MultiLayerSwitch-CAM/TCAM

Question 1

What does TCAM stand for?

Answer 1

Ternary Content Addressable Memory.

Question 2

What information does the TCAM table hold?

Answer 2

ACLs, next-hop routes, and QOS info.

Question 3

What is the TCAM?

Answer 3

TCAM is a memory that stores masks and pattern information for faster L3/L2 lookups. It should match CEF in terms of contents but not possible to verify.

Question 4

What does CAM stand for?

Answer 4

Content Addressable Memory.

Question 5

What is CAM?

Answer 5

CAM is specifically used for MAC address lookups where every bit in the lookup key must find an exact match.

Question 6

What is the default behavior of the switch when no match is found in CAM?

Answer 6

The switch will flood by default if there is no available CAM entry.

Question 7

What is the default MAC Address Age Timer?

Answer 7

The default *MAC Address Age Timer* is five minutes.

Question 8

How many CAM tables are on a switch?

Answer 8

One CAM table per VLAN. When a VLAN is created a CAM table is also created.

Question 9

Where are security and QoS ACLs stored?

Answer 9

TCAM

Question 10

How often are CAM table entries aged?

Answer 10

300 sec

Question 11

What are TCAM entries composed of?

Answer 11

value, mask, and result (VMR) combinations

Question 12

What is the size of a TCAM value?

Answer 12

134 bits, consisting of source and destination addresses and protocol information from the packet or frame

Question 13

How long are TCAM masks?

Answer 13

134 bits

Question 14

By default how long are CAM table entries kept before they are deleted?

Answer 14

300 seconds.

Question 15

What are the name differences between the Layer-3 and Layer-2 forwarding tables?

Answer 15

-Layer-2 is the CAM.-Layer-3 is the FIB.

Question 16

TCAM entries are organized by which of its three components?

Answer 16

Mask.

Question 17

In a switch, what is the CAM?

Answer 17

Content-Addressable Memory, or the address table. It holds the MAC, egress port, VLAN ID, and a time stamp.

Question 18

What are TCAM entries composed of?

Answer 18

-Values, Mask, and Result (VMR) combinations.-Values are 134-bit, containing source and dest IP address and protocol information. -Masks are 134-bit (self explanatory)-Results are numeric values that represent what action to take.

Question 19

Each TCAM mask can have/has how many values associated with it?

Answer 19

8 Values for each Mask

Question 20

What two components are part of the TCAM operation?

Answer 20

Feature Manager and Switching Database Manager.

Question 21

What is an LOU and when is it used?

Answer 21

Logical Operation Unit, used when an ACL line uses a port operator like gt, lt, or range. The Feature Manager uses this to compile the TCAM entry for the ACL.

Question 22

What happens if a CAM table is full?

Answer 22

A switch will flood all frames like a hub

Question 23

Where are MAC address Stored?

Answer 23

CAM Table

Question 24

Define the CAM table.

Answer 24

Content Addressable Memory table, AKA MAC address table.

Question 25

Define the TCAM table.

Answer 25

Ternary Content Addressable Memory table. Used in L3 switches.

Question 26

CAM table entries are purged when….

Answer 26

a MAC is seen on a different port

Question 27

What is the FM?

Answer 27

Feature Manager - after the ACL is created, the FM compiles the ACEs into the table

Question 28

What are LOU register pairs?

Answer 28

used when ACLs specify port ranges…used by TCAM