Single router for P/PE functions


I'm pretty confident that a router can be used to perform P & PE functions simultaneously. What about from a best practice perspective? Is this something that should be completely avoided? Why? We're considering doing this as a temporary workaround but we all know temporary usually lasts a long time. I'd like to know what kind of mess awaits if we let this one go.


Not only can they, it's done quite frequently. I just completed a

Kinda depends on what you're doing exactly, but like Erik said, it certainly
possible and depending on your particular needs, it might not be much of an
issue at all.

Can you describe your scenario a bit more?


Collapsing P/PE functions certainly saves CAPEX, the downside is that you might need to reload your PE (affecting customers) due to a core feature upgrade or bug fix, or the other way around. With separate P and PE functions and PEs being dual attached to two Ps, you can reboot P layer with minimal end customer impact.

I'd imagine that in smaller networks it makes more sense to collapse compared to larger network, because a smaller network has fewer customers to be affected by each router problem.

It's basically "put all the eggs in one basket" kind of issue, it's easier to carry around but you lose more when something happens.

Hi dave,

Our setup was a dual ring with two devices common to both rings. It used a
full mesh of LSP's but the majority of traffic was L3VPN. There were some
VPLS connections as well, maybe a total of 30 VLAN's. LSP's were set up with
static path's the short way around the ring and a standby active secondary
path the long way around. Convergence time for a failure on either ring was
barely noticable. I am no longer with that organization so I can't get
access to the gear anymore :frowning:

From my experience, you are probably just asking the EX4200 to do more than

it was made to do. That is a lot of CCC circuits to reallocate on the fly,
especially for a smaller device. You may me able to reduce convergence time
by making your LSP's static with a standby secondary so the path is
preconfigured when a failover occurs, the only problem with this is the
scalability gets poor quickly as you start to add devices.


Hi All

Any one is using PWE solutions?

Any good/bad experience with this technology?



We're trying to save on Transport links. Instead of multi-homing each PE to 2 Ps, we're considering building a ring: P-PE-PE-PE-P. This ring follows the transport ring. Each link would be engineering to make sure it can handle all of the traffic from all 3PEs in case of a failure. As the network grows, we could get individual transport links from PE-P.

Apart from bandwidth, I was curious if there were other problems I related to doing this that I wasn't thinking of. Thanks for all the replies. Much appreciated.


What if there is a problem from software, filter, mis-configuration from
one of the routers ?
It will affect whole ring network, not just that problem router.

Also if there is routing protocol bounce because of link flapping, it
will be propagate through the ring forever.


Serge Vautour wrote: