Allied Telesis X900 User Manual 4

Allied Telesis www.alliedtelesis.com

Network Resiliency Solutions

x900 Advanced Gigabit Layer 3+ Expandable Switches

Tested Solution: VCStack + Link Aggregation

Prior to the advent of the Virtual Chassis Stacking (VCStack) solution, high availability in enterprise networks was achieved by
provisioning redundant links (with STP) and redundant routers (with VRRP). In normal operation, bandwidth and routing power would
sit idle in the network.

Allied Telesis now provides a truly resilient network. In normal operation, all bandwidth and all routing power in the network are fully
available for use all the time. If a link or device fails, some of the bandwidth or forwarding power will be lost, but the network will still
be fully operational and all remaining resources will continue to be fully utilized.

Diagram 1: VCStack + Link Aggregation

Key Benefits of the solution

Full bandwidth utilization and maximum availability

The key advantage comes from configuring the links from the edge to the core using 802.3ad link aggregation.This is possible
because VCS supports link aggregation on ports across different virtual chassis members, providing:

■

Full network bandwidth, as both ports are active; no links are blocked, as some would be with spanning tree.

■

Minimal network disruption if a link fails. The process within a switch when an aggregated link fails is very simple and the vir tual
chassis almost instantly adapts its data forwarding on the loss of the link.

Servers

8600

8000S

1 Gigabit link

10/100 link

Link aggregation

x900

CORE

8000S
Stack

EDGE

Customers benefits

Customer requirements met with the VCStack + Link Aggregation resiliency solution:

■

A resilient solution without using Spanning Tree

■

A simpler replacement for VRRP and/or other legacy redundancy protocols

■

Simpler network management - the virtual chassis is managed as a single unit.

Allied Telesis www.alliedtelesis.com

NETWORK RESILIENCY SOLUTIONS

| VCStack + Link aggregation

Allied Telesis Products

The following products support Vir tual Chassis Stacking:

■

SwitchBlade x908 advanced Layer 3 modular switch

■

x900-12X and 24X series advanced Gigabit L3+ expandable switches

This solution utilizes the following products at the network edge:

■

AT-8600 series Layer 3 Fast Ethernet switches

■

AT-8000S series stackable Fast Ethernet edge switches

x900-24XT

x900-24XT

8600 8000S

Server farm

Resiliency Link

10/100

1 Gigabit
Stacking
Link Aggregation

The dedicated stacking link is backed up by
a further resiliency link. If the stacking link
fails, communication between the stack
members is maintained to enable graceful
reconfiguration.

Link aggregation to the servers
creates a resilient connection to
important data, providing
load-sharing and high availability.

Link aggregation between the virtual
chassis and edge switches provides full
bandwidth and resiliency and negates the
need to configure spanning tree.

8000S

Stack

Stackable edge switches
increase resiliency and
port density, while
providing simplified
management as a single
virtual switch.

All switch tables are
synchronized across the
stack, ensuring no loss of
forwarding information in
the event of a stack
member failing.

Please see "Resilient Networking with VCStack" for more information on Allied Telesis Virtual Chassis Stacking solution.

www

.alliedtelesis.com/solutions

Allied Telesis www.alliedtelesis.com

NETWORK RESILIENCY SOLUTIONS

| VCStack + Link aggregation

x900 Configuration

log buffered level errors
log host 192.168.10.11
log host 192.168.10.11 level debugging

access-list 1 permit 192.168.10.13
snmp-server enable trap auth nsm
snmp-server community public ro 1
snmp-server host 192.168.10.13 version 2c public

stack resiliencylink eth0
stack 1 priority 1

vlan database

vlan 169-172 state enable

interface port1.0.1

switchport
switchport mode access
switchport access vlan 169
static-channel-group 1

interface port2.0.1

switchport
switchport mode access
switchport access vlan 169
static-channel-group 1

interface port1.0.3

switchport
switchport mode access
switchport access vlan 170
static-channel-group 2

interface port2.0.3

switchport
switchport mode access
switchport access vlan 170
static-channel-group 2

interface port1.0.5

switchport
switchport mode access
switchport access vlan 171
static-channel-group 3

All log messages are sent to a syslog server. Higher-severity
log messages are also buffered on the switch itself

A resiliency link backs up the dedicated stacking link. If the
stacking link fails, communication is maintained to allow
graceful reconfiguration

Use priority to pre-elect the VCStack master switch

Allow read-only SNMP monitoring from one management
station

Create link aggregation groups across the VCStack
members for resiliency. One for servers, and three for
edge switches

Create VLANs. VLAN 169 for ser vers, and VLANs 170-172
for connectivity to edge switches