Preventing EIGRP SIA Connections.

For preventing SIA (Stuck-in Active) connections in EIGRP, Cisco has introduced a new IOS feature (12.1(5) or later) that will generate 2 packet types SIA-Query and SIA-Reply automatically with no configuration required.


For Example: Router A, B and C are connected each other. Router A Send a Query to Router B for Network 172.10.30.0/24.Router B has no Entry for this Network, so it queries to Router C.But there is a problem in the link between Router B and C, because of this packet might lost or Delayed. Router A has no visibility of downstream progress and assumes it has problem with Router B.in this case after the default period of 3 minutes Router A will reset the neighbour relation with Router B.

But with the Active Enhancement feature of SIA-Query and Reply ,Router A queries down stream Router B (with SIA-Query) at the midway point of the active default timer(one and half minutes) about the status of the route. Router B responds (with SIA-Reply) that it is searching for a replacement route. After receiving this SIA-Reply packet, Router A validates the status of Router B and does not terminate the neighbour relationship.