Enterasys SmartSwitch 2H252 Owner's manual

9033559-01
IP TOS Supplement
for Local Management
User’s Guides

NOTICE
Enterasys Networks and its licensors reserve the right to make changes in specifications and other information contained
in this document without prior notice. The reader should in all cases consult Enterasys Networks to determine whether
any such changes have been made.
The hardware, firmware, or software described in this manual is subject to change without notice.
IN NO EVENT SHALL ENTERASYS NETWORKS AND ITS LICENSORS BE LIABLE FOR ANY INCIDENTAL, INDIRECT,
SPECIAL, OR CONSEQUENTIAL DAMAGES WHATSOEVER (INCLUDING BUT NOT LIMITED TO LOST PROFITS)
ARISING OUT OF OR RELATED TO THIS MANUAL OR THE INFORMATION CONTAINED IN IT, EVEN IF ENTERASYS
NETWORKS AND ITS LICENSORS HAVE BEEN ADVISED OF, KNOWN, OR SHOULD HAVE KNOWN, THE POSSIBILITY
OF SUCH DAMAGES.
Enterasys Networks, Inc.
35 Industrial Way
Rochester, NH 03866-5005
Enterasys Networks, Inc. is a subsidiary of Cabletron Systems, Inc.
2000 by Enterasys Networks, Inc.
All Rights Reserved
Printed in the United States of America
Order Number: 9033559-01 October 2000
Enterasys Networks, MATRIX, and SmartSwitch are trademarks of Enterasys Networks or its licensors.
All other product names mentioned in this manual may be trademarks or registered trademarks of their respective
companies.

1
Overview
This supplement provides information concerning the IP TOS Rewrite feature added to the Priority
Classification Configuration screen. This information applies to the following:
•2nd and 3rd generation devices with firmware revision 4.07.xx and higher
•SmartSwitch 9000 series 9x5xx devices with firmware revision 1.07.xx and higher
This supplement supersedes the information in the Priority Classification Configuration section in
the following documents:
•SmartSwitch Series 2E253, 2H252, 2H253 and 2H258 Local Management User’s Guide
(9033069)
•MATRIX E7 Series and SmartSwitch 6000 Series Modules (6x2xx and 6x3xx) Local
Management User’s Guide (9034046-02)
•SmartSwitch 9000 9x5xx-Series Local Management User’s Guide (9033130-05)
1.0 IP TOS REWRITE FEATURE
The Type of Service (TOS) field [also known as the Differential Services (DF) field in RFC 2474]
is an 8-bit field. It is located in the IP packet and used by a device to indicate the precedence or
priority of a given frame (see Figure 1). The TOS layer-3 priority indicator enables the ability to
signal the frame priority from end to end as the frame makes its way through the network.
Figure 1 Datagram, Layer 2 and Layer 3
NOTE:
“2nd generation devices” refers to the 2x2xx standalone and 6x2xx module series
devices of the SmartSwitch 6000 family.
“3rd generation devices” refers to the 6x3xx series modules devices of the SmartSwitch
6000/Matrix E7 family.
Destination
Address
(DA)
Source
Address
(SA)
VLAN
Priority
Type of
Service
(8-bits)
3559_1
Layer 2 Layer 3
Addr
Length
Version
VLAN
Priority
Type of
Service
(8-bits)

2
This IP TOS Rewrite feature enables a Network Administrator to assign Layer 3 TOS
characteristics to incoming frames and set the switch to rewrite the 8-bit TOS value in the Layer 3
information portion of incoming frames.
The SmartSwitch/Matrix products enable you to configure the switch to:
•Insert a user-defined 8-bit value into the layer-3 TOS field.
•Write over an existing TOS value. This is useful when the Network Administrator wants to
enforce a specific priority policy in the network.
The IP TOS Rewrite parameters are set using the Priority Classification Local Management
screen. The screen has been updated to allow you to configure the new IP TOS field for any IP
frame classification. A selection field is displayed for all supported classification rules. The default
value is “NO CHANGE”. You can optionally specify TOS=PID, whereby the precedence sub-field
in the TOS field to match the value of the priority in the classification rule. You can also specify a
CUSTOM TOS value between 0 and 255. This allows you to specify an IP TOS value for a
particular need.
2.0 PRIORITY CLASSIFICATION CONFIGURATION SCREEN
When to Use
To perform the following functions:
•Display the current Priority, Classification, and Description entries of each classification rule.
•Assign priorities according to Classification Rules.
•Add/delete a priority and associated protocol entry.
•Access the Protocol Port Configuration screen.
•Assign an 8-bit TOS (also known as DF) value to incoming IP frames.
•Write over an existing TOS value.
When a frame is received that already contains an 802.1Q frame tag, frame classification is not
implemented. Instead, the frame is processed by the SmartSwitch according to the information
contained in the 802.1Q frame tag.
How to Access
Use the arrow keys to highlight the PRIORITY CLASSIFICATION CONFIGURATION menu
item in the 802.1p Configuration Menu screen and press ENTER. The Priority Classification
Configuration screen, Figure 2, displays.

3
Screen Example
Figure 2 Priority Classification Configuration Screen
Field Descriptions
Refer to Table 1 for a functional description of each screen field.
Table 1 Priority Classification Configuration Screen Field Descriptions
Use this field … To…
PID
(Selectable) – top of
screen
Display the Priority Identifiers (PIDs) currently associated with
protocol classifications. To see which ports are assigned to a
PID/Classification, or to add/remove a port from a PID/Classification,
used in the Protocol Port Configuration screen.
Classification
(Selectable) – top of
screen
Display the classification associated with the priority in the PID
column, which may be selected to call up the Protocol Port
Configuration screen.
Description
(Selectable) – top of
screen
Provide a brief description of the classification.
30793_97w
RETURN
EXIT
Description

ADD
IP: 123.123.030.006 Mask: 255.255.255.255.255
IP: 123.123.030.007 Mask: 255.255.255.255.255
0x8137
0x0800
0x9999
PID Classification
 
7 Bilateral IP Address
6 Dest IP Address
1 Ethernet II Type
1 Ethernet II Type
5 802.3 SAP
PREVIOUS NEXTDEL ALL
Classification Rule
PID: CLASSIFICATION: IP ADDRESS: MASK:
5 [ Bil IP Address ] 123.123.030.006 255.255.255.255.255
New IP TOS: [NO CHANGE]

4
PID
(Modifiable) –
bottom of screen
Enter the priority value that will be associated with the classification
selected in the Classification field. A PID from 0 to 7 may be typed
into the field, where 0 is the lowest priority and 7 is the highest priority.
Classification
(Selectable) – bottom
of screen
Select the classification that will be associated with the priority
selected in the PID field. There can be up to three fields involved
depending on the classification selected. At the time of this printing,
the selections available in each field are listed in Table 2.
NOTE: Besides the PID selected, the order in which a frame is
transmitted also depends on the Classification Precedence
Rules discussed in Section 2.1. These rules come into effect
when there are multiple classifications configured in the
SmartSwitch.
ADD
(Toggle) – bottom of
screen
Add the current Classification Rule (PID and Classification selections)
to the screen.
DEL ALL/DEL
MARKED
(Toggle) – bottom of
screen
Delete all or one or more marked entries, simultaneously. The DEL
ALL command is the default and it is used to simultaneously delete all
the configured information Classification Rules. The DEL MARKED
command appears in place of the DEL ALL command when one or
more lines are marked for deletion.
Table 1 Priority Classification Configuration Screen Field Descriptions (Cont’d)
Use this field … To…

5
Table 2 provides a list of the classifications that can be selected in the Classification field and the
associated subclassifications.
Table 2 Classification List
Classification Subclassification
and Options Custom or Mask Value
Ethernet II Type> Ethernet II Type:
-IPX
- DOD IP
- ARP
- RARP
- AppleTalk
- Banyan Vines
- DECNET
- CUSTOM > Type Value: 0x00001
802.3 SAP>
New IP TOS:
- NO CHANGE
- TOS=PID
- CUSTOM>
Same
Same
Same
Same
Same
SSAP/DSAP (803.2):
- IP
TOS: Value = 0x00
- IPX
- IPX RAW
- BANYAN
- SNA
- CUSTOM > DSAP/SSAP Type: 0x0000
IP TOS
New IP TOS:
- NO CHANGE
- TOS=PID
- CUSTOM>
Type of Service:
0x0000
TOS: Value = 0x00

6
IP Protocol Type
New IP TOS:
- NO CHANGE
- TOS=PID
- CUSTOM>
IP Protocol Type:
TCP
TOS: Value = 0x00
- UDP
- ICMP
- IGMP
- OSPF
- CUSTOM > Protocol Type: 000
IPX COS IPX Class Of Service:
000
IPX Packet Type IPX Packet Type:
- Hello or SAP
- RIP
- Echo Packet
- Error Packet
- Netware 386/SAP
- Seq. Pkt Protocol
- Netware 286
- CUSTOM > IPX Packet Type: 00
Src IP Address
New IP TOS:
- NO CHANGE
- TOS=PID
- CUSTOM>
IP Address:
000.000.000.000
TOS: Value = 0x00
Mask:
000.000.000.000
Table 2 Classification List (Cont’d)
Classification Subclassification
and Options Custom or Mask Value