How to Configure Link Aggregation in Solaris 11 (Trunk V/s Datalink multipathing (DLMP))

Link aggregations enable you to pool multiple datalink resources that you administer as a single unit. By combining the resources of the multiple datalinks and dedicating them to serving the system’s network operations, the system’s performance is greatly improved.

The image above shows an example of a link aggregation configured on a system, in which an aggregation aggr1 consists of 4 underlying datalinks, net0 through net3. These datalinks are dedicated to serving the traffic that traverses the system through the aggregation. The underlying links are hidden from external applications. Instead, the logical datalink aggr1 is accessible.

Link aggregation has the following features:

Increased bandwidth: The capacity of multiple links is combined into one logical link.
Automatic failover and failback: By supporting link-based failure detection, traffic from a failed link is failed over to other working links in the aggregation.
Improved administration: All underlying links are administered as a single unit.
Less drain on the network address pool: The entire aggregation can be assigned one IP address.
Link protection: You can configure the datalink property that enables link protection for packets flowing through the aggregation.
Resource management: Datalink properties for network resources as well as flow definitions enable you to regulate applications’ use of network resources.

Note: Link aggregations perform similar functions as IP network multipathing (IPMP) to improve network performance and availability.

Types of Link Aggregation

Trunk Aggregations

Trunk aggregations benefit a variety of networks with different traffic loads. For example, if a system in the network runs applications with distributed heavy traffic, you can dedicate a trunk aggregation to that application’s traffic to avail the increased bandwidth. For sites with limited IP address space that nevertheless require large amounts of bandwidth, you need only one IP address for a large aggregation of interfaces. For sites that need to hide the existence of internal interfaces, the IP address of the aggregation hides its interfaces from external applications.

In Oracle Solaris, when you create link aggregation, the aggregation is by default created in trunk mode. Typically, systems that are configured with link aggregations also use an external switch to connect to other systems.

Trunk aggregations also support back-to-back configuration. Instead of using a switch, two systems are directly connected together to run parallel aggregations. The most common application for back-to-back link aggregations is the configuration of mirrored database servers.

Datalink Multipathing (DLMP) Aggregations

A trunk aggregation generally suffices for the requirements of a network setup. You can span trunk aggregation to multiple switches but requires switch configuration and switch-vendor proprietary extensions to work. DLMP aggregations can span over multiple switches.

In a trunk aggregation, every port is associated with every configured datalink over the aggregation. In a DLMP aggregation, a port is associated with any of the aggregation’s configured datalinks as well as with the primary the interface and VNICs over that aggregation.

You can switch between a trunk aggregation and a DLMP aggregation by using the dladm modify-aggr command, provided that you use only the options supported by the specific type.

Note: If you switch from a trunk aggregation to a DLMP aggregation, you must remove the switch configuration that was previously created for the trunk aggregation.

DLMP aggregation supports link-based and probe-based failure detection to ensure continuous availability of the network to send and receive traffic.

Creating a Trunk Aggregation

The example below shows the commands to create a link aggregation with two underlying datalinks, net0 and net1. The aggregation is also configured to transmit LACP packets. The example begins with the removal of existing IP interfaces over the underlying datalinks.

# ipadm show-if
IFNAME    CLASS         STATE     ACTIVE     OVER 
lo0       loopback      ok        yes        -- 
net0      ip            ok        no         -- 
net1      ip            ok        no         --

# ipadm delete-ip net0 
# ipadm delete-ip net1

# dladm create-aggr -L active -l net0 -l net1 aggr0

# dladm show-aggr
LINK     MODE     POLICY    ADDRPOLICY     LACPACTIVITY     LACPTIMER 
aggr0    trunk    L4        auto           active           start

Creating a DLMP Aggregation

The example below shows how to create a DLMP aggregation. The aggregation has four underlying datalinks.

# dladm create-aggr –m dlmp -l net0 -l net1 -l net2 -l net3 speedway0

# dladm show-link
LINK           CLASS      MTU     STATE      OVER
net0           phys       1500    up         --
net1           phys       1500    up         --
net2           phys       1500    up         --
net3           phys       1500    up         --
speedway0      aggr       1500    up         net0 net1 net2 net3

# dladm show-aggr
LINK         MODE    POLICY    ADDRPOLICY    LACPACTIVITY     LACPTIMER 
speedway0    DLMP    --        --            --               --

Configuring Probe-Based Failure Detection for DLMP Aggregation

The example below shows how to configure probe-based failure detection for a DLMP aggregation.

# dladm show-aggr
LINK         MODE    POLICY    ADDRPOLICY    LACPACTIVITY     LACPTIMER 
speedway0    DLMP    --        --            --               --

# dladm set-linkprop –p probe-ip=+ speedway0 
# dladm set-linkprop –p probe-fdt=15 speedway0

# dladm show-linkprop –p probe-ip,probe-fdt speedway0
LINK         PROPERTY     PERM    VALUE     EFFECTIVE     DEFAULT     POSSIBLE 
speedway0    probe-ip     rw      +         +             --          -- 
speedway0    probe-fdt    rw      15        15            10          1-600

Sunday, 21 October 2018