HSRP, VRRP, and GLBP¶
Redundancy Considerations¶
- How fast can this happen?
- How does the client know?
- What about ARP cache issues?
- What if just the WAN link fails?
HSRP vs VRRP vs GLBP¶
- Cisco Hot-Standby Router Protocol (HSRP):
- Created by Cisco, for Cisco in 1994
- Uses a default hello timer of 3 seconds with a hold timer of 10 seconds
- Virtual Router Redundancy Protocol (VRRP):
- Created by the IETF in 1999
- Works between multiple vendors
- Has faster timers than HSRP by default - hello of 1 second, hold timer of 3 seconds
- Gateway Load Balancing Protocol (GLBP):
- Created by Cisco, for Cisco in 2005
- Identical features to HSRP, but allows active-active connection that adds load balancing
HSRP¶
- Gateways organised into standby groups
- One gateway active, others in standby state
- Phantom (virtual) router IP and MAC address generated
- Hello messages sent once every 3 seconds, dead after 10 sec
Mac Address Structure:
- 0000.0C07.ACXX
- 0000.0C - Cisco Vendor ID
- 07.AC - HSRP ID
- XX - Standby group number
HSRP Base Configuration¶
- Step 1: Create standby group
- Step 2: Reassign IP Addresses
- Step 3: Verify
- Step 4: optimize and tune
# Switch A
int vlan 70
standby 1 ip 172.30.70.1
standby 1 priority 150
# Switch B (default priority of 100)
int vlan 70
standby 1 ip 172.30.70.1
standby 1 priority 100
# Verify
show standby
Tuning and Optimizing HSRP¶
- Priority
- Preempt
- Tracking
- Timers
standby group 1 preempt
standby 1 track f0/23 60
standby 1 preempt delay reload 180
standby 1 timers msec 150 msec 700
VRRP¶
- Active/standby becomes master/backup
- Standby group becomes VRRP group
- master router can share virtual IP
- One second hello timer, three times hello = down time (+ skew timer)
VRRP Configuration¶
- Step 1: Configure VRRP Group
- Step 2: Optimize settings
- Step 3: Verify
# Master
int f0/0
vrrp 20 ip 172.30.4.90
vrrp 20 preempt
vrrp 20 timers advertise msec 100
# Backup
# same, except instead of advertise, learn
# Verify
show vrrp
GLBP¶
- Single VIP with Multiple MACs
- Active Virtual gateway (AVG) acts as the 'point man'
- Other routers act as active virtual forwarders (AVF)