[j-nsp] M7i qos question.

Harry Reynolds harry at juniper.net
Wed Sep 6 10:59:13 EDT 2006


If you want all egress traffic to bear the same tos marking then it
seems you could just apply a custom rewrite rule to the desired egress
interface to maps all traffic classes (only two will be defined by
default) to the desired rewrite pattern. I would be concerned that the
resulting homogeny may lead to stability issues should network control
get trashed when users are active, and highly recommend that you *not*
remark the NC traffic in queue 3. This would yield two or three possible
markings for traffic leaving the desired egress interfaces; bearer
traffic and NC with optional low/high drop probability marking.

This approach does not require any input firewall filters for MF
classification, but assumes ingress NC is marked in accordance with the
input classifier. You need to ensure that a compatible input classifier
is in effect on all ingress interfaces, especially if you are trying to
preserve NC as a separate FC. If not mistaken the default classifier is
for IP precedence with ieee802 bits ignored. To support ieee802 or dscp
marking I believe you will need to apply a default ieee/dscp classifier
to all ingress interfaces as well.

Something like this for ieee:


[edit]
harry at vpn03# show class-of-service 
interfaces {
    fe-1/1/3 {
        unit 0 {
            rewrite-rules {
                ieee-802.1 test; <<< for all (ethernet) egress
interfaces
            }
        }
    }
    fe-1/1/1 {
        unit 0 {
            classifiers {
                ieee-802.1 default; <<< for all (ethernet) ingress
interfaces
            }
        }
    }
}
rewrite-rules {
    ieee-802.1 test {
        forwarding-class assured-forwarding {
            loss-priority low code-point 011;
            loss-priority high code-point 011;
        }
        forwarding-class best-effort {
            loss-priority low code-point 011;
            loss-priority high code-point 011;
        }
        forwarding-class expedited-forwarding {
            loss-priority low code-point 011;
            loss-priority high code-point 011;
        }
        forwarding-class network-control {
            loss-priority low code-point 110;
            loss-priority high code-point 111;
        }
    }
}


HTHs

 

> -----Original Message-----
> From: juniper-nsp-bounces at puck.nether.net 
> [mailto:juniper-nsp-bounces at puck.nether.net] On Behalf Of 
> Szilard Matyas
> Sent: Wednesday, September 06, 2006 5:43 AM
> To: juniper-nsp at puck.nether.net
> Subject: [j-nsp] M7i qos question.
> 
> Hi all, 
>    
>   I would like to set the dscp or ieee802.1 cos for all 
> packets that leave an interface. 
>   In the documentation I have seen that packet rewrite has 
> been  based on forwarding classes. I think it is bit complex 
> solution for our simple issue.
>   Because I have to create a firewall policy matching packets 
> based on some criteria, have to assign these packets to a 
> forwarding class.  Then I have to apply this policy to any 
> input interface(vlan), because packets could come from many 
> sources, and I have to make the rewrite rule based on 
> forwarding classes.
>   Could somebody know a simple solution to rewrite every 
> packet the leave an interface with a dscp or cos value ?
>    
>   Regards, 
>    
>   szicsu
>    
> 
>  		
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