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Beginner

EIGRP Routing Issue

Hi,

I have got a remote office which is a few hops away with subnet 192.168.25.0/24 using LES links. Our other service provider connects some of our other remote sites via MPLS cloud to our core. One of these connected sites is a 192.168.44.0/24 subnet. I need our subnet 25.0/24 to be available at 44.0/24 hence am required to create a VLAN 25 on our core Cat 4506 switches but once i create a VLAN 25 then routing points the 25.0/24 subnet to be directly connected instead to going out the right path. Currently using EIGRP across the infrastructure. Please see below some details of routes before and after.

BEFORE when the VLAN 25 is disabled:

CSW#sh ip route 192.168.25.1

Routing entry for 192.168.25.0/24

  Known via "eigrp 200", distance 90, metric 3328, type internal

  Redistributing via eigrp 200

  Last update from 172.19.102.2 on Vlan102, 00:00:07 ago

  Routing Descriptor Blocks:

  * 172.19.102.2, from 172.19.102.2, 00:00:07 ago, via Vlan102

      Route metric is 3328, traffic share count is 1

      Total delay is 30 microseconds, minimum bandwidth is 1000000 Kbit

      Reliability 255/255, minimum MTU 1500 bytes

      Loading 6/255, Hops 2

AFTER when the VLAN 25 is enabled:

CSW#conf t

Enter configuration commands, one per line.  End with CNTL/Z.

CSW(config)#int vlan 25

CSW(config-if)#no shut

CSW(config-if)#exit

CSW(config)#exit

CSW1#sh ip route 192.168.25.1

Routing entry for 192.168.25.0/24

  Known via "connected", distance 0, metric 0 (connected, via interface)

  Redistributing via eigrp 200

  Routing Descriptor Blocks:

  * directly connected, via Vlan25

      Route metric is 0, traffic share count is 1

Kindly advise.

Many thanks in advance.

Everyone's tags (2)
2 ACCEPTED SOLUTIONS

Accepted Solutions
Hall of Fame Master

EIGRP Routing Issue

There are quite a few things about your environment that we do not know and they would help us to figure out what suggestions to make. So some clarification of your network topology would be helpful.

But if I am understanding correctly you have a network 192.168.25.0/24 at a remote site. Then you created a vlan on your core switch and assigned network 192.168.25.0/24 on the core switch. The result is that now you have network 192.168.25.0 appearing in two separate places in your network. That is a serious problem and the result is that your core thinks that it is a local connection and will no longer forward to the remote site.

My suggestion is to remove vlan 25 from your core and then to figure out a different routing solution that would make network 192.168.25.0 be advertised to the 44.0 site.

HTH

Rick

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Engager

Re: EIGRP Routing Issue

I agree with Rick. I seriously do not recommend creating your 192.168.25.0 network on your core (it already exists in your network!), it can cause major problems if were not careful. Am I missing something here?

You have the 25.0 network on a dedicated LES circuit on some other site, connected in your environment, and you want to advertise this network in to the MPLS cloud - office(s)/site(s) connected. So it will be reachable.

Shouldn't it be simple enough to advertise the 25.0 network into the 'MPLS Cloud' (MPLS VPN - I assume) Then your remote sites in this environment would be able to reach 25.0 network and vice versa (if routing is fully converged and routes are propagated).

Is there a routing protocol being used between you and the provider to learn routes both for your core's and remote sites?

Advertisement path:

  • Remote Site 192.168.25.0/24 (connected via LES) EIGRP enabled
  • Avertised via EIGRP 200 (172.19.102.2) on vlan 102 [Up to this point all is good - your core is able to reach there]
  • You need to advertise this from the core into the MPLS cloud i.e. your provider so your other remote sites will have a route to get to this network
  • Your provider then advertises the prefix to you at the remote site so now you should have a route to get to the 25.0 network

This is all assuming that you are using a dynamic routing protocol between yourself and your MPLS provider and that I have understood the scenario. Please confirm and provide more details.

Hope this helps

Please rate useful posts & remember to mark any solved questions as answered. Thank you.

Please rate useful posts & remember to mark any solved questions as answered. Thank you.

View solution in original post

3 REPLIES 3
Hall of Fame Master

EIGRP Routing Issue

There are quite a few things about your environment that we do not know and they would help us to figure out what suggestions to make. So some clarification of your network topology would be helpful.

But if I am understanding correctly you have a network 192.168.25.0/24 at a remote site. Then you created a vlan on your core switch and assigned network 192.168.25.0/24 on the core switch. The result is that now you have network 192.168.25.0 appearing in two separate places in your network. That is a serious problem and the result is that your core thinks that it is a local connection and will no longer forward to the remote site.

My suggestion is to remove vlan 25 from your core and then to figure out a different routing solution that would make network 192.168.25.0 be advertised to the 44.0 site.

HTH

Rick

If you found this post helpful, please let the community know by clicking the helpful button!
By doing so, and until end of January, you are helping Doctors Without Borders

View solution in original post

Engager

Re: EIGRP Routing Issue

I agree with Rick. I seriously do not recommend creating your 192.168.25.0 network on your core (it already exists in your network!), it can cause major problems if were not careful. Am I missing something here?

You have the 25.0 network on a dedicated LES circuit on some other site, connected in your environment, and you want to advertise this network in to the MPLS cloud - office(s)/site(s) connected. So it will be reachable.

Shouldn't it be simple enough to advertise the 25.0 network into the 'MPLS Cloud' (MPLS VPN - I assume) Then your remote sites in this environment would be able to reach 25.0 network and vice versa (if routing is fully converged and routes are propagated).

Is there a routing protocol being used between you and the provider to learn routes both for your core's and remote sites?

Advertisement path:

  • Remote Site 192.168.25.0/24 (connected via LES) EIGRP enabled
  • Avertised via EIGRP 200 (172.19.102.2) on vlan 102 [Up to this point all is good - your core is able to reach there]
  • You need to advertise this from the core into the MPLS cloud i.e. your provider so your other remote sites will have a route to get to this network
  • Your provider then advertises the prefix to you at the remote site so now you should have a route to get to the 25.0 network

This is all assuming that you are using a dynamic routing protocol between yourself and your MPLS provider and that I have understood the scenario. Please confirm and provide more details.

Hope this helps

Please rate useful posts & remember to mark any solved questions as answered. Thank you.

Please rate useful posts & remember to mark any solved questions as answered. Thank you.

View solution in original post

Beginner

EIGRP Routing Issue

Hi Bilal,

Many thanks for your response.

I will contact our MPLS service provider and discuss this further. Our MPLS service provider is using, i believe subinterfaces on ASR 1002 router and wants us to create a VLAN 25 so that the interface status comes up. I haven't got much details about the configs of their box but will let you know how it goes.

Thank you once again.

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