Static trunk

The switch uses the links you configure with the Port/Trunk Settings screen in the menu interface or the trunk command in the CLI to create a static port trunk. The switch offers two types of static trunks: LACP and Trunk.

Table 8: Trunk types used in static and dynamic trunk groups

Trunking method

LACP

Trunk

Dynamic

Yes

No

Static

Yes

Yes

The following table describes the trunking options for LACP and Trunk protocols.

Table 9: Trunk configuration protocols

Protocol

Trunking Options

LACP (802.3ad)

Provides dynamic and static LACP trunking options.
  • Dynamic LACP — Use the switch-negotiated dynamic LACP trunk when:

    • The port on the other end of the trunk link is configured for Active or Passive LACP.

    • You want fault-tolerance for high-availability applications. If you use an eight-link trunk, you can also configure one or more additional links to operate as standby links that will activate only if another active link goes down.

  • Static LACP — Use the manually configured static LACP trunk when:

    • The port on the other end of the trunk link is configured for a static LACP trunk.

    • You want to configure non-default spanning tree or IGMP parameters on an LACP trunk group.

    • You want an LACP trunk group to operate in a VLAN other than the default VLAN and GVRP is disabled. (See VLANs and dynamic LACP.)

    • You want to use a monitor port on the switch to monitor an LACP trunk.

For more information, see Trunk group operation using LACP.

Trunk

(non-protocol)

Provides manually configured, static-only trunking to:

  • Most Switches and routing switches are not running the 802.3ad LACP protocol.

  • Windows NT and HPE-UX workstations and servers

Use the Trunk option when:

  • The device to which you want to create a trunk link is using a non-802.3ad trunking protocol.

  • You are unsure which type of trunk to use, or the device to which you want to create a trunk link is using an unknown trunking protocol.

  • You want to use a monitor port on the switch to monitor traffic on a trunk.

See Trunk group operation using the "trunk" option.
Table 10: 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, it is recommended to leave 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. It is recommended 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. See: Recommended port mode setting for LACP example

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. See Trunk group operation using LACP.
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 a listing of which screens show which trunk types, see How the switch lists trunk data.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. See Outbound traffic distribution across 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 ports C1 and C2 are configured as a static trunk named Trk1, they are listed in the Spanning Tree display as Trk1 and do not appear as individual ports in the Spanning Tree displays. See A port trunk in a Spanning Tree listing.When Spanning Tree forwards on a trunk, all ports in the trunk will be forwarding. Conversely, when Spanning Tree blocks a trunk, all ports in the trunk are blocked.

A dynamic LACP trunk operates only with the default Spanning Tree settings. Also, this type of trunk appears in the CLI show spanning-tree display, but not in the Spanning Tree Operation display of the Menu interface.

If you remove a port from a static trunk, the port retains the same Spanning Tree settings that were configured for the trunk.In the below Example:, ports C1 and C2 are members of TRK1 and do not appear as individual ports in the port configuration part of the listing.See: A port trunk in a Spanning Tree listing example

IP multicast protocol (IGMP):

A static trunk of any type appears in the IGMP configuration display, and you can configure IGMP for a static trunk in the same way that you would configure IGMP 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.) Also, creating a new trunk automatically places the trunk in IGMP Auto status if IGMP is enabled for the default VLAN.A dynamic LACP trunk operates only with the default IGMP settings and does not appear in the IGMP configuration display or show ip igmp listing.

VLANs:

Creating a new trunk automatically places the trunk in the DEFAULT_VLAN, regardless of whether the ports in the trunk were in another VLAN. Similarly, removing a port from a trunk group automatically places the port in the default VLAN. You can configure a static trunk in the same way that you configure a port for membership in any VLAN.

For a dynamic LACP trunk to operate in a VLAN other than the default VLAN (DEFAULT_VLAN), GVRP must be enabled. See Trunk group operation using LACP.

Port security:

Trunk groups (and their individual ports) cannot be configured for port security, and the switch excludes trunked ports from the show port-security listing. If you configure non-default port security settings for a port, then subsequently try to place the port in a trunk, you see the following message and the command is not executed:< port-list> Command cannot operate over a logical port.

Monitor port:

A trunk cannot be a monitor port. A monitor port can monitor a static trunk but cannot monitor a dynamic LACP trunk.

Recommended port mode setting for LACP

switch(config)# 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

A port trunk in a Spanning Tree listing

Port  Type      Cost Priority State      | Designated Bridge
----- --------- ---- -------- ---------- + -----------------
C3    100/1000T 5    12B      Forwarding | 0020c1-b27ac0
C4    100/1000T 5    12B      Forwarding | 0060b0-889e00
C5    100/1000T 5    12B      Disabled   | 
C6    100/1000T 5    12B      Disabled   | 
Trk1            1    64       Forwarding | 0001e7-a0ec00