ds2exp; a possible mapping [was Re: [mpls-linux-general] Re: MPLS-Diffserv Instructions + Counters]

[<pim...@in...>]

> This is due to the value you assigned to the mask used by ds2exp (0xf). The role of the mask is the following: a 64-sized array is used to maintain ds-exp couples; the exp value is stored in the element of index ds & mask. When a packet must be sent, its DSCP is ANDed with mask and the result is the index of the element which contain the EXP to set.

here what I plan to use in the next RSVP-TE release:

ds2exp:0x38:0xa:1:0x12:2:0x1a:3:0x22:4:0x2e:5

This maps:
AF1x -> 1
AF2x -> 2
AF3x -> 3
AF4x -> 4
EF -> 5

with:
(this code is GPL'ed ;)
// DSCPstring -> DSCPnum
struct  {char a[4]; uint8_t b;}  dscpe [] = { 
  {"BE",     0 },
  {"AF11",   0x0a},
  {"AF12",   0x0c},
  {"AF13",   0x0e},
  {"AF21",   0x12}, 
  {"AF22",   0x14}, 
  {"AF23",   0x16}, 
  {"AF31",   0x1a},
  {"AF32",   0x1c},
  {"AF33",   0x1e},
  {"AF41",   0x22}, 
  {"AF42",   0x24}, 
  {"AF43",   0x26}, 
  {"EF",     0x2e}};

Any comments or thoughts on this mapping?

Pim.

> This means that in your examples also packets with DSCP of 0x1e, 0x3e, 0x4e... will be marked with an EXP of 0x06.
> If you don't want this, use a mask of 0x3f (the maximum allowed)
> 
> > I think in my last mail, I mentioned this occurred with the exp2ds, my
> > mistake... it is for ds2exp as shown above.
> >
> > A3) "mpls_in" for origin edge MPLS router.
> >
> > --------------START-----------------------------------------
> >
> > 0x40031c00 70/6952/0 gen 199 0 1 POP EXP2DS( EXP(2)->DS(1a) ) PEEK
> >
> > --------------END--------------------------------------------
> >
> > B1) Script for edge MPLS router at other end.
> >
> > --------------SCRIPT STARTS-----------------------------------------
> >
> > #!/bin/sh
> > # Mplsadm path
> > MPLSADM=/usr/src/SW/mpls-beta-1_128/mpls-linux-1128/utils/mplsadm2
> > $MPLSADM -d
> > $MPLSADM -v -L eth1:0
> > $MPLSADM -v -A -I gen:199:0
> > $MPLSADM -v -A -O gen:19:eth1:ipv4:192.168.0.129
> > OUT_KEY_19=$(grep 'gen 19' /proc/net/mpls_out | cut -c3-10)
> > $MPLSADM -v -O key:$OUT_KEY_19 -o
> > set_exp:2:push:gen:19:set:eth1:ipv4:192.168.0.129
> > iptables -A OUTPUT -d 192.168.0.168/29 -j MPLS --set-key $OUT_KEY_19
> > iptables -A FORWARD -d 192.168.0.168/29 -j MPLS --set-key $OUT_KEY_19
> > $MPLSADM -d
> >
> >
> > --------------SCRIPT ENDS--------------------------------------------
> >
> > The above marks outgoing packets with EXP of 2.
> >
> > Thus from the above script A1), the origin edge router when receiving a
> > incoming packet with EXP 2 from router which has ran script B1), it should
> > mark the DSCP of the packet to 0x1a before forwarding it, right? But, it
> > doesn't, it always marks it to a value of 0x3e, and I am unsure why...
> >
> 
> Are you sure that at the origin edge router packets arrive with EXP 2 ?
> Since I have some doubt that set_exp works correctly, could you try an equivalent instruction (e.g. ds2exp) ?
> If this test works, problems are due to set_exp...
> 
> Let me know,
> Stefano
> 
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-- 
Pim Van Heuven            Ghent University - IMEC
Department  of  Information  Technology   (INTEC)
Sint-Pietersnieuwstraat, 41 B-9000, Gent, Belgium
pim...@in...
        DiffServ/MPLS(RSVP-TE) for Linux:
        http://dsmpls.atlantis.rug.ac.be