Cisco Catalyst 3550 Command Reference Manual page 238

sdm prefer
Do not use the routing template if you do not have routing enabled on your switch. Entering the sdm
prefer routing global configuration command prevents other features from using the memory allocated
to unicast and multicast routing in the routing template (approximately 17 K for Fast Ethernet switches
and 30 K for Gigabit Ethernet switches).
When running the Web Cache Communication Protocol (WCCP) or multiple Virtual Private Network
(VPN) routing/forwarding (multi-VRF) instances in customer edge (CE) devices (multi-VRF CE), extra
fields are required in the routing tables stored in TCAM. You must use the extended-match keyword
with the default, access, or routing templates to enable the switch to support 144-bit Layer 3 TCAM
when using these features. The keyword reformats the memory space allocated for routing, reducing the
number of allowed unicast routes by half.
Table 2-12
Gigabit Ethernet switch.
Fast Ethernet ports. The first six rows in the tables (unicast MAC addresses through multicast routes)
represent approximate hardware boundaries set when a template is selected. If a section of a hardware
resource is full, all processing overflow is sent to the CPU, seriously impacting switch performance.
The last two rows, the total number of routed ports and SVIs and the number of Layer 2 VLANs, are
guidelines used to calculate hardware resource consumption related to the other resource parameters.
The number of subnet VLANs (routed ports and SVIs) are not limited by software and can be set to a
number higher than indicated in the tables. If the number of subnet VLANs configured is lower or equal
to the number in the tables, the number of entries in each category (Unicast addresses, IGMP groups,
and so on) for each template will be as indicated. As the number of subnet VLANs is increased, CPU
utilization will typically increase. If the number of subnet VLANs is increased beyond the number
indicated in the tables, the number of supported entries in each category may decrease depending on
features that are enabled. For example, if PIM-DVMRP is enabled with more than 16 subnet VLANs,
the number of entries for multicast routes will be in the range of 1K-5K entries for the access template.
Table 2-12 Approximate Number of Feature Resources Allowed by Each Template for Gigabit Ethernet Switches
Resource
Unicast MAC addresses
IGMP groups (managed by Layer 2
multicast features such as MVR or IGMP
snooping)
QoS classification ACEs
Security ACEs
Unicast routes
Multicast routes
Routed interfaces (routed ports and SVIs) 16
Layer 2 VLANs
1. When the extended-match keyword is used with the indicated template. This keyword affects only the number of unicast routes allowed.
Catalyst 3550 Multilayer Switch Command Reference
2-212
lists the approximate number of each resource supported in each of the four templates for a
Table 2-13 lists the approximate number supported for a switch with mostly
Default Template
6 K
6 K
2K
2 K
1
12 K or 6 K
6 K
1 K
Access Template Routing Template
2 K 6 K
8 K 6 K
2 K 1 K
4 K 1 K
1
4 K or 2 K 24 K or 12 K
8 K 6 K
16 16
1 K 1 K
Chapter 2 Cisco IOS Commands
VLAN Template
12 K
6 K
2 K
2 K
1
0
0
16
1 K
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