Cisco Catalyst 2000 Configuration Handbook page 173

152 Cisco LAN Switching Configuration Handbook
d. (Optional) Control access to the virtual server. To allow only specific clients to
e. (Optional) Assign connections from the same client to the same real server:
f.
The virtual server appears as IP address ip-address (default 0.0.0.0 or "all net-
works") with network-mask (default 255.255.255.255).
With IOS SLB, it provides load balancing for the specified tcp or udp port: dns
or 53 (Domain Name System), ftp or 21 (File Transfer Protocol), https or 443
(HTTP over Secure Socket Layer), www or 80 (HTTP), telnet or 23 (Telnet),
smtp or 25 (SMTP), pop3 or 110 (POPv3), pop2 or 109 (POPv2), nntp or 119
(Network News Transport Protocol), or matip-a or 350 (Mapping of Airline
Traffic over IP, type A). A port number of 0 can be given to indicate that the vir-
tual server accepts connections on all ports.
Other alternatives to a port number are wsp (connectionless WSP, port 9200),
wsp-wtp (connection-oriented WSP, port 9201 with WAP FSM), wsp-wtls (con-
nectionless secure WSP, port 9202), and wsp-wtp-wtls (connection-oriented
secure WSP, port 9203).
The service keyword can be given to force SLB to assign all connections associ-
ated with a given service-name (ftp or wsp-wtp) to the same real server. On a
CSM, only ftp connections are allowed to be coupled to the originating control
session.
use the virtual server, enter
(virtual-server) client ip-address network-mask
Clients having IP addresses within the range given by ip-address (default 0.0.0.0,
or all addresses) and network-mask (default 255.255.255.255, or all networks)
are allowed to connect to the virtual server. The network-mask in this case
resembles the mask of an access list, where a 1 bit ignores and a 0 bit matches.
On a CSM, you can use the exclude keyword to disallow the IP addresses speci-
fied.
(virtual-server) sticky duration [group group-id] [netmask netmask]
For a given client, connections are assigned to the last-used real server for
duration in seconds (0 to 65,535). Virtual servers can be assigned to a group-id
(0 to 55; default 0), associating them as a single group. A netmask (default
255.255.255.255) can be given such that all client source addresses within the
mask are assigned to the same real server.
(Optional) Hold connections open after they are terminated:
(virtual-server) delay duration
After a TCP connection is terminated, SLB can maintain the connection context
for duration (1 to 600 seconds, default 10 seconds). This can be useful when
packets arrive out of sequence, and the connection is reset before the last data
packet arrives.