Foundry Networks FESX User Manual

Foundry Configuration Guide for the FESX, FSX, and FWSX
20 - 26 © Foundry Networks, Inc. December 2005
enter the CIDR equivalent of “4.0.0.0 0.255.255.255” as “4.0.0.0/8”. The CLI automatically converts the CIDR
number into the appropriate ACL mask (where zeros instead of ones are the significant bits) and changes the non-
significant portion of the IP address into zeros.
NOTE: If you enable the software to display IP sub-net masks in CIDR format, the mask is saved in the file in
“/<mask-bits>” format. To enable the software to display the CIDR masks, enter the ip show-subnet-length
command at the global CONFIG level of the CLI. You can use the CIDR format to configure the ACL entry
regardless of whether the software is configured to display the masks in CIDR format.
If you use the CIDR format, the ACL entries appear in this format in the running-config and startup-config files, but
are shown with sub-net mask in the display produced by the show ip access-list command.
Using an Extended ACL as Input to the Distribution List
To use an extended ACL to configure an OSPF distribution list for denying specific routes, enter commands such
as the following:
The first three commands configure an extended ACL that denies routes to any 4.x.x.x destination network with a
255.255.0.0 network mask and allows all other routes for eligibility to be installed in the IP route table. The last
three commands change the CLI to the OSPF configuration level and configure an OSPF distribution list that uses
the ACL as input. The distribution list prevents routes to any 4.x.x.x destination network with network mask
255.255.0.0 from entering the IP route table. The distribution list does not prevent the routes from entering the
OSPF database.
Syntax: [no] ip access-list extended <acl-name> | <acl-id>
Syntax: deny | permit <ip-protocol> <source-ip> <wildcard> <destination-ip> <wildcard>
The <acl-name> | <acl-id> parameter specifies the ACL name or ID.
The deny | permit parameter indicates whether packets that match the policy are dropped or forwarded.
The <ip-protocol> parameter indicates the type of IP packet you are filtering. When using an extended ACL as
input for an OSPF distribution list, specify ip.
The <source-ip> <wildcard> parameter specifies the source address for the policy. Since this ACL is input to an
OSPF distribution list, the <source-ip> parameter actually is specifying the destination network of the route.
The <wildcard> parameter specifies the portion of the source address to match against. The <wildcard> is a four-
part value in dotted-decimal notation (IP address format) consisting of ones and zeros. Zeros in the mask mean
the packet’s source address must match the <source-ip>. Ones mean any value matches. For example, the
<source-ip> and <wildcard> values 4.0.0.0 0.255.255.255 mean that all 4.x.x.x networks match the ACL.
If you want the policy to match on all network addresses, enter any any.
If you prefer to specify the wildcard (mask value) in Classless Interdomain Routing (CIDR) format, you can enter a
forward slash after the IP address, then enter the number of significant bits in the mask. For example, you can
enter the CIDR equivalent of “4.0.0.0 0.255.255.255” as “4.0.0.0/8”. The CLI automatically converts the CIDR
number into the appropriate ACL mask (where zeros instead of ones are the significant bits) and changes the non-
significant portion of the IP address into zeros.
FESX424 Router(config)# ip access-list extended no_ip
FESX424 Router(config-ext-nacl)# deny ip 4.0.0.0 0.255.255.255 255.255.0.0
0.0.255.255
FESX424 Router(config-ext-nacl)# permit ip any any
FESX424 Router(config-ext-nacl)# exit
FESX424 Router(config)# router ospf
FESX424 Router(config-ospf-router)# distribute-list no_ip in

Foundry Networks FESX Specifications

General

Brand	Foundry Networks
Model	FESX
Category	Switch
Language	English