User guide

New and Changed Information
26
Release Notes for Cisco 2500 Series for Cisco IOS Release 12.0 T
78-5563-07 Rev.H0
Annex-G (X.25 over Frame Relay)
Annex G (X.25 over Frame Relay) facilitates the migration from an X.25 backbone to a Frame Relay
backbone by permitting encapsulation of CCITT X.25/X.75 traffic within a Frame Relay connection.
Annex G has developed to accommodate the many Cisco customers in Europe, where X.25 still is a
popular protocol. With Annex G, the process of transporting X.25 over Frame Relay has been
simplified, by allowing direct X.25 encapsulation over a Frame Relay network.
This simple process is largely achieved using X.25 profiles (similar to dialer profiles), which were
created to streamline the configuration of X.25 on a per DLCI basis. X.25 profiles can contain any
existing X.25 command and, once created and named, can be simultaneously associated with more than
one Annex G DLCI connection, just using the profile name.
CDP Additions for Cisco IOS
The Cisco Discovery Protocol (CDP) is a media-independent device discovery protocol that runs on all
cisco manufactured equipment, including routers, bridges, access servers, and switches. Each device
sends periodic messages to a multicast address. Each device listens to the periodic messages sent by
others in order to learn about neighboring devices and determine when their interfaces to the media go
up or down. With CDP, network management applications can learn the device type and the SNMP
agent address of neighboring devices. This process enables applications to send SNMP queries to
neighboring devices.
CDP runs on all media that support Subnetwork Access Protocol (SNAP), including local-area network
(LAN), Frame Relay, and Asynchronous Transfer Mode (ATM) media. CDP runs over the data link
layer only. Therefore, two systems that support different network-layer protocols can learn about each
other.
Each device configured for CDP sends periodic messages to a multicast address. Each device advertises
at least one address at which it can receive SNMP messages. The advertisements also contain
time-to-live, or holdtime, information, which indicates the time a receiving device should hold CDP
information before discarding it.
Additions for Cisco Discovery Protocol (CDP) include the following:
• new SYSLOG output for instances of mismatching native VLAN IDs (IEEE 802.1Q) on connecting
ports and port duplex state values on connecting devices.
• cdp advertise-v2 command and new output from show cdp commands
The benefits include, transparent support of X.25 encapsulation over the Frame Relay network; direct
X.25 configurations on a per DLCI basis; multiple Annex G DLCIs can use the same X.25 profile;
multiple logical X.25 SVCs per Annex G link, and the fact that Cisco routers already contain the
functionality necessary to perform the framing and frame removal required by Annex G.
DistributedDirector
Cisco DistributedDirector provides dynamic, transparent, and scalable Internet traffic load distribution
between multiple topologically dispersed servers. DistributedDirector is the only global Internet service
scaling solution that utilizes Cisco Internetwork Operating System (Cisco IOS) software and leverages
routing table information in the network infrastructure to make “network intelligent” load distribution
decisions.