Saturday, September 4, 2021

Extreme Switch - Extended Edge Switching (aka, VPEX)

  • Overview

Extreme Networks' Extended Edge Switching is a great solution that simplifies the deployment and operation of edge switches - especially across a campus switched network. The Extended Edge Switching technology is based on the IEEE 802.1BR (Bridge Port Extension) standard. It is also known as Virtual Port Extender (VPEX). The solution has been supporting since the EXOS version 22.5. The Port Extenders do not perform switching functions, but they rely on the Aggregation Switch.

Cisco has a similar solution called Fabric Extender (FEX), which was launched in 2009. With Nexus 2000 FEXes, it extends the switching fabric of the core and aggregated switches - Nexus 5000/6000/7000/9000 series switches.

We can compare this solution as a concept that we insert additional switching modules into a chassis-based platform like Cisco Catalyst 9400 Series, Extreme VSP 8600, etc. However, these modular platform supports a fixed number of line cards or interface modules. This is why network vendors came up with this extender solution.

Extreme Extended Edge Switching
(YouTube, 4:22)

  • Advantages

✓ Centralized, single point of control/management for reduced complexity and operational expense
✓ Simplifies deployment of operation of Edge Switches by establishing an Aggregation Switch as a Controller
✓ Provides agility, flexibility, and simplicity at scale, which can be integrated into existing network infrastructures
✓ Simplifies operational model that reduces the cost
✓ Eliminates the need for individual manual provisioning and configuration
✓ Versatile design options – all based on the 802.1BR standard

  • Supported Platforms

The ExtremeSwitching 5420, 5520, X465, X590, X670-G2 and X690 Series platforms are supported as EXOS aggregation switches within an Extended Edge Switching design.

In addition, ExtremeSwitching V300 and V400 models are available as Extended Edge Switching edge devices (BPEs).

  • Architecture

<Extended Edge Switching extends aggregation switch features to V400>

The Extreme Edge Switching solution effectively replaces traditional full-function access switches with V300 or V400 edge devices. The V300/V400 devices in turn are transparently managed and controlled by the EXOS aggregation switch, eliminating the need to manually provision and configure the individual V300/V400 device.

Within this architecture, V300/V400 devices can be seen as functioning as "virtual line cards" of the EXOS aggregation switch - all operating within a larger "distributed chassis" domain. The V300/V400 devices and the EXOS aggregation switch use the standard 802.1BR protocol to communicate with one another.

Detection and bring up of the BPE involves several standard protocols
LLDP (Link Layer Discovery Protocol) - initial device type and capability detection
ECP (Edge Control Protocol) - reliable transport layer
PE-CSP (Port Extender-Control and Status Protocol)– primary means for CB to configure and control BPE
LACP (Link Aggregation Control Protocol) – establishes LAG on cascade<->upstream connection

  • Components

▶ Controlling Bridge (CB) = Aggregation Switch, models on the Supported Platforms

✓ The CB is the single and only point of management
✓ ALL data-plane packet processing and filtering performed by CB
✓ All configuration occurs locally on CB
✓ EXOS licenses apply to CB. BPE does not require additional licenses.
✓ Up to 48 x V300/V400 devices can be supported on a single EXOS aggregation switch

▶ Bridge Port Extender (BPE) = Extender, V300 or V400

✓ The BPE devices are managed like slots in a chassis
✓ No need for a console or OOB Mgmt connection to the BPE
✓ The user issues all configuration/debug/diagnostics via the CB

V400 Port Extenders
- Available with or without PoE
- 24 and 48 port models
- Two 10 Gigabit SFP+ interfaces
- Up to 8 Stackable V400s

  • Topology/Deployment Options

V300/V400 switches can be connected to each EXOS aggregation switch via a cascade or ring configuration to minimize the impact of aggregation switch failure or interruption of service.

▶ Cascade of Edge Devices for Flexible Design

V300 and V400 devices can be cascaded to create a virtual stacking capability. Up to four (4) V300 or V400 edge devices can be cascaded off a single high-speed link or alternatively via a LAG back to the EXOS aggregation switch. This minimizes the need for individual fiber cable runs from each V400 device, providing flexible deployment either within the wiring closet or at the network edge.

▶ Ring Support for Additional Edge Resiliency

Cascaded V300 or V400 devices can also be configured in a ring topology for additional resiliency. In this topology, the first and last V300/V400 devices in the cascade are connected to the EXOS aggregation switch.

If any V300/V400 device in the ring should fail, traffic can then be re-routed in the other direction across the ring to the aggregation switch. Up to eight V300/V400 devices can joined in a ring.

▶ High-Availability, Redundant Aggregation Switches

Aggregation Switch can be connected via an MLAG to provide redundant design to minimize service interruption in event of a failure of one of the Aggregation Switches.

  • Extended Edge Switching on Stacking

Starting from EXOS 31.4, Extended Edge Switching on Stacking is supported. With Extended Edge Switching on Stacking, Extended Edge uses the stack, rather than Multi-chassis Link Aggregation Group (MLAG), to provide redundancy to a Bridge Port Extender (BPE). This is done by having certain components of EXOS synchronize their primary and backup nodes with respect to the Extended Edge Switching state. 

The primary node performs all Extended Edge Switching controlling bridge functions while the backup is kept in sync with the primary. This simplifies configuration, as all stack switches are managed with a single configuration file and control point that resides on the elected primary switch. The backup switch can become the primary switch upon failure of the primary switch if the failure is caused by a crash, a power-off, or a management action.

All nodes in a stack running Extended Edge Switching must be controlling bridge capable. Any attempt to add a non-capable slot to a stack running Extended Edge Switching will fail. Enabling Extended Edge Switching on a stack that contains a non-capable node will fail.

You must use the same class of controlling bridge for both the primary and backup. For example, if an X465 series switch is the primary node, then the backup must also be an X465 series switch.

The primary-capable node in a stack that has the least maximum supported number of BPEs determines the maximum for the stack.

* Note: The V300-8P-2T-W BPE requires PoE, and therefore can only connect to the ExtremeSwitching X465, 5420, and 5520 series switches.

* Note: ExtremeSwitching X670-G2 is not supported with Extended Edge Switching on Stacking.

New CLI Command
show vpex stacking

* Related posts: Extreme Switch - Summit Stacking

* Reference links:

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