DSCP to MPLS EXp bit mapping how ???

hjerbandi · ‎12-23-2003

If Ip precedence is used, then mapping the same to exp bit is one-2-one. If DSCP is used, then how is the mapping done to exp bit which hs only 8 possible values and where as dscp can hv 64 possible vaues..

any ur/doc explaning thi mapping would be apperciated.

thx

hanu

Harold Ritter · ‎12-23-2003

No matter if you you DSCP or IP precedence, only the first 3 bits of the IP header TOS field are used since the exp bits field is 3 bit long.

The mapping from DSCP to MPLS exp bits is:

0-7 to 0

8-15 to 1

16-23 to 2

24-31 to 3

32-39 to 4

40-47 to 5

48-55 to 6

56-63 to 7

Hope this helps,

Harold Ritter
Sr Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
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hjerbandi · ‎12-23-2003

hi

thx for the explanation, i see the same mapping done in Ip solution centre also. Got confused with one of the rfc explaining about mpls and Diff serv :)

thx

hanu

startx001 · ‎07-06-2018

regarding this control plane packets ( cs6 and cs7 ) are they mapped to exp bits ? are this contol plane pakrets labeled ?