for trunking. Otherwise, you must manually
ensure that the mode setting for each port in a trunk is compatible
with the other ports in the trunk.
Example 82 Recommended port mode setting for LACP
(HP_Switch_name#) show interfaces config
Port Settings
Port Type | Enabled Mode Flow Ctrl MDI
----- --------- + ------- ------------ --------- ----
1 10/100TX | Yes Auto Enable Auto
2 10/100TX | Yes Auto Enable MDI
All of the following operate on a per-port basis, regardless of trunk membership:
• Enable/Disable
• Flow control (Flow Ctrl)
LACP is a full-duplex protocol.
Trunk configuration: All ports in the same trunk group must be the same trunk type
(LACP or trunk.) All LACP ports in the same trunk group must be
either all static LACP or all dynamic LACP.
A trunk appears as a single port labeledDyn1(for an LACP
dynamic trunk) or Trk1 (for a static trunk of type LACP, Trunk)
on various menu and CLI screens.
For spanning-tree or VLAN operation, configuration for all ports
in a trunk is done at the trunk level. (You cannot separately
configure individual ports within a trunk for spanning-tree or
VLAN operation.)
Traffic distribution: All of the switch trunk protocols use the SA/DA (source
address/destination address) method of distributing traffic across
the trunked links.
Spanning Tree: 802.1D (STP) and 802.1w (RSTP) Spanning Tree operate as a
global setting on the switch (with one instance of Spanning Tree
per switch.) 802.1s (MSTP) Spanning Tree operates on a
per-instance basis (with multiple instances allowed per switch.)
For each Spanning Tree instance, you can adjust Spanning Tree
parameters on a per-port basis.
A static trunk of any type appears in the Spanning Tree
configuration display, and you can configure Spanning Tree
parameters for a static trunk in the same way that you would
configure Spanning Tree parameters on a non-trunked port.
(Note that the switch lists the trunk by name—such as Trk1—and
does not list the individual ports in the trunk.) For example, if
148 Port Trunking