Re: [WISPA] OSPF Route Cost Calculations
The problem is I need to know if there is a tool or set of guidelines to determine the proper path cost and priorities in an OSPF network so that when a link goes down the next best route is chosen. On 3/4/2011 8:01 PM, Patrick Shoemaker wrote: This is too general of a question to answer. What exactly was the problem you encountered? -- Scott Reed Owner NewWays Networking, LLC Wireless Networking Network Design, Installation and Administration Mikrotik Advanced Certified www.nwwnet.net (765) 855-1060 WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
Re: [WISPA] OSPF Route Cost Calculations
Basically, what is the fastest link in your network? Let's say you have a GigE link. You'll set that cost to 1. Let's say you have a backup link that is a licensed 18GHz link that runs 350 Mbps. You would make that cost a 3. Then, you have a half-duplex Ubiquiti link. Normally you would count it as 100 Mbps but since it's half duplex, you might want to divied it by two. So, instead of setting it to 10, you'd set it to 20. If you have equal cost link but want one favored over the other, adjust the priority. Then, make sure you are using the correct type 1/type 2 calculations for your network typology. WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
Re: [WISPA] OSPF Route Cost Calculations
Can someone explain, in plain English, the difference between type 1 and type 2 calculations? Mikortik only explains it is white box vs something else. Cisco says A type 1 route has a metric that is the sum of the internal OSPF cost and the external redistributed cost. A type 2 route has a metric equal only to the redistributed cost. Justin -- Justin Wilson j...@mtin.net Aol Yahoo IM: j2sw http://www.mtin.net/blog xISP News http://www.twitter.com/j2sw Follow me on Twitter Wisp Consulting Tower Climbing Network Support On 3/5/11 10:49 AM, can...@believewireless.net p...@believewireless.net wrote: Basically, what is the fastest link in your network? Let's say you have a GigE link. You'll set that cost to 1. Let's say you have a backup link that is a licensed 18GHz link that runs 350 Mbps. You would make that cost a 3. Then, you have a half-duplex Ubiquiti link. Normally you would count it as 100 Mbps but since it's half duplex, you might want to divied it by two. So, instead of setting it to 10, you'd set it to 20. If you have equal cost link but want one favored over the other, adjust the priority. Then, make sure you are using the correct type 1/type 2 calculations for your network typology. -- -- WISPA Wants You! Join today! http://signup.wispa.org/ -- -- WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
Re: [WISPA] OSPF Route Cost Calculations
On Sat, 2011-03-05 at 10:56 -0500, Justin Wilson wrote: Can someone explain, in plain English, the difference between type 1 and type 2 calculations? Mikortik only explains it is white box vs something else. Cisco says A type 1 route has a metric that is the sum of the internal OSPF cost and the external redistributed cost. A type 2 route has a metric equal only to the redistributed cost. In broad strokes, the cost between any two points on an OSPF network is the sum of the interface costs between the two routers in question following a particular path (there could be more than one). As suggested before, a white board is good for this. Start with, say 10, for every interface. Then start adding up the costs for paths that are important to you. If a path is being chosen that you don't want, start incrementing the cost on both sides of the link until the correct path has a lower cost. If your external routes are type 1, a router will take that cost into account when determining which route is better (if there is more than one learned). If it's type 2, it will only use the metric assigned to it when it's injected/learned by into OSPF. A MikroTik example regarding default routes (though any external route should do the same)... ---Type-2--- Router A: /router ospf instance set default distribute-default=if-installed-as-type-2 set default metric-default=10 Router B: /router ospf instance set default distribute-default=if-installed-as-type-2 set default metric-default=20 ---Type-1--- Router A: /router ospf instance set default distribute-default=if-installed-as-type-1 set default metric-default=10 Router B: /router ospf instance set default distribute-default=if-installed-as-type-1 set default metric-default=10 In the Type-2 case, router X will always choose router A's default route, if it's being injected. In the Type-1 case, router X will choose the default route that has a lower OSPF path cost. It's Saturday morning and I didn't double check any books, so please be gentle if I missed some subtle detail. :-) -Kristian WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
Re: [WISPA] OSPF Route Cost Calculations
What is the largest value you can put in for an OSPF cost? I'd almost recommend multiplying all of those numbers by 10 so you can do the fine level tweaking between the links. - Mike Hammett Intelligent Computing Solutions http://www.ics-il.com On 3/5/2011 9:49 AM, can...@believewireless.net wrote: Basically, what is the fastest link in your network? Let's say you have a GigE link. You'll set that cost to 1. Let's say you have a backup link that is a licensed 18GHz link that runs 350 Mbps. You would make that cost a 3. Then, you have a half-duplex Ubiquiti link. Normally you would count it as 100 Mbps but since it's half duplex, you might want to divied it by two. So, instead of setting it to 10, you'd set it to 20. If you have equal cost link but want one favored over the other, adjust the priority. Then, make sure you are using the correct type 1/type 2 calculations for your network typology. WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
Re: [WISPA] OSPF Route Cost Calculations
On 03/05/2011 05:23 PM, Mike Hammett wrote: What is the largest value you can put in for an OSPF cost? I'd almost recommend multiplying all of those numbers by 10 so you can do the fine level tweaking between the links. See http://www.workrobot.com/sysadmin/routing/ospf_costs.html for a brief discussion of auto-costing in Cisco (and some other devices). It also gives a brief discussion of type1 vs type2 announcements. -- * Butch Evans * Professional Network Consultation* * http://www.butchevans.com/* Network Engineering * * http://store.wispgear.net/* Wired or Wireless Networks * * http://blog.butchevans.com/ * ImageStream, Mikrotik and MORE! * *NOTE THE NEW PHONE NUMBER: 702-537-0979 * WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
Re: [WISPA] OSPF Route Cost Calculations
This is too general of a question to answer. What exactly was the problem you encountered? -- Patrick Shoemaker Vector Data Systems LLC shoemak...@vectordatasystems.com office: (301) 358-1690 x36 http://www.vectordatasystems.com On 3/4/2011 7:08 PM, Scott Reed wrote: Does any one have a tool or guidelines for setting cost and priority on OSPF interfaces? We had a link go down today. OSPF did what it should, but it did not move to the preferred alternate route. I got it there by changing some costs, but I need a way to get it right without needing a failure to tell me it is wrong. WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
Re: [WISPA] OSPF Route Cost Calculations
On Fri, Mar 04, 2011 at 07:08:55PM -0500, Scott Reed wrote: Does any one have a tool or guidelines for setting cost and priority on OSPF interfaces? We had a link go down today. OSPF did what it should, but it did not move to the preferred alternate route. I got it there by changing some costs, but I need a way to get it right without needing a failure to tell me it is wrong. A/Several big white board(s) and do the dijkstra algorithm on it/them for every possible path? Or, call it maintenence and manually break OSPF on one leg at a time between 2 and 6 am. Tweaking all the costs on all the hops for a very interconnected OSPF network could be a large project. I'm just happy if things can limp along until I get a chance to look at it and see if I can help things. -- Scott LambertKC5MLE Unix SysAdmin lamb...@lambertfam.org WISPA Wants You! Join today! http://signup.wispa.org/ WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
