OSPF area, area ranges problem

Gregy · Sat Nov 10, 2007 10:12 am

Hi,
I have a little problem here. Could somebody help me?

I have network of mikrotik routers. I use OSPF for dynamic routing and so far I had only backbone area. But now I wish to create another Becouse the routing table grows bigger and bigger. But even if I have different area, routes from that area are still distributed to another routers. I tried to setup "area range" on border router but it didn't help. It added the "area route" but the other routes are there also.

Router in the backbone area:

/ routing ospf 
set router-id=0.0.0.0 distribute-default=never \
    redistribute-connected=as-type-1 redistribute-static=as-type-1 \
    redistribute-rip=no redistribute-bgp=no metric-default=1 \
    metric-connected=20 metric-static=20 metric-rip=20 metric-bgp=20 
/ routing ospf area 
set backbone area-id=0.0.0.0 type=default translator-role=translate-candidate \
    authentication=none disabled=no 
/ routing ospf interface 
set FIXME interface=all cost=10 priority=1 authentication-key="" \
    network-type=broadcast retransmit-interval=5s transmit-delay=1s \
    hello-interval=10s dead-interval=40s 
set FIXME interface="ether1->LUKAS DOMA-CIS 5GNET SMRKOVICE" cost=10 \
    priority=1 authentication-key="" network-type=broadcast \
    retransmit-interval=5s transmit-delay=1s hello-interval=10s \
    dead-interval=40s 
/ routing ospf network 
add network=10.11.5.44/30 area=backbone disabled=no 
add network=10.11.150.0/24 area=backbone disabled=no

border router:

#
/ routing ospf 
set router-id=10.200.1.1 distribute-default=never redistribute-connected=no \
    redistribute-static=no redistribute-rip=no redistribute-bgp=no \
    metric-default=1 metric-connected=20 metric-static=20 metric-rip=20 \
    metric-bgp=20 
/ routing ospf area 
set backbone area-id=0.0.0.0 type=default translator-role=translate-candidate \
    authentication=none disabled=no 
add name="lukas" area-id=10.200.0.0 type=default \
    translator-role=translate-never authentication=md5 default-cost=1 \
    disabled=no 
/ routing ospf area range 
add area=lukas range=10.200.0.0/16 cost=default advertise=yes disabled=no 
/ routing ospf interface 
set FIXME interface=LAN-integrovana cost=10 priority=1 \
    authentication-key="doma" network-type=broadcast retransmit-interval=5s \
    transmit-delay=1s hello-interval=10s dead-interval=40s 
set FIXME interface=WAN-pci cost=10 priority=1 authentication-key="" \
    network-type=broadcast retransmit-interval=5s transmit-delay=1s \
    hello-interval=10s dead-interval=40s 
/ routing ospf network 
add network=10.200.1.0/24 area=lukas disabled=no 
add network=10.11.150.0/24 area=backbone disabled=no

router in the "lukas" area:

/ routing ospf 
set router-id=0.0.0.0 distribute-default=never \
    redistribute-connected=as-type-1 redistribute-static=as-type-1 \
    redistribute-rip=no redistribute-bgp=no metric-default=1 \
    metric-connected=20 metric-static=20 metric-rip=20 metric-bgp=20 
/ routing ospf area 
set backbone area-id=0.0.0.0 type=default translator-role=translate-candidate \
    authentication=none disabled=no 
add name="lukas" area-id=10.200.0.0 type=default \
    translator-role=translate-never authentication=md5 default-cost=1 \
    disabled=no 
/ routing ospf interface 
set FIXME interface=CLI cost=10 priority=1 authentication-key="doma" \
    network-type=broadcast retransmit-interval=5s transmit-delay=1s \
    hello-interval=10s dead-interval=40s 
set FIXME interface=RASIN->CEREKVICE cost=10 priority=1 \
    authentication-key="cere--kvice" network-type=point-to-point \
    retransmit-interval=5s transmit-delay=1s hello-interval=10s \
    dead-interval=40s 
/ routing ospf network 
add network=10.200.5.36/30 area=lukas disabled=no 
add network=10.200.5.40/30 area=lukas disabled=no

Thanks for helping.

GWISA · Sun Nov 11, 2007 11:03 pm

set the area range on your 'lukas' router... you want it to broadcast a summary route back to the backbone network.

CarulloS · Mon Nov 12, 2007 2:42 am

How many routers would you say is the realistic limit for a network. In my case, I plan on having less than 32 total in the backbone and due to design reasons I prefer to keep one backbone area like this.

Does anyone think this will present a problem for me running MT 532as or better?

Thanks,
Scott

GWISA · Thu Nov 15, 2007 1:29 pm

Cisco's OSPF design guidelines state the following should not be exceeded:

Routers per area - 50
Neighbours per router - 60
Areas per router - 3
A router may not be a designated router (DR) or a backup designated router (BDR) for more than one LAN

janisk · Thu Nov 15, 2007 2:09 pm

GWISA already answered this question very good, same applies to RouterOS.

EDIT:

i should add that this highly depends on the network and actual number of stations, for example - if you have more than 50 /24 networks you should think about dividing them into areas

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