01-05-2010 06:57 AM - edited 03-04-2019 07:07 AM
Hi
EIGRP supports unequal loadbalancing but applying variance command causes packet drops.
I have done as of this url
http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a008009437d.shtml#topic1
Site_A connects to Site_B over GRE Tunnel with two different media and different bandwidth using eigrp as routing protocol.
Both GRE Tunnels terminates on Same Router.
Connection= Site_A to Site_B
Media = Ethernet using SatelliteLink
Bandwidth = 1MB
Type : GRE Tunnel
Connection= Site_A to Site_B
Media = Ethernet Using service Provider
Bandwidth = 2.5MB
Type : GRE Tunnel
If Both Tunnels are up then packet drops are seen, if anyone tunnel is up there is no packet drops.
Configuration of * Site_A *
interface Tunnel1
description "VSAT Link"
ip address 192.168.1.1 255.255.255.252
keepalive 3 10
tunnel source 10.10.10.2
tunnel destination 172.17.17.2
interface Tunnel2
description "2MB Link"
ip address 192.168.2.1 255.255.255.252
keepalive 3 10
tunnel source 192.168.100.2
tunnel destination 10.100.200.2
router eigrp 1
network 192.168.1.0 0.0.0.3
network 192.168.2.0 0.0.0.3
Any help
Thanks
ST
01-07-2010 01:33 PM
Hello Mohamed,
please consider the following facts:
Saquid's wan links are not equal in performance and type see initial post.
Here, use of variance would be wise to make possible to take in account these differences.
My first impression was that the drops were only on the slower path, for the default equal cost paths so I've suggested to use bandwidth and variance to differentiate paths to be able to put more traffic on the better link.
However, later show commands from Saquid show that output drops are present in both tunnels and actually counter is greater on tunnel going on better path.
Saquid has already tried with a different IOS release with no improvement.
To be noted that Saquid says that drops happen only if both tunnels are up and he doesn't see drops if only one tunnel is up.
We need to be sure that tunnels are stable and that no recursion happens.
Recursion is : if tunnel1 destination is advertised inside EIGRP running on tunnel1 or tunnel2.
Saquid: look at logs to see if tunnels have up/downs events also check with both tunnel up
sh ip route t1-destination
sh ip route t2-destination
the destination have to be learned by different means then the EIGRP protocol running on the tunnels.
This is the requirement for stable tunnels and correct routing. Eventually EIGRP routing needs to be tuned (route filtering)
Hope to help
Giuseppe
01-07-2010 02:03 PM
Hi Giuslar
i tested what Mohammed inform but that didnt help, now config is back as per your last input.
I have one EIGRP Process so how could recursive happen.
If I do show IP route 10.10.10.0 it shows reachable via Tunnel1 and Tunnel2
what are other means to check tunnel stability and you shed more lights on route-filtering an if needed in my case.
Thanks in advance.
ST
01-07-2010 02:43 PM
Hello Saquib,
when I mean tunnel destination I mean the public IP address that will receive the GRE packet.
you need to check tunnels stability and that tunnel destinations = public ip addresses are not advertised in EIGRP.
use
sh log
sh ip route t1-destination
sh ip route t2-destination
we need to verify all possible causes, also you may want to use extended ping to verify reachability of these destinations.
However, problems in the public network would result in lost packets in transit not in output drops on the GRE tunnels
Also important, are these GRE tunnels protected by IPSec? = are you using crpyto maps to encrpypt GRE packets for security
in this case (if using IPsec) can we check with sh diag that the VPN module is present in the ISR router?
Hope to help
Giuseppe
01-08-2010 03:50 AM
Thanks Giuseppe for all help
When packet drop was noticed I removed the IPSEC from the GRE Tunnel.
As of now its only GRE Tunnel. Public IP are not advertised in EIGRP
I have retested reaching my next hop and reaching public IP on other side but didnt find any packet loss.
Did extended ping but no packet drop.
If I have both tunnels with equal bandwidth then what config is reqd for OSPF instead of EIGRP
Thanks
ST
Discover and save your favorite ideas. Come back to expert answers, step-by-step guides, recent topics, and more.
New here? Get started with these tips. How to use Community New member guide