Cisco CCNA (200-301)IP ConnectivityMedium
A company implements GLBP for the 172.16.30.0/24 VLAN using four member routers. Which statement accurately describes how GLBP differs from HSRP and VRRP in this deployment?
- AGLBP allows only one router to actively forward traffic while the others remain in standby
- BGLBP requires a separate virtual IP address to be configured on each of the four routers
- CGLBP elects a single Active Virtual Gateway that also becomes the only Active Virtual Forwarder
- DGLBP allows all four routers to simultaneously forward traffic by assigning multiple virtual MAC addresses
Show answer & explanationAnswer & explanation
Correct answer: D. GLBP allows all four routers to simultaneously forward traffic by assigning multiple virtual MAC addresses
GLBP's key advantage over HSRP/VRRP is active load balancing: one router is elected Active Virtual Gateway (AVG) and assigns different virtual MAC addresses to each participating router, making them Active Virtual Forwarders (AVFs) that all actively forward traffic for different clients simultaneously.
Why the other options are wrong
- A. That describes HSRP/VRRP's active/standby model, not GLBP's load-balancing design.
- B. GLBP uses a single shared virtual IP address, not separate ones per router.
- C. The AVG assigns MACs but does not have to be the only forwarder; multiple AVFs handle forwarding.
GLBP Load Balancing
Gateway Load Balancing Protocol allows multiple routers to actively forward traffic for a single virtual IP by assigning each router a distinct virtual MAC address as an Active Virtual Forwarder.
- One router is elected AVG to manage virtual MAC assignment
- Up to 4 AVFs can forward traffic simultaneously
- Unlike HSRP/VRRP, GLBP uses all available bandwidth rather than one active path
Memory trick: GLBP Gives Load Balancing Power to everyone