January 2013 - Reading Time: 7 min
Designing a robust and highly available internet edge is a core requirement for enterprise networks in 2013. With increasing reliance on SaaS applications and externally hosted services, downtime at the perimeter can have catastrophic implications. In this article, we explore the strategic deployment of first-hop redundancy protocols — namely VRRP and HSRP — to achieve resilience at the internet edge.
Understanding the Internet Edge
The internet edge typically includes redundant ISPs, firewalls, and border routers. The goal is to maintain connectivity even in the face of hardware failure or a provider outage. However, one of the trickiest components is the gateway IP used by internal hosts or firewalls to reach the outside world. If that gateway IP is tied to a single router, failure of that device results in loss of outbound connectivity.
Introducing VRRP and HSRP
Virtual Router Redundancy Protocol (VRRP) and Hot Standby Router Protocol (HSRP) are designed to solve this problem. Both allow a group of routers to present a virtual IP address as the default gateway. One router is active at any given time, while others remain on standby, ready to take over if the active router becomes unavailable.
HSRP Configuration Overview
HSRP is Cisco proprietary and widely deployed in Cisco environments. Here's a sample configuration for HSRP on two routers sharing the 10.1.1.1 virtual gateway:
interface GigabitEthernet0/0
ip address 10.1.1.2 255.255.255.0
standby 1 ip 10.1.1.1
standby 1 priority 110
standby 1 preempt
standby 1 authentication md5 key-string securekey
The other router would use a priority of 100, acting as the standby. The preempt command ensures the higher priority router reclaims the active role when it comes back online.
VRRP Configuration Overview
VRRP is an open standard (RFC 5798) and functions similarly. A basic configuration on an interface might look like:
interface GigabitEthernet0/0
ip address 10.1.1.3 255.255.255.0
vrrp 1 ip 10.1.1.1
vrrp 1 priority 120
vrrp 1 preempt
Again, other routers in the group will assume control of the virtual IP if the master fails.
Deployment Tips
- Ensure proper interface tracking to adjust priority when WAN links fail.
- Use authentication to prevent rogue devices from joining the redundancy group.
- Test failover scenarios during maintenance windows to validate behavior.
- In multi-VLAN environments, configure HSRP/VRRP for each subnet as needed.
Design Considerations
When deploying redundant internet paths, it’s essential to think beyond the routers. Firewalls, WAN optimizers, and load balancers should also support high availability. Consider using asymmetric routing detection and NAT reflection techniques to accommodate failovers cleanly. In more complex setups, dynamic routing protocols like BGP can be integrated with HSRP/VRRP to automate failover based on upstream reachability.
Final Thoughts
In 2013, business continuity demands that enterprises eliminate single points of failure at the network edge. HSRP and VRRP remain essential building blocks in high availability architectures. Whether you’re designing for a small business or a multinational enterprise, redundancy at the gateway level is an investment that pays off in uptime and reliability.