I am trying to understand what the anchor terminology is as it's being applied inconsistently. For example, we have a WLC in the DMZ for guest wifi and that WLC is being referred as an anchor. But then I am seeing log messages on that WLC's that are saying "Mobility anchor data path down. MobilityAnchorAddressType= 1 MobilityAnchorAddress= 126.96.36.199", where the 188.8.131.52 is the IP address of the downstream WLC. So, which one is the anchor here? Appreciate a clarification.
Yes Anchor WLC mean where you provide Point of Presence (PoP) to a wireless client (in otherwords where wired network will see from where the wireless client coming with an IP address). An anchor WLC always pair with a Foreign controller where clients Point of Attachement (PoA), at Foreign controller there may not be any layer 3 information about client.
In guest auto-anchoring solution, under WLAN you have to configure the mobility anchor (in DMZ controller we configure itself as mobility anchor, where in foreign controllers we configure DMZ WLC as mobility anchor). In this way always L3 guest traffic terminate at your DMZ controller. In this scenario, Anchor & Foreign controller role termed as "Export-Anchor" & "Export-Foreign"
Below post may help you as well to understand this.
I understand the basic premise of the anchor WLC vs the foreign WLC and the PoP vs PoA respectively. What throws me off, however, is that the Auto-Anchor Mobility seems to be using the reverse nomenclature, such as the DMZ Controller that the client is roaming to becomes the anchor controller as opposed to the foreing controller.