Routing between sites.

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Apr 26th, 2006
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I have some routing questions about the site diagram I have attached.


Redlines T1

Blueline 256K


Currently all the routers in my org have a static "IP ROUTE 0.0.0.0 0.0.0.0 site A address" in them. I realize this destroys the redundancy that the existing datalines provide based on the drawing. What should be done if I remove the IP ROUTE 0.0.0.0 ...... from the routers will RIP take over and allow the network to function. What is the best config for routing traffic on a network like this.



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Richard Burts Wed, 04/26/2006 - 11:04
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Jason


I am not sure that the static default route that you describe does destroy redundancy in your network. If you are running RIP it would be helpful to know how RIP is configured and what it is advertising. And it would be helpful to know some specifics of what you mean when you say that the static default route specifies a siteA address? Which address? is it the address of the connected interface (different for each site) or is it some other address?


I assume that RIP is advertising the addressing of the various sites. To the extent that is true then RIP will be advertising the various paths to the site addresses and siteB (for example) will learn that the best path to siteC is the directly connected link but if that link fails there is an alternate link through siteA to siteC and even an alternate path through siteB through siteA to siteC. So the redundancy works.


The configured static default route will only be used to determine a path to destinations that are not advertised by RIP. It seems to me that the picture shows a pretty functional network with an adequate level of redundancy in its network paths.


HTH


Rick

pearsonjl Wed, 04/26/2006 - 12:14
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I am not sure how to tell if rip is turned on.


The static routs in each router point to site A the address to site A is changed in each router per the ip that is assigned to the link.


i.e. site B ip route 0.0.0.0 0.0.0.0 10.244.0.1

site C ip route 0.0.0.0 0.0.0.0 10.246.0.1


I did notice in the graphic I have 2 site B that is a typo I am sure you still get the just of it.


I guess my end question is assuming rip is turned on can I remove the ip routes and how do I set up costing of the links so the T1's to our main site are used first and only if they fail does it look for a shorter path. I would think RIP would take care of this and the router would use OSPF to determin the correct path.

Richard Burts Wed, 04/26/2006 - 12:31
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Jason


The easiest way to see what is turned on is to do show ip protocol. If you do this command on each router and post the output it would help us to understand what is happening at each site. It would also be helpful if you would post the output of show ip route from siteA and from one of the other sites.


HTH


Rick

pearsonjl Wed, 04/26/2006 - 13:09
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Here is a show ip protocol form site C


Routing Protocol is "eigrp 100"

Outgoing update filter list for all interfaces is not set

Incoming update filter list for all interfaces is not set

Default networks flagged in outgoing updates

Default networks accepted from incoming updates

EIGRP metric weight K1=1, K2=0, K3=1, K4=0, K5=0

EIGRP maximum hopcount 100

EIGRP maximum metric variance 1

Redistributing: eigrp 100

Automatic network summarization is not in effect

Maximum path: 4

Routing for Networks:

10.0.0.0

52.0.0.0

Routing Information Sources:

Gateway Distance Last Update

10.241.0.2 90 06:31:33

10.242.0.1 90 06:31:33

10.246.0.1 90 06:31:33

Distance: internal 90 external 170


Here is site A

Routing Protocol is "eigrp 100"

Outgoing update filter list for all interfaces is

Incoming update filter list for all interfaces is

Default networks flagged in outgoing updates

Default networks accepted from incoming updates

EIGRP metric weight K1=1, K2=0, K3=1, K4=0, K5=0

EIGRP maximum hopcount 100

EIGRP maximum metric variance 6

Redistributing: eigrp 100

Automatic network summarization is not in effect

Routing for Networks:

10.0.0.0

52.0.0.0

Routing Information Sources:

Gateway Distance Last Update

10.248.0.2 90 07:07:18

10.249.0.2 90 07:07:18

10.240.0.2 90 07:07:18

10.244.0.2 90 07:07:18

10.245.0.2 90 07:07:18

10.246.0.2 90 06:40:05

Distance: internal 90 external 170



The 52. address range is for some really old systems that still exist and cannot be easily changed.


pearsonjl Wed, 04/26/2006 - 13:13
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The 248, 249 , and 240 are some small sites off of site A, This should still not change the basic question of is rip on and can I remove the static routes.

vladrac-ccna Wed, 04/26/2006 - 15:13
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Hello there,


just for the rip question. yes, you could rip or any other IGP to do the kind of routing you need, i.e. remove your static default routes.


My suggestion is to keep the EIGRP working and advertise a default route from site A towards the other sites, the rest is up with the routing protocol, just make sure you have the bandwidth configured correctly in each interface and you're good to go.


btw, if the network is only what we see on the diagram you can make site D a stub network too.


Vlad


Richard Burts Thu, 04/27/2006 - 02:39
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Jason


The output of show ip protocol clearly shows that RIP is not active on those routers. So I do not believe that there is any question about removing RIP since it is not there. However the output show that EIGRP is present and is routing for network 10.0.0.0 and network 52.0.0.0. EIGRP like RIP is a dynamic routing protocol.


The original post raised the question about RIP and I am not sure why. I believe the operation is basically as I described in an earlier post. There is a dynamic routing protocol running so that each site will dynamically choose the optimum path to each of the other sites and will fail over to alternate paths if there is a problem on any link. The configured static default routes provide routing logic for destinations that are not in network 10.0.0.0 or in 52.0.0.0. I do not see any particular reason to remove the static routes. As Vlad points out it could be possible to have EIGRP advertise the default route from siteA but the static routes should work ok. The original post was not specific about whether there is access to networks other than 10.0.0.0 or 52.0.0.0 (or whether EIGRP might be advertising a default route). The output of show ip route from siteC and from siteA might help us understand this aspect better.


Thinking about the dynamic routing protocol I believe that there is an advantage in running EIGRP rather than RIP. This is because EIGRP will consider bandwidth in choosing the optimum path where RIP will only look at hop count. So the decision made by EIGRP will recognize the different bandwidth of the alternate links in this network.


HTH


Rick

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