EIGRP on 6500 Newbie Question

[angel-moon]

Hello All,

Here is the scenario  6500 with EIGRP already enabled.  It has a Point to Point connection to another location.  If I add a 2nd Point to Point (Different carrier ) is ther eanyting I need to do to the config after I put the IP address on teh interface to get EIGRP to start using that 2nd circuit as well as the 1st?  WHen I do a SHow ip EIGRP 700 interfaces I see several interfaces listed along with the 2 interfaces with the P2P circuits but only the existing interface shows a value under Mean SRTT and Multicast Flow Timer.

Thanks in advance!  All replies rated

[Jon Marshall]

Is the second link the same speed ?

If so EIGRP should in theory show equal cost paths via both links.

For a route at the remote location eg. 192.168.3.0/24 can you post -

1) "sh ip eigrp topology all 192.168.3.0/24"

2) "sh ip route 192.168.3.0/24"

I am assuming you have an EIGRP neighborship on the second link.

Jon

[Richard Burts]

If I am understanding the question correctly then I believe that the original poster is asking what does he need to do to get the neighborship on the second link. We need to know more about how the 6500 is configured to be able to give good answers for this question. It is possible that the 6500 is already configured so that the IP address of the new interface does match an existing network statement under EIGRP. And in that case the neighborship will exist (assuming that the peer router is correctly configured for EIGRP also). If the address on the new interface does not match a network statement under EIGRP then he will need to add a network statement under EIGRP that does match the address on the new interface.

HTH

Rick

[angel-moon]

The network is configured as a network under EIGRP.  

[Masoud Pourshabanian]

Hello,

If you add the ip address of your new link under EIGRP section on both sides correctly,  routes will be advertised.

Then you need to consider the purpose of the second link. It is going to be a backup link or you want to loadbalance across both links. To achieve one of those, you need to play with cost.

To manipulate the cost, you can use "bandwitdh command" under the old and new link configuration. If you set the same bandwidth on the 4 edges of the links, you will probably loadbalance across the links. if you set the bandwidth of the old link higher, your old link is prefered and the new link is backup.

Just to mention, bandwidth command is not related to the actual bandwidth of the links. It is only a parameter for routing protocol to figure out the best path.

As john mentioned, if the second link is the same as the old link, the result would be loadbalancing if the EIGRP parameters are default.

Hope it helps,

Masoud

[Richard Burts]

If you want to configure one link as primary and the other link as backup it may be better to change the delay on the interface rather than the bandwidth.

HTH

Rick

[angel-moon]

The purpose of the 2nd link is to provide more bandwidth.  take two 50Mbps circuits and make it into a 100Mbps virutal pipe if possible but I don;t think we can with 2 different providers.  If not then they should both be active.

[Masoud Pourshabanian]

You can not say taking two links and make them into a 100Mbps. You can say load balancing across two links to utilize them even links are from different service providers.

If the type of links are the same and the parameters of current EIGRP are default, you just need to add the IP address of new link under EIGRP section.

If it is not this way, you need to manipulate metric a little bit to achieve that. It is not deficult. Only a few commands.

Masoud

[angel-moon]

Thanks,

Here is the output from those commands

6513#show ip eigrp topology 172.xx.xx.0/30
EIGRP-IPv4 Topology Entry for AS(100)/ID(172.xx.xx.xx) for 172.xx.xx.0/30
  State is Passive, Query origin flag is 1, 1 Successor(s), FD is 28416
  Descriptor Blocks:
  172.xx.xx.xx (GigabitEthernet3/24), from 172.xx.xx.xx, Send flag is 0x0
      Composite metric is (28416/384), route is Internal
      Vector metric:
        Minimum bandwidth is 100000 Kbit
        Total delay is 110 microseconds
        Reliability is 255/255
        Load is 1/255
        Minimum MTU is 1500
        Hop count is 1

6513#show ip route 172.xx.xx.0/30
                                    ^
% Invalid input detected at '^' marker.

6513#show ip route 172.xx.xx.0
Routing entry for 172.xx.xx.0/30
  Known via "eigrp 100", distance 90, metric 28416, type internal
  Redistributing via eigrp 100
  Last update from 172.xx.xxxx on GigabitEthernet3/24, 5d03h ago
  Routing Descriptor Blocks:
  * 172.xx.xx.xx, from 172.xx.xx.xx, 5d03h ago, via GigabitEthernet3/24
      Route metric is 28416, traffic share count is 1
      Total delay is 110 microseconds, minimum bandwidth is 100000 Kbit
      Reliability 255/255, minimum MTU 1500 bytes
      Loading 1/255, Hops 1

[Jon Marshall]

Can you answer Rick's point ie. I was assuming you had setup EIGRP but you may not have configured it yet.

You need to include a network statement under EIGRP for the new IP subnet used on the link at both ends.

[Richard Burts]

Thanks for the additional information. But it is not clear to me what is the relationship of these displays to the new interface that you were asking about?

It would be helpful if you would post the configuration of the new interface and post the configuration of EIGRP. While not necessary it would be helpful if you also post the output of these commands

show ip interface brief

show ip eigrp interface

show ip eigrp neighbor

HTH

Rick