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Catalyst 3550 Multilayer Switch Software Configuration Guide
78-11194-09
Chapter 7 Administering the Switch
Optimizing System Resources for User-Selected Features
You can also enable the switch to support 144-bit Layer 3 TCAM, allowing extra fields in the stored
routing tables, by reformatting the routing table memory allocation. Using the extended-match keyword
with the default, access, or routing templates reformats the allocated TCAM by reducing the number of
allowed unicast routes, and storing extra routing information in the lower 72 bits of the Layer 3 TCAM.
The 144-bit Layer 3 TCAM is required when running the Web Cache Communication Protocol (WCCP)
or multiple VPN routing/forwarding (multi-VRF) instances in customer edge (CE) devices (multi-VRF
CE) on the switch.
lists the approximate number of each resource supported in each of the four templates for
Catalyst 3550 Gigabit Ethernet switches.
compares the four templates for a Catalyst 3550
switch with primarily 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 shown. As the number of subnet VLANs increases, CPU utilization
typically increases. If the number of subnet VLANs increases beyond the number shown in the tables,
the number of supported entries in each category could 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 7-5
Approximate Resources Allowed in Each Template for Gigabit Ethernet Switches
Resource
Default Template
Access Template
Routing Template
VLAN Template
Unicast MAC addresses
6 K
2 K
6 K
12 K
IGMP groups (managed by Layer 2
multicast features such as MVR or
IGMP snooping)
6 K
8 K
6 K
6 K
QoS classification ACEs
2 K
2 K
1 K
2 K
Security ACEs
2 K
4 K
1 K
2 K
Unicast routes
12 K or 6 K
1
1.
When the extended-match keyword is used with the listed template. This keyword affects only the number of unicast routes allowed.
4 K or 2 K
1
24 K or 12 K
1
0
Multicast routes
6 K
8 K
6 K
0
Subnet VLANs (routed ports and SVIs)
16
16
16
16
Layer 2 VLANs
1 K
1 K
1 K
1 K
Table 7-6
Approximate Resources Allowed in Each Template for Fast Ethernet Switches
Resource
Default Template
Access Template
Routing Template
VLAN Template
Unicast MAC addresses
5 K
1 K
5 K
8 K
IGMP groups (managed by Layer 2
multicast features such as MVR and
IGMP snooping)
1 K
2 K
1 K
1 K