QTECH
Software Configuration Manual
8-117
8.2.14
Configure route convergence in OSPF
Route convergence is : ABR can convergent the route information with the same prefix together and
distribute one route to other area. One area can configure many convergent network interface so that OSPF can
convergent many network interface. ABR sends route information to other area to generate Sum_net_Lsa
（
Type 3
LSA
）
with the unit of network interface. If there are some continuous network interface in area, use area range
command to convergent these continous network interface to be one network interface. ABR sends one convergent
LSA and LSA located in specified convergent network will not be sent separately which can reduce the scale of
LSDB in other areas.
Convergent them to be one network interface : 202.38.0.0 255.255.0.0
Once adding convergent network interface of some network interface to area, the internal route whose IP
address locates in this network interface will not be broadcasted to other area but broadcast the abstract information
of the whole convergent network route. If the network interface is restricted by keyword not-advertise, the abstract
information to this network route will not be broadcasted. This network is demonstrated by IP address/ mask.
Receiving convergent network and restricting it will reduce the exchange volume of route information in areas.
Caution : Route convergence is effective in ABR configuration.
Configure it in OSPF protocol configuration mode :
Configure OSPF area route convergence
area
area-id
range
address mask
[
advertise | notadvertise
]
Cancel OSPF area route convergence
no area
area-id
range
address mask
By default, route in areas will not be convergent.
Example :
!Convergent 202.38.160.0 255.255.255.0 and 202.38.180.0 255.255.255.0to be one route 202.38.0.0
255.255.0.0
QTECH(config-router-ospf)#area 1.1.1.1 range 202.38.0.0 255.255.0.0
8.2.15
Configure OSPF virtual connection
After dividing SOPF areas, not all areas are equal. One area with the area-id being 0.0.0.0 is different which
is called BackboneArea. The update of OSPF route in non- BackboneArea is through BackboneArea. OSPF protocol
regulates : all non- BackboneArea must be connected with BackboneArea, that is, there must be at least one
interface of ABR in area 0.0.0.0. If there is an area which is not physically connected with BackboneArea 0.0.0.0,
there must establish a virtual connection.
If the physical connection cannot be proved because of the restriction of network topology, create virtual
connection. Virtual connection means two ABRs set up a physical connection through interbal route area of a
non-Back Bone Area. The ends must be ABR and it can be effective when configuring at both two sides. Virtual
connection is marked by route ID of the opposite end. The internal area supported a non-Back Bone Area for the two
ends of the virtual connection is called Transit Area and its area number must be demonstrated when configuring.
Virtual connection is activated after the calculation of transmitting area route which equals to form
point-to-point link between two ends, so in this connection, it can also configure interface parameter as physical
interface, such as sending HELLO packet interval.
“Logical channel” means serval routers running OSPF between two ABRs which only transmit packet (the
destination address of protocol packet are not these routers, so packet is transmitted as general IP packet) and two
ABRs can straightly transmit router information. Here, router information means type 3 LSA generated by ABR, so
the synchronization of routers in area do not changed.
Caution : If autonomy system is divided to be one or more areas, there must be one Back Bone area to
guarantee the straightly or logically connection between other areas and Back Bone area and Back Bone area itself
must be connected.
Configure it in OSPF protocol configuration mode :
Create and configure virtual connection
area
area-id
virtual-link
router-id
[
hello-interval
seconds
] [
retransmit- interval
seconds
]
[
transmit-delay
seconds
] [
dead-interval
seconds
] { [
authentication-key
key
] |
[
message-digest-key
keyid
md5
key
] }
Cancel created virtual connection
no area
area-id
virtual-link
router-id
[
hello-interval
seconds
] [
retransmit- interval
seconds
]
[
transmit-delay
seconds
] [
dead-interval
seconds
] { [
authentication-key
key
] |
