[j-nsp] M20 packet marking for IPv6 and IPv4

[Gary Tate]

The subject is very broad and not easily explained.  The short 
answer to you direct question is that packets can be classified as 
they enter a router into a forwarding class by various methods. 
This marks the packet to be placed into a Queue on the outgoing 
interface.  When the packet leaves the router the DSCP (or EXP etc) 
bits are re-written depending on the re-write rules.  There are a 
set of default re-write rules already activated which you can see 
using the command:

'show class-of-service rewrite-rule'

This is the general mechanism but the subject is very broad and not 
easily explained in one e-mail.

Let me give you some pointers and some links to other documentation.

Some examples:

If you wish to change the DSCP bits of packets that enter the router 
with more granularity then you need to apply a filter or classifier 
on the input interface.

You can match on most of the IPv4 and IPv6 header and mark the DSCP 
bits accordingly.

Here is a simple filter example:

filter test {
     term a {
         from {
             protocol ipv4;
         }
         then {
             forwarding-class assured-forwarding;
             accept;
         }
     }
     term b {
         from {
             protocol ipv6;
         }
         then {
             forwarding-class best-effort;
             accept;
         }
     }
}

Here is an example of classifying a whole logical unit to a 
forwarding class:

set class-of-service interfaces ge-0/0/0 unit 1 forwarding-class 
expedited-forwarding

Interface configuration:
http://www.juniper.net/techpubs/software/junos/junos62/swconfig62-interfaces/html/
CoS overview:
http://www.juniper.net/techpubs/software/junos/junos62/swconfig62-interfaces/html/interfaces-cos-overview.html#1015298
CoS configuration:
http://www.juniper.net/techpubs/software/junos/junos62/swconfig62-interfaces/html/statement-hierarchy-interfaces.html#1013885

Here is a link on configuring firewalls:
http://www.juniper.net/techpubs/software/junos/junos62/swconfig62-policy/download/firewall-config.pdf

I hope this helps
Gary

Dragan Mickovic wrote:
> Not much expirience with this topic, but I think the following will give you
> some idea:
> 
> http://www.juniper.net/techpubs/software/junos/junos62/swconfig62-interfaces/html/statement-hierarchy-interfaces2.html#1013915
> 
> micko
> 
> On Thu, Feb 12, 2004 at 03:53:47PM -0300, Giuliano Cardozo Medalha wrote:
> 
>>Hi,
>>
>>We need help about juniper M20 routers.
>>
>>With a router with a Gigabit Ethernet IQ interface and POS STM-1 for WAN 
>>conection,
>>how is possible to mark packets IPv4 and IPv6 with DSCP field ?
>>
>>What command should be used to mark IP packets on M20 router .... junos 
>>6.2 ?
>>
>>Thanks a lot
>>
>>Giuliano
> 
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