Hi there,

We are having a problem with advertising a range of public IP's from our main breakout router which has a BGP session with our Back haul provider. The two networks 188.95.40.0/21 and 46.227.144.0/21 are defined in the /BGP/Networks but only one of them the "188.95.." is being advertised and the other one is not. I have copied the configs below. Could you please advise.

Thanks.


/routing bgp instance> print
Flags: X - disabled
0 name="default" as=49441 router-id=0.0.0.0 redistribute-connected=yes redistribute-static=yes redistribute-rip=yes redistribute-ospf=no
redistribute-other-bgp=no out-filter="" client-to-client-reflection=yes ignore-as-path-len=no routing-table=""


/routing bgp network> print
Flags: X - disabled
# NETWORK SYNCHRONIZE
0 188.95.40.0/21 yes
1 46.227.144.0/21 yes


/routing bgp advertisements> print
PEER PREFIX NEXTHOP AS-PATH ORIGIN LOCAL-PREF
Goscomb 188.95.40.0/23 93.89.94.174 igp
Goscomb 188.95.40.0/21 93.89.94.174 igp
Gradw... 188.95.40.0/23 79.135.121.6 igp
Gradw... 188.95.40.0/21 79.135.121.6


/routing bgp peer> print
Flags: X - disabled, E - established
# INSTANCE REMOTE-ADDRESS REMOTE-AS
0 E default 93.89.94.173 39326
1 E default 79.135.121.5 29676


/routing bgp> export
# feb/03/2012 09:53:30 by RouterOS 4.15
# software id = MXT6-VSKC
#
/routing bgp instance
set default as=49441 client-to-client-reflection=yes comment="" disabled=no ignore-as-path-len=no name=default out-filter="" redistribute-connected=\
yes redistribute-ospf=no redistribute-other-bgp=no redistribute-rip=yes redistribute-static=yes router-id=0.0.0.0 routing-table=""
/routing bgp network
add comment="" disabled=no network=188.95.40.0/21 synchronize=yes
add comment="" disabled=no network=46.227.144.0/21 synchronize=yes
/routing bgp peer
add address-families=ip as-override=no comment="" default-originate=never disabled=no hold-time=3m in-filter=bgp-in instance=default multihop=no \
name=Goscomb nexthop-choice=default out-filter=bgp-out passive=no remote-address=93.89.94.173 remote-as=39326 remove-private-as=yes \
route-reflect=no tcp-md5-key="" ttl=default use-bfd=no
add address-families=ip as-override=no comment="" default-originate=never disabled=no hold-time=3m in-filter=bgp-in instance=default multihop=no \
name=Gradwell1 nexthop-choice=force-self out-filter=bgp-out passive=no remote-address=79.135.121.5 remote-as=29676 remove-private-as=no \
route-reflect=no tcp-md5-key="" ttl=default use-bfd=no
add address-families=ip as-override=no comment="" default-originate=never disabled=yes hold-time=3m in-filter=bgp-in instance=default multihop=yes \
name=Hambo nexthop-choice=default out-filter=bgp-out passive=no remote-address=188.95.44.66 remote-as=56329 remove-private-as=no route-reflect=no \
tcp-md5-key="" ttl=default use-bfd=no

If you don't have exact route in routing table then turn off synchronization

Thanks lot for this mrz, that actually solved the problem. So whats the basic purpose of the synchronize feature?

Synchronize allows you to only advertise a route when your iBGP or OSPF actually knows how to route it. There are a number of scenarios in which this makes sense.

Most recently I used this when building some failover routes. Two routers connect to an upstream and have different paths (multiple routing hops) to the client subnet. If one of the paths breaks i don't want that specific border router to announce the subnet any more. Using sync this becomes automatic.

Regardt

Thats great. Thanks regardtv.