Alcatel-Lucent omnistack 6300 Guía Del Usuario

 
Also, the switch will automatically set the 802.1p value with the “default priority” if the packet has to go out on a 
tagged interface. (The egress interface has to insert a VLAN header in the packet)  
 
All incoming untagged packets are prioritized based on the interface default priority. 
These packets will have their 802.1p value set with the default priority value when exiting the switch 
 
By default, the default 802.1p is 0  

♦  Incoming untagged packets will be queued to priority queue 2  (see CoS/queue table) 

♦  When exiting the switch, these packets will have their 802.1p set to 0 on the VLAN header 
 
When setting  “Console(config-if)# switchport priority default 7” on an interface 

♦  Incoming untagged packets will be queued to priority queue 7  (see CoS/queue table) 

♦  When exiting the switch, these packets will have their 802.1p set to 7 on the VLAN header 

When “map ip precedence” or “map ip dscp” or ACL-CoS are configured, the switch does not use the interface 
default priority to queue the incoming untagged packets but “ip precedence”, “ip dscp” or ACL that matches the 
packets to determine to priority queue. 
(See next chapters) 

These switches also support a port default priority for untagged packets. 
However, there will be an incompatibility for the default priority 0 1 and 2 since they are not mapped to the same 
priority queues. 
Default priority 0 is the lowest priority whereas on OmniStack 6300-24, default priority is priority 2. 
 

As explained before, the switch always maps a CoS to an egress priority queue. 
The switch never directly maps an 802.1p value (or ToS/Dscp), or an interface default priority to a queue. 
It first links the 802.1p (or ToS/Dscp) or the default interface priority to a CoS value and then maps that CoS 
value to the egress priority queue. 
You can change the CoS/Queue table to force some CoS values to be mapped to some specific queues. 
That will not modify the packets, it just modifies the queuing of the packets. 
 
The table is set for the entire switch. 
 
Ex: To map CoS 1 to priority queue 5 
Console(config-if)# queue cos-map 5  1 
 

Priority Queue 

2 

1 3 4 5 6 7 

CoS value 

0 

2 3 4 5 6 7 

 
Also, you can map all CoS values to the same queue.  
That will give the same priority for all packets. 
To set priority 0 for all CoS you will use the command: 
Console(config-if)# queue cos-map 0 0 1 2 3 4 5 6 7 
 

Priority 

Queue 

0 0 0 0 0 0 0 0 

CoS 

value 

0 1 2 3 4 5 6 7 

 

CLI requires going to the interface command mode to change the table, even if the table is not interface-related. 

There is no CoS/queue concept. However, they do support the same idea with the “mapping” policies. 
You can configure some policies to map an 802.1p/TOS/DSCP to another 802.1p/TOS/DSCP, using the map 
groups. 
That will change both priority queue and the 802.1p/TOS/DSCP value inside the packet.