Packet Tracer: Load Balancing with GLBP and FHRP
- 1. Rafat Khandaker Packet tracer HSRP / VRRP /GLBP 05-18-16 . 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.