Cisco® CCDA Exam Notes : Isdn Primary Rate Interface, Trunking Protocols, And Catalyst Switches.

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21. ISDN: The ISDN Primary Rate Interface (PRI, also known as 23B+D1) service delivers 23 B channels and one 64KBPS D channel for a total bit rate of up to 1.544 MBPS.

ISDN BRI will have 2B + 1D channels, the total bandwidth is 64X2 +16 = 144 KBPS

22. The most important design rule for 100MBPS Ethernet is that the round trip collision delay must not exceed 512 bit times, which is same as that of 10BaseT. However, a bit time in 100BaseT is 10 times smaller. Therefore, a bit time on a 100 MBPS Ethernet is 0.01 microseconds, compared to 0.1 microseconds on a 10 MBPS Ethernet. Therefore, the maximum round trip delay for a 100 MBPS Ethernet is 5.12 microseconds whereas that of 10BaseT is 51.2 microseconds.

23. Cisco switches support the following trunking protocols:

  • ISL (Inter Switch Link) and
  • 802.1q

24. Class I repeaters have a latency of 0.7 microseconds and only one repeater hop is allowed.

Class II repeaters have a latency of 0.46 microseconds and one or two repeater hops are allowed.

25. Cisco Routers:

1600 series access routers: These are inexpensive, easy to use, multiprotocol routers. Cisco 1600, and 2600 series routers have optional expansion modules.

The 4000 series routers have the following features:

  • High-density LAN connectivity
  • Medium-density WAN and dial up connectivity: Up to 16 ISDN BRI / 32 sync/ async serial ports or combination
  • FDDI / IBM internetworking connectivity

26. CiscoView can be integrated with several other network management platforms like HP OpenView, IBM NetView, CiscoWorks etc. to provide a better system to manage Cisco devices.

27. Route summarization reduces the route distribution and route-processing overhead in a network.

28. The HSSI interface on a Cisco router can support speeds up to 52 MBPS.

29. Catalyst switches:

  • Catalyst 1800 is a Token Ring switch that has 16 dedicated or shared ports in the base unit plus two feature -card slots.
  • Catalyst 2900 Fast Ethernet switch is a 14 port, fixed configuration, fast Ethernet switch. Catalyst 1900 Ethernet switch features 25 switched Ethernet ports providing attachment to individual workstations and 10BaseT hubs. It also has two 100BaseT ports for high-speed connectivity to servers and backbones.
  • The catalyst 2820 Ethernet switch has 25 switched Ethernet ports and two high-speed expansion slots.

30. Bandwidths (typical):

  • Dial up: up to 56 KBPS
  • ISDN BRI: up to 2 numbers of 64 KBPS B channels and 16 KBPS D channels
  • T1: 1.544 MBPS
  • E1: 2.048 MBPS
  • DS3: 44.736 MBPS

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