Reference Architecture

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connecting bridge or server. Both links from the bridge network can actively forward and receive
traffic. VLT provides a replacement for Spanning Tree-based networks by providing both redundancy
and active-active full bandwidth utilization.
Major benefits of VLT technology are:
1. Dual control plane on the access side that lends resiliency.
2. Full utilization of the active LAG interfaces.
3. Rack-level maintenance is hitless and one switch can be kept active at all times.
Note that the two switches can also be stacked together. However, this is not recommended, as this
configuration will incur downtime during firmware updates of the switch or failure of stack links.
NPAR configuration:
In Active System 800v, each port of the Broadcom 57810-k Dual port 10GbE KR Blade NDCs in the
PowerEdge M620 blade servers, and the Broadcom 57810 Dual Port 10Gb Network Adapters in
PowerEdge R620 rack servers is partitioned into four ports using NPAR to obtain a total of eight I/O
ports on each server. As detailed in the subsequent sections, one partition each on every physical I/O
port is assigned to management traffic, vMotion traffic, VM traffic and iSCSI traffic.
The Broadcom NDC and the Broadcom Network Adapter allow setting a maximum bandwidth limitation
to each partition. Setting maximum bandwidth at 100 will prevent the artificial capping of any
individual traffic type during periods of non-contention. For customers with specific requirements,
NPAR maximum bandwidth settings may be modified to limit the maximum bandwidth available to a
specific traffic type, regardless of contention.
The Broadcom NDC and the Broadcom Network Adapter also allow setting relative bandwidth
assignments for each partition. While utilizing NPAR in conjunction with Data Center Bridging (DCB) and
Data Center Bridging Exchange (DCBX), the relative bandwidth settings of the partitions are not
enforced. Due this fact, the relative bandwidth capability of the Broadcom NDCs and the Broadcom
Network Adapters are not utilized in Active System 800v.
iSCSI hardware offload: In Active System 800v, iSCSI hardware offload functionality is used in the
Broadcom 57810-k Dual port 10GbE KR Blade NDCs in the PowerEdge M620 blade servers, and also in
the Broadcom 57810 Dual Port 10Gb Network Adapters in the PowerEdge R620 rack servers. The iSCSI
offload protocol is enabled on one of the partitions on each port of the NDC or the Network Adapter.
With iSCSI hardware offload, all iSCSI sessions are terminated on the Broadcom NDC or on the
Broadcom Network Adapter.
Traffic isolation using VLANs: Within the converged network, the LAN traffic is separated into four
unique VLANs; one VLAN each for management, vMotion, VM traffic, and out-of-band management. The
iSCSI traffic also uses a unique VM. Network traffic is tagged with the respective VLAN ID for each
traffic type in the virtual switch. Routing between the management and out-of-band management
VLANs is required to be configured in the core or the Force10 S4810 switches. Additionally, the Force10
S4810 switch ports that connect to the blade servers are configured in VLAN trunk mode to pass traffic
with different VLANs on a given physical port. The table 2 below provides an overview of different
traffic types segregated by VLANs in the Active System 800v, and which edge devices with which they
are associated.