ELS Messages for Open Shortest Path First (SPF)


SPF.001

Level:
UE-ERROR
Short Syntax:
SPF.001 Bad length pkt, from IP_source , type OSPF_packet_type
Long Syntax:
SPF.001 Bad length packet, from IP_source , type OSPF_packet_type
Description:
An OSPF packet has been received. The OSPF length field indicates a longer packet than indicated by the IP header length field. The packet is discarded.

SPF.002

Level:
UE-ERROR
Short Syntax:
SPF.002 Bad pkt checksum, from IP_source , type OSPF_packet_type
Long Syntax:
SPF.002 Bad packet checksum, from IP_source , type OSPF_packet_type
Description:
An OSPF packet has been received. The packet has an invalid OSPF checksum. The packet is discarded.

SPF.003

Level:
UE-ERROR
Short Syntax:
SPF.003 Bad OSPF version, from IP_source , type OSPF_packet_type
Long Syntax:
SPF.003 Bad OSPF version, from IP_source , type OSPF_packet_type
Description:
An OSPF packet has been received. The version field in the OSPF header is not equal to 1. The packet is discarded.

SPF.004

Level:
UE-ERROR
Short Syntax:
SPF.004 Duplicate Router ID, from IP_source , type OSPF_packet_type
Long Syntax:
SPF.004 Duplicate Router ID, from IP_source , type OSPF_packet_type
Description:
An OSPF packet has been received. The router ID specified in the OSPF header is equal to the router's own ID. Either two interfaces are attached to the same network (OK) or there is a conflict in the assignment of OSPF router IDs (serious). The packet is discarded.

SPF.005

Level:
UE-ERROR
Short Syntax:
SPF.005 No matching ifc for pkt from IP_source , type OSPF_packet_type
Long Syntax:
SPF.005 No matching SPF-interface for packet from IP_source , type OSPF_packet_type
Description:
An OSPF packet has been received. Either the IP destination specified in the packet is not acceptable, or the parameters in the OSPF header (like area ID) do not match the parameters configured for the receiving interface. The packet is discarded.

SPF.006

Level:
UE-ERROR
Short Syntax:
SPF.006 Authentication failure, from IP_source , type OSPF_packet_type
Long Syntax:
SPF.006 Packet authentication failure, from IP_source , type OSPF_packet_type
Description:
An OSPF packet has been received which fails to authenticate. The packet is discarded.

SPF.007

Level:
UE-ERROR
Short Syntax:
SPF.007 No matching nbr for pkt from IP_source , type OSPF_packet_type
Long Syntax:
SPF.007 No matching OSPF neighbor for packet from IP_source , type OSPF_packet_type
Description:
An OSPF packet has been received. The packet is not a hello packet, and does not match any existing OSPF neighbor. The packet is discarded.

SPF.008

Level:
UE-ERROR
Short Syntax:
SPF.008 Bad pkt type from IP_source , type OSPF_packet_type
Long Syntax:
SPF.008 Bad packet type received from IP_source , type OSPF_packet_type
Description:
An OSPF packet has been received. The OSPF packet type field is invalid. The packet is discarded.

SPF.009

Level:
UI-ERROR
Short Syntax:
SPF.009 No buffer for mcast to IP_destination
Long Syntax:
SPF.009 No buffer for multicast packet to IP_destination
Description:
An attempt was made to send a multicast packet on a non-broadcast network by expanding the packet on the link level. This expansion failed due to insufficient buffer resources.

SPF.010

Level:
P-TRACE
Short Syntax:
SPF.010 Received packet type OSPF_packet_type from IP_source
Long Syntax:
SPF.010 Received packet type OSPF_packet_type from IP_source
Description:
An OSPF packet of the specified type was received.

SPF.011

Level:
U-TRACE
Short Syntax:
SPF.011 Sending unicast type OSPF_packet_type dst IP_destination
Long Syntax:
SPF.011 Sending unicast type OSPF_packet_type dst IP_destination
Description:
Unicast OSPF packet of specified type has been sent to the specified IP destination.

SPF.012

Level:
P-TRACE
Short Syntax:
SPF.012 Sending mcast type OSPF_packet_type , dst IP_destination net network
Long Syntax:
SPF.012 Sending multicast, type OSPF_packet_type , destination IP_destination net network
Description:
Multicast OSPF packet of specified type sent out specified interface.

SPF.013

Level:
U-INFO
Short Syntax:
SPF.013 Rxmitting type OSPF_packet_type , IP_source -> IP_destination
Long Syntax:
SPF.013 Retransmitting packet, type OSPF_packet_type , IP_source -> IP_destination
Description:
Unicast OSPF packet of specified type is being retransmitted.

SPF.014

Level:
UI-ERROR
Short Syntax:
SPF.014 No FSM match, ifc interface_IP_address , state interface_state , event interface_event
Long Syntax:
SPF.014 No FSM match, interface interface_IP_address , state interface_state , event interface_event
Description:
The specified event occurred while an interface was in the specified state. This occurrence was not covered by the interface Finite State Machine. The event is ignored.

SPF.015

Level:
U-INFO
Short Syntax:
SPF.015 State change, ifc interface_IP_address , new state new_interface_state , event interface_event
Long Syntax:
SPF.015 State change, interface interface_IP_address , new state new_interface_state , event interface_event
Description:
The specified event occurred on the specified interface, causing its state to transition.

SPF.016

Level:
UE-ERROR
Short Syntax:
SPF.016 No match for hlo (virtual link) from IP_source
Long Syntax:
SPF.016 No match for hello received on virtual link, from IP_source
Description:
A hello packet was received that could only match a virtual link, yet that link is not configured. The packet is discarded.

SPF.017

Level:
UE-ERROR
Short Syntax:
SPF.017 Network mask mismatch with IP_source
Long Syntax:
SPF.017 Network mask mismatch in hello from IP_source
Description:
Hello packet received from neighbor. Neighbor disagrees with this router concerning the network mask of their common network. The packet is discarded.

SPF.018

Level:
UE-ERROR
Short Syntax:
SPF.018 Hello interval mismatch with IP_source
Long Syntax:
SPF.018 Hello interval mismatch in hello from IP_source
Description:
Hello packet received from neighbor. Neighbor disagrees with this router concerning the hello interval to be used on the common network. The packet is discarded.

SPF.019

Level:
UE-ERROR
Short Syntax:
SPF.019 Dead interval mismatch with IP_source
Long Syntax:
SPF.019 Dead interval mismatch in hello from IP_source
Description:
Hello packet received from neighbor. Neighbor disagrees with this router concerning the ``dead router interval'' to be used on the common network. The packet is discarded.

SPF.020

Level:
UI-ERROR
Short Syntax:
SPF.020 No FSM match, nbr neighbor_IP_address , state neighbor_state , event neighbor_event
Long Syntax:
SPF.020 No FSM match, neighbor neighbor_IP_address , state neighbor_state , event neighbor_event
Description:
The specified event has been generated for the specified neighbor, which is currently in the specified state. This was not anticipated by the neighbor Finite State Machine. The event is ignored.

SPF.021

Level:
U-INFO
Short Syntax:
SPF.021 State change, nbr neighbor_IP_address , new state neighbor_state , event neighbor_event
Long Syntax:
SPF.021 State change, neighbor neighbor_IP_address , new state neighbor_state , event neighbor_event
Description:
The specified event has been generated, causing the specified neighbor to transfer to a new state.

SPF.022

Level:
UI-ERROR
Short Syntax:
SPF.022 Outstanding DD pkt not avail for nbr neighbor_IP_address
Long Syntax:
SPF.022 Outstanding Database Description packet not avail for neighbor neighbor_IP_address
Description:
An attempt was made to retransmit a Database Description packet to the specified neighbor, but the packet could not be found. Retransmission is aborted.

SPF.023

Level:
UI-ERROR
Short Syntax:
SPF.023 Unable to get pkt, to IP_destination , ifc interface_IP_address
Long Syntax:
SPF.023 Unable to get packet to send to IP_destination , out interface interface_IP_address
Description:
An attempt was made to send an OSPF packet to the specified destination. The specified interface has been aborted due to lack of buffers.

SPF.024

Level:
UE-ERROR
Short Syntax:
SPF.024 Bad length LS adv from neighbor_IP_address
Long Syntax:
SPF.024 Bad length Link state advertisement received from neighbor_IP_address
Description:
A link state advertisement has been received from the specified neighbor, and the advertisement's length field indicates that the entire advertisement is NOT fully contained in the received Link State Update Packet. The partial advertisement is discarded.

SPF.025

Level:
UE-ERROR
Short Syntax:
SPF.025 from neighbor_IP_address , adv. cksum fl: ( LS_type , advertisement_ID )
Long Syntax:
SPF.025 from neighbor_IP_address , LS advertisement checksum fails: LS type LS_type id advertisement_ID
Description:
A link state advertisement has been received. The advertisement is identified by its LS type and two-part originating ID (see OSPF specification section 12.1). The checksum field contained in the advertisement is invalid. The advertisement is ignored.

SPF.026

Level:
UE-ERROR
Short Syntax:
SPF.026 from neighbor_IP_address , bad type, adv: ( LS_type , advertisement_ID )
Long Syntax:
SPF.026 from neighbor_IP_address , bad LS type, advertisement: typ LS_type id advertisement_ID
Description:
A link state advertisement has been received. The advertisement's LS type field is invalid. The advertisement is ignored.

SPF.027

Level:
UE-ERROR
Short Syntax:
SPF.027 from neighbor_IP_address , ext adv on VL: ( LS_type , advertisement_ID )
Long Syntax:
SPF.027 from neighbor_IP_address , AS external link adv. on Virtual Link: typ LS_type id advertisement_ID
Description:
A link state advertisement has been received. It was received over a virtual link, yet its LS type is equal to AS external link. The advertisement is ignored.

SPF.028

Level:
U-INFO
Short Syntax:
SPF.028 from neighbor_IP_address , old adv: ( LS_type , advertisement_ID )
Long Syntax:
SPF.028 from neighbor_IP_address , old LS advertisement: typ LS_type id advertisement_ID
Description:
A link state advertisement has been received. The advertisement is older than the current database copy. The received advertisement is ignored.

SPF.029

Level:
U-INFO
Short Syntax:
SPF.029 from neighbor_IP_address , self update: ( LS_type , advertisement_ID )
Long Syntax:
SPF.029 from neighbor_IP_address , self update: typ LS_type id advertisement_ID
Description:
A link state advertisement exists. The router itself originated the advertisement yet the advertisement is newer than the database copy. This indicates that the advertisement originated before the router was last started. This causes the router to either advance the LS sequence number and originate a new instantiation of the advertisement, or flush the advertisement, if it is a summary LSA and the attached area does not wish to import summary LSAs anymore.

SPF.030

Level:
U-INFO
Short Syntax:
SPF.030 from neighbor_IP_address , new adv: ( LS_type , advertisement_ID )
Long Syntax:
SPF.030 from neighbor_IP_address , new LS advertisement: typ LS_type id advertisement_ID
Description:
A link state advertisement has been received. The advertisement is newer than the current database copy. This advertisement is flooded out all other interfaces, and installed in the routing database.

SPF.031

Level:
U-INFO
Short Syntax:
SPF.031 from neighbor_IP_address , Old ack for adv: ( LS_type , advertisement_ID )
Long Syntax:
SPF.031 from neighbor_IP_address , Old acknowledgement for advertisement: typ LS_type id advertisement_ID
Description:
An unexpected link state acknowledgement has been received. The acknowledgement, however, is for a previous instantiation of the link state advertisement.

SPF.032

Level:
U-INFO
Short Syntax:
SPF.032 Bad ack from neighbor_IP_address for adv: ( LS_type , advertisement_ID )
Long Syntax:
SPF.032 Bad acknowledgment from neighbor_IP_address for advertisement: typ LS_type id advertisement_ID
Description:
An unexpected link state acknowledgement has been received. The acknowledgement however is for the current instantiation of the link state advertisement.

SPF.033

Level:
U-INFO
Short Syntax:
SPF.033 LS update retransmission to neighbor_IP_address
Long Syntax:
SPF.033 LS update retransmission to neighbor neighbor_IP_address
Description:
A Link State Update packet containing retransmitted link state advertisements has been unicast to the specified neighbor. This probably indicates packet loss during the flooding procedure.

SPF.034

Level:
U-INFO
Short Syntax:
SPF.034 LS ack sent direct to neighbor_IP_address
Long Syntax:
SPF.034 LS acknowledement sent directly to neighbor neighbor_IP_address
Description:
A Link State Acknowledgement packet has been sent directly to the specified neighbor. This is in response to duplicate link state advertisements received from the neighbor. This probably indicates packet loss during the flooding procedure.

SPF.035

Level:
U-INFO
Short Syntax:
SPF.035 Flushing advertisement: ( LS_type , advertisement_ID )
Long Syntax:
SPF.035 Flushing advertisement: typ LS_type id advertisement_ID
Description:
A link state advertisement contained in the link state database has not been refreshed for 2 hours. The advertisement is deleted from the database. This probably indicates that the originator of the advertisement is unreachable. See section 14 of the OSPF specification.

SPF.036

Level:
U-INFO
Short Syntax:
SPF.036 Originating adv: ( LS_type , advertisement_ID )
Long Syntax:
SPF.036 Originating LS advertisement: typ LS_type id advertisement_ID
Description:
A link state advertisement is being (re)originated by the router. This can be due to topological change, or the necessity to refresh.

SPF.037

Level:
U-INFO
Short Syntax:
SPF.037 new route to destination , type route_type cost route_cost
Long Syntax:
SPF.037 New route to destination destination , type route_type cost route_cost
Description:
The SPF routing table build process has detected a new best route to specified destination, having the specified cost.

SPF.038

Level:
P-TRACE
Short Syntax:
SPF.038 NBMA hello sent to dest neighbor_IP_address
Long Syntax:
SPF.038 NBMA hello sent to IP destination neighbor_IP_address
Description:
An OSPF hello has been sent to the specified IP destination. This has been done over a non-broadcast, multi-access interface.

SPF.039

Level:
U-INFO
Short Syntax:
SPF.039 The OSPF routing protocol is en/dis abled
Long Syntax:
SPF.039 The OSPF routing protocol is en/dis abled
Description:
Printed on router startup. Indicates operational status of the SPF protocol.

SPF.040

Level:
U-INFO
Short Syntax:
SPF.040 SPF Interface interface_IP_address is not an IP address, Interface not installed
Long Syntax:
SPF.040 SPF Interface interface_IP_address is not an IP address, Interface not installed
Description:
Printed on router startup when an OSPF interface address is configured, yet this address has not also been configured in the IP console. OSPF interface is not installed.

SPF.041

Level:
U-INFO
Short Syntax:
SPF.041 Non-Broadcast net interface_IP_address is not an SPF interface
Long Syntax:
SPF.041 Non-Broadcast net interface_IP_address is not an SPF interface
Description:
Printed on router startup when OSPF non-broadcast parameters have been configured for a non-existent OSPF interface. These configuration parameters are ignored.

SPF.042

Level:
P-TRACE
Short Syntax:
SPF.042 protocol (disabled): IP_source -> IP_destination , type OSPF_packet_type discarded
Long Syntax:
SPF.042 protocol (disabled): IP_source -> IP_destination , type OSPF_packet_type discarded
Description:
The OSPF protocol is disabled, yet an OSPF protocol packet has been received. The packet is discarded.

SPF.043

Level:
U-INFO
Short Syntax:
SPF.043 Duplicate LS ack received from neighbor_IP_address
Long Syntax:
SPF.043 Duplicate LS acknowledgment received from neighbor neighbor_IP_address
Description:
Unexpected link state acknowledgements have been received from the specified neighbor. This probably indicates packet loss during the flooding procedure.

SPF.044

Level:
UE-ERROR
Short Syntax:
SPF.044 from neighbor_IP_address , bad age field, adv ( LS_type , advertisement_ID )
Long Syntax:
SPF.044 from neighbor_IP_address , bad age field, advertisement: typ LS_type id advertisement_ID
Description:
A link state advertisement has been received. The advertisement's LS age field is invalid. The advertisement is ignored.

SPF.045

Level:
U-INFO
Short Syntax:
SPF.045 non-existent transit area proposed_transit_area , VL discarded
Long Syntax:
SPF.045 Transit area proposed_transit_area not configured, virtual link discarded
Description:
A virtual link has been configured to have a certain transit area, yet that area has not been defined. The virtual link is ignored.

SPF.046

Level:
U-INFO
Short Syntax:
SPF.046 No backbone configured, VLs discarded
Long Syntax:
SPF.046 Backbone area is not configured, all virtual links discarded
Description:
Virtual links cannot be used unless a backbone area is configured.

SPF.047

Level:
U-INFO
Short Syntax:
SPF.047 destination now unreachable
Long Syntax:
SPF.047 Destination destination now unreachable
Description:
The destination has been found to be unreachable during the routing table build process.

SPF.048

Level:
UE-ERROR
Short Syntax:
SPF.048 AS ext adv limit exceeded; adv ignored
Long Syntax:
SPF.048 Limit of AS external advertisements exceeded; advertisement discarded
Description:
The estimated number of advertisements has been exceeded. New AS external advertisements are ignored in order to put a limit on router heap usage.

SPF.049

Level:
UE-ERROR
Short Syntax:
SPF.049 AS ext adv limit exceeded; origination deferred
Long Syntax:
SPF.049 Limit of AS external advertisements exceeded; origination deferred
Description:
The estimated number of advertisements has been exceeded. The origination of new AS external advertisements is deferred in order to put a limit on router heap usage.

SPF.050

Level:
U-INFO
Short Syntax:
SPF.050 from neighbor_IP_address , MaxAge: ( LS_type , advertisement_ID )
Long Syntax:
SPF.050 from neighbor_IP_address , received unexpected MaxAge: typ LS_type id advertisement_ID
Description:
A link state advertisement has been received. Its age is MaxAge, and there is no current instantiation of the advertisement in the router's database. The advertisement is acknowledged and then discarded without flooding.

SPF.051

Level:
UE-ERROR
Short Syntax:
SPF.051 bad adv/ovflo: ( LS_type , advertisement_ID )
Long Syntax:
SPF.051 error in advertisement or routing overflow: typ LS_type id advertisement_ID
Description:
A link state advertisement has been received. The advertisement contains an error, or cannot be added to the database due to routing table overflow. In any case, the advertisement is discarded.

SPF.052

Level:
UE-ERROR
Short Syntax:
SPF.052 Stub area mismatch with IP_source
Long Syntax:
SPF.052 Stub area mismatch in hello from IP_source
Description:
Hello packet received from neighbor. Neighbor disagrees with this router concerning the attached area's ability to process AS external link advertisements. Hello packet is ignored.

SPF.053

Level:
UE-ERROR
Short Syntax:
SPF.053 from neighbor_IP_address , recvd in stub area, adv ( LS_type , advertisement_ID )
Long Syntax:
SPF.053 from neighbor_IP_address , type 5 LSA in stub area, adv: typ LS_type id advertisement_ID
Description:
A type 5 link state advertisement has been received. The advertisement is being flooded through a stub area, and is therefore ignored.

SPF.054

Level:
C-INFO
Short Syntax:
SPF.054 Dijkstra calculation performed: Number_areas area(s)
Long Syntax:
SPF.054 Dijkstra calculation performed, on Number_areas area(s)
Description:
As a result of a topology change, the routing table has been recalculated, starting with the Dijkstra calculation.

SPF.055

Level:
U-INFO
Short Syntax:
SPF.055 Network LSA w/ old Adv Rtr: ( LS_type , advertisement_ID )
Long Syntax:
SPF.055 Network LSA with old Advertising Router: ( LS_type , advertisement_ID )
Description:
A network links advertisement having one of our addresses as Link State ID, but whose Advertising Router is not our Router ID, has been received. These advertisements are flushed, as they are assumed to be out-of-date.

SPF.056

Level:
U-INFO
Short Syntax:
SPF.056 Reparsing Network LSA: Link_State_ID
Long Syntax:
SPF.056 Reparsing Network LSA: Link_State_ID
Description:
A network link is being reparsed, owing to the fact that there are multiple network-LSAs in the network with the same Link State ID. This indicates that a router has changed OSPF Router IDs, and has originated the same router-LSA before and after the change. This is a normal, but rare, event.

SPF.057

Level:
UI-ERROR
Short Syntax:
SPF.057 Send unicast type OSPF_packet_type dst IP_destination fld, rsn reason_code , net network
Long Syntax:
SPF.057 Sending unicast type OSPF_packet_type dst IP_destination failed, reason reason_code , network network
Description:
Sending of a unicast OSPF packet of specified type failed to the specified IP destination. The reason_code is the internal error code for the failure.
Cause:
Miscellaneous handler error. (Reason code 1.)
Action:
Check for error messages from handler for network_name.
Cause:
Output queue overflow, or other flow control. (Reason code 2.)
Action:
Alleviate congestion.
Cause:
Network down. (Reason code 3.)
Action:
See why handler thinks network is down.
Cause:
Dropped by handler to avoid looping, or bad broadcast. (Reason code 4.)
Action:
Check configuration.
Cause:
Host down. (Reason code 5.)
Action:
See why handler thinks host is down.

SPF.058

Level:
UI-ERROR
Short Syntax:
SPF.058 Send multicast type OSPF_packet_type dst IP_destination fld, rsn reason_code , net network
Long Syntax:
SPF.058 Sending multicast type OSPF_packet_type dst IP_destination failed, reason reason_code , network network
Description:
Sending of a multicast OSPF packet of specified type failed to the specified IP destination. The reason_code is the internal error code for the failure.
Cause:
Miscellaneous handler error. (Reason code 1.)
Action:
Check for error messages from handler for network_name.
Cause:
Output queue overflow, or other flow control. (Reason code 2.)
Action:
Alleviate congestion.
Cause:
Network down. (Reason code 3.)
Action:
See why handler thinks network is down.
Cause:
Dropped by handler to avoid looping, or bad broadcast. (Reason code 4.)
Action:
Check configuration.
Cause:
Host down. (Reason code 5.)
Action:
See why handler thinks host is down.

SPF.059

Level:
UI-ERROR
Short Syntax:
SPF.059 Rxmit type OSPF_packet_type fld, IP_source -> IP_destination , rsn reason_code , net network
Long Syntax:
SPF.059 Retransmitting packet failed, type OSPF_packet_type , IP_source -> IP_destination , reason reason_code , network network
Description:
Retransmission of unicast OSPF packet of specified type failed. The reason_code is the internal error code for the failure.
Cause:
Miscellaneous handler error. (Reason code 1.)
Action:
Check for error messages from handler for network_name.
Cause:
Output queue overflow, or other flow control. (Reason code 2.)
Action:
Alleviate congestion.
Cause:
Network down. (Reason code 3.)
Action:
See why handler thinks network is down.
Cause:
Dropped by handler to avoid looping, or bad broadcast. (Reason code 4.)
Action:
Check configuration.
Cause:
Host down. (Reason code 5.)
Action:
See why handler thinks host is down.

SPF.060

Level:
UI-ERROR
Short Syntax:
SPF.060 NBMA hello disc to dest neighbor_IP_address , rsn reason_code , net network
Long Syntax:
SPF.060 NBMA hello disc to IP destination neighbor_IP_address , reason reason_code , network network
Description:
An OSPF hello has was discarded when attempting to send to the specified IP destination. This was attempted over a non-broadcast, multi-access interface. The reason_code is the internal error code for the failure.
Cause:
Miscellaneous handler error. (Reason code 1.)
Action:
Check for error messages from handler for network_name.
Cause:
Output queue overflow, or other flow control. (Reason code 2.)
Action:
Alleviate congestion.
Cause:
Network down. (Reason code 3.)
Action:
See why handler thinks network is down.
Cause:
Dropped by handler to avoid looping, or bad broadcast. (Reason code 4.)
Action:
Check configuration.
Cause:
Host down. (Reason code 5.)
Action:
See why handler thinks host is down.

SPF.061

Level:
U-INFO
Short Syntax:
SPF.061 non-existent area proposed_area , interface interface_IP_address not installed
Long Syntax:
SPF.061 OSPF area proposed_area not configured, interface interface_IP_address not installed
Description:
Printed on router startup when an OSPF interface address is configured, but the attached area is not defined. Hence, the OSPF interface is not installed.

SPF.062

Level:
UE-ERROR
Short Syntax:
SPF.062 LS node alloc fld, ty ls_node_type , sz ls_node_size
Long Syntax:
SPF.062 LS node allocation failed, type ls_node_type , size ls_node_size
Description:
The router has run out of memory. As a result, OSPF is unable to allocate a node for later insertion into the link state database for either the advertisement that we have just received, or the advertisement that we are trying to originate.

SPF.063

Level:
U-INFO
Short Syntax:
SPF.063 router ID changed from oldRouterID to newRouterID
Long Syntax:
SPF.063 router ID has changed from oldRouterID to newRouterID
Description:
The OSPF router ID has changed due to either learning an address dynamically, or losing the previously learnt address.