Re: Multiple OSPF areas on the same router [7:13108]
Guy, A router which belongs to multiple OSPF area's is called an Area Border Router (ABR). All ABR's must belong to area 0 (The OSPF Backbone area) in addition to any other areas they belong to. For each area a router is a member of, it must store all of the LSA's for that area, and participate in the Dykstra SPF calculations for that area. So, the more area's a router is a member of, the higher the CPU and memory load on the router. Recommendations for the maximum number of areas a router should belong to vary. It isn't an exact science. The number of routers, the number of circuits (networks), and the stability of the circuits in each area will affect the max number of areas you can support on a single ABR. That said, 6 areas plus area 0 on a single router is probably to high. 3-4 areas plus area 0 is generally a good rule of thumb. Again, keep in mind there are many variables which affect how many areas a router can support and so each situation must be considered individually. ---Jon Lupi, Guy @groupstudy.com on 07/20/2001 01:29:41 PM Please respond to Lupi, Guy Sent by: [EMAIL PROTECTED] To: [EMAIL PROTECTED] cc: Subject: Multiple OSPF areas on the same router [7:13108] Lets say you have a router with 6 DS3s, has anyone ever heard that it is not a good practice to have each DS3 be its own area? I was talking to someone and they said that it may not be a good idea to have multiple areas on the same router, but I have never heard that. Thanks. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=13115t=13108 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Multiple OSPF areas on the same router [7:13108]
Multiple areas on a single router means that SPF algorithm will be run multiple times. This could be processor intensive, depending on how many routers you have per area. CM -Original Message- From: [EMAIL PROTECTED] on behalf of Lupi, Guy Sent: 20 July 2001 17:29 To: [EMAIL PROTECTED] Subject:Multiple OSPF areas on the same router [7:13108] -- From: Lupi, Guy[SMTP:[EMAIL PROTECTED]] Sent: Friday, July 20, 2001 6:29:41 PM To: [EMAIL PROTECTED] Subject: Multiple OSPF areas on the same router [7:13108] Auto forwarded by a Rule Lets say you have a router with 6 DS3s, has anyone ever heard that it is not a good practice to have each DS3 be its own area? I was talking to someone and they said that it may not be a good idea to have multiple areas on the same router, but I have never heard that. Thanks. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=13116t=13108 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Multiple OSPF areas on the same router [7:13108]
are you running full bgp routes on the router that you want to put 6 areas on. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] Sent: Friday, July 20, 2001 1:55 PM To: [EMAIL PROTECTED] Subject: Re: Multiple OSPF areas on the same router [7:13108] Guy, A router which belongs to multiple OSPF area's is called an Area Border Router (ABR). All ABR's must belong to area 0 (The OSPF Backbone area) in addition to any other areas they belong to. For each area a router is a member of, it must store all of the LSA's for that area, and participate in the Dykstra SPF calculations for that area. So, the more area's a router is a member of, the higher the CPU and memory load on the router. Recommendations for the maximum number of areas a router should belong to vary. It isn't an exact science. The number of routers, the number of circuits (networks), and the stability of the circuits in each area will affect the max number of areas you can support on a single ABR. That said, 6 areas plus area 0 on a single router is probably to high. 3-4 areas plus area 0 is generally a good rule of thumb. Again, keep in mind there are many variables which affect how many areas a router can support and so each situation must be considered individually. ---Jon Lupi, Guy @groupstudy.com on 07/20/2001 01:29:41 PM Please respond to Lupi, Guy Sent by: [EMAIL PROTECTED] To: [EMAIL PROTECTED] cc: Subject: Multiple OSPF areas on the same router [7:13108] Lets say you have a router with 6 DS3s, has anyone ever heard that it is not a good practice to have each DS3 be its own area? I was talking to someone and they said that it may not be a good idea to have multiple areas on the same router, but I have never heard that. Thanks. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=13118t=13108 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Multiple OSPF areas on the same router [7:13108]
Core routers do this all the time. They end up being ABRs and you need to make sure that the router has a lot of beef to it to be able to efficiently handle all of the LSDBs thrown at it from each area. - Original Message - From: Lupi, Guy To: Sent: Friday, July 20, 2001 10:29 AM Subject: Multiple OSPF areas on the same router [7:13108] Lets say you have a router with 6 DS3s, has anyone ever heard that it is not a good practice to have each DS3 be its own area? I was talking to someone and they said that it may not be a good idea to have multiple areas on the same router, but I have never heard that. Thanks. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=13124t=13108 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Multiple OSPF areas on the same router [7:13108]
couple of weeks ago I posted links to Cisco design documents that talked about Cisco recommendations with regards to number of routers per area and number of areas per router. check out the design guides on CCO. follow the links to technical documents. Chuck -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Lupi, Guy Sent: Friday, July 20, 2001 10:30 AM To: [EMAIL PROTECTED] Subject: Multiple OSPF areas on the same router [7:13108] Lets say you have a router with 6 DS3s, has anyone ever heard that it is not a good practice to have each DS3 be its own area? I was talking to someone and they said that it may not be a good idea to have multiple areas on the same router, but I have never heard that. Thanks. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=13164t=13108 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
