How we can set a load balance or load sharing over WAE cluster

gbruque99 · ‎11-25-2009

Hi, At this time we have a cluster with two WAEs 7341 ( 4 HDD with 300GB each) connected to a Cisco 7609 router, they are communicating using layer 2 for redirect and return packets between them, the WAEs are caching HTTP, DNS, HTTP and FTP-NATIVE, we think in an acceptable perfomance, but we see more load over WAE1 than WAE2. The WAEs have the same configuration, by this behavior the diskS usage from WAE 1 is dramatically highest versus disks usage WAE 2, the traffic amount handled by wae cluster is in average 700Mbits in rush hours.

We are trying to find a way/configuration to achieve a better load balance/sharing like 50/50 for both WAEs. This is our current problem. Thanks for the help you can brings us.

CONTENT ENGINE WAE 1 & WAE 2

wccp router-list 1 5.5.5.5

wccp port-list 1 80
wccp web-cache router-list-num 1 weight 50   l2-redirect   mask-assign assign-method-strict l2-return
wccp dns router-list-num 1 weight 50   l2-redirect    mask-assign assign-method-strict l2-return
wccp ftp-native router-list-num 1 l2-redirect   mask-assign   assign-method-strict l2-return
wccp https-cache accept-all
wccp version 2

cfolkerts · ‎12-01-2009

It appears that you are using the default mask-assign value of 0x1741. Using the default value will sometimes create a situation where one WAE will be more utilized than the other. You can change the mask-assign value depending on your internal IP addressing scheme which will yield a better ratio of utilization. Below is some information regarding mask-assign values. It was taken from the following link.

http://www.cisco.com/en/US/docs/solutions/Enterprise/Data_Center/WAASDC11.html#wp44443

Masking

Mask assignment can further enhance the performance of L2 redirection. The ternary content addressable memory (TCAM) can be programmed with a combined mask assignment table and redirect list. All redirected packets are switched in hardware, potentially at line rate. The current Catalyst platform supports a 7-bit mask, with default mask of 0x1741 on the source IP address. Fine tuning of the mask can yield better traffic distribution to the WAEs. For example, if a network uses only 191.x.x.x address space, the most significant bit can be re-used on the last 3 octets, such as 0x0751, because the leading octet (191) is always the same.

The following examples show output from show ip wccp 61 detail with a mask of 0x7. Notice that four WAEs are equally distributed from address 0 to 7.

wccp tcp-promiscuous mask src-ip-mask 0x0 dst-ip-mask 0x7

        Value SrcAddr    DstAddr    SrcPort DstPort CE-IP

        ----- -------    -------    ------- ------- -----

        0000: 0x00000000 0x00000000 0x0000  0x0000  0x0C141D05 (12.20.29.5)

        0001: 0x00000000 0x00000001 0x0000  0x0000  0x0C141D05 (12.20.29.5)

        0002: 0x00000000 0x00000002 0x0000  0x0000  0x0C141D06 (12.20.29.6)

        0003: 0x00000000 0x00000003 0x0000  0x0000  0x0C141D06 (12.20.29.6)

        0004: 0x00000000 0x00000004 0x0000  0x0000  0x0C141D08 (12.20.29.8)

        0005: 0x00000000 0x00000005 0x0000  0x0000  0x0C141D08 (12.20.29.8)

        0006: 0x00000000 0x00000006 0x0000  0x0000  0x0C141D07 (12.20.29.7)

        0007: 0x00000000 0x00000007 0x0000  0x0000  0x0C141D07 (12.20.29.7)

Regards