[j-nsp] Do-it-yourself Logical Tunnel

Richard A Steenbergen ras at e-gerbil.net
Sun Jan 17 19:01:57 EST 2010

So, I have some logical tunnels between two logical systems, where one
system provides a l2circuit transport service using the lt as a
endpoint, and the other system runs IP over that l2circuit to speak to
another router. This works fine, except for some reason known only to
Juniper, IPv6 on a logical tunnel is only supported when you use frame
relay encapsulation. If you configure it to use vlan, IPv4 works fine,
but IPv6 is not supported. This means that the other endpoint pretty
much needs to be another Juniper doing the exact same config, and
therein lies my problem. I'd like to talk to another endpoint that isn't
a Juniper on an lt, so I really need it to use ethernet encaps.

My idea for how to accomplish this was to create my own loopback using a
switch and a hairpin, plus a little vlan rewrite. I'd also prefer to do
the rewrites on the Juniper side. I could do it on the Cisco switch, but
I don't trust it not to do something stupid, especially since I'm doing
this over a port-channel. I was thinking the easiest way to handle this
was to rewrite the vlan that I transmit (so I don't have to deal with
making sure that it maps the incoming packet to the correct subint), but
I haven't had any luck. The best I've been able to come up with so far
results in:

[edit logical-systems blah interfaces ae0]
  'unit 116'
    vlan map ae0: input-vlan-map or output-vlan-map can only be 
specified in vlan-ccc, extended-vlan-ccc, vlan-vpls or 
extended-vlan-vpls encapsulations
error: configuration check-out failed

Which means I can do the transmit rewrite on the vlan-ccc side, but I 
can't do the rewrite on the IP side. Does anybody have any ideas for how 
to do this? If the above is true, it means I'll have to do both tx and 
rx rewrites on the vlan-ccc side.

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)

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