Due to the number of ISPs that provide web hosting services to their customers, there is a need to support hundreds to thousands of virtual web sites on relatively few web servers. Virtual Web Hosting Applications extend past the ISP and into the market place. Some Web Vendors use Domain Names as search engines or to categorize the streaming media.
The basic concept is that the web-hoster has a few machines, typically from two to ten, that mirror the content. Each machine has hundreds to thousands of sites on it. The servers determine which site is requested based on the IP address, port, or Domain Name. When you try to load balance such a site, the load balancer must be able to configure with many services and virtual IP addresses or Domain Names.
Cisco has developed a solution for the need to provide this type of service. The Virtual Web Hosting Software allows the web hoster to configure a service with either a range of IP addresses or a range of ports. A content rule with either a range of VIPs or a list of Domain Names is configured to map to the servers. A content rule with a range or a list can map to a server without a range. This allows a many-to-one mapping.
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This document is not restricted to specific software and hardware versions.
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When you configure the VIP and service ranges, Cisco recommends that you stay within the subnet that you use. The CSS does not arp for IP addresses that are not on the subnet of the circuit.
For example, if you configure the circuit for 10.10.10.1/24 and configure the VIP range as 10.10.10.2 range 400, the CSS does not arp for any of the addresses beyond 10.10.10.254.
However, if you configure the circuit for 10.10.10.1/24 and configure the VIP range as 10.10.10.2 range 200, the CSS does arp for all addresses in the range.
For large VIP ranges, Cisco recommends that you have the upstream router advertise a route through the CSS to the VIP subnets in order to prevent arp storms and excessive failover times with redundancy.
This diagram provides an example:
Configure the CSS with four content rules, one for each VIP range, and four services for each server in order to prevent issues with network numbers and subnet broadcast numbers (0 and 255).
In order to prevent issues with arp storms, it is best to configure the upstream router to route all of the VIP addresses to the CSS. If you configure the VIP ranges on the same subnet as the circuit, the CSS does arp for them. Also, when you have a large number of VIPs, it takes a long period of time for redundancy to take effect.
The CSS can be configured to advertise the routes to the VIPs.
Note: You can only configure local services with ranges and add to content rules with ranges.
Configure the service.
config service web1 ip address 10.0.0.1 range 50 or port 40000 range 50 (the range can be from 2 to 65535) protocol tcp keepalive type http keepalive method get keepalive uri "/index.html" (the keepalive will be sent to the first IP or port in the range) active
Configure the rule with the use of a VIP range.
config owner virtual_sites content virtual_rule vip address 22.214.171.124 range 50 port 80 protocol tcp add service web1 add service web2 active
Note: Cisco does not recommend the configuration of more than 1,000 domain names.
config dql my_domains domain www.customer1.com index 1 description "aaa company" domain www.customer2.com index 2 domain www.customer3.com index 3 domain www.customer4.com index 4 domain www.customer5.com index 5 domain www.customer6.com index 6 domain www.customer7.com index 7 domain www.customer8.com index 8 domain www.customer9.com index 9 domain www.customer10.com index 10 domain www.customer11.com index 11 domain www.customer12.com index 12 domain www.customer13.com index 13 domain www.customer14.com index 14 domain www.customer15.com index 15 domain www.customer16.com index 16 domain www.customer17.com index 17 domain www.customer18.com index 18 domain www.customer19.com index 19 domain www.customer20.com index 20 domain www.customer21.com index 21 domain www.customer22.com index 22 domain www.customer23.com index 23 domain www.customer24.com index 24 domain www.customer25.com index 25 domain www.customer26.com index 26 domain www.customer27.com index 27 domain www.customer28.com index 28 domain www.customer29.com index 29 domain www.customer30.com index 30 domain www.customer31.com index 31 domain www.customer32.com index 32 domain www.customer33.com index 33 domain www.customer34.com index 34 domain www.customer35.com index 35 domain www.customer36.com index 36 domain www.customer37.com index 37 domain www.customer38.com index 38 domain www.customer39.com index 39 domain www.customer40.com index 40 domain www.customer41.com index 41 domain www.customer42.com index 42 domain www.customer43.com index 43 domain www.customer44.com index 44 domain www.customer45.com index 45 domain www.customer46.com index 46 domain www.customer47.com index 47 domain www.customer48.com index 48 domain www.customer49.com index 49 domain www.customer50.com index 50
Configure a rule with the use of the DQL.
config owner virtual_sites content virtual_rule dql my_domains vip address 126.96.36.199 port 80 protocol tcp add service web1 add service web2 active
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Refer to Cisco Technical Tips Conventions for information on conventions used in this document.