This document discusses simulating failsafe protocols like GLBP and FHRP to provide load balancing and redundancy. It provides an overview of GLBP, explaining that it uses Active Virtual Gateways and Active Virtual Forwarders to assign routers as primary and secondary access to the virtual gateway IP. It also discusses FHRP protocols like HSRP and VRRP, noting that HSRP is Cisco proprietary while VRRP is an IETF standard. The document goes on to describe configuring GLBP across three routers to demonstrate how traffic would be load balanced and how a backup router would take over if the primary fails.

1. Rafat Khandaker
Packet tracer
HSRP / VRRP /GLBP
05-18-16
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ABSTRACT
In this lab, I will simulate failsafe protocols designed in Cisco routers and layer 3
switches to simulate load balance or distribute traffic through a network. Many protocols such as,
GLBP and FHRP protocols can be used to simulate load balancing functions. In this lab I will
research GLBP and FHRP protocols and explain the difference between them.
GLBP ( summary )

2. Gateway Load Balancing Protocol, contains AVG roles or "Active virtual gateway,"
while AVFs are " Actvie Virtual forwarders. AVG and AVF assign rotuers as the primary and
secondary access to the gateway. AVG's are responsible for assigning other routers, within the
same group, with a virtual mac within the range 0007.b4xx.xxyy. The Gatway and foreworders
use the same virtual ip address. Members within the group request virtual macs from the AVG
through hello packets. "This protocol was designed to allow distribution of bandwidth in a
network for load balancing or even create a failsafe. The protocol GLBP, itself, is a cisco
proprietary protocol that transmit on multicast address: 224.0.0.102. Load balancing with
RR,weighted or host confguration. Contains upto 1,024 groups with upto 4 virtual forwarders per
group. The default hello and deadtimes are 3 tp 10 seconds. Has a default priority of 100 and can
be manually adjusted. Can only be configured on Router and 4500,6500-series catalyst switches.
Preempt has to be configured manually to set the backup virtual gateway to AVG with a priority
higher than the current AVG
So basically, The benefits of implementing GLBP within a network are.
Load sharing , Multiple virtual routing, pre-emption (backup) and authentication (plain text
passwords).
According to the cisco documentation, GLBP can be implemented with the following commands

3. First Hop Redundancy Protocol. ( FHRP )
Offers redundancy incase a router fail but does not load balance.
HSRP
Hot Standby Router Protocol ,this is a Cisco Proprietary protocol which operate on
multicast address 224.0.0.2. They operate at active or standby. Hello packets are sent every 3
second with 10 second dead time by default. The priority is set to 100, higher priority takes
value. Other routers are usually set to listen phase. Can support upto 255 groups. Contains a
virtual mac address is at format : 0000.0c07.xxxx. Can be used on routers and layer 3 switches.
Preempt has to be configured manually.
VRRP
Virtual router redundancy protocol is an IETF standard protocl, which is industrial and
can be used by non cisco routers. Use multicast address 224.0.0.18. Default preempt ( with upto
255 groups. Hello and dead times are set to 1 second to 3 seconds with a default priority of 100.
Uses virtual mac address 0000.5e00.01.xx . Master router is active, on router with the highest
priority value. Used on routers and L3 switches.
SIMULATION
AFTER CONFIGURING THE INTERFACE

4. all the interfaces are configured, all is left is for the GLBP to be configured on the interface to
allow traffic load to be distributed across the three routers. I am also going to simulate a situation
where link failures can occur to see the reaction of the GLBP protcol.
Packet tracer will not allow me to configure the routers to use GLBP.
to configure GLBP on R0 ( default priority )
config t
int fa0/0
glbp 1 ip 192.168.1.1 ( configure ip address for default gateway )
glbp 1 timers msec 500 msec 1500 ( timers of the intervals, set lower for faster convergance)
glbp 1 preempt ( backup )
glbp 1 load-balancing weighted ( configure load balance to weighted )

5. glbp 1 weighting 100 lower 90 upper 95 ( weight settings .. with thresholds)
glbp 1 weighting track 1 decrement 5 ( when link fail, it will decrement threshold by 5 )
glbp 1 weigting track 2 decrement 5
exit
track 1 int fa0/0 line protocol
track 2 int s2/0 line-protocol
exit
show glbp ( check configuration )
R1
int fa0/1
glbp 1 ip 192.168.1.1
glbp 1 timers msec 500 msec 1500
( use #debug glbp events = Command to view virtual mac arp request)
( R1 will assign AVF for the same ip address on different virtual mac address)
glbp 1 priority 110
glbp 1 preempt
glbp 1 weighting 200 lower 100 upper 110
glbp 1 load-balancing weighted
glbp 1 weighting track 2 decrement 10 ( balancing to the next interface )
glbp 1 weighting track 3 decrement 10
exit
track 1 int fa0/0 line-protocol
track 2 int s2/0 line-protocol
track 3 int s3/0 line-protocol ( basically we can see that the load for the next backup is being
distributed )
end

6. show glbp ( check configuration )
R3
int fa0/0
glbp 1 ip 192.168.1.1
glbp 1 timers msec 500 msec 1500
glbp 1 priority 95
glbp 1 preempt
glbp 1 weighting 100
glbp 1 load-balancing weighted
exit
show glbp
R2 ( show glbp now should show the role as AVG due to higher priority )
When router 2 fails ( shutdown ) lets say for administration.. router 1 should take over the
network.
R1 ( debug glbp events )
( The AVG router should be active while the other routers are in standby... )
SUMMARY
In this lab I have studied load balancing and the different protocols to administer within
cisco routers.