After a route-target change on a county MAC-VRF, remote MACs withdraw from several leaves. What control-plane membership effect explains that?
Select an answer to reveal the explanation.
Short Explanation
Tweaking route targets is like changing which club badges get you into the overlay room—lose the badge match and those MAC/IP routes get shown the door. That withdrawal is expected membership behavior, not an MTU mystery or an underlay protocol conversion.
Full Explanation
After a route-target change on a county MAC-VRF, remote MACs withdraw from several leaves because changing EVPN route-target import or export alters which MAC/IP routes are accepted into the VRF. Previously imported MACs withdraw when membership no longer matches—expected control-plane policy behavior that change control must anticipate, not a random SNMP or MTU symptom.
Route-target changes do not only rename SNMP sysName; they directly affect which EVPN routes enter tenant tables. An RT edit does not force all underlay BGP sessions to switch permanently to OSPF. MAC withdrawals after an RT change do not prove VXLAN data-plane MTU is too large.
Exam caveat: RT policy defines EVPN membership; withdrawals after RT edits are often correct, so validate remaining imports intentionally during civic change windows.
Operational check: snapshot EVPN routes before RT changes; afterward confirm intended VNIs still import and unintended ones withdraw; restore RT alignment immediately if MAC tables emptied beyond the approved change plan.
In civic fabric operations, retain the correct idea—Changing EVPN route-target import/export alters which MAC/IP routes are accepted into the VRF, so previously imported MACs can withdraw when membership no longer matches—and reject distractors that confuse layers or tools. Specifically, do not treat “Route-target changes only rename SNMP sysName and cannot affect MAC tables.” as valid, do not accept “Any RT edit forces all underlay BGP sessions to switch permanently to OSPF.” as a substitute design, and do not operationalize “MAC withdrawals after an RT change prove VXLAN data-plane MTU is too large.” in production runbooks. Re-validate after changes with show commands for sessions, routes, VTEP reachability, and a simple tenant traffic test appropriate to the VNI under review.