Just wanna clear my self one one thing.....i know in LAN if we want to make a perticular router DR we can configure a loopback address......if this is so then or what perpose we use priority.......which is 1-255.......cheers second thing is when we configure loopback address.....and that router is then configured on WAN.....why the loopback ip address is coming in gateway when i use show ip protocol??? thanks in advance
first of all it will look for the priority, higher the priority router will become DR and BDR... if priority of all ther router are same then it will elect the DR and BDR on the basies of the numarically higer IP address...
and you second point i am not able to understand what you are looking for exactly... so make it more clear...
First, I believe Loopback interface has nothing to do with DR/BDR enlection, bcoz DR/BDR election is the property of the interface that connects to a BMA network. Loopback interface are always treated as Stub network in OSPF and no neighborship will be formed in that subnet. In a BMA (Ethernet or FastEthernet network) router interface with highest IP address will become DR and if you want to overcome this you can use "Priority" to make a particular router in that BMA as DR.
Second, In the output of "show ip protocols" gateway will list you the Routing Information Sources i.e the routers that are there in that particular area running OSPF. When you create a Loopback interface and configure OSPF on that router then the Loopback IP will be the RouterID and you can see that in all the router of that area when you give "sho ip protocols"
"DR and BDR election is done via the Hello protocol. Hello packets are exchanged via IP multicast packets (Appendix B) on each segment. The router with the highest OSPF priority on a segment will become the DR for that segment. The same process is repeated for the BDR. In case of a tie, the router with the highest RID will win. "
So the router ID (usually Loopback IP) is part of the DR/BDR election process in case the priority is the same (f.e. with default priority settings).
Loopback interfaces are only used as Router ID. Priority is what OSPF uses to elect DR/BDR, which will need to be configured on the interface connected to the broadcast network (e.g. Ethernet) where OSPF needs to elect DR/BDR.
show ip protocols use Router IDs to display list of routers. Since you have configured a Loopback address on the router, it'll be used as the Router ID and displayed on the show ip protocols command across the WAN.
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.