Configuring Advanced Subnet Access - Extreme Networks Altitude 4700 Series Product Reference Manual

Available Protocols
Protocols that are not pre-configured can be specified using the drop down list within the Transport
column within the Subnet Access and Advanced Subnet Access screens. They include:
ALL—Enables all of the protocol options displayed in the drop-down menu (as described below).
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TCP—Transmission Control Protocol is a set of rules for sending data as message units over the
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Internet. TCP manages individual data packets. Messages are divided into packets for efficient
routing through the Internet.
UDP—User Datagram Protocol is used for broadcasting data over the Internet. Like TCP, UDP runs on
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top of Internet Protocol (IP) networks. Unlike TCP/IP, UDP/IP provides few error recovery services.
UDP offers a way to directly connect, and then send and receive datagrams over an IP network.
ICMP—Internet Control Message Protocol is tightly integrated with IP. ICMP messages are used for
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out-of-band messages related to network operation. ICMP packet delivery is unreliable. Hosts cannot
count on receiving ICMP packets for a network problem.
AH—Authentication Header is one of the two key components of IP Security Protocol (IPsec). The
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other key component is Encapsulating Security Protocol (ESP).
AH provides authentication, proving the packet sender really is the sender, and the data really is the
data sent. AH can be used in transport mode, providing security between two end points. Also, AH
can be used in tunnel mode, providing security like that of a Virtual Private Network (VPN).
ESP—Encapsulating Security Protocol is one of two key components of IPsec. The other key
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component is Authentication Header (AH). ESP encrypts the packets and provides authentication
services. ESP can be used in transport mode, providing security between two end points. ESP can
also be used in tunnel mode, providing security like that of a Virtual Private Network (VPN).
GRE—General Routing Encapsulation supports VPNs across the Internet. GRE is a mechanism for
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encapsulating network layer protocols over any other network layer protocol. Such encapsulation
allows routing of IP packets between private IP networks across an Internet using globally assigned
IP addresses.

Configuring Advanced Subnet Access

Use the Advanced Subnet Access screen to configure complex access rules and filtering based on source
port, destination port, and transport protocol. To enable advanced subnet access, the subnet access rules
must be overridden. However, the Advanced Subnet Access screen allows you to import existing subnet
access rules into the advanced subnet access rules.
Altitude 4700 Series Access Point Product Reference Guide
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