[j-nsp] L2Circuits vs L2 VPN

[Piotr Marecki]

Ehlo,

Docs are correct , although semantics may be misleding sometimes...

In that particular example docs are refering CCC circuit-cross connect ( 
which is the oldest
method for JNPR to do l2 over mpls ) but  its proprietary and uses one RSVP 
LSP per l2 circuit
(or rather two LSPs for bidirectional communication).
You can configure that kind of interconnection under [edit protocols 
connections] stanza. There is no notion of
hierarchy in circuit-cross connect like you can find in L2VPN and PW docs.

Other JNPR L2 over MPLS are l2circuit ( pseudo wire emulation ) , L2VPNs and 
VPLS ( eth specific ). Apart from signalization
protocol L2VPN and l2circuits have other differences ( like on2one vs 
one-to-many etc ) but as you pointed it out correctly , they both exchange
circuit "demultiplexor" labels and thus are able to use same PSN tunnel for 
different  circuits.

rgrds

Piotr Marecki




> Can someone explain what is the difference between L2 Circuits and L2 VPNs
> besides the obvious (which is signaling LDP vs BGP).
>
> Junos 9.1 doc states this in the VPN conf guide, page 509.
>
> "A Layer 2 circuit is similar to a circuit cross-connect (CCC), except
> that multiple Layer 2 circuits can be transported over a single
> label-switched path
> (LSP) tunnel between two provider edge (PE) routers. In contrast, each CCC
> requires
> a dedicated LSP."
>
> What does it mean the each CCC requires a dedicated LSP? If I build a
> transport tunnel using LDP, then all L2 VPN instances between two PEs will
> use the same tunnel, no matter whether ai use CCC or not.
>
> Thanks,
> Marlon
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