GLBP is not recommended in Layer 2 looped designs with blocking links at the access layer.
GLBP is best when there is no L2 connection between the Dist switches, only L3. This non-looped approach leaves both uplinks forwarding from the access switch and no matter which switch GLBP selects as the default gateway it is only one hop away.
Hope this help. Please rate all helpful posts. :)
-Brad
