MPLS destroys my network

[snaandmvswillrise]

I have a straight IP network with EIGRP as a IGP. I want to run MPLS so we can offer VPN services.

I have deployed MBGP already and everything is fine. Now I want to configure MPLS.

I have selected a link to one of our POP sites, which has various routers at the remote site. There is about 10Mbps of traffic on this link at any one time.

This is the config I then add at each end of the link:

int FastEthernet0/0.300

mpls ip

mpls label protocol tdp

tag-switching mtu 1530

tag-switching ip

When I do this, traffic drops to about 5Mbps and people start screaming at me. When I take these commands off traffic goes back to 10Mbps and everyone is happy.

What do I need to do to get MPLS deployed in my network, and not affect existing IP traffic?

I am not sure why I have a problem because I am not creating any VRF's at this point.

I have tried this on several links and the same thing happens. I am running the latest IOS 12.2 I can get.

What am I doing wrong?

[romccallum]

a few questions here.

Routers? what are they 2600's?

Also

mpls ip

mpls label protocol tdp

tag-switching mtu 1530

tag-switching ip

Why are you running TDP? Also mpls ip and tag-switching ip are the same commands.

[snaandmvswillrise]

Thank you for your interest -

One end is a 3600, the other end a 7500 (RSP4).

I have a lot of 7200's in the network also, I am happy to use another link if you feel 7200's are better.

Same thing happens with LDP or TDP. I was just playing around... same goes for the duplicate command. Help!

[Harold Ritter]

Do you have Ethernet interfaces in this network? Make sure that the switches you use also support baby giant frames (slightly greater than 1500 bytes).

Hope this helps,

[snaandmvswillrise]

No switch on the WAN link, our Metro WAN links are wireless - so that means our wireless devices (that supply Ethernet interface to the router) need to support "baby giant frames"?

Elsewhere I have seen a reccomendation of MPLS MTU of 1526. So I will follow up with our wireless vendor if they can handle that.

In some cases we have 6500's, 3550's and 2950's on our routers. Any problems there?

Thanks!

[Harold Ritter]

"mpls mtu 1526" should be more than ok for MPLS vpn. If you use l2vpn services such as EoMPLS though, you will probably require an MTU size larger than 1526 as EoMPLS has a 22 bytes header + 4 bytes for the VC label + 4bytes for the IGP label + possibly additional labels for TE and FRR.

Please refer to the following URL for giant frame support on the switches you mentioned.

http://www.cisco.com/en/US/products/hw/switches/ps700/products_configuration_example09186a008010edab.shtml

Hope this helps,

[snaandmvswillrise]

My wireless vendor tells me they drop all frames above 1518 bytes.

From what I have described previously, will this cause the problems I am having?

[Harold Ritter]

Is this 1518 bytes including ethernet header (sa,da, ethertype) and FCS or 1518 bytes of payload.

If it is the former then it could certainly cause the king of issue you are seeing.

Hope this helps,

[snaandmvswillrise]

Thanks again for your help

1518 bytes including header is the limitation of our wireless transmission equipment. As there is also some 2950's still around I have another limitation there also, Cisco quote 1500 byte MTU limit on those.

Can I simply use the MPLS MTU command and set a value of say, 1450 bytes. Cisoc documentation says this command will cause IOS to do IP fragmentation, and I will not have any MPLS frames that approach the limits any more?

Potentially I could disable the DF bit at ingress points to my network using route maps to make this work?

Thanks

[Harold Ritter]

I would not recommend deploying MPLS unless all of your L2 devices (wireless equipment and switches) support baby giants.

Fragmentation in the core could lead to suboptimal performance.

What is the purpose of deploying MPLS in your network? L2VPN, L3VPN, others?

Hope this helps,

[danielvilla]

Hello there,

Prior you must be sure that CEF is enable in all routers, it's mandatory.

I'm think EIGRP is no good enougth to build the topologies tables necessaries to populate the LIB table. You need to use a link-state protocol as IGP (Personally I prefer OSPF).

Do you have any TDP adjacencies? what about your LFIB?; I think you need prior to deploy MPLS in your network run a Link-State protocol.

Please visit the folloing link, could be a good guide to troubleshooting:

http://www.cisco.com/en/US/partner/tech/tk436/tk428/technologies_tech_note09186a0080094b4e.shtml

Regards

Daniel

[Harold Ritter]

A Link State routing protocol is only required if you are going to use MPLS TE as well.

EIGRP is just fine if TE is not a requirement.

Hope this helps,