Review Questions

1:	What is the most important difference between BGP-4 and earlier versions of BGP? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
2:	What two problems was CIDR developed to alleviate? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
3:	What is the difference between classful and classless IP routers? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
4:	What is the difference between classful and classless IP routing protocols? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
5:	Given the addresses 172.17.208.0/23, 172.17.210.0/23, 172.17.212.0/23, and 172.17.214.0/23, summarize the addresses with a single aggregate, using the longest possible address mask. ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
6:	What is an address prefix? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
7:	The routing table in Example 2-16 is taken from a classless router. To what next -hop address does the router forward packets with each of the following destination addresses? 172.20.3.5 172.20.1.67 172.21.255.254 172.16.50.50 172.16.0.224 172.16.51.50 172.17.40.1 172.17.41.1 172.30.1.1 Example 2-16 The Routing Table for Review Question 7 Stratford# show ip route Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default Gateway of last resort is not set 172.20.0.0 is variably subnetted, 6 subnets, 2 masks D 172.20.0.0 255.255.0.0 [90/409600] via 172.20.5.2, 00:01:50, Ethernet0 D 172.20.2.0 255.255.255.0 [90/409600] via 172.20.6.2, 00:01:50, Ethernet1 D 172.20.3.0 255.255.255.0 [90/5401600] via 172.20.6.2, 00:01:50, Ethernet1 C 172.20.5.0 255.255.255.0 is directly connected, Ethernet0 C 172.20.6.0 255.255.255.0 is directly connected, Ethernet1 C 172.20.7.0 255.255.255.0 is directly connected, Ethernet2 172.16.0.0 is variably subnetted, 3 subnets, 2 masks D 172.16.50.0 255.255.255.0 [90/409600] via 172.20.6.2, 00:01:50, Ethernet1 D 172.16.0.0 255.255.255.0 [90/460800] via 172.20.6.2, 00:01:51, Ethernet1 D 172.16.0.0 255.255.0.0 [90/409600] via 172.20.7.2, 00:01:51, Ethernet2 172.17.0.0 is subnetted (mask is 255.255.255.0), 1 subnets D 172.17.40.0 [90/2841600] via 172.20.7.2, 00:01:52, Ethernet2 D 172.16.0.0 (mask is 255.240.0.0) [90/409600] via 172.20.5.2, 00:01:52, Ethernet0 Stratford#
8:	Explain how summarization helps hide network instabilities. ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
9:	Explain how summarization can cause asymmetric traffic patterns. ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
10:	Is asymmetric traffic undesirable? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
11:	What is a NAP? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
12:	What is a route server? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
13:	What is a provider-independent address space, and why can it be advantageous to have one? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
14:	Why can it be a problem to have a /21 provider-independent address space? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
15:	What is a routing policy? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
16:	What is the underlying protocol that BGP uses to reliably connect to its neighbors? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
17:	What are the four BGP message types, and how is each one used? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
18:	In what state or states can BGP peers exchange Update messages? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
19:	What is NLRI? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
20:	What is a path attribute? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
21:	What are the four categories of BGP path attributes? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
22:	What is the purpose of the AS_PATH attribute? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
23:	What are the different types of AS_PATH? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
24:	What is the purpose of the NEXT_HOP attribute? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
25:	What is the purpose of the LOCAL_PREF attribute? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
26:	What is the purpose of the MULTI_EXIT_DISC attribute? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
27:	What attribute or attributes are useful if a BGP speaker originates an aggregate route? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
28:	What is a BGP administrative weight? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
29:	Given an EBGP route and an IBGP route to the same destination, which route will a BGP router prefer? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
30:	A router has two IBGP routes to the same destination. Path A has a LOCAL_PREF of 300 and three AS numbers in the AS_PATH. Path B has a LOCAL_PREF of 200 and two AS numbers in the AS_PATH. Assuming no other differences, which path will the router choose? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
31:	What is route dampening ? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
32:	Define the penalty, suppress limit, reuse limit, and half-life as they apply to route dampening. ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
33:	What is IGP synchronization, and why is it important? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
34:	Under what circumstances can you safely disable IGP synchronization? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
35:	What is a BGP peer group ? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
36:	What is a BGP community? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
37:	What is a route reflector? What is a route reflection client? What is a route reflection cluster? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
38:	What is the purpose of the ORIGINATOR_ID and the CLUSTER_LIST path attributes? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
39:	What is a BGP confederation? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
40:	Can route reflectors be used within confederations? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
41:	What is the purpose of the next-hop-self function? Are there any reasonable alternatives to using this function? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________