Gateway Load Balancing Protocol (GLBP) as we all know is a Cisco's protocol to deal with the failure of the default gateways in the LAN but when compared with any other protocol of similar nature (HSRP, VRRP etc) it stands much ahead of all these protocols. GLBP is a feature rich protocol with superb ease of configuration.
Lets have a look at the benefits which GLBP provides by default -
GLBP simply overcomes the issues related to HSRP & VRRP multi-group loadsharing and failover management issues. It doesn't requires different subnets and groups to load balance your LAN traffic, its embeded algorithms can take care of this. lets see how does GLBP performs this magical stuff -
Lets have a look at the benefits which GLBP provides by default -
GLBP Advantages -
• Efficient use of network resources: multiple paths upstream from the gateways can be utilized simultaneously.
• Higher availability:
GLBP offers enhanced redundancy eliminating single point of failure of
the first-hop gateway. An enhanced object-tracking feature can be used
with GLBP to ensure the redundancy implementation mirrors network
capabilities. This same feature is also available for HSRP and VRRP.
• Automatic load balancing: Off-net traffic is shared among available gateways on a per-host basis, according to the defined load-balancing algorithm.
• Lower administration costs:
Since all hosts on a subnet can use a common default gateway while load
balancing is still achieved, administration of multiple groups and
gateways is unnecessary.
• Simpler Access-layer design: More efficient use of resources is now possible without configuring additional VLANs and subnets.
GLBP simply overcomes the issues related to HSRP & VRRP multi-group loadsharing and failover management issues. It doesn't requires different subnets and groups to load balance your LAN traffic, its embeded algorithms can take care of this. lets see how does GLBP performs this magical stuff -
GLBP
specifies a protocol that provides load balancing over multiple
gateways via a single virtual IP address and multiple virtual MAC
addresses.
The members of a GLBP group elect one gateway to be the Active Virtual Gateway (AVG)
for that group. Other members of the group provide backup for the AVG
in case it later becomes unavailable. The AVG assigns a virtual MAC
address to each member of the GLBP group. These gateways become the Active Virtual Forwarder (AVF) for that virtual MAC address, and assume responsibility for forwarding packets sent to the virtual MAC address.
The
AVG is responsible for answering ARP requests for the virtual IP
address. Load sharing is achieved by answering these requests with the
specific virtual MAC addresses allocated to each of the virtual
forwarders.
Performing all these tasks with a single protocol, sounds too technical but as I said earlier - GLBP is very easy to configure, If you are not confident about the fine-tuning, Just enable GLBP and be rest assured it would do much good for your network, Also lets a have look at the sample command set (Config example) -
Router1
track 30 interface Serial3/0 line-protocol up delay 30
!
interface FastEthernet1/0
ip address 10.44.1.1 255.255.255.0
duplex full
glbp 1 ip 10.44.1.10
glbp 1 weighting 100 lower 95
glbp 1 weighting track 30
glbp 1 forwarder preempt delay minimum 0
Router2
track 30 interface Serial3/0 line-protocol up delay 30
!
interface FastEthernet1/0
ip address 10.44.1.2 255.255.255.0
duplex full
glbp 1 ip 10.44.1.10
glbp 1 priority 95
glbp 1 weighting 100 lower 95
glbp 1 weighting track 30
glbp 1 forwarder preempt delay minimum 0
I am sure you people enjoyed getting acquinted to this awesome protocol. So, next time onward try your hands on GLBP instead of HSRP.
For list of Cisco Configuration Video's - Click here
For list of Cisco Configuration Video's - Click here
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