Re: [mpls-linux-general] MPLS and scheduling for QoS

[James R. L. <jl...@mi...>]

You can use the exp2tc instruction on the ILMs you create on E3 and E4.
Of course you will need to map the 'TC' to a queue.

On Tue, May 13, 2008 at 02:21:50PM +0200, luc...@li... wrote:
> Hi, 
> I'm testing MPLS with linux schedulers in order to do some reservation and shaping in case of congestion on the default routes.
> Now I'm working on a in-line testbed (just to get familiar with schedulers), belonging to the bigger one of MPLS Linux Lab examples by Irina Dumitrascu and Adrian Popa.
> It is like this:
> 
> A3----------E1----------E3----------E4----------A2
>            (LER)       (LSR)       (LER)
> 
> I've made the first tries with only one HTB scheduler on E1, sending 3 flows from A3 to A2 marked differently in the DSCP field.
> My configuration is the following:
> 
> 
> 
> key_1=`mpls nhlfe add key 0 instructions ds2exp 0xf 0x06 0x3 exp2tc 0x3 0x1 push gen 500 nexthop ath1 ipv4 10.0.5.3|grep key|cut -c 17-26`
> key_2=`mpls nhlfe add key 0 instructions ds2exp 0xf 0x07 0x6 exp2tc 0x6 0x2 push gen 500 nexthop ath1 ipv4 10.0.5.3|grep key|cut -c 17-26`
> key_3=`mpls nhlfe add key 0 instructions exp2tc 0x0 0x3 push gen 500 nexthop ath1 ipv4 10.0.5.3|grep key|cut -c 17-26`
> 
> 
> iptables -t mangle -A FORWARD -s 172.16.30.0/24 -m dscp --dscp 0x06 -j mpls --nhlfe $key_1
> 
> iptables -t mangle -A FORWARD -s 172.16.30.0/24 -m dscp --dscp 0x07 -j mpls --nhlfe $key_2
> 
> iptables -t mangle -A FORWARD -s 172.16.30.0/24 -m dscp --dscp 0x00 -j mpls --nhlfe $key_3
> 
> 
> ip route add 172.16.20.0/24 via 10.0.5.3 mpls $key_1
> ip route append 172.16.20.0/24 via 10.0.5.3 mpls $key_2
> 
> It seems to work fine.
> Now I want to use schedulers also in E3 and E4, but I wonder if I have to do all the matching from DSCP to EXP to TC, or if, after that matching on E1, the following routers can avoid doing that.
> The same question in about iptables and iproute, can I do only the MPLS XC and then enable qdiscs on E3 and E4?
> 
> My goal would be avoiding reading the IP header information (DSCP in this case) in the core of the network, I would like to exploit the information extracted at the ingress LER.
> I hope I have been clear.
> Thank you for help,
> Luca
> 
> 
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-- 
James R. Leu
jl...@mi...