[j-nsp] Understanding DPC Cards

[Richard A Steenbergen]

On Tue, May 04, 2010 at 05:05:04PM -0400, Paul Stewart wrote:
> 
> Can someone give me in "simple terms" what the differences are between
> "chassis network-services Ethernet" and "chassis network-services IP"?  

When Juniper came out with the MX they had two large potential customer
bases with two different uses for the platform, and wanted to create a
differentiated price point so they could compete with both groups. To do 
this, they made a chassis network-services mode, and sold a -X and -R 
version of the same card at different prices. If you configure 
"network-services ethernet" both -X and -R cards will work, but if you 
configure "network-services ip" any -X cards in the chassis will shut 
down.

The "ethernet" mode lets you use the box for L2, or have just enough IP
to use as a signaling for l3vpns, but not enough IP to do actual routing 
(i.e. bgp will not exchange inet/unicast afi/safi's, etc). If you want 
to do full routing, you need the -R cards, and you need to configure the 
chassis for network-services ip.

> On the MX it seems this is quite different?  I have the following:

IMHO using an MX for L2 is blasphemy, and you should have your head
examined if you actually want to use it this way. This is the networking 
version of buying a GT-R and then only driving it on sundays down 25mph 
side streets. :)

> I'm sure this isn't correct J This is what I created after reading
> some of the Juniper docs with a lack of understanding what
> "flexible-ethernet-services" actually refers too.. 

Flexible ethernet services is a mode that lets you mix and match 
multiple types of L2 and L3 encapsulations under a single physical 
interface, in any way you'd like. This is different from earlier 
generations of Juniper hardware, which had very specific requirements 
and restricted ranges of what you could configure. For example, back in 
the day if you wanted to have one subinterface do family inet and 
another subinterface do vlan-ccc (say for example as an l2circuit 
endpoint), you had to do the ip on vlan IDs < 512 and the vlan-ccc on 
vlan IDs 512-1024. With flexible ethernet services you can do it however 
you'd like. That it is even a configuration option at all and not just 
default is a holdover from the days when it wasn't supported on every 
kind of interface. All MX interfaces support it now, so it's probably 
what you want to use if for no other reason than it saves you a flap if 
you ever need to turn it on later. 

-- 
Richard A Steenbergen <ras at e-gerbil.net>       http://www.e-gerbil.net/ras
GPG Key ID: 0xF8B12CBC (7535 7F59 8204 ED1F CC1C 53AF 4C41 5ECA F8B1 2CBC)