It is somewhat irritating that we have three protocols which accomplish nearly the same tasks. HSRP and VRRP are practically identical, while GLBP expands their functionality to offer load balancing. Interestingly, VRRP does not support IPv6, as IPv6 can provide more robust router discovery through its Neighbor Discovery Protocol. Cisco has included IPv6 support in HSRP and GLBP, though.
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Protocol |
HSRP (Hot Standby Router protocol) |
VRRP (Virtual Redundancy Router Protocol) |
GLBP (Gateway Load Balancing Protocol) |
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Router role |
– 1 active router.- 1 standby router.- 1 or more listening routers. |
– 1 master router.- 1 or more backup routers. |
– 1 AVG (Active Virtual Gateway).- up to 4 AVF routers on the group (Active Virtual Forwarder) passing traffic.- up to 1024 virtual routers (GLBP groups) per physical interface. |
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– Use virtual ip address. |
– Can use real router ip address, if not, the one with highest priority become master. |
– Use virtual ip address. |
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Scope |
Cisco proprietary |
IEEE standard |
Cisco proprietary |
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Election |
Active Router: |
Master Router: (*) |
Active Virtual Gateway: |
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Optimization features |
Tracking |
yes |
yes |
yes |
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Preempt |
yes |
yes |
yes |
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Timer adjust |
yes |
yes |
yes |
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Traffic type |
224.0.0.2 – udp 1985 (version1) |
224.0.0.18 – IP 112 |
224.0.0.102 udp 3222 |
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Timers |
Hello – 3 seconds |
Advertisement – 1 second |
Hello – 3 seconds |
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(Hold) 10 seconds |
(Master Down Interval)3 * Advertisement + skew time |
(Hold) 10 seconds |
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(Skew time)(256-priority) / 256 |
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Load-balancing functionality |
– Multiple HSRP group per interface/SVI/routed int. |
– Multiple VRRP group per interface/SVI/routed int. |
Load-balancing oriented- Weighted algorithm.- Host-dependent algorithm. – Round-Robin algorithm (default). |
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Requires appropriate distribution of Virtual GW IP per Clients for optimal load-balancing.(generally through DHCP) |
Requires appropriate distribution of Virtual GW IP per Clients for optimal load-balancing.(generally through DHCP) |
Clients are transparently updated with virtual MAC according to load-balancing algorithm through ARP requesting a unique virtual gateway. |
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