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# Key Protocols and Interfaces: Broadcom NetXtreme™ Gigabit Ethernet Adapter User's Guide

Adapter Teaming

Failover Teaming

VLANs Overview

## Adapter Teaming

Teaming provides traffic load balancing and redundant adapter operation in the event that a network connection fails. When multiple Gigabit Ethernet Adapters are installed in the same server, they can be grouped into teams. Each team with up to 8 ports or 8 adapters can be configured on the server. If traffic is not identified on any of the adapter team members connections due to failure of the adapter, cable, switch port, or switch (where the teamed adapters are attached to separate switches), the load distribution is reevaluated and reassigned among the remaining team members. In the event all the primary adapters are down, the hot standby adapter becomes active. Existing sessions are maintained, causing no user impact.
BASP supports three schemes of load balancing: Smart Load Balancing, Link Aggregation (802.3ad), and Generic Link Aggregation (Trunking).

| NOTE - Broadcom NetXtreme™ Gigabit Ethernet Adapters can be grouped into teams with an Intel® 82559 LOM.

### Smart Load Balancing (SLB)™

Broadcom implementation of load balancing based on IP flow. This feature supports balancing IP traffic across multiple adapters (i.e., team members) in a bi-directional manner. In this mode, all adapters in the team have separate MAC addresses. It provides automatic fault detection and dynamic failover to other team member or to a hot standby member; this is done independently of layer 3 protocol (IP, IPX, Net Beui). It works with existing layer 2 and 3 switches.

### Link Aggregation (802.3ad)

This mode supports Link Aggregation through static configuration and conforms to the IEEE 802.3ad specification. Configuration software allows you to statically configure which adapters they want to participate in a given team. Future releases will support LACP. If the link partner is not correctly configured for 802.3ad link configuration, errors are detected and noted. With this mode, all adapters in the team are configured to receive packets for the same MAC address. The outbound load-balancing scheme is determined by our BASP driver. The team’s link partner determines the load-balancing scheme for inbound packets.

### Generic Link Aggregation (Trunking)

This mode is very similar to 802.3ad in that all adapters in the team need to be configured to receive packets for the same MAC address. However, this mode does not provide LACP or marker protocol support. This mode supports a variety of environments where the NICs’ link partners are statically configured to support a proprietary trunking mechanism. For instance, this mode could be used to support Lucent’s "OpenTrunk" or Cisco’s Fast EtherChannel (FEC). Basically, this mode is a "light" version of the 802.3ad link aggregation. This approach is much simpler in that there is not a formalized link aggregation control protocol. As with the other modes, the creation of teams, and the allocation of physical adapters to various teams, is done statically via user configuration software.

Trunking supports load balancing and failover for both outbound and inbound traffic.

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## Failover Teaming

Failover Teaming provides redundant adapter operation in the event that a network connection fails. When multiple Gigabit Ethernet Adapters are installed in the same server, they can be paired into Teams. Each team must have at least one adapter, but can support up to eight adapters. The number of teams is limited by the number of adapters that are installed.

If the primary adapter in a team is disconnected because of failure of the adapter, cable, or switch port, the secondary team member becomes active, redirecting both inbound and outbound traffic originally assigned to the primary adapter. Sessions will be maintained, causing no impact to the user.

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## VLANs Overview

VLANs allow you to split your physical LAN into logical subparts, to create logical segmentation of workgroups and to enforce security policies among each logical segment. Each defined VLAN behaves as its own separate network, with its traffic and broadcasts isolated from the others, increasing bandwidth efficiency within each logical group. Up to 64 VLANs can be defined for each Broadcom adapter on your server, depending on the amount of memory available in your system.

Although VLANs are commonly used to create individual broadcast domains and/or separate IP subnets, it is sometimes useful for a server to have a presence on more than one VLAN simultaneously. Broadcom adapters support multiple VLANs on a per-port or per-interface basis, allowing very flexible network configurations.

> Figure 1. Example of Servers Supporting Multiple VLANs with Tagging

The figure above shows an example network that uses VLANs. In this example network, the physical LAN consists of a switch, two servers, and five clients. The LAN is logically organized into three different VLANs, each representing a different IP subnet. The features of this network are described in the following table:

Table 1. Example VLAN Network Topology

Component | Description
VLAN #1 | An IP subnet consisting of the Main Server, PC #3, and PC #5. This subnet represents an engineering group.
VLAN #2 | Includes the Main Server, PCs #1 and #2 via shared media segment, and PC #5. This VLAN is a software development group.
VLAN #3 | Includes the Main Server, the Accounting Server and PC #4. This VLAN is an accounting group.
Main Server | A high-use server that needs to be accessed from all VLANs and IP subnets. The Main Server has a Broadcom adapter installed. All three IP subnets are accessed via the single physical adapter interface. The server is attached to one of the switch ports, which is configured for VLANs #1, #2, and #3. Both the adapter and the connected switch port have tagging turned on. Because of the tagging VLAN capabilities of both devices, the server is able to communicate on all three IP subnets in this network, but continues to maintain broadcast separation between all of them.
Accounting Server | Available to VLAN #3 only. The Accounting Server is isolated from all traffic on VLANs #1 and #2. The switch port connected to the server has tagging turned off.
PCs #1 and #2 | Attached to a shared media hub that is then connected to the switch. PCs #1 and #2 belong to VLAN #2 only, and are logically in the same IP subnet as the Main Server and PC #5. The switch port connected to this segment has tagging turned off.
PC #3 | A member of VLAN #1, PC #3 can communicate only with the Main Server and PC #5. Tagging is not enabled on PC #3’s switch port.
PC #4 | A member of VLAN #3, PC #4 can only communicate with the servers. Tagging is not enabled on PC #4’s switch port.
PC #5 | A member of both VLANs #1 and #2, PC #5 has an Broadcom adapter installed. It is connected to switch port #10. Both the adapter and the switch port are configured for VLANs #1 and #2 and have tagging enabled.

| NOTE - VLAN tagging is only required to be enabled on switch ports that create trunk links to other switches, or on ports connected to tag-capable end-stations, such as servers or workstations with Broadcom adapters.

### VLANs Support

Virtual Local Area Networks (VLANs) are commonly used to split up groups of network users into manageable broadcast domains, to create logical segmentation of workgroups, and to enforce security policies among logical segments.

Each Team supports up to 64 VLANs. Note that only Broadcom adapters and Alteon® AceNIC adapters can be part of a team with VLANs. With multiple VLANs on an adapter, a server with a single adapter can have a logical presence on multiple IP subnets. With multiple VLANs in a team, a server can have a logical presence on multiple IP subnets and benefit from load balancing and failover.

| NOTE - Adapters that are members of a failover team can also be configured to support VLANs. Since VLANs are not supported for an Intel® LOM if an LOM is a member of a failover team, VLANs cannot be configured for that team.

### Adaptive Interrupt Frequency

The adapter driver intelligently adjusts host interrupt frequency based on traffic conditions, to increase overall application throughput. When traffic is light, the adapter driver interrupts the host for each received packet, minimizing latency. When traffic is heavy, the adapter issues one host interrupt for multiple, back-to-back incoming packets, preserving host CPU cycles.

### Dual DMA Channels

The PCI interface on the Gigabit Ethernet Adapter contains two independent DMA channels for simultaneous read and write operations.

### 32-bit or 64-bit PCI Bus Master

Compliant with PCI Local Bus Rev 2.2, the PCI interface on the Gigabit Ethernet Adapter is compatible with both 32-bit and 64-bit PCI buses. As a bus master, the adapter requests access to the PCI bus, instead of waiting to be polled.

### ASIC with Embedded RISC Processor

The core control for the Gigabit Ethernet Adapter resides in a tightly integrated, high-performance ASIC. The ASIC includes dual RISC processors. This provides the flexibility to add new features to the card and adapt it to future network requirements via software download. This also enables the adapter drivers to exploit the built-in host offload functions on the adapter as host operating systems are enhanced to take advantage of these functions.

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