Dynamic routing issue

[Bruno Silva]

Hello,

well, my question is: I have one central route (Cisco Catalyst 3750G-48TS-S) and twenty Switch with layer three ios (Cisco 3560G-24) conected in star topology....

What i want to know is, how central router can communicate with just another router (Cisco 1841) that is behind any 3560G layer three switch?

the cisco 1841 is always the same router that could be behind any other cisco 3560G switch.

Thanks a lot for your patience!

Bruno

[Bruno Silva]

YOu mean..... in eigrp process of 3560 i will not announce this network... i'll announce only from 1841??

I was thinkink that each eigrp process should announce himself networks.

[John Blakley]

Do you have servers at each location? I might be able to write a python script that you could run on the server. It's definitely not perfect, but the script could ping your ip address to see if it's responding. If it starts to respond, it could telnet into the switch for you and add the appropriate lines to eigrp. That may be workable, but it's definitely a hack.

Well, you would need a common subnet for an adjacency, so from what I can figure the only common subnet would be the 3560 that's already advertising it.

HTH,
John

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[Bruno Silva]

Yes.... but in 3560 site location will be suficient, no?

I think this is workable and the unique solution.

[John Blakley]

You'll need a server at each location that can ping the ip address when it's up. I'll have no way of testing this for you, but I can write something up and slightly test it before posting it. What OS do you run on your servers?

HTH,
John

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[Bruno Silva]

It's Windows Server 2008.

Yes, each location where is the 3560 switch, is a HP server with that OS.

[John Blakley]

Bruno,

I wrote a script for you. Please test and let me know what happens. I commented throughout to let you know where you need to change to your information. You're going to need python installed on the computer that you want to run this from. You can download that from http://www.python.org. Download version 2.7 and not 3.x. This script will not work with 3.x. After you install it, you'll need to set up a schedule under Windows to run it. I would suggest not doing it to frequent, but maybe every 15 minutes or so.

What the script will do will ping the address of your router. If the router responds, it will connect to your 3560 and add the network statement under your eigrp config. If the router is not responding, it will connect to the 3560 and remove the network statement. It will keep track of when the last time was responding by a text file that will be located in the same folder as the script is ran from. If the line in the text file is respond=0, that means it wasn't responding, and respond=1 means that it was responding. It uses this for comparison if it will add/remove the eigrp config.

Copy both logFile.txt and modEIGRP.py to a folder and run from there. Let me know how it works out for you. If you have any questions, please let us know.

HTH,

John

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*** Disclaimer ***

I did not test this as it stands. I tested logging in and creating an acl on an access point. I cannot be held responsible if this does damage to your network or equipment.

[Jon Marshall]

John

Very generous effort in writing a script for this. Thanks again for getting involved in the thread. Few ratings due from me i think.

Jon

[John Blakley]

Thank you Jon. It was no problem at all. I'm still not sure how well this is going to work. I have a feeling that we're going to see some other oddities after it kicks in.


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[Bruno Silva]

Hello John....

Spectacular!

Well, i have to solve another problem before that... form my server i can´t ping vlan 506 interface.

!

interface GigabitEthernet0/4

description Servidor

switchport access vlan 115

switchport mode access

!

interface GigabitEthernet0/5

description Wimax

switchport trunk encapsulation dot1q

switchport trunk allowed vlan 500-508

switchport mode trunk

!

interface Vlan115

description SEGMENTO_PO

ip address 192.168.130.1 255.255.255.0

ip pim sparse-mode

no ip mroute-cache

!

interface Vlan215

description SEGMENTO_CCC

ip address 10.10.10.113 255.255.255.248

ip pim sparse-mode

no ip mroute-cache

!

interface Vlan500

description VLAN_WIMAX_GESTION

ip address 10.10.50.43 255.255.255.0

!

interface Vlan506

description WIMAX_UM6

ip address 10.10.56.16 255.255.255.0

ip pim sparse-mode

no ip mroute-cache

!

Should i add a route on server to achieve that vlan? sounds me like 3560 siwtches can´t route that.

When i get this problem solved, i'll use your script but for the 8 vlan!

[John Blakley]

Isn't the server local to the 3560? If so, you would be going to the default gateway that's configured on the server and the switch should respond to icmp requests if the interface is up. I'm assuming that g0/4 is the server. Can you ping 192.168.130.1 from the server?

HTH,
John

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[Bruno Silva]

YEs, John... i can ping default gateway 192.168.130.1. Indeed, Server is the interface g0/4, but i can´t ping ip 10.10.56.16 from the vlan 506 on interface g0/5 that is always up/up.

[John Blakley]

I'm confused now. Please post:

"show ip int brie | e unassig"

"show ip route"

Being that you have eigrp configured on these switches, I'm going to assume that you have "ip routing" enabled because I believe the switch screams at you that it's not when trying to enable a routing protocol on a non-routing switch. That being said, the switch should know how to get to the 10.10.56.0 and 192.168.130.0 subnets because they're locally connected.

Currently, does your server/switch connection look like this?:

Server ----- (connects to 3560)

When you ping 10.10.56.16 from the server, you get timeouts? What is the default gateway set to on the server?

HTH,
John

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[Bruno Silva]

Yes, i have ip routing enable on 3560 switch.

At the moment i can´t get show ip int brief and sh ip route... but i'll download it ASAP.

When i ping 10.10.56.16 i get timeout.

The default gateway set on the server is 192.168.130.1.

[John Blakley]

From your server, can you ping any of the other SVIs? Like 10.10.50.43? If the interface is up and routing enabled, you should be able to ping it. You need to be able to get that part resolved before you can run the script since it's going to depend on being able to get to it...

HTH,
John

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[Bruno Silva]

John,

i'll try to ping another SVIs tomorrow on the site. From where am i, i can´t do it.

Yeh, it's very strange can´t ping. The script only works with that problem solved.

Another curiosity..... Would you design a network like this on the same way, or you'll use another dynamic routing protocol like ospf or rip...?