Cisco Cisco MGX-FRSM-HS2 B Serial Frame Service Module Fascicule
Solution Overview
© 2011 Cisco and/or its affiliates. All rights reserved. This document is Cisco Public Information.
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for the requirements of today's data center networks. Cisco NX-OS is built on the industry-proven Cisco MDS 9000
SAN-OS Software, adding virtualization, Layer 2, and Layer 3 features and protocols required in the data center
environment. Cisco NX-OS includes high-availability features, such as granular process modularity, In-Service
Software Upgrade (ISSU), and stateful process restart, that are specifically targeted at the service-level
requirements of the enterprise or service provider data center.
Aggregation Layer
The aggregation layer of the data center provides connectivity for the access-layer switches in the server farm and
aggregates them into a smaller number of interfaces to be connected to the core layer. In most data center
environments, the aggregation layer is the transition point between the purely Layer 3 routed core layer, and the
Layer 2 switched access layer. IEEE 802.1Q trunks extend the server farm VLANs between the access and
aggregation layers.
The aggregation layer also provides a common connection point for inserting services into the data flows between
clients and servers, or between tiers of servers in a multi-tier application. The Cisco Nexus 7000 Series offers unique
virtualization features such as VDCs and vPCs that are critical for aggregation-layer switches. As shown in Figure 7,
three VDCs are used in the solution to segregate three different service groups inside the same physical Cisco
Nexus 7000 Series Switch. Horizontal collapsing of the aggregation layer with VDCs has a significant effect on the
data center space, power, and cooling, as discussed previously.
Access Layer
The access layer provides the physical-level attachment to the server resources and operates in Layer 2 or Layer 3
mode. The mode plays a critical role in meeting particular server requirements such as network interface card (NIC)
teaming, clustering, and broadcast containment. The access layer is the first oversubscription point in the data
center because it aggregates the server traffic onto Gigabit EtherChannel or 10 Gigabit Ethernet and 10 Gigabit
EtherChannel uplinks to the aggregation layer. Spanning tree or Layer 3 routing protocols are extended from the
aggregation layer into the access layer, depending on which access-layer model is used. Cisco recommends
implementing access-layer switches logically paired in groups of two to support server redundant connections or to
support diverse connections for production, backup, and management Ethernet interfaces.
Service Layer
As illustrated in Figure 7, the service layer is implemented using VSS. The VSS technology allows the grouping of
two Cisco Catalyst 6500 Series Switches into a single virtual switch. A VSS system provides physical infrastructure
redundancy while simultaneously simplifying the logical topology of the data center.
Figure 8 illustrates the concept of VSS. The left side of Figure 8 represents the physical layout of the VSS: two Cisco
Catalyst 6500 Series Switches are physically connected through a virtual switch link (VSL). The two switches are
members of a virtual switch domain, and as the right side of the figure shows, this construct forms a single logical
switch with a single control plane: a virtual switching system.
Figure 8. Virtual Switch System