05-13-2007 09:05 AM - edited 03-03-2019 04:57 PM
I am in the midst of installing a 2nd MPLS WAN to our branches and running into a bit of a problem.
In branches in which both MPLS clouds terminate into a single router I am getting a problem in which routes are swinging through the branch rather than one of the headend routers.
Is there a way to restrict advertisement of restricting advertisement to same AS marked networks? I would never want one of my branches to route any traffic other than their regional networks.
Right now I am getting intermittent route loops where a network goes around both MPLS clouds and never terminates.
05-13-2007 09:10 AM
Hi,
Are you running routing protocols, or just static routes.
BR,
Mohammed Mahmoud.
05-13-2007 09:24 AM
I am running EIGRP as my IGP both at the core and at the branches.
Here is an example. This router is running BGP and EIGRP and is learning 192.168.52.0/24 from a GRE/VPN tunnel.
Routing entry for 192.168.52.0/24
Known via "bgp 65002", distance 20, metric 0
Tag 1803, type external
Redistributing via eigrp 1
Advertised by eigrp 1 metric 10000 1 255 1 1500
bgp 65002 (self originated)
Last update from 172.20.56.1 1w3d ago
Routing Descriptor Blocks:
* 172.20.56.1, from 172.20.56.1, 1w3d ago
Route metric is 0, traffic share count as 1
AS Hops 4
Route tag 1803
So instead of taking the direct path through the tunnel it goes out through MPLS1 to a single router branch then off to MPLS2 back to another hub router and then back to original hub router via EIGRP...
Known via "eigrp 1", distance 170, metric 258816
Tag 1803, type external
Redistributing via eigrp 1
Advertised by bgp 65002
Last update from 10.250.11.4 on FastEthernet1/0, 19:24:22 ago
Routing Descriptor Blocks:
* 10.250.11.4, from 10.250.11.4, 19:24:22 ago, via FastEthernet1/0
Route metric is 258816, traffic share count is 1
Total delay is 110 microseconds, minimum bandwidth is 10000 Kbit
Reliability 255/255, minimum MTU 1500 bytes
Loading 1/255, Hops 1
Hub 1, I assume, is choosing to go through the WAN because the administrative cost is lower for a BGP learned route than an EIGRP learned route.
I really don't want this sort of thing to happen ever.
05-13-2007 09:53 AM
Hi,
As far as I can see you either need to manipulate the EIGRP metrics or run EBGP on your branches.
The actual cisco advice is to run EBGP between the CE and the PE. Then its a lot more easier to influence routing with parameters like for instance Local Preference.
HTH
Regards,
Bjornarsb
05-13-2007 10:02 AM
I do run EBGP at the branches. In the branches in question they are configured as follows..
router bgp 65002
bgp log-neighbor-changes
neighbor 172.21.109.81 remote-as 1803
neighbor 172.26.171.1 remote-as 13979
!
address-family ipv4
neighbor 172.21.109.81 activate
neighbor 172.26.171.1 activate
no auto-summary
no synchronization
network 172.21.109.80 mask 255.255.255.252
network 192.168.71.0
network 192.168.171.0
network 208.0.248.104 mask 255.255.255.252
exit-address-family
!
Here is one of the head routers...
router bgp 65002
bgp log-neighbor-changes
neighbor 172.20.56.1 remote-as 1803
!
address-family ipv4
redistribute static route-map PavoniaDMZ
neighbor 172.20.56.1 activate
auto-summary
no synchronization
network 10.250.11.0
network 151.139.0.0
network 170.61.0.0
network 172.17.0.0
network 172.18.0.0
network 172.20.0.0
network 172.20.56.0
network 172.21.0.0
network 172.22.0.0
network 172.23.0.0
network 172.24.0.0
network 172.27.0.0
network 172.30.0.0
network 192.168.52.0
network 192.168.54.0
network 192.168.252.0
network 199.105.176.0
network 208.134.161.0
exit-address-family
It is configured the same way on the other hub router but it is pointing to AS 13979.
05-13-2007 10:41 AM
Hi,
We need to see where you do the redistribution between EBGP and EIGRP, please post a topology and the configuration of one of the affected routers and one of the hub routers, this might be a mutual redistribution problem.
BR,
Mohammed Mahmoud.
05-13-2007 11:09 AM
I posted that information upthread. Sorry, I thought I had responded to you.
I suspect it is a mutual redistribution problem.
So my topology is as follows.
Branchrouter1(AS65002)---MPLS1(AS1803)---HUB1---CoreNetwork1(AS65002)
Branchrouter1(AS65002)---MPLS2(AS13979)---HUB2---CoreNetowrk1(AS65002)
The 2 HUBS are connected via EIGRP but NOT BGP. They are both redistributing the same networks.
Should I create an IBGP connection between the 2 HUBS?
05-13-2007 11:18 AM
Here is what I get when I do sho commands
sho ip route 192.168.52.0
Routing entry for 192.168.52.0/24
Known via "bgp 65002", distance 200, metric 258816, type internal
Redistributing via eigrp 1
Last update from 10.250.11.5 00:02:18 ago
Routing Descriptor Blocks:
* 10.250.11.5, from 10.250.11.5, 00:02:18 agosho ip eigrp 1 topology 192.168.52.0
IP-EIGRP (AS 1): Topology entry for 192.168.52.0/24
State is Passive, Query origin flag is 1, 1 Successor(s), FD is 256256
Routing Descriptor Blocks:
172.20.56.1, from Redistributed, Send flag is 0x0
Composite metric is (256256/0), Route is External
Vector metric:
Minimum bandwidth is 10000 Kbit
Total delay is 10 microseconds
Reliability is 255/255
Load is 1/255
Minimum MTU is 1500
Hop count is 0
External data:
Originating router is 10.150.200.13 (this system)
AS number of route is 65002
External protocol is BGP, external metric is 0
Administrator tag is 1803 (0x0000070B)
sho ip bgp 192.168.52.0
BGP routing table entry for 192.168.52.0/24, version 25172
Paths: (1 available, best #1, table Default-IP-Routing-Table)
Advertised to update-groups:
1
Local
10.250.11.5 from 10.250.11.5 (172.26.252.2)
Origin incomplete, metric 258816, localpref 100, valid, internal, bes
Route metric is 258816, traffic share count is 1
AS Hops 0
05-13-2007 11:30 AM
Hi,
As far as i understand EIGRP is only implemented between HUB1 and HUB2, why not running iBGP and then we can play with BGP, and remove the EIGRP redistribute problem, and what do you mean by "They are both redistributing the same networks" ?
HTH, please do rate all helpful replies,
Mohammed Mahmoud.
05-13-2007 11:37 AM
Behind the hubs is my data center core networks.
I would still need to redistribute networks between EIGRP and BGP since my core is running EIGRP.
I have redistribute eigrp in both HUB BGP processes and the routing information is essentially the same. I was responding to your comment about mutual redistribtuion.
05-13-2007 12:54 PM
Hi,
Lets build up the case logically, the branch routers run eBGP with both MPLS clouds, while each of the head routers run eBGP with only one of the MPLS clouds.
Both MPLS clouds send the routes to the branch routers, but the problem is that routing loops occur at the branch router.
Am i correct till now ?
Please send FULL routing configuration for the 2 hub routers and one of the affected branch routers.
HTH,
Mohammed Mahmoud.
05-13-2007 04:36 PM
Thanks for the help Mohammed.
I figured out the problem. The network wasn't properly advertising in EIGRP but there was a network statement in one of my routers for the network causing it to be advertised on BGP but not in EIGRP.
05-13-2007 09:56 AM
Hi,
Can you please past your configuration, and your topology.
BR,
Mohammed Mahmoud.
Find answers to your questions by entering keywords or phrases in the Search bar above. New here? Use these resources to familiarize yourself with the community: