Scenarios
The following scenarios and questions are designed to draw together the content of the chapter and to exercise your understanding of the concepts. There is not necessarily a right answer. The thought process and practice in manipulating the concepts are the goals of this section. The answers to the scenario questions are found at the end of this chapter.
Scenario 15-1
The company Humugos is waiting for the consultant to configure the network. The requirement is to give each country in which Humugos operates its own autonomous system number. The countries will be connected via eBGP and will use leased lines. The autonomous system numbers are private because the connection to the Internet is dealt with by an ISP at each local site. For the first phase of the switchover, EIGRP is removed from the connections between the countries, and the BGP configuration needs to be implemented to ensure a smooth transition. The intention is for each country to have the same configuration to ease management and troubleshooting.
| 1. | Using the diagram in Figure 15-3 as a reference, issue the commands that need to be configured at each country or autonomous system. The private autonomous system numbers range from 64,512 to 65,535.
Figure 15-3. Diagram for Scenario 15-1
Figure 15-3 has been simplified and does not contain all the autonomous systems that Humugos network engineers must take into consideration. |
| 2. | What commands would indicate that there was a problem of scaling? |
Scenario 15-2
A small company called Insolvent, Inc., has a main office in Chicago and satellite offices on the west coast of the United States. The company has recently changed its routing protocol to OSPF.
Insolvent has a connection to the Internet from each site, over which it does all its business. The link is a fractional T1 at the satellite offices and a full T1 at the main office. The network administrator at the main office is responsible for the corporate network and is currently trying to recruit staff to manage the local networks. The network administrator was advised at a technical seminar that BGP is what is needed to connect to the Internet. Figure 15-4 shows the network.
Figure 15-4. Diagram for Scenario 15-2
| 1. | Given the description of the company and with reference to Figure 15-4, do you agree that BGP is a requirement for this network? Give reasons for your answer. |
| 2. | What alternatives are available? |
| 3. | Give the alternative configuration commands for the satellite site to connect to the Internet. |
| 4. | What commands would show that the link is up and operational? |
Scenario 15-3
Review the output in Example 15-6, and answer the following questions.
Example 15-6. Scenario 15-3 Output
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Code View: FARADAY-gw# show ip bgp neighbor
BGP neighbor is 155.94.83.1, remote AS 2914, external link
Index 1, Offset 0, Mask 0x2
BGP version 4, remote router ID 129.250.116.16
BGP state = Established, table version = 457046, up for 1w5d
Last read 00:00:20, hold time is 180, keepalive interval is 60 seconds
Minimum time between advertisement runs is 30 seconds
Received 890723 messages, 0 notifications, 0 in queue
Sent 36999 messages, 0 notifications, 0 in queue
Inbound path policy configured
Outbound path policy configured
Outgoing update AS path filter list is 1
Route map for incoming advertisements is limit-verioverdi
Connections established 3; dropped 2
Last reset 1w5d, due to : User reset request
No. of prefix received 11031
No. of prefix received 11031
Connection state is ESTAB, I/O status: 1, unread input bytes: 0
Local host: 155.94.83.2, Local port: 11036
Foreign host: 155.94.83.1, Foreign port: 179
Enqueued packets for retransmit: 0, input: 0 mis-ordered: 0 (0 bytes)
Event Timers (current time is 0x845DFA38):
Timer Starts Wakeups Next
Retrans 18473 11 0x0
TimeWait 0 0 0x0
AckHold 86009 50293 0x0
SendWnd 0 0 0x0
KeepAlive 0 0 0x0
GiveUp 0 0 0x0
PmtuAger 0 0 0x0
DeadWait 0 0 0x0
iss: 829352113 snduna: 829702916 sndnxt: 829702916 sndwnd: 16004
irs: 625978143 rcvnxt: 652708970 rcvwnd: 16342 delrcvwnd: 42
SRTT: 300 ms, RTTO: 607 ms, RTV: 3 ms, KRTT: 0 ms
minRTT: 4 ms, maxRTT: 764 ms, ACK hold: 300 ms
Flags: higher precedence, nagle
Datagrams (max data segment is 536 bytes):
Rcvd: 122915 (out of order: 0), with data: 105023, total data bytes: 26731112
Sent: 109195 (retransmit: 11), with data: 18461, total data bytes: 350802
!
!
BGP neighbor is 144.39.228.49, remote AS 701, external link
Index 2, Offset 0, Mask 0x4
BGP version 4, remote router ID 144.39.3.104
BGP state = Established, table version = 457055, up for 2w0d
Last read 00:00:08, hold time is 180, keepalive interval is 60 seconds
Minimum time between advertisement runs is 30 seconds
Received 50265 messages, 0 notifications, 0 in queue
Sent 37016 messages, 0 notifications, 0 in queue
Inbound path policy configured
Outbound path policy configured
Outgoing update AS path filter list is 1
Route map for incoming advertisements is limit-uunetmemenet
Connections established 2; dropped 1
Last reset 2w0d, due to : Peer closing down the session
No. of prefix received 1635
Connection state is ESTAB, I/O status: 1, unread input bytes: 0
Local host: 144.39.228.50, Local port: 179
Foreign host: 144.39.228.49, Foreign port: 11013
Enqueued packets for retransmit: 0, input: 0 mis-ordered: 0 (0 bytes)
Event Timers (current time is 0x845F16B8):
Timer Starts Wakeups Next
Retrans 20357 4 0x0
TimeWait 0 0 0x0
AckHold 29701 26058 0x0
SendWnd 0 0 0x0
KeepAlive 0 0 0x0
GiveUp 0 0 0x0
PmtuAger 0 0 0x0
DeadWait 0 0 0x0
iss: 3360945234 snduna: 3361331966 sndnxt: 3361331966 sndwnd: 15890
irs: 2976917809 rcvnxt: 2977685910 rcvwnd: 15072 delrcvwnd: 1312
SRTT: 306 ms, RTTO: 642 ms, RTV: 15 ms, KRTT: 0 ms
minRTT: 4 ms, maxRTT: 908 ms, ACK hold: 300 ms
Flags: passive open, nagle, gen tcbs
Datagrams (max data segment is 1460 bytes):
Rcvd: 48675 (out of order: 0), with data: 29705, total data bytes: 768119
Sent: 46955 (retransmit: 4), with data: 20353, total data bytes: 386750
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| 1. | How many sessions are active? |
| 2. | What is the state of the sessions, and what do the states mean? |
