Core

• Not all datacenter designs needs a core layer
• Access to aggregation, aggregation to core : 10 or 40GBps
• CEF load balancing tuning (L3 + L4)
• Core should run L3 only, Aggregation acts as L3/L2 boundry to access
• Core runs OSPF / EIGRP with aggregation

Aggregration

OSPF

• Datacenter Core as NSSA.
  • Campus core wille be your backbone area (area 0).
• Summerize Routes to Campus.
• Default Route from campus.
• Authentication / tuning.

Eigrp

• Summery-addressto advertize campus default.
• Summery-address to sum up datacenter.
• Authentication / tuning.

Service modules

• Using Cisco Modular switches for service modules:
  • Content switching (CSM) / Application Control Engine ( ACE )
  • Firewall Service Module ( FWSM )
  • Intrustion Prevention ( IPS )
  • Wireless ( WISM )

Access-layer

Looped designs, redundant linked blocked by STP.
All links in the layer2 domain.

Designs without STP implementation ( Faster convergence):

Flexlink design ( Disables STP with Active/Passive links).

Layer 3 access layer design:

• Each pair of switches are a L2 domain.
• Access layer uplinks are load balanced.
• STP still runs on the access layer.
• IP address space takes more management.
• Difficult migration.
• Service Modules needed within access layer switches.