NETWORKING: Maipu 1800 Testing Report for Load Balancing Scenario

Hi Friends, Below is testing report of Load balancing and back up scenario using Maipu 1800 Routers.

Objective-

Maipu 1800 CPE router need to perform load balancing in between two outgoing interfaces F0 and F1
If one WAN link is down, then another wan link will be primary, vice versa.
As the faulty link is restored, Both WAN link should do load balancing for LAN traffic.

Topology –

Description –

Load Balancing

Load balancing is based on a combination of source and destination packet information; it allows you to optimize resources by distributing traffic over multiple paths for transferring data to a destination. You configure load balancing on outbound interfaces on a per-destination or per-packet basis.

Types Load balancing – Per destination load balancing and Per packet load balancing.

Per-Destination and Per-Packet

Per-destination load balancing allows the router to distribute packets based on the destination address, and uses multiple paths to achieve load sharing. Packets for a given source-destination host pair are guaranteed to take the same path, even if multiple paths are available. For example, given two paths to the same network, all packets for destination1 on that network go over the first path, all packets for destination2 on that network go over the second path, and so on. Per-destination load balancing is enabled by default when you start the router, and is the preferred load balancing for most situations.

Per-packet load balancing allows the router to send successive data packets over paths without regard to individual hosts or user sessions. It uses the round-robin method to determine which path each packet takes to the destination. With per-packet load balancing enabled, the router sends one packet for destination1 over the first path, the second packet for (the same) destination1 over the second path, and so on. Per-packet load balancing ensures balancing over multiple links.

Although path utilization with per-packet load balancing is beneficial, packets for a given pair of source-destination hosts might take different paths. This means that per-packet load balancing can introduce reordering of packets. This load balancing method would be inappropriate for certain types of data traffic (such as voice traffic over IP) that depend on packets arriving at the destination in sequence.

Use per-packet load balancing to ensure that a path for a single source-destination pair does not get overloaded. If the bulk of data passing through parallel links is for a single pair, per-destination load balancing overloads a single link while other links have very little traffic. Enabling per-packet load balancing allows you to use alternate paths to the same busy destination.

Devices used in Testing –

Maipu 1800-22-AC

IOS Details –

Main Configuration:

interface fastethernet0

description ### ISP1 ###

ip address 100.1.1.1 255.255.255.252

keepalive gateway 100.1.1.2

exit

interface fastethernet0

description ### ISP2 ###

ip address 200.1.1.1 255.255.255.252

keepalive gateway 200.1.1.2

exit

interface vlan1

description ### LOCAL LAN ###

ip address 201.1.1.1 255.255.255.0

exit

ip route 0.0.0.0 0.0.0.0 100.1.1.2

ip route 0.0.0.0 0.0.0.0 200.1.1.2

Output –

Show ip route

router#sh ip route

S 0.0.0.0/0 [1/100] via 100.1.1.2, 0:01:10, fastethernet0

S 0.0.0.0/0 [1/100] via 200.1.1.2, 0:01:04, fastethernet1

Notes –

By default per destination load balancing will work.
To configure per packet load balancing

router(config)#ip load-sharing per-packet

After above configuration, load balancing will work per packet basis.
As F0 (ISP-1) link is down, all LAN traffic will take F1 as primary path, vice versa.
After faulty link restored, Traffic will be again go with configured load balancing algorithm.