3-3
Cisco CRS-1 Carrier Routing System SIP and SPA Hardware Installation Guide
OL-17439-01
Chapter 3 Overview: Cisco CRS-1 Shared Port Adapters
Bandwidth Oversubscription
If you are using only Gigabit Ethernet SPAs on the Cisco CRS-1 SIP-800, then the SIP can be
oversubscribed. The Cisco CRS-1 SIP-800 can pass a maximum of 40 Gbps of traffic, so if you have six
8-Port Gigabit Ethernet SPAs operating at almost full capacity, the SIP is oversubscribed.
If you are using any Packet Over Sonet (POS) SPAs in the Cisco CRS-1 SIP-800, regardless of the
bandwidth of the SPA interfaces (OC-3c/STM-1, OC-12c/STM-4, OC-48c/STM-16, or
OC-192c/STM-64), no oversubscription of either PLIM ASIC is allowed, nor can the total bandwidth of
the SIP exceed 40 Gbps. For this reason, you can install a maximum of four OC-192c/STM-64 POS
SPAs in the Cisco CRS-1 SIP-800. Two of them must be installed in subslots 0, 1, or 3; the other two
must be installed in subslots 2, 4, or 5. The following arrangement of SPAs within the SIP indicates a
valid configuration that optimizes the use of the available PLIM ASIC bandwidth:
In this example, because at least one OC-192c/STM-64 POS SPA is installed, the maximum bandwidth
allowed on the first PLIM ASIC (associated with subslots 0, 1, and 3) is 20 Gbps, and the total capacity
of the SIP is controlled to be 40 Gbps or less. The total bandwidth usage required in this example is
36 Gbps.
The ingress oversubscription of Cisco CRS-1 SIP-800 with ATM SPA is supported in the following
conditions:
•
The ATM SPAs are allowed to come up even when the total ingress traffic from all the Gigabit
Ethernet SPAs exceeds 40-Gbps capacity when a combination of Gigabit Ethernet SPAs and ATM
SPAs is used.
•
Traffic is restricted to 40 Gbps per MSC when even a single POS SPA is inserted. In this case, the
newly inserted ATM SPA is not allowed to come up.
•
Overall traffic to a single PLIM ASIC does not exceed 20 Gbps while sending policed traffic on the
Gigabit Ethernet.
•
If oversubscription occurs, then the excess ingress traffic might be dropped.
If you attempt to install a SPA that oversubscribes the SIP, the SPA does not power up, and you receive
an error message similar to the following:
LC/0/2/CPU0:Jan 31 11:52:57.335 : jacket[159]: %JACKET-3-RULES_FATAL_ERROR
: SPA subslot 4: FAILED: Not enough bandwidth for 1xOC192 POS/RPR HHSPA with XFP
Table 3-2
provides information about the bandwidth for each port (per-port bandwidth) on a SPA and the
cumulative bandwidth (total bandwidth) for all ports available on the SPA.
Subslot 0:
OC-192c/STM-64 POS SPA
Subslot 1:
OC-192c/STM-64 POS SPA
Subslot 2:
8-Port Gigabit Ethernet SPA
Subslot 3:
Empty
Subslot 4:
8-Port Gigabit Ethernet SPA
Subslot 5:
4-Port OC-3c/STM-1 POS SPA
Table 3-2
SPA Bandwidth Capacity
SPA
Per-Port Bandwidth
Number of Ports
Total Bandwidth
1-Port Clear Channel OC-3 ATM SPA
155.52 Mbps
1
155.52 Mbps
3-Port Clear Channel OC-3 ATM SPA
155.52 Mbps
3
466.56 Mbps
1-Port Clear Channel OC-12 ATM SPA
622.08 Mbps
1
622.08 Mbps
4-Port OC-3c/STM-1 POS SPA
155.52 Mbps
4
622.08 Mbps
8-Port OC-12c/STM-4 Multirate POS SPA
155.52 Mbps or
622.08 Mbps
8
5 Gbps
1
