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HP 5500 Ei 5500 Si Switch Series Configuration Guide

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The default priority mapping tables (see Appendix A Default priority mapping tables ) are available for 
priority mapping. In most cases, they are adequate for priority mapping. If a default priority mapping 
table cannot meet your requirements, you can modify the priority mapping table as required.  
Priority trust mode on a port 
The priority trust mode on a port decides which priority is used for priority mapping table lookup. Port 
priority was introduced to use for priority mapping in addition to priority fields carried in packets. The HP 
5500 EI and 5500 SI Switch Series provides the following priority trust modes: 
•   Using the 802.1p priority carried in packets for priority mapping.  
•   Using the DSCP carried in packets for priority mapping.  
•   Using the port priority as the 802.1p priority for priority mapping. The port priority is user 
configurable.  
The priority mapping procedure varies with the priori ty modes. For more information, see the subsequent 
section. 
Priority mapping procedure 
On receiving an Ethernet packet on a port, the switch  marks the scheduling priorities (local precedence 
and drop precedence) for the Ethernet packet. This procedure is done according to the priority trust 
mode of the receiving port and the 802.1q  tagging status of the packet, as shown in Figure 6.
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Figure 6 Priority mapping procedure for an Ethernet packet 
 
 
The priority mapping procedure shown in Figure 6 applies in the absence of priority marking. If priority 
marking is configured, the switch performs priority marking before priority mapping. The switch then uses 
the re-marked packet-carried priority for priority mapping or directly uses the re-marked scheduling 
priority for traffic scheduling depending on your configuration. Neither priority trust mode configuration 
on the port nor port priority configuration takes effect.  
Configuration guidelines 
You can modify priority mappings by modifying priori ty mapping tables, priority trust mode on a port, 
and port priority.  
HP recommends planning QoS throughout the netw ork before making your QoS configuration.  
Configuring a priority mapping table 
To configure a priority mapping table:
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Step Command Remarks 
1.  Enter system view. 
system-view N/A 
2.  Enter priority 
mapping table 
view.   qos map-table 
{ dot1p-dp |  dot1p-lp | dscp-dot1p  | 
dscp-dp |  dscp-dscp }  N/A
 
3.  Configure the 
priority mapping 
table.   import
 import-value-list  export export-value   Newly configured 
mappings overwrite the 
old ones. 
 
 
Configuring a port to trust packet priority for priority 
mapping 
When you configure the trusted packet priority type on an interface or port group, use the following 
priority trust modes: 
•  dot1p —Uses the 802.1p priority of received packets for mapping.  
•   dscp—Uses the DSCP precedence of received IP packets for mapping.  
•   untrust—Uses port priority as the 802.1p priority for priority mapping.  
To configure the trusted packet priority type on an interface or port group: 
 
Step Command Remarks 
1.   Enter system view 
system-view N/A 
2.  Enter interface view or 
port group view. 
• Enter interface view: 
interface  interface-type 
interface-number 
•  Enter port group view: 
port-group manual  port-group-name
 
Use either command. 
Settings in interface view take 
effect on the current interface. 
Settings in port group view take 
effect on all ports in the port group. 
 
3.  Configure the trusted 
packet priority type for 
the interface.  
• Trust the DSCP priority in packets: 
qos trust dscp 
• Trust the 802.1p priority in packets: 
qos trust dot1p 
• Trust the port priority: 
undo qos trust  Use either command. 
By default, the device trusts the port 
priority.
 
 
Changing the port priority of an interface 
To change the port priority of an interface:  
Step  Command Remarks 
1.  Enter system view. 
system-view N/A
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    							 31 
Step Command Remarks 
2.  Enter interface view or 
port group view. 
• Enter interface view: 
interface  interface-type 
interface-number 
•  Enter port group view: 
port-group manual 
port-group-name   Use either command. 
Settings in interface view take effect on 
the current interface. Settings in port 
group view take effect on all ports in the 
port group.  
3.
  Set the port priority of 
the interface.   qos priority 
priority-value  The default port priority is 0.
 
 
Displaying priority mappings 
 
Task Command Remarks 
Display priority 
mapping table 
configuration. display qos map-table
 [ dot1p-dp | dot1p-lp | dscp-dot1p  
|  dscp-dp |  dscp-dscp ] [ |  { begin | exclude | include } 
regular-expression  ]  Available in any view 
Display the trusted 
packet priority type on 
a port.
  display qos trust
 interface  [ interface-type 
interface-number  ] [ | { begin  | exclude  | include  } 
regular-expression  ]  Available in any view
 
 
Priority trust mode configuration example 
Network requirements 
As shown in Figure 7 , Device A is connected to GigabitEthernet 1/0/1 of Device C, Device B is 
connected to GigabitEthernet 1/0/2 of Device C, and the packets from Device A and Device B to Device 
C are not VLAN tagged.  
Make configurations to have Device C preferentially process packets from Device A to Server when 
GigabitEthernet 1/0/3 of Device C is congested. 
Figure 7  Network diagram
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Configuration procedure 
# Assign port priority to GigabitEthernet 1/0/1 and GigabitEthernet 1/0/2. Make sure that the priority 
of GigabitEthernet 1/0/1 is higher than that of GigabitEthernet 1/0/2, and no trusted packet priority 
type is configured on GigabitEthernet 1/0/1 or GigabitEthernet 1/0/2. 
 system-view 
[DeviceC] interface gigabitethernet 1/0/1 
[DeviceC-GigabitEthernet1/0/1] qos priority 3 
[DeviceC-GigabitEthernet1/0/1] quit 
[DeviceC] interface gigabitethernet 1/0/2 
[DeviceC-GigabitEthernet1/0/2] qos priority 1 
[DeviceC-GigabitEthernet1/0/2] quit 
Priority mapping table and priority marking 
configuration example 
Network requirements 
As shown in Figure 8, the com pany’s enterprise network interconnects all departments through Device. 
The network is described as follows: 
•   The marketing department connects to GigabitEthernet 1/0/1 of Device, which sets the 802.1p 
priority of traffic from the marketing department to 3. 
•   The R&D department connects to GigabitEthernet 1/0/2 of Device, which sets the 802.1p priority 
of traffic from the R&D department to 4. 
•   The management department connects to GigabitEthernet 1/0/3 of Device, which sets the 802.1p 
priority of traffic from the management department to 5. 
Configure port priority, 802.1p-to-local mapping table, and priority marking to implement the plan as 
described in  Tabl e  3. 
Table 3  Configuration plan 
Traffic 
destination  Traffic priority

 order Queuin
g plan 
Traffic source 
Output queue Queue priority 
Public servers  R&D department > 
management 
department > marketing 
department  R&D department  6  High Management department  4 
Medium 
Marketing department  2 Low 
Internet Management 
department > marketing 
department > R&D 
department
  R&D department  2  Low Management department  6 
High 
Marketing department  4  Medium
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    							 33 
Figure 8 Network diagram 
 
 
Configuration procedure 
1. Configure trusting port priority: 
# Set the port priority of GigabitEthernet 1/0/1 to 3. 
 system-view 
[Device] interface gigabitethernet 1/0/1 
[Device-GigabitEthernet1/0/1] qos priority 3 
[Device-GigabitEthernet1/0/1] quit 
# Set the port priority of GigabitEthernet 1/0/2 to 4. 
[Device] interface gigabitethernet 1/0/2 
[Device-GigabitEthernet1/0/2] qos priority 4 
[Device-GigabitEthernet1/0/2] quit 
# Set the port priority of GigabitEthernet 1/0/3 to 5. 
[Device] interface gigabitethernet 1/0/3 
[Device-GigabitEthernet1/0/3] qos priority 5 
[Device-GigabitEthernet1/0/3] quit 
2. Configure the priority mapping table: 
# Configure the 802.1p-to-local mappi ng table to map 802.1p priority values 3, 4, and 5 to local 
precedence values 2, 6, and 4. This guarant ees the R&D department, management department, 
and marketing department decreased prio rities to access the public server. 
[Device] qos map-table dot1p-lp 
[Device-maptbl-dot1p-lp] import 3 export 2 
[Device-maptbl-dot1p-lp] import 4 export 6
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    							 34 
[Device-maptbl-dot1p-lp] import 5 export 4 
[Device-maptbl-dot1p-lp] quit 
3. Configure priority marking: 
# Mark the HTTP traffic of the management  department, marketing department, and R&D 
department to the Internet with 802.1p priorities  4, 5, and 3, respectively. Use the priority 
mapping table you have configured to map the 802.1p priorities to local precedence values 6, 4, 
and 2, respectively, for differentiated traffic treatment.  
# Create ACL 3000 to match HTTP traffic.  
[Device] acl number 3000 
[Device-acl-adv-3000] rule permit tcp destination-port eq 80 
[Device-acl-adv-3000] quit 
# Create class  http and reference ACL 3000 in the class.  
[Device] traffic classifier http 
[Device-classifier-http] if-match acl 3000 
[Device-classifier-http] quit 
# Configure a priority marking policy for the ma nagement department, and apply the policy to the 
incoming traffic of GigabitEthernet 1/0/3.  
[Device] traffic behavior admin 
[Device-behavior-admin] remark dot1p 4 
[Device-behavior-admin] quit 
[Device] qos policy admin 
[Device-qospolicy-admin] classifier http behavior admin 
[Device-qospolicy-admin] quit 
[Device] interface gigabitethernet 1/0/3 
[Device-GigabitEthernet1/0/3] qos apply policy admin inbound 
# Configure a priority marking policy for the ma rketing department, and apply the policy to the 
incoming traffic of GigabitEthernet 1/0/1.  
[Device] traffic behavior market 
[Device-behavior-market] remark dot1p 5 
[Device-behavior-market] quit 
[Device] qos policy market 
[Device-qospolicy-market] classifier http behavior market 
[Device-qospolicy-market] quit 
[Device] interface gigabitethernet 1/0/1 
[Device-GigabitEthernet1/0/1] qos apply policy market inbound 
# Configure a priority marking policy for the  R&D department, and apply the policy to the 
incoming traffic of GigabitEthernet 1/0/2.  
[Device] traffic behavior rd 
[Device-behavior-rd] remark dot1p 3 
[Device-behavior-rd] quit 
[Device] qos policy rd 
[Device-qospolicy-rd] classifier http behavior rd 
[Device-qospolicy-rd] quit 
[Device] interface gigabitethernet 1/0/2 
[Device-GigabitEthernet1/0/2] qos apply policy rd inbound
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Configuring traffic policing, traffic shaping, 
and line rate 
Both bridge mode (Layer 2) and route mode (Layer 3) Ethernet ports support the traffic shaping and line 
rate functions. The term  interface i n  t h i s  ch a p t e r  c o l l e c t ive ly  re fe rs  t o  t h e s e  t yp e s  o f  p o r t s.  Yo u  c a n  u s e  t h e  
port  link-mode  command to set an Ethernet port to  operate in bridge or route mode (see  Layer 2—LAN 
Switching Configuration Guide ). 
The 5500 SI Switch Series does not support Layer 3 Ethernet ports.  
Overview 
Traffic policing, traffic shaping, and rate limit are Qo S technologies that help assign network resources, 
such as assign bandwidth. They increase network performance and user satisfaction. For example, you 
c a n  c o n f i g u r e  a  f l o w  t o  u s e  o n l y  t h e  r e s o u r c e s  c o m m i t t e d  t o  i t  i n  a  c e r t a i n  t i m e  r a n g e .  T h i s  a v o i d s  n e t w o r k  
congestion caused by burst traffic. 
Traffic policing, generic traffic shaping (GTS), and li ne rate limit the traffic rate and resource usage 
according to traffic specifications. Once a particular flow exceeds its specifications, such as assigned 
bandwidth, the flow is shaped or policed to make sure that it is under the specifications. You can use 
token buckets for evaluating traffic specifications. 
Traffic evaluation and token buckets 
A token bucket is analogous to a container that hold s a certain number of tokens. Each token represents 
a certain forwarding capacity. The system puts tokens  into the bucket at a constant rate. When the token 
bucket is full, the extra tokens cause the token bucket to overflow. 
Evaluating traffic with the token bucket 
A token bucket mechanism evaluates traffic by looking at the number of tokens in the bucket. If the 
number of tokens in the bucket is enough for forwarding the packets, the traffic conforms to the 
specification, and is called conforming traffic. Otherwise, the traffic does not conform to the 
specification, and is called excess traffic. 
A token bucket has the following configurable parameters: 
•   Mean rate at which tokens are put into the bucket,  which is the permitted average rate of traffic. It 
is usually set to the committed information rate (CIR). 
•   Burst size or the capacity of the token bucket. It is the maximum traffic size permitted in each burst. 
It is usually set to the committed burst size (CBS). The set burst size must be greater than the 
maximum packet size. 
Ea c h  a r r i vi n g  p a c ke t  i s  e v a l u a t e d.  I n  e a c h  e v a l u a t i o n,  i f  t h e  n u m b e r  o f  t o ke n s  i n  t h e  b u c ke t  i s  e n o u g h,  t h e  
traffic conforms to the specification and the tokens  for forwarding the packet are taken away; if the 
number of tokens in the bucket is not enough, the traffic is excessive.
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Complicated evaluation 
You can set two token buckets, bucket C and bucket E, to evaluate traffic in a more complicated 
environment and achieve more policing flexibility.  For example, traffic policing uses the following 
parameters: 
•   CIR—Rate at which tokens are put into bucket C.  It sets the average packet transmission or 
forwarding rate allowed by bucket C. 
•   CBS—Size of bucket C, which specifies the transient burst of traffic that bucket C can forward. 
•   Peak information rate (PIR) —Rate at which tokens are put into bu cket E, which specifies the average 
packet transmission or forwarding rate allowed by bucket E. 
•   Excess burst size (EBS)—Size of bucket E, which specifies the transient burst of traffic that bucket E 
can forward. 
CBS is implemented with bucket C, and EBS with bucket E. In each evaluation, packets are measured 
against the following bucket scenarios: 
•   If bucket C has enough tokens, packets are colored green. 
•   If bucket C does not have enough tokens but bucket E has enough tokens, packets are colored 
yellow. 
•   If neither bucket C nor bucket E has sufficient tokens, packets are colored red. 
Traffic policing  
 IMPORTANT: 
The 5500 EI switch supports policing the inbound 
traffic and the outbound traffic, and the 5500 SI 
supports policing only the incoming traffic.  
 
A typical application of traffic policing is to supervise the specification of certain traffic entering a 
network and limit it within a reasonable range, or to  discipline the extra traffic to prevent aggressive 
use of network resources by a certain application. For example, you can limit bandwidth for HTTP 
packets to less than 50% of the total. If the traffic of  a certain session exceeds the limit, traffic policing can 
drop the packets or reset the IP precedence of the packets.  Figure 9 sho
 ws an example of policing 
outbound traffic on an interface.
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Figure 9 Traffic policing 
 
 
Traffic policing is widely used in policing traffic entering the networks of internet service providers (ISPs). 
It can classify the policed traffic and take pre-defined policing actions on each packet depending on the 
evaluation result: 
•  Forwarding the packet if the evaluation result is conforming 
•   Dropping the packet if the evaluation result is excess 
•   Forwarding the packet with its precedence, which can be 802.1p priority (available only for green 
packets), DSCP, and local precedence, re-marked if the evaluation result is conforming 
Traffic shaping  
 IMPORTANT: 
Traffic shaping shapes the outbound traffic. 
 
Traffic shaping limits the outbound traffic rate by buffering exceeding traffic. You can use traffic shaping 
to adapt the traffic output rate on a device to the input traffic rate of its connected device to avoid packet 
loss.  
The difference between traffic polici
ng and GTS is that packets to be dropped with traffic policing are 
retained in a buffer or queue with GTS, as shown in  Figure 10. W
 hen enough tokens are in the token 
bucket, the buffered packets are sent at an even rate. Traffic shaping can result in additional delay and 
traffic policing does not.
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