A separate EoMPLS
service topology may then be built for each service. For example,
?– POTS voice may be supported by a VPLS instance for each aggregation ring of
U-PEs, with each MSAN appearing as a single MAC address in the VPLS and with
the two N-PEs at the head-end acting as routers for the VPLS (using VRRP for
router redundancy). MPLS PE devices are typically highly resilient and have fast
restoration and advanced QoS support??”helping to ensure the voice service is as
robust as the TDM voice service it replaces.
MPLS 461
?– Broadband Internet may be backhauled using a redundant pseudowire from the
U-PE, with a primary path to one N-PE (typically one of the N-PEs at the head-end of
the ring) and a backup path to another. Each N-PE is directly connected to a BRAS or
integrates BRAS functionality. This design avoids the PEs having to learn customer
MAC addresses (which would reduce scalability). If an N-PE or BRAS fails, then the
customer devices will reestablish PPPoE sessions to the backup.
?– Video on Demand may be transported over a VPLS per-aggregation ring, in much
the same fashion as POTS voice. Video servers or caches may be connected directly
to the N-PEs at the head-end locations.
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