The document discusses various techniques for global server load balancing (GSLB) including DNS-based methods, host route injection (HRI), and a new proposed technique called virtual block injection (VBI). It outlines the requirements for internet data centers (IDCs), describes existing GSLB methods and their pros and cons, and analyzes the potential benefits and limitations of VBI which aims to simplify routing changes compared to other methods. The document also considers factors that determine the applicability of different GSLB solutions depending on network topology and control.

1. Global Server Load Balancing Dima Krioukov [dima@nortelnetworks.com] Alex Kit [akit@winstar.com] October 24, 2000

6. Hosting Infrastructure Web User Content Owner IDC Owner ISP OSS

7. ASP Infrastructure End Customer ASP Applications Operations ISP/Backbone Access IDC

8. IDC IDC Core (Routing) Distribution (L3 Switching) Tier Tier Tier LB Tier Load Balancing (L4 Switching) Port Density (L2 Switching) Servers SAN

12. LSNAT Router LB S1 S2 S3 X Y src/ dst Layer Ingress Client_Port S1_Port dst Client_IP S1_IP dst LB_MAC S1_MAC dst Client_Port Virtual_Port dst Client_IP Virtual_IP dst dst Router_MAC Virtual_MAC Client_Port Client_IP LB_MAC Client_Port Client_IP Router_MAC S1_IP src L3 src src src src src Virtual_IP L3 S1_Port L4 Virtual_Port L4 S1_MAC L2 Y Virtual_MAC L2 X Egress Segment

13. LSNAT + Source NAT Router LB S1 S2 S3 X Y src/ dst Layer Ingress LB_V_Port S1_Port dst LB_V_IP S1_IP dst LB_V_MAC S1_MAC dst Client_Port Virtual_Port dst Client_IP Virtual_IP dst dst Router_MAC Virtual_MAC LB_V_Port LB_V_IP LB_V_MAC Client_Port Client_IP Router_MAC S1_IP src L3 src src src src src Virtual_IP L3 S1_Port L4 Virtual_Port L4 S1_MAC L2 Y Virtual_MAC L2 X Egress Segment

14. DSR Router LB S1 S2 S3 1 2 3 Virtual_Port Client_Port Virtual_IP Client_IP S1_MAC Virtual_MAC 2 Client_Port Virtual_Port Client_IP Virtual_IP Router_MAC S1_MAC 3 src/ dst Layer 1 Virtual_Port dst Virtual_IP dst dst Virtual_MAC Client_Port Client_IP Router_MAC src src src L3 L4 L2

15. Tunneling Router LB S1 S2 S3 1 2 3 Int: V_IP Int: C_IP V_Port C_Port Ext: S1_IP Ext: LB_IP S1_MAC LB_MAC 2 C_Port V_Port C_IP V_IP R_MAC S1_MAC 3 src/ dst Layer 1 V_Port dst V_IP dst dst V_MAC C_Port C_IP R_MAC src src src L3 L4 L2

21. How it works IDC1 IDC2 LB IDC3 LB Customer LDNS ADNS Client RDNS 1 2 3 4 5 5 6 6 6

22. How it works IDC1 IDC2 LB IDC3 LB Customer LDNS ADNS Client RDNS 7 7 8 10 11 9

32. NAT Based Client IDC1, “ wrong” V1.1; V1.2 IDC2, “ right” V2.1; V2.2 3 2 1 1 V1.1 C C V2.2 dst V1.1 C src L3 3 2

33. “Remote Servers” Client IDC1, “ wrong” V1.1 IDC2, “ right” V2.1 2 1 C V1.1 4 1 V1.1 C V1.1 V2.1 dst V2.1 V1.1 src L3 3 2 3 4

38. Internet Infiltrations IDC2 LB IDC1 LB Customer LB LB LB Client LB LB LB

39. Internet Infiltrations IDC2 LB IDC1 LB Customer LB LB LB Client LB LB

40. LDNS modifications in CDNs IDC2 LB IDC1 LB Customer LDNS Client ASP Backbone

42. How it works AS1 AS2 V/20, AS3 V/20, AS3 Client ISP1 ISP2 IDC1, R1/20 IDC2, R2/20

43. How it works AS1 AS2 V/20, AS3 Client ISP1 ISP2 IDC1, R1/20 IDC2, R2/20

44. How it works AS1 AS2 V/20, AS3 V/20, AS3 Client ISP1 ISP2 IDC1, R1/20 IDC2, R2/20

46. Test Network

48. Route Flapping AS1 AS2 V/20, AS3 V/20, AS3 Client Router ISP1 ISP2 IDC1, R1/20 IDC2, R2/20 UDP TCP