PM8610-BIAP PMC [PMC-Sierra, Inc], PM8610-BIAP Datasheet - Page 300

• Manufacturer Part Number: PM8610-BIAP
• Description: SBS Telecom Standard Product Data Sheet Preliminary
• Manufacturer: PMC [PMC-Sierra, Inc]

Proprietary and Confidential to PMC-Sierra, Inc., and for its Customers’ Internal Use
Document ID: PMC-2000168, Issue 3
Figure 25 Time:Space:Time Switching in one NSE-20G and four Single-Ported SBSs
Consider a request to route an octet from ingress port i to egress port j, where i and j range from
0 to 3, over four ports corresponding to the four SBS devices. To make this connection, we must
find a timeslot in the NSE-20G which can accept an octet from the ingress SBS and send an octet
to the egress SBS. If the NSE-20G has these two slots free in the same timeslot, then the SBSs
must also have the corresponding slot free. The actual routing of the sample is accomplished in
several steps. The octet is:
It may not be possible to find a free time that connects the ingress SBS to the egress SBS, even
though both SBS devices have unused capacity into the NSE-20G core (the ingress SBS may
have a free timeslot at time i and the egress SBS may have a free timeslot at time j, but i ~= j).
Such cases require a more complex algorithm which is capable of disconnecting and reconnecting
other connections to make space for the new i to j connection. (Disconnection and reconnection
of other connections is done hitlessly by NSE/SBS fabrics.) This more sophisticated algorithm is
described in the remainder of this section.
I
Mapped to the free timeslot by the ingress SBS port,
Picked up by the NSE-20G in that timeslot on the port from the ingress SBS and mapped to
the port which leads to the egress SBS,
Picked up by the egress SBS in the expected timeslot.
0
1
2
3
0
(S=1, T=2) => SBS => (S=1, T=0) => NSE => (S=0, T=0) => SBS => (S=0, T=3)
(S=3, T=2) => SBS => (S=3, T=3) => NSE => (S=1, T=3) => SBS => (S=1, T=0)
1
Time
2
3
III
II
0
1
2
3
0
1
2
3
Space Switching
0
0
by NSE
1
1
Time
Time
2
2
3
3
SBS Telecom Standard Product Data Sheet
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0
1
2
3
0
1
Time
2
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