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Multiple ATM Virtual Circuits over a Single Pseudowire Example
Figure 127 on page 554 shows a Martini circuit deployment in which the CE-side
devices on either side of the network send and receive ATM cells. An MPLS tunnel
that connects two E Series provider edge routers, PE1 and PE2, and ATM
cross-connects provide a pseudowire between the ATM VCs on the two routers. PE2
is the remote router located at the other side of the service provider core. A customer
edge ATM switch, CE1, and the provider edge router, PE1, on one side of the core
are connected by an ATM port. Similarly, PE2 and CE2 are connected by an ATM
port. The necessary MPLS Martini circuit configuration and VPI/VCI range configuration
are added to the ATM ports on PE1 and PE2. The LDP signaling protocol performed
the signaling operation and set up the pseudowire (a pair of unidirectional LSPs, from
PE1 to PE2 and from PE2 to PE1) for transporting the ATM cells between CE1 and
CE2.
Figure 127: Martini Circuit Deployment for Transmission of Multiple ATM VCs over a SIngle Pseudowire
PE2 PE1
Service Provider MPLS Backbone Network
pseudo wire LSP
pseudo wire LSP
ATM switch ATM switch
Customer switch 1 (CE1) Customer switch 2 (CE2)
g016511
CE1 transmits ATM cells on the ATM port connected to PE1. The transmitted cells
contain VPI/VCI values that are within the range specified as part of the MPLS Martini
configuration on the ATM port of PE1. If cell concatenation is configured on that ATM
port of PE1, PE1 accumulates the received ATM cells. If cell concatenation is not
specified, cell concatenation count is reached, or the concatenation timer expired,
PE1 encapsulates the ATM cells with a control word, adds the pseudowire label and
transport label, and forwards the resulting MPLS labeled packet to be delivered to
PE2.
PE2 receives the MPLS-labeled packet and strips the labels on the packet. The
bottommost label indicates to PE2 that the packet contains ATM cells to be forwarded
on the ATM port connected to CE2. PE2 extracts the ATM cells from the packet,
checks whether the VPI/VCI value on the ATM cells fall within the configured VPI/VCI
range on the ATM port, and forwards those ATM cells whose VPI/VCI values fall within
the configured range to CE2. PE2 discards the ATM cells that do not fall within the
configured VPI/VCI range. For data traffic traversing from CE2 to CE1, the same
workflow is followed with the roles reserved—PE2 as the transmitter of MPLS labeled
packet and PE2 as the receiver of MPLS labeled packet.
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Multiple ATM Virtual Circuits over a Single Pseudowire Example
JUNOSe 11.0.x BGP and MPLS Configuration Guide