On my site we are in the proceess of implementing MPLS for sharing the traffic with existing IPLC's and DS3 links. Currently we are running eigrp and sharing the load on all the IPLC's and DS3's. Our challenge is after imlementing MPLS we needs to share the load on MPLS also. On our network Voice : Data ratio is 80 : 20 %.
Can you give us some guidlines on the routing protocol which we can choose here and the protocol which can be used between our router and service provider network.
Your traffic sharing across interface, should not depend on MPLS. The way that the traffic is shared is dependent on the content of the routing table. Also, routing protocols like EIGRP are capable of doing unequal load balance. I therefore think that you can continue with which ever routing protocol you are using now, if it is giving you your desired traffic share pattern.
The choice of IP routing protocol between you and your MPLS provider depends on the provider. Cisco PE routers support for PE-CE routing: static, RIPv2, EIGRP, OSPF, eBGP (on limited platforms ISIS).
In case the SP has no Cisco PE, EIGRP is not an option. Other protocols are maybe not part of the SP offerings. So first you need to check with the SP.
Second, there are some issues to tackle with respect to IP routing loops, arising from the fact, that the SP internally uses MBGP for customer routes.
In case the SP does not support EIGRP for PE-CE routing, you will get external EIGRP routes learned through MPLS. Then there will be no unequal cost load sharing, because EIGRP will never use an external route as long as there is the same network learned internally. The only option is to send dedicated networks through MPLS and other networks through your existing links. This way you have to manually adjust everything and might also loose redundancy and dynamic rerouting.
In case EIGRP is used for PE-CE, then you might get what you would like to have. Still, it depends on the SP configuration and especially on the metrics set during MBGP->EIGRP redistribution. Based on the settings the advertised metric might not reflect the real bandwidth along the path to the destination network through MPLS.
Another osption would be to use EIGRP over GRE tunnels between your sites across the MPLS VPN. This however needs careful design to void flapping tunnels (tunnel destination learned through the tunnel). Second you potentially will have MTU issues across the GRE tunnel.
So to summarize:
1) "load sharing" can be done manually (like with static routing) with any PE-CE protocol. But surely not like you are used to with EIGRP in your existing network, but based on selected networks being only reachable through MPLS.
2) load sharing might work with EIGRP as PE-CE protocol depending on the SP settings/configuration in his network.
3) You need to check the options with the SP and especially need to announce the existance of the additional links between your locations to avoid possible routing loops.
4) load sharing across GRE tunnels might be an option, but it is not easy to implement and rises the complexity of your network.
Thanks to all for your support. As of now we have planned to go with static routes since SP is not supporting for EIGRP. We selected some internal subnets and will pump the data via MPLS. Now the issue raise at redundancy part. I am working on this. If some one has any idea please reply to me..
Martin : Thank you very much for ur detailed reply.
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