Chapter 7. Routing on the EX
Wait, routing in a Layer 2/LAN switching book! What gives?
EX switches run JUNOS software, and therefore inherit a rich legacy of carrier-grade routing support. EX routing support pretty much comes for free, which is to say IPv4 routing is included in the base EX chassis. There are no special “routing-enabled” EX software images, or added hardware requirements, or any special commands to turn on/enable IP routing. You simply have to decide that Layer 3 forwarding is desired, determine which routing protocols to use, and then configure the EX to route as you would any other JUNOS device.
In many network designs, the optimal solution combines Layer 2 switching at the edge with Layer 3 routing in the distribution and core layers. The built-in (rather than bolted-on) nature of EX routing support makes the deployment of such hybrid networks both simple and reliable, given the known stability of JUNOS routing and the respectable Layer 3 scaling limits supported by the EX platforms.
Large enterprise networks or service provider data centers may warrant the extended routing capabilities of a purpose-built routing platform such as a J Series, MX Series, or even M or T Series routing platform.
It should be noted that the goal here is to expose the reader to general EX routing capabilities and basic configurations and operational verification examples. A detailed discussion of IP routing and routing protocols, including aggregate and generated routes, multicast, OSPF, ...
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