mpls over microwave

Anyone doing MPLS over microwave radios? Please
share your experiences on list or off.


We are. What would you like to know?

Shouldn't really be any different as long as your gear supports the appropriate MTUs.

I have been running MPLS over TDM and Ethernet microwave for about 8 years and the only issues are with microwave fade.

Nathan Sipes
Principal Network Architect
Tel: 713-369-9866
FAX: 303-763-3510
Kinder Morgan
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Houston, TX

Not doing anymore, but I have in a previous life. It works. What's more important is how you engineered your radios and what you're using...

Best regards,

I work for a fixed wireless provider, and our mpls-capable backhauls are
all running mpls with 9200 MTU with no problem. The only weirdness I
encounter is if I have multiple equal-cost routes to the same location, one
over MPLS and one not, end up having ping/unreachable issues from my
monitoring equipment. The solution has been to cost one path (the MPLS)
lower than the other. The only other problem I had was with radio's that
didn't support larger 9000+ byte MTU packets - we've phased that radio out
for now. if you run MPLS with 1500 byte MTU, you'll have issues with 1500
byte packets with the DF-bit set. That was a nasty discovery in the
production network, your mileage will not vary with that problem.

eric at techintegrity dot com
619-335-8148 voice & text
ericlouie on Twitter

Done it, and it works well. Used Motorola radios, and the key is the radio and building that part of the infrastructure right. The MPLS is just another IP packet to the wireless. Always used Ethernet handoffs on the radios to keep things simple.

Make sure you have good line of site, have ample fade or lack of, and you take vegetation growth in to consideration. Also make sure you buy stuff that handles jumbo frames and enable that, so that you don't have issues with fragmentation.

We run Dragonwave systems and have no issues at all. MPLS in itself doesn't make a difference since the gear is a straight Ethernet link. Just make sure your gear handles your frame sizes and tagging and you should be good.

As long as your radio link is engineered right you should have high reliability. The key is having enough margin to maintain links during fades. So for example our link runs at -34 dbm and our receivers are good down to about -65 dbm at this rate. That gives us a roughly 35 dbm margin for degradation before the modems will change modulation a to a lower speed. Here in chicago we have seen maybe a total of an hour of weather related fade in a 10 years period on a 20 mile link running 600 Mbps. They are very popular for low latency since they actually have less latency than fiber. The high frequency traders pay big bucks to get on the microwaves between markets because of that trait. Microwaves through air are faster than photons in a fiber cable.

Steven Naslund
Chicago IL

Aviat Networks has recently released a microwave router with MPLS features, it's basically a router inside the microwave indoor unit.

What we've found what hurts with anything over microwave is when you're running n+n links over long haul and the RF modulation steps down on one of those links and decreases your bandwidth, the Aviat solution is apparently meant to solve this with the RF cards talking directly to the on-board router and giving your MPLS nodes a kick to shift traffic in the right direction.



We run few mpls links ( 7600s/3600s on the mpls side mostly ) over Ceragon wireless gear. Nothing too fancy, I just treat them as switches ( or even just "cables" for some boxes, not doing mac learning at all ). No issues whatsoever on the networking side.

My thoughts and words are my own.

Kind Regards,


We run MPLS over wireless links of all kinds quite extensively. The key is to make sure that packet loss is at a minimum (duh), and to ensure that your wireless links have a large enough MTU to pass the additional bytes for each label. Other than that, we treat the wireless links as wires.

I'm curious why you'd have multiple paths in your network (equal-cost to
boot) where some support and others don't.


because I have a partial implementation of MPLS routers. Whether the
routers support MPLS or not, the routing on an OSPF level doesn't depend on
MPLS being enabled. Eventually everything will be MPLS-capable. The MPLS
network is not multiple-path. The OSPF network is.