There are a few ways to leak routes in and out of virtual routers in Junos. On the list is a cool feature called the logical tunnel interface.

So, what am I talking about?  One way to separate traffic on a router is to use virtual routers (VRs) so that you wind up with multiple routing tables on the same router.  This separate traffic, but you will usually (read: always) have a demand to get traffic from one VR to another.  There are a few different way to do that (see rib-group, instance-import, next-table, et al.), but one really cool way to do it is through logical tunnel interfaces.

ACLs in IPv6 aren’t that different from what you’re used to dealing with in the IPv4 world.  You create a list of denies and permits for use with some other structure like filtering, PBR, and all sorts of other stuff.  Let’s take a look at building an ACL and filtering traffic with it.

For those playing at home, here’s the setup I used to generate the configs and get the output.  Execute some click action for the whole thing.

I posed the philosophical question on Twitter the other day asking if single trunk links should be in an EtherChannel bundle just in case you need to expand later.  I didn’t really expect an answer, but the ever-verbose @WannabeCCIE pointed out (in not so many words) that you should watch your IDBs.  What is that?

That’s an interface descriptor block.  I admit that I’m not intimately familiar with them, bu they’re data structs in IOS used to keep track of the interfaces on that device.  They come in two flavors - hardware and software.  HWIDBs usually represent a physical interface but they also represent tunnels, SVIs, PortChannels, subinterfaces, and any other virtual interface that you can configure.  The SWIDBs represent the layer-2 encapsulation of each HWIDB, so you’ll see entries talking about Ethernet, HDLC, PPP, etc.  That means that every interface you have on a router consumes two IDBs (there are always exceptions).  That’s important because each platform and IOS version combination has a limit to the number IDBs that device supports.