The PHB information treatment in the Differentiated Service network

1. The PHB information treatment in the Differentiated Service network Seiichiro Toda Graduate School of Media and Governance Keio University kiri@ht.sfc.keio.ac.jp

2. Summary • Inter-domain usage of DiffServ architecture • SLA (Service Level Agreement) is transmitted between BB(Bandwidth Broker)s • Local allocation of DSCP(DiffServ Code Point) value is done by Local BB

3. Keywords of DiffServ architecture • DS Domain • DS boundary node (Edge router) • DS interior node (Core router) • BB(Bandwidth Broker) • DSCP(DS CodePoint) • PHB(Per Hop Behavior) • SLA(Service Level Agreement)

4. DSCP value for this flow is “X”. DSCP value “X” rewrite to “Y”. BB C Forward message by PHB “DSCP:Y”. C S C C C R Forward message by PHB “DSCP:X”. BB C SLA: Value “X” in the domain A should be “Y” in the domain B DS domain A DS domain B E : Core router :Edge router :DS domain C : Sender : Receiver : Bandwidth Broker S R BB DiffServ architecture E

5. PHB information and SLA • PHB is decided by BB administrator • PHB information is different in every DS domain • PHB information is exchanged between the DS domains as SLA(Service Level Agreement)

6. What is the problem of Inter-domain DS Architecture • SLA have to be exchanged between DS administrators • SLA can not be configured dynamically • exchaged via phone, e-mail, etc… • Cost for exchanging SLA in Inter-domain DS Architecture • Dynamic SLA configuration

7. PHB information and DSCP value in DS domain A PHB information in B Reserved information in domain B and C Reservation information in C A view of Dynamic SLA configuration BB-A BB-B BB-C C C S E E C C R C C C C C C DS domain A DS domain B DS domain C

8. Advantages of this architecture • Administrators do not need to configure each BB • scalability • BBs only need to communicate with neighbor DS domain BBs • BBs do not take care about per-flow information

9. Parameters • Parameters to exchange SLA information dynamically • DSCP value in each domain • PHB information • required bandwidth etc… • Time for the PHB to be available

10. Assumption • BB knows neighbor DS domain BBs • BB has bandwidth information about its managing domain • the solutions of these assumption are out of scope

11. Message exchange • Send parameters to BB within neighbor DS domain • Next BB assigns new DSCP value for received PHB information • Write about received information to PHB information table • Send new parameters to next DS domain

12. PHB information table contents • Maximum rate of bandwidth • DSCP value • DSCP value in neighbor DS domain • Assigned bandwidth information • Keep reservation time • Domain ID which use this DSCP value

13. DSCP :011000 require: 2M time:1200-2400 PHB information in B bandwidth(B):2M bandwidth(C):1.2M Reservation information in C lookup PHB information table and assign DSCP value/write this information PHB information table for A (Max bandwidth:5M) DSCP in A assigned domains DSCP in B time . . . . . . . . . . 2M 101000 011000 1200-2400 A,D . . . . . ex. Message exchange DS domain A DS domain B DS domain C BB-A BB-C BB-B

14. Assign new DSCP value • Define maximum bandwidth to allow reservation for each neighbor DS domain • When required bandwidth is more than maximum • Assign DSCP value with maximum allowed bandwidth • When required bandwidth is less than maximum • Assign DSCP value with required bandwidth

15. DSCP limitations • 6 bits DSCP field can express only 64 types of PHBs • Some request should aggregate • Complex PHB information is difficult to describe • When there are no more DSCP values… • Assign closest DSCP value in the PHB table • Stop exchanging PHB information

16. Static & Dynamic SLA • This architecture gives SLA with simple PHB information • Static SLA will be used when complex SLA is needed • Some DSCP values are used for static SLA

17. Refresh message • Routing information changes • Unused DSCP value prevent others from reserving new DSCP value • PHB information should be refreshed every keep-alive time • BBs can know the change of routing information

18. Security Issues • Security • IPsec • Integrity • something like RSVP integrity

19. Conclusion • The dynamic SLA configuration model is defined • By using this model, BB can exchange their own PHB information with neighbor BBs

20. Future schedule • Design PHB information table details • Add Integrity considerations to this model • Design protocol for inter-domain PHB configuration

21. APPENDIX

22. DiffServ • Distinguish packet from DSCP value • DS interior nodes decide packet forwarding priority only checking DSCP value • DS boundary nodes rewrite DSCP value for their own domain

23. DSCP (DS CodePoint) • The (IPv4 TOS / IPv6 Traffic Class) octet　→DS field • Six bits of the DS field are used as a codepoint 0 1 2 3 4 5 6 7 (bit) DSCP CU DSCP : differentiated services codepoint CU : currently unused

24. PHB (Per-Hop Behavior) • DSCP value decided by PHB • Consist of required bandwidth etc...

25. BB (Bandwidth Broker) • Management correlation between PHB information and DSCP information • Admission control • Compare flow information and PHB information