I did a lab scenario utilizing bgp router refectors and and ran into a problem in which the router reflector would not reflect routes until I disabled sychronization. Could someone further explain the mechanics behind this.
It doesn't make sense to me how a route reflector passing bgp table routes from one client to another would anything to do with the synchronization between the IGP table and the BGP table????
Syncronization in BGP is useing for waiting BGP to announce the networks untill all routers which are useing IGP will know the way to that networks. So if on all routers in your AS you are useing only BGP and no IGP (IGRP, OSPF, RIP for example), BGP will not announce some network untill all routers will know the route to it via IGP. And because you haven't the IGP, BGP will waite all the time. So you must disable syncronization to give the BGP to announce the network without waiting while the routers in your AS will knew the route to it via IGP.
the synchronisation rule (my explanation) is that of the route is not learnt via an IGP, then it cannot be installed in the routing table or advertised to it's peers as intermediate devices may not know of the route. This prevents packets being blackholed by a non-BGP speaking router.
Imagine four routers A, B C and D, A and C are iBGP peers, C and D eBGP peers. If A advertises a prefix to C and C advertises this to D, the situation that may arise is if D forwards a packet to the prefix learnt by A, then C can forward the packet to A, but B doesn't know have the prefix, so drops the packet. Hence why synchronisation is used.
This is actually a pretty cool feature, i didn't even know it existed until I was looking for a solution to advertise a subnet (prefix in BGP talk), only if a certain condition existed. This is exactly what conditional advertisements does
j ai une question j ai achete un routeur cisco 887VA-k9 , je le configuré avec la configuration ci- dessous
si je le lier avec mon pc portable sur l un de ses ports directement ça marche toute est bien ( la connexion internet + m...
Attached policy provides CLI access to the Cisco 4G router over text messaging. Two files are in the attached .tar file:
2. PDF with instructions on how to load and use the .tcl file.