Configuring DSCP on SPARC Enterprise(XSCF)

Configuring DSCP

The Sun SPARC Enterprise Server Administration Guide explains how to set up DSCP, but it is really quite simple. The easiest method is using the syntax:

    setdscp -i NETWORK -m NETMASK 

Choose a network address (be sure to pick a subnet that is not in use at your facility) and the corresponding netmask, and setdscp will do the rest. For example, in my lab the subnet 192.168.244.0 is unused, so I do:

    XSCF> setdscp -i 192.168.224.0 -m 255.255.255.0 

There are other ways to set up the DSCP network addresses, but this is really the best approach.

setdscp will assign an IP address to the SP, and reserve one IP address for every possible domain (the M9000-64 supports 24 domains, so a maximum of 25 IP addresses are reserved). A common question that's asked is, if you're running PPP between the SP and each domain, don't you need to two addresses for each domain, one for the domain and one for the SP? No, not really. Since routing is done based on the destination address, we can get away with using the same IP address for the SP on every PPP link. So technically speaking, the NETWORK and NETMASK are not defining a DSCP subnet; they are defining a range of IP addresses from which DSCP selects endpoint addresses. A subtle difference, but still a difference.

On the SP, showdscp will display the IP addresses assigned to each domain and the SP, for example:

    XSCF> showdscp      DSCP Configuration:      Network: 192.168.224.0     Netmask: 255.255.255.0       Location     Address     ----------   ---------     XSCF         192.168.224.1     Domain #00   192.168.224.2     Domain #01   192.168.224.3     Domain #02   192.168.224.4     Domain #03   192.168.224.5 

In Solaris, the prtdscp(1M) command will display the IP address of that domain and the SP (prtdscp is located in /usr/platform/SUNW,SPARC-Enterprise/sbin). You can get the same basic information from ifconfig sppp0:

    % /usr/platform/SUNW,SPARC-Enterprise/sbin/prtdscp     Domain Address: 192.168.224.2     SP Address: 192.168.224.1      % ifconfig sppp0     sppp0: flags=10010008d1 mtu 1500 index 3             inet 192.168.224.2 --> 192.168.224.1 netmask ffffff00