Routing Flashcards
or 0.0.0.0, a designation for a gateway in a routing table, representing a network ID that is directly connected to the router (no gateway needed)
On-link
a relative value in a routing table which determines the cost of using that route - the router will send a packet down a route with the lowest cost
metric
a feature in many networks where the internal IP addresses are hidden on the LAN but are still able to communicate on the Internet - this is used to protect computers and conserve IP addresses
network address translation (NAT)
the most common form of NAT, where a router records the source and destination IP addresses as well as the port number, then swaps the source IP address with that of the external IP address and the port number with another port number; those numbers are then compared when a packet is received
port address translation (PAT)
a form of NAT where a single machine, such as a Web server, is given a static address that is not private, allowing one outside of the network to access the device
Static NAT (SNAT)
a form of NAT where a specific local address is designated for various services, and outside sources can request a service from it; however, the port for that service is hidden, and instead a router translates the incoming port number into a recorded ip address and other port number; the service is mapped to a specific IP address and port number
port forwarding
a form of NAT in which a number of computers share a pool of routable IP addresses even numbering less than the total number of computers - the NAT doles out IP addresses at the request of a computer needing to access the Internet
dynamic NAT (DNAT), also pooled NAT
switching metric (for comptia, also routing metric) that determines the largest frame that technology can handle
maximum transmission unit (MTU)
routing protocol that calculates the total cost of each routes and chooses the one with the lowest cost
distance vector routing protocol
the first distance vector routing protocol, which had a max hop count of 15, had issues with network overloads from updates, did not use VLSM, and had no authentication
routing information protocol version 1 (RIPv1)
a current distance vector routing protocol which has authentication and VLSM, but still has a number of problems, like having a large time to convergence for large WANs
routing information protocol version 2 (RIPv2)
one or more networks governed by a single dynamic routing protocol
autonomous system (AS)
numbers used by AS’s to communicate with each other rather than IP addresses, currently 32-bit with a dot between each 16-bit part
autonomous system number (ASN)
generic name for a protocol used by AS’s to communicate with each other
exterior gateway protocol (EGP)
the one protocol used for communicate between autonomous systems
border gateway protocol (BGP)
generic name for a protocol used by networks within an AS to communicate
interior gateway protocol (IGP)
name given to AS-to-AS routers
edge router
a simplication of routing tables to managable levels by only keeping track of routers connections to subsets of locations
route aggregation
a type of dynamic routing protocol where routers only forward individual route changes rather than the whole routing table at regular intervals
link state
the commonly-used IGP in the world, it establishes relationships with neighboring routers using “Hello” packets, exchange info via LSA packets, then decide their own optimal routes, reaching convergence quickly; the metric of this protocol is cost, and they use LSA’s to recompute new routes in the event of a route going down
Open Shortest Path First (OSPF)
packets sent from router to router in an OSPF area, these contain information on routers and networks
link state advertisement
a link state dynamic routing protocol that works with IPv6 addresses and is the de facto standard for ISPs
Intermediate System to Intermediate System (IS-IS)
proprietary protocol of Cisco that is not entirely distance vector or link state; it contains aspects of both, and is called by Cisco an advanced distance vector protocol (might be called this on exam)
Enhanced Interior Gateway Routing Protocol (EIGRP)
ability of routers to use two different routing protocols separately, such as taking routes learned by one protocol and announcing them over another protocol
route redistribution
the Cisco console (serial) cable used for connecting to their routers
roller (Yost) cable
a program used to access and configure a managed device
terminal emulator
advanced tools that describe, visualize, and configure the entire network, including routers, switches, and even computers
Network Management Software (NMS)