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New Member

WAAS reporting PT Asymmetric on the Core End

Hi,

I have a working WAAS setup between remote site the central / core site. Its accelerating well as configured except for servers on the Central site that use HSRP  and send the reply traffic towards their default gateway (Gateway2) while the request would have arrived via the other HSRP gateway (Gateway1). The WAE device is hanging off Gateway1 and uses WCCP. Here is how it draws out.

Traffic path for request:

Client----(WAN)---Gateway1----WAE----Gateway1-------Server

Traffic path for reply:

Server---Gateway2---Gateway1---WAE---Gateway1----(WAN)----Client

The WAE reports (show stat conn) that the traffic path is asymmetric and doesn't do any acceleration on the traffic. The WAE in this case is just a Cisco 2911 router with SRE-710 running WAAS image.

Thanks,

Rick.

5 REPLIES
New Member

Re: WAAS reporting PT Asymmetric on the Core End

Can anyone please tell if this is expected. Simply, if a WCCP router sends traffic out on the LAN side using one interface but received it from the LAN through another interface, Is it considered asymetric from the perspective of WAAS device which directly and only connects to the WCCP router ?

                WAN

                 |

WAAS-------WCCP-Router <--------------VLAN2----Router2

                 |                                                                 |

                VLAN1------------------>Server----------->VLAN1

Please note that VLAN1 is defined on both the routers. The "Server" has default gateway set to the HSRP address that is active on Router2. Return traffic from server has to hit Router2 first and then routed to WCCP-Router which will forward it to the WAAS using wccp.

Thanks,

Rick.

Cisco Employee

Re: WAAS reporting PT Asymmetric on the Core End

Not Really, All waas want to see is a complete TCP flow. So if SYN go via VLAN2 and SYN-ACK came back via VLAN1, and for example WAN interface has both 61/62 redirect applied as IN/OUT. then WAAS will indeed see complete TCP handshake.

The most common issue could be here as how server would behave since this is not an optimal design / recommendation.

Ahsan

New Member

Re: WAAS reporting PT Asymmetric on the Core End

Thanks Ahsan,

I was expecting the same that the complet SYN and SYN+ACK flow through the WAAS box would make it happy with the connection. Another server which has HSRP gateway set to WCCP-Router itsself has got no issues accelerating traffic.

                WAN

                 |

WAAS-------WCCP-Router <-----------------   VLAN1

                 |                                            |

                VLAN1------------------>Server2-------

The server in question would see the Source MAC in the request packet from WCCP-Router but it will send the reply packet towards Router2's MAC address as the destination, as it is its default gateway.

Thanks,

Rick.

Cisco Employee

Re: WAAS reporting PT Asymmetric on the Core End

In this case both routers needs WCCP enable, and an egress method needs to be define on waas. so

A: We can still see complete flow.

B: WAAS would send the traffic back to the router it came from and will not follow default GW.

If this is true and you still see an issue, then we may need further investigation using a TAC case. Thanks.

Ahsan

New Member

Re: WAAS reporting PT Asymmetric on the Core End

Thanks Ahsan,

I have opened a TAC case on this.

Regards,

Rick.

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