Cisco WAAS (Basic concepts)

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WAAS is a symmetric solution requiring a WAAS component on both sides of the conversation. Peer-to-peer. WAN traffic between WAAS components is highly optimized while still visible to QoS/Management applications

WAAS devices auto-discover each other without any user intervention allowing optimization not only to the data center but between WAAS enabled branches

The WAAS administrator can classify which WAN traffic should be optimized based on criteria such as protocol (port number), source and/or destination IP address and/or network. 

WAAS Overview Application Acceleration Transparency

Packet network transparency (L3/L4 headers) allows application acceleration components to maintain compliance with existing network features

•WAAS Overview TFO Auto-Discovery – TCP SYN

•When the client sends a TCP-SYN packet, WAE1 will apply TCP options to identify itself and specify the optimizations that it would like to apply

•The modified TCP-SYN packet is then forwarded to the server, and intercepted on the other side 

•WAAS Overview TFO Auto-Discovery – TCP SYN (Cont.)

•Once WAE2 receives the TCP-SYN packet with the options marked, it then knows WAE1’s details and desire to optimize this connection

•The TCP-SYN packet is then forwarded to the server 

•WAAS Overview TFO Auto-Discovery – TCP SYN-ACK

•When the server responds with the TCP SYN-ACK, WAE2 then marks TCP options to acknowledge optimization and to identify itself to WAE1

The marked TCP SYN-ACK packet is then forwarded towards the client and intercepted on the other side

•WAAS Overview TFO Auto-Discovery – TCP SYN-ACK (Cont.)

•When WAE1 receives the TCP SYN-ACK with the optimization confirmation and details about WAE2, the defined policy (or negotiated optimizations) can then be acknowledged

•The TCP SYN-ACK packet is then forwarded to the client 

•WAAS Overview TFO Auto-Discovery – TCP ACK

•After the SYN-ACK is received, the TCP proxy is initiated for the connection, and WAE1 sends a TCP ACK to WAE2 to acknowledge optimizations

•WAE2 can then send a TCP ACK to Server B

Client A sends a TCP ACK to WAE1