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Networking II Exam 1
Terms in this set (47)
Classless Inter-Domain Routing (CIDR)
a new addressing scheme for the internet which allows for more efficient allocation of IP addresses than the old Class A, B, C address scheme.
Why do we need CIDR?
Running out of IP addresses and running out of capacity in the global routing tables.
twisted pair cable used for carrying signals.
Non-volatile Random Access Memory (NVRAM)
This contains the startup configuration for the router. (startup-config).
Contains IOS, the Cisco Operating System. Type of memory in a 1700 or 2500 series router.
Difference between DTE and DCE
DTE devices are PC or NIC cards. DCE devices are Modems and CSU/DSU.
Variable Length Subnet Mask (VLSM)
Routing protocols, such as RIP-2, OSPF and IGP, support this. Advantages to using this include a more efficient use of IP addresses and multiple subnet masks permit route aggregation.
used to connect identical interfaces such as two Ethernet interfaces within a computer. They have identical transit/receive (Tx/Rx) pins.
protocols that enable a message to move through the system that help to implement the OSI Layer 3 Network Lyaer. They are used between routers to direct user traffic; to provide enough information in its network layer to allow a packet to be forwarded from one host to another based on the addressing scheme. IP, IPX, APPLETALK
protocols that enable the routers to do its job of routing, building routing tables, exchanging routing tables. They are used between routers to maintain and build routing tables; to communicate between routers; to allow one router to share its routing information with neighboring other routers. RIP, IGRP, OSPF.
this determines the best path based on the number of hops. The route with the least number of hops is considered to be the best route. This will pass entire routing tables to neighboring routers. This utilizes Bellman Ford algorithm to forward routing table information.
Two important distance vector protocols
RIP and IGRP
this determines the topology of the entire internetwork. OSPF is an important protocol. This uses Dijkstra's algorithm to gain a picture of the entire topology of a network.
Routing Information Protocol (RIP)
Distance Vector protocol that uses hop count to determine the best path. This has a maximum number of hops at 15.
as packets travel back and forth through the same routers, this increases to infinity. A maximum number of this is needed to solve the infinity problem.
this is a distance vector rule that packets cannot be sent back in the direction from which they came.
If a router detects that a network is down, it enters a 16 for the hop count in its routing table for that network. Thus, other routers will see an unreachable hop count and not attempt to send that packet in that direction.
this is basically an enforced time delay to prevent updates in a rapidly changing network from changing the routing table too quickly. As routing tables circulate throughout a network, it is possible for an outdated table to have inaccurate information. This gives the new accurate routing tables time to circulate. After this expires, the newly arrived table can be considered accurate.
Disadvantages of Distance Vector Routing
Scalability: RIP cannot scale up to a larger network due to too many periodic updates.
Convergence: RIP and IGRP are slow to announce updates to other routers because of the fact that the router sends its entire routing table with the changed link.
Loops: this will generally occur when routing tables contain inconsistent data. A non-converged router may continuously loop packets around the network despite the fact that the destination node may be down.
Speed: What if there is a faster T1 route that has more hops than a 56k route with fewer hops? Recall, RIP only employs hop count when making a forwarding decisions.
RIP vs IGRP
RIP takes 30 sec to send out the periodic update to other nodes, while IGRP takes 90 sec.
This does not share RIP's hop count limitation.
This converges faster than RIP, thereby avoiding the routing loops caused by limitation.
consumes significantly less bandwidth than IGRP because it is able to limit the exchange of routing information to include only the changed information.
Administrative Distances (AD)
these are used to measure the trustworthiness of routing information passed from a neighbor router. This is a number between 0 to 255, where 0 is the most trusted and 255 is the least trusted.
Difference between RIP v1 and RIP v2
v2 allows for VLSM
bandwidth, delay of the line, load, reliability, maximum transmission unit (MTU) are used to determine the best route
1. Routers have a complete view of the network
2. Bi-directional communication
3. Enhanced metrics such as cost for superior path selection.
4. Link state can be triggered by topology (link status) changes that result in faster convergence. It does not have to wait for the 30-second periodic update.
1. Complex configuration (lots of overhead running)
2. Prone to flooding (obstruction) due to much overhead (LSP, HELLO, Updates etc.)
3. Convergence is slow
4. Processor intensive (Use RIP or IGRP if using older system versions)
1. classless support, and VLSM support
2. Quick convergence (though not as quick as EIGRP)
3. Route Propagation is based on multicast and triggered by a change in topology. In contrast, RIPv1 uses periodic broadcast every 30 secs.
4. No hop count limit
5. typical topology that OSPF can handle in hierarchical. In contrast, RIP is a flat network
6. Dijkstra Algorithm to calculate route.
this is a group of connected routers
Area Border Routers (ABR)
A router that connects another area to the backbone (Area 0) within the same Autonomous System.
Two or more routers have interfaces directly connected.
The relationship between two OSPF routers that allow them to share route updates. OSPF only shares updates with neighbors who have established this.
Link State Advertisement (LSA)
This is the packet type used by OSPF to share route updates. These are exchanges by routers who have established adjacency.
Name two link-state protocols
IS-IS and OSPF
What is a type of hybrid protocol?
Bandwidth, Delay, Load, Reliability
EIGRP quiet protocol
this means it sends relatively few messages
Diffusing Update Algorithm (DUAL)
this is used by EIGRP for selecting and maintaining the best path.
supports multiple Autonomous Systems and VLSM
What is a discontinuous network
Something that EIGRP supports
What is an Autonomous System?
1. Routers working within the same domain (Area Bounds)
2. Router working with the same routing protocols
3. Autonomous Numbers break up networks for simplicity
4. under the same administration
this is the protocol that provides dynamic connectivity but assumes that all autonomous systems are connected in a tree topology. It uses a very simple design. For exterior routing between autonomous systems.
For routing inside autonomous systems.
Which routing protocol is best used for small networks
Which routing protocol is best used for large networks