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	==Layer 3==		==Layer 3==
	Stateful services requiring Layer 2 connectivity cannot be provisioned from		Stateful services requiring Layer 2 connectivity cannot be provisioned from

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Revision as of 15:46, 7 September 2010

Kapitel 5 fra CCDP ARCH bogen.

Cisco Catalyst 6500 serie switches Cisco Data Center Technologies

Designing The Core and Aggregation Layers

Data Center Design Architectural Overview

Data Center arkitekturen er baseret på en tre lags model.

• Core laget består af høj-hastigheds OSI lag 3.
• Aggregation laget forbinder Access-Laget med enten OSI lag 2 eller OSI lag 3.
• Access Laget giver fysisk forbindelse til Serverne.

fordele ved tre-lags modellen

• Hvis det er nødvendigt at samme VLAN skal være på flere Access Switche samtidig kan Aggregation-Switchene-----

Data Center Core layer design

Data Center Core Layer Design

OSI Lag 3 design for Data center Core

Routnings Protokoller

OSPF

OSPF Routnings Protokol design for Data Center Core

EIGRP

EIGRP Routnings Protokol design for Data Center Core

Aggregation Layer

Scalering af Data Center Aggregation laget

Spanning tree design

Cisco anbefaler at benytte sig af RPVST+.

Data Center Spanning Tree design (Aggregation switche Root/HSRP)

Aktiv STP,HSRP og Service Context Alignment

Active/Standby Service Module Design

I tegningen herunder er den ene Aggregation Switch Active og den anden Standby for al trafikken fra Access laget.

• Cisco 6500 med FSWM 2.x

Aggregation switche Aktiv/Standby STP,HSRP og Service Module design, eksempel 1

Aggregation switche Aktiv/Standby STP,HSRP og Service Module design, eksempel 2

Active/Active Service Module Design

I tegningen herunder er begge Aggregation Switche Active for hver deres VLAN's.

• Cisco 6500 med FSWM 3.1

Anvendelse af VRF (MPLS) i Data centeret

Anvendelse af VRF'er i Data Centeret

Access Lag

Lag 2 - Looped design

I Lag to Looped Design er VLAN's termineret i Aggregation laget og Lag 2 services som NIC teaming, Clustering og Statefull Services som for eksempel Firewall, Server Load Balancing, SSL kan udføres på ISO lag 2. Lag tre Routning foregår på Aggregations laget.

Lag 2 - Looped design
Looped design Square Access	Looped design Triangle Access

Lag 2 - Loop frit design

I Lag to Loop frit design er der ikke VLAN på Aggregationslaget modsat Looped design (Se overnfor). Ved omvendt U er det dog muligt at have VLAN på Aggregationslaget. Lag to services er supporteret. Lag tre Routning foregår på Aggregations laget.

Loop fri Access topologi. - U Access

Loop fri Access topologi - Omvendt U Access

Sammenligning af lag to Access designs

Sammenligning af lag 2 Access Designs

Lag 3 på Access laget

Statefull Services som kræver lag to konnektivitet kan ikke udføres af Aggregationslaget hvis Lag tre Routning foregår på Access-laget.

OSI Lag 3 på Access laget

Multicast Source Support

OSI Lag 3 på Access laget Multicast Support

6500 Services Module Placement Considerations

6500 Switch Fabrics

Active STP, HSRP, and Service Context Alignment

Active/Standby alignment

Active/Active alignment

Establisheing Inbound Path Prefenrece

Route Health Injection(RHI) tillader at en Cisco CSM/ACE i en 6500 switch installerer en hoste route til den virtuelle server. /32 routen fjerner problemer med asymmetriske routing.

Designing the Access Layer

VRFs in the datacenter

Layer 2 looped

VLANs are extended into the aggregation layer. Layer 2 services such as NIC teaming, clustering, and stateful services from the aggregation layer such as a firewall, SLB, and SSL can be provided across Layer 2 models. Layer 3 routing is first performed in the aggregation layer.

Layer 2 Looped designs

The Layer 2 looped triangle in Figure 5-14 has the following features:

• Supports VLAN extension/Layer 2 adjacency across the access layer.
• Resiliency is achieved with dual-homing and RSTP.
• Quick convergence with RSTP.
• Supports stateful services at the aggregation layer.
• Proven and widely used.

The Layer 2 looped square in Figure 5-14 has the following features:

• Supports VLAN extension/Layer 2 adjacency across the access layer.
• Resiliency is achieved with dual homing and STP.
• Quick convergence with 802.1w and 802.1s.
• Supports stateful services at the aggregation layer.
• Supports more access layer switches, optimizing 10 Gigabit Ethernet aggregation layer density.
• Active/active uplinks align well to active/active service module designs.

Layer 2 loop free

VLANs are not extended into the aggregation layer. Layer 2 services are supported. Layer 3 routing is first performed in the aggregation layer.

Loop-Free

The following are characteristics of loop-free U access:

• VLANs are contained in switch pairs (no extension outside of switch pairs).
• No STP blocking; all uplinks are active.
• Layer 2 service modules black-hole traffic on uplink failure.

The following are characteristics of loop-free inverted U access:

• Supports VLAN extension.
• No STP blocking; all uplinks are active.
• Access switch uplink failure black-holes single attached servers.
• ISL scaling considerations.
• Supports all service module implementations.

Loop-Free U Design and Layer 2 Service Modules

Layer 3

Stateful services requiring Layer 2 connectivity cannot be provisioned from the aggregation layer. Layer 3 routing is first performed in the access layer.

Eksterne henvisninger

• Data Center design
• Cisco catalyst 6500 serie præsentation