3550 Series Switches

The 3550 Series Intelligent Ethernet switch comprises a number of fixed configuration switches
that can be operated in a stand-alone fashion or joined together in a stack. More powerful than
the 2950 switches, they provide several enhancements to both security and quality of service
(QoS), thanks in part to the additional layer 3 capability of the IOS.
All Catalyst 3550 models have the Cisco Cluster Management Suite (CMS) software embedded
in the operating system. (CMS is discussed later in this chapter.)
The 3550 series switches operate using a distributed shared-memory switching fabric. The
forwarding decisions, at layers 2, 3, and 4, as well as CEF, are taken by “satellite” ASICs located
near the main shared memory. Figure 21.8 shows the relationship between the shared memory,
the decision-making satellite ASICs, and the ring request mechanism.

3550 switch architecture
Control
Plane
CPU
Shared Memory
TCAM
Satellite
Satellite
Satellite
Forwarding
Marking Policing


The 3550 switches operate at both layer 2 and layer 3, and use a CAM for address lookup
at both layers for 10/100 Mbits/second interface traffic. All switches in the range use TCAM for
faster switching because of the proliferation of Gigabit interfaces. You can tell which version of
the switch you are connected to by using the show version command:
Terry_3550#show version
Cisco Internetwork Operating System Software
IOS (tm) C3550 Software (C3550-I5K2L2Q3-M),
Version 12.1(13)EA1a, RELEASE SOFTWARE (fc1)
Copyright (c) 1986-2003 by cisco Systems, Inc.
Compiled Tue 25-Mar-03 23:56 by yenanh
Image text-base: 0x00003000, data-base: 0x008BA914
ROM: Bootstrap program is C3550 boot loader
Terry_3550 uptime is 4 days, 23 hours, 10 minutes
System returned to ROM by power-on
System image file is "flash:/c3550-i5k2l2q3-mz.121-13.EA1a.bin"
[output cut]
cisco WS-C3550-24-PWR (PowerPC) processor
(revision B0) with 65526K/8192K bytes of memory.
Processor board ID CAT0709X07M
Last reset from warm-reset
Bridging software.
Running Layer2/3 Switching Image
Ethernet-controller 1 has 12 Fast Ethernet/IEEE 802.3 interfaces
Ethernet-controller 2 has 12 Fast Ethernet/IEEE 802.3 interfaces
Ethernet-controller 3 has 1 Gigabit Ethernet/IEEE 802.3 interface
Ethernet-controller 4 has 1 Gigabit Ethernet/IEEE 802.3 interface
24 FastEthernet/IEEE 802.3 interface(s)
2 Gigabit Ethernet/IEEE 802.3 interface(s)

Terry_3550#
Shown next is the output from the show tcam command executed on the same switch.
Very few entries exist in this TCAM, but the command can be used to view the remaining
TCAM capacity:
Terry_3550#show tcam ?
inacl Show Ingress ACL TCAM
outacl Show Egress ACL TCAM
pbr Show PBR TCAM
qos Show Ingress QoS TCAM
Terry_3550#show tcam qos ?
<1-1> TCAM ID
Terry_3550#show tcam qos 1 ?
entries Show entry information
masks Show mask information
port-labels Show port label information
size Show size
statistics Show statistics
vlan-labels Show vlan label information
Terry_3550#show tcam qos 1 statistics
QoS TCAM#1: Number of active labels: 0
QoS TCAM#1: Number of masks allocated: 4,available:412
QoS TCAM#1: Number of entries allocated: 1,available:3327
Terry_3550#