How “Router Affinity” is affecting the communication initiated from Proxy

Products

• ProxySG Software - SGOS

Issue/Introduction

Definition for "Router Affinity"

By default, the ProxySG uses the configured return method to return bypassed traffic to the router that redirected it and uses regular routing table lookups to determine the next hop for intercepted traffic. With router affinity, the ProxySG also uses the configured return method to return intercepted client- and/or server-bound traffic to the WCCP router that redirected it, bypassing the routing table lookup.

Note: Router Affinity option is available from SGOS 5.5.x

Router Affinity OFF

• Bypassed Traffic – Will use the same method by which it came in. i.e. Return traffic will still be using GRE/L2.
• Intercepted Traffic – Will use route lookup and pass the traffic based on that. This includes the requests to OCS and response to client.

Router Affinity ON

• Bypassed Traffic – Will use the same method by which it came in. i.e. Return traffic will still be using GRE/L2.
• Intercepted Traffic – Will use the same method by which it came in (GRE/L2). This includes the requests to OCS and response to client.

    Going a bit deeper into packet level, the intercepted communication will be seen as below

Client Request – 1 to 5
OCS Request & Response – 6 to 12
Client Response – 13 to 14
   
Router Affinity OFF

1)    Router to Proxy:    SYN (GRE)
2)    Proxy to Router:    SYN,ACK (No GRE)
3)    Router to Proxy:    ACK (GRE)
4)    Router to Proxy:    GET /index.html (GRE) <--------- Request from Client
5)    Proxy to Router:    ACK (No GRE)

6)    Proxy to Router:    SYN (No GRE)
7)    Route to Proxy:        SYN,ACK (GRE)
8)    Proxy to Router:    ACK (No GRE)
9)    Proxy to Router:    GET /index.html (No GRE) <------Request to OCS
10)    Router to Proxy:    ACK (GRE)
11)    Router to Proxy:    200 OK (GRE) <--------- Response from OCS
12)    Proxy to Router:    ACK (No GRE)

13)    Proxy to Router:    200 OK (No GRE) <--------- Response to Client
14)    Router to Proxy:    ACK (GRE)

   

Router Affinity ON (Server)

1)    Router to Proxy:    SYN (GRE)
2)    Proxy to Router:    SYN,ACK (No GRE)
3)    Router to Proxy:    ACK (GRE)
4)    Router to Proxy:    GET /index.html (GRE) <--------- Request from Client
5)    Proxy to Router:    ACK (No GRE)

6)    Proxy to Router:    SYN (GRE)
7)    Route to Proxy:        SYN,ACK (GRE)
8)    Proxy to Router:    ACK (GRE)
9)    Proxy to Router:    GET /index.html (GRE) <------Request to OCS
10)    Router to Proxy:    ACK (GRE)
11)    Router to Proxy:    200 OK (GRE) <--------- Response from OCS
12)    Proxy to Router:    ACK (GRE)

13)    Proxy to Router:    200 OK (No GRE) <--------- Response to Client
14)    Router to Proxy:    ACK (GRE)
 

Router Affinity ON (Client)

1)    Router to Proxy:    SYN (GRE)
2)    Proxy to Router:    SYN,ACK (GRE)
3)    Router to Proxy:    ACK (GRE)
4)    Router to Proxy:    GET /index.html (GRE) <--------- Request from Client
5)    Proxy to Router:    ACK (GRE)

6)    Proxy to Router:    SYN (No GRE)
7)    Route to Proxy:        SYN,ACK (GRE)
8)    Proxy to Router:    ACK (No GRE)
9)    Proxy to Router:    GET /index.html (No GRE) <------Request to OCS
10)    Router to Proxy:    ACK (GRE)
11)    Router to Proxy:    200 OK (GRE) <--------- Response from OCS
12)    Proxy to Router:    ACK (No GRE)

13)    Proxy to Router:    200 OK (GRE) <--------- Response to Client
14)    Router to Proxy:    ACK (GRE)
 

Router Affinity ON (Both)

1)    Router to Proxy:    SYN (GRE)
2)    Proxy to Router:    SYN,ACK (GRE)
3)    Router to Proxy:    ACK (GRE)
4)    Router to Proxy:    GET /index.html (GRE) <--------- Request from Client
5)    Proxy to Router:    ACK (GRE)

6)    Proxy to Router:    SYN (GRE)
7)    Route to Proxy:        SYN,ACK (GRE)
8)    Proxy to Router:    ACK (GRE)
9)    Proxy to Router:    GET /index.html (GRE) <------Request to OCS
10)    Router to Proxy:    ACK (GRE)
11)    Router to Proxy:    200 OK (GRE) <--------- Response from OCS
12)    Proxy to Router:    ACK (GRE)

13)    Proxy to Router:    200 OK (GRE) <--------- Response to Client
14)    Router to Proxy:    ACK (GRE)