Lab Four: Dynamic Routing Protocols (RIP, OSPF, and BGP)
Members:
Edmund Chang
70813570
Lin He
52924739
Negar Mohades
Prelab 4
1.) The command that configures a Linux PC as an IP router is:
echo "1" > /proc/sys/net/ipv4/ip_forward
2.) The main differences between a distance vector routing protocol and a link state
routing protocol are:
--link-state algorithms send small updates everywhere, while distance vector
algorithms send larger updates only to neighboring routers.
--Because they converge more quickly, link-state algorithms are somewhat less
prone to routing loops than distance vector algorithms.
--link-state algorithms require more CPU power and memory than distance vector
algorithms.
--Link-state protocols are generally more scalable than distance vector protocols.
3.) The differences between an intradomain routing protocol (interior gateway
protocol IGP) and in interdomain routing protocol (exterior gateway protocol EGP)
are:
--Intradomain Routing Protocols work only within domains.
--Interdomian Routing Protocols work within and between domains.
An example of an intradomain protocol is RIP and OSPF.
An example of an interdomain protocol is BGP.
4.) Zebra supports RIP, GDP, and OSPF routing protocols.
5.) The process zebra updates the routing tables and exchanges routes between different routing protocols.
6.) The user starts zebra and then the specific routing protocol using for example ‘zebra start’ and then ‘ripd
start’. Then he or she telnets into the localhost on the 2602 port using this command ‘telnet localhost 2602’
and then logs in and it emulates a real router OS such as the Cisco IOS.
7.) RIP 2 enabled RIP messages to carry more information, which permitted the use of a simple
authentication mechanism to secure table updates. More importantly, RIP 2 supported subnet masks, a
critical feature that was not available in RIP.
8.) Passive mode means that the host receives and processes incoming routing messages but does not
transmit routing messages. Active routers advertise their routes (reachability information) to others; passive
routers listen and update their routes based on advertisements but do not advertise (flood). Typically,
routers run RIP in active mode, while hosts use passive mode.
9.) When the RIP sends routing-update when the network topology changes. When a router receives a
routing update that includes changes to an entry, it updates its routing table to reflect the new route. After
updating its routing table, the router immediately begins transmitting routing updates to inform other
network routers of the change. These updates are sent independently of the regularly scheduled updates that
RIP routers send. These independently sent updates are called triggered updates.
10.) Split-horizon is a mechanism that prevents incorrect routing information from being propagated. The
split horizon rule prohibits a router from advertising a route through an interface that the router itself is
using to reach the destination. In other words, its routing technique prevents information from exiting the
router interface from which that information was received. Split-horizon updates are useful in preventing
routing loops. In general, split horizon with poisoned reverse is safer than simple split horizon. If two
gateways have routes pointing at each other, advertising reverse routes with a metric of 16 will break the
loop immediately. If the reverse routes are simply not advertised, the erroneous routes will have to be
eliminated by waiting for a timeout. However, poisoned reverse does have a disadvantage: it increases the
size of the routing messages.
11.) Network areas usually are connected to other network areas via routers, making up a single
autonomous system. An autonomous system is a collection of networks under a common administration
sharing a common routing strategy. Autonomous systems are subdivided by areas. In other words, an
autonomous systerm (AS) is a collection of IP networks under control of a single entity, typically an
Internet Serivce Provider or a very large organization with redundant connections to the rest of the internet.
A unique AS number is allocated to each AS for use in BGP routing. The numbers are assigned by the
same authorities that allocate IP addresses. Types of AS are Multihomed AS, Stub AS, and Transit AS.
12.) UCI’s AS # is Number 2. NACS.uci.edu has AS Number 1.
13.) A Stub AS is only connected to one other AS. For routing purposes, it could be regarded as a simple
extension of the other AS. In fact, most networks with a single Internet connection don't have a unique AS
number assigned, and their network addresses are treated as part of the parent AS.
2
A Transit AS has connections to more than one other AS and allows itself to be used as a conduit
for traffic (transit traffic) between other AS's. Most large Internet Service Providers are transit AS's.
A Multihomed AS has connections to more than one other AS, but does not allow transit traffic to
pass, though its interior hosts may route traffic through multiple AS's. This is the typical configuration for a
large corporate network with multiple redundant Internet connections, but which does not wish to pass
traffic for others.
Prelab 5
1.) UDP and TCP use port numbers to identify applications. A globally unique address
at the transport layer consists of the tuple: <IP address, port number>
2.) The syntax is:
Sender:
Receiver:
ttcp -ts -l500 -n4 -p2222 -D 10.0.2.6
ttcp -rs - l500 -n4 -p2222
3.)
a.) PMTU discovery is described in RFC1191. When a connection is
established, the two hosts involved exchange their TCP maximum segment size
(MSS) values. The smaller of the two MSS values is used for the connection. The
MSS for a system is usually the MTU at the link layer minus 40 bytes for the IP and
TCP headers.
That is defined as the MTU (Maximum Transmission Unit) on the network segment.
Since TCP/IP is routed through many different segment, you get path MTU: the
maximum size an IP packet on a specific path.
If the packet is LARGER that this value, it will be fragmented by the router. Now,
there is a flag that can be set to tell routers "do not fragment packet" and it is
mainly used in path MTU discovery (see below).
Path MTU discovery will tell you what the path MTU is. It is simply done as follow:
send ICMP packets with the "do not fragment" flag set and, as long as you receive
and answer, increase the packet size. Once you've got a "Must fragment but Do Not
Fragment flag set" answer, you know the path MTU.
b.) The maximum size of a UDP diagram cannot exceed 65508, according to
experimental results.
c.) ICMP Network Unreachable. No, the MTU of the next is returned.
d.) TCP avoids fragmentation in this way: when a TCP connection is
established, the sender and receiver negotiates the maximum segment size (MSS),
so that no fragmentation occurs at their outgoing interfaces. The smaller value is
used for the MSS.
4.) 34568 to 36615.
5.)
a.) Nagle’s = This algorithm limits the number of small segments that a TCP
sender can transmit without waiting for an acknowledgement. This is accomplished
by having the receiver delay a period of time; if during this delay the receiver has
data for the sender, ACKs can be piggybacked to the data, therefore saving
transmissions of segments.
b.) Karn’s = In Karn's algorithm, when a segment is retransmitted, the
current RTO value is doubled, instead of being calculated based on previous RTO
3
measurements. They are used to help with inefficiency when there are fewer
transmissions than there are characters.
6.)
a.) Delayed acknowledgements are used to keep the number of segments
with a small payload small.
b.) Piggybacked acknowledgements are acknowledgements that "ride" with
data, in order to reduce the number of transmissions.
7.) TCP calucates RTO from the delay between transmission of a segment and the
receipt of the acknowledgement for that segment.
8.)
a.) Sliding window flow control prevents the receiver from being overloaded
with data. It does this by restricting the amount of data it is willing to receive.
b.) TCP congestion has two phases: slow start and congestion avoidance. The
sender is in slow start when the congestion window (cnwd) is less than or equal to
the slow start threshold (ssthresh). When the cnwd is bigger than the ssthresh, the
TCP sender is in the congestion avoidance phase. This results in the sender reducing
his sending rate.
c.) Fast retransmit works by immediately retransmitting segments that are
presumed lost (when three duplicate ACKs are received). It does not wait for the
timer to expire. Fast recovery works by dividing the slow-start threshold by half of
the value in the congestion window, and setting the congestion window to that value.
This occurs when the retransmission timer times out or when three duplicate ACKs
arrive.
Report
Questions from EXERCISE 2:
1). Explanation of the fields in the RIP message:
-- command: the type of message
-- version: the version of RIP used
-- routing domain: network prefix A set of routers exchanging routing information
within an administrative domain.
-- ip addresses: the network addresses of the other networks on the other side of the
router. An identifier for a computer or device on a TCP/IP network. Includes Address
Family, Route Tag(used to distinguish between internal routes and external routes), IP
Address(the IP address for the network), Netmask(subnet mask for the network), Next
Hop(IP address of the next hop where the packets for the network should be forwarded),
and Metric(shows how many hops within the network have been traversed on the way to
the destination. A valid number is 1 to 15 and 16 is for an unreachable route.
Outputs from Step 4
‘show ip rip’ for PC1
ripd# show ip rip
Codes: R - RIP, C - connected, O - OSPF, B - BGP
(n) - normal, (s) - static, (d) - default, (r) - redistribute,
(i) - interface
Network
C(i) 10.0.1.0/24
R(n) 10.0.2.0/24
R(n) 10.0.3.0/24
Next Hop
0.0.0.0
10.0.1.1
10.0.1.1
Metric
1
2
3
From
self
10.0.1.1
10.0.1.1
Time
02:59
02:59
4
R(n) 10.0.4.0/24
10.0.1.1
4 10.0.1.1
02:59
‘show ip rip’ for PC2
ripd# show ip rip
Codes: R - RIP, C - connected, O - OSPF, B - BGP
(n) - normal, (s) - static, (d) - default, (r) - redistribute,
(i) - interface
R(n)
C(i)
R(n)
R(n)
Network
10.0.1.0/24
10.0.2.0/24
10.0.3.0/24
10.0.4.0/24
Next Hop
10.0.2.1
0.0.0.0
10.0.2.2
10.0.2.2
Metric
2
1
2
3
From
10.0.2.1
self
10.0.2.2
10.0.2.2
Time
02:58
02:54
02:54
‘show ip rip’ for PC3
ripd# show ip rip
Codes: R - RIP, C - connected, O - OSPF, B - BGP
(n) - normal, (s) - static, (d) - default, (r) - redistribute,
(i) - interface
R(n)
R(n)
C(i)
R(n)
Network
10.0.1.0/24
10.0.2.0/24
10.0.3.0/24
10.0.4.0/24
Next Hop
10.0.3.2
10.0.3.2
0.0.0.0
10.0.3.3
Metric
3
2
1
2
From
10.0.3.2
10.0.3.2
self
10.0.3.3
Time
02:58
02:58
02:52
‘show ip rip’ for PC4
ripd# show ip rip
Codes: R - RIP, C - connected, O - OSPF, B - BGP
(n) - normal, (s) - static, (d) - default, (r) - redistribute,
(i) - interface
R(n)
R(n)
R(n)
C(i)
Network
10.0.1.0/24
10.0.2.0/24
10.0.3.0/24
10.0.4.0/24
Next Hop
10.0.4.3
10.0.4.3
10.0.4.3
0.0.0.0
Metric
4
3
2
1
From
10.0.4.3
10.0.4.3
10.0.4.3
self
Time
02:55
02:55
02:55
Outputs from Step 5
‘netstat –rn’ for PC1
Kernel IP routing table
Destination
Gateway
10.0.4.0
10.0.1.1
10.0.1.0
0.0.0.0
10.0.2.0
10.0.1.1
10.0.3.0
10.0.1.1
127.0.0.0
0.0.0.0
Genmask
255.255.255.0
255.255.255.0
255.255.255.0
255.255.255.0
255.0.0.0
Flags
UG
U
UG
UG
U
MSS
0
0
0
0
0
Window
0
0
0
0
0
irtt
0
0
0
0
0
Iface
eth0
eth0
eth0
eth0
lo
Genmask
255.255.255.0
255.255.255.0
255.255.255.0
255.255.255.0
255.0.0.0
Flags
UG
UG
U
UG
U
MSS
0
0
0
0
0
Window
0
0
0
0
0
irtt
0
0
0
0
0
Iface
eth0
eth0
eth0
eth0
lo
‘netstat –rn’ for PC2
Kernel IP routing table
Destination
Gateway
10.0.4.0
10.0.2.2
10.0.1.0
10.0.2.1
10.0.2.0
0.0.0.0
10.0.3.0
10.0.2.2
127.0.0.0
0.0.0.0
5
‘netstat –rn’ for PC3
Kernel IP routing table
Destination
Gateway
10.0.4.0
10.0.3.3
10.0.1.0
10.0.3.2
10.0.2.0
10.0.3.2
10.0.3.0
0.0.0.0
127.0.0.0
0.0.0.0
Genmask
255.255.255.0
255.255.255.0
255.255.255.0
255.255.255.0
255.0.0.0
Flags
UG
UG
UG
U
U
MSS
0
0
0
0
0
Window
0
0
0
0
0
irtt
0
0
0
0
0
Iface
eth0
eth0
eth0
eth0
lo
Genmask
255.255.255.0
255.255.255.0
255.255.255.0
255.255.255.0
255.0.0.0
Flags
U
UG
UG
UG
U
MSS
0
0
0
0
0
Window
0
0
0
0
0
irtt
0
0
0
0
0
Iface
eth0
eth0
eth0
eth0
lo
‘netstat –rn’ for PC4
Kernel IP routing table
Destination
Gateway
10.0.4.0
0.0.0.0
10.0.1.0
10.0.4.3
10.0.2.0
10.0.4.3
10.0.3.0
10.0.4.3
127.0.0.0
0.0.0.0
2). Differences in the output of commands:
a. ‘show ip rip’ gives a cost metric while ‘netstat –rn’ doesn’t.
b. ‘netstat –rn’ shows the loopback interface while ‘show ip rip’ doesn’t. It
also has netmask and interface information.
c. ‘show ip rip’ also has a time and from column and specifies if the
connection is RIP or OSPF, etc.
3). Output of ‘traceroute’ from Step 7
[root@PC1 floppy]# traceroute 10.0.4.10
traceroute to 10.0.4.10 (10.0.4.10), 30 hops max, 38 byte packets
1
2
3
4
10.0.1.1 (10.0.1.1) 1.747 ms 0.907 ms 1.032 ms
10.0.2.2 (10.0.2.2) 2.689 ms 1.328 ms 1.298 ms
10.0.3.3 (10.0.3.3) 2.982 ms 1.704 ms 1.644 ms
10.0.4.10 (10.0.4.10) 3.519 ms 1.518 ms 1.383 ms
4.) Answers to questions from Step 8 with captured packets to support answers:
1. The destination IP address of RIP packets is 224.0.0.9.
Internet Protocol, Src Addr: 10.0.1.1 (10.0.1.1), Dst Addr:
224.0.0.9 (224.0.0.9)
2. No, only from neighbors.
3. Response; each router sends the RIP message to other neighbor routers to
update routing entries. This is why it was always "response".
Routing Information Protocol
Command: Response (2)
Version: RIPv2 (2)
4. 86 bytes, 2 routing entries. In each message, the network addresses on the
other side of the routers are sent to the PC.
Questions from EXERCISE 3(A):
Output from Step 2
‘netstat –rn’ for PC1
Kernel IP routing table
Destination
Gateway
10.0.4.0
10.0.1.1
Genmask
255.255.255.0
Flags
UG
MSS Window
0 0
irtt Iface
0 eth0
6
10.0.1.0
10.0.2.0
10.0.3.0
127.0.0.0
0.0.0.0
10.0.1.1
10.0.1.1
0.0.0.0
255.255.255.0
255.255.255.0
255.255.255.0
255.0.0.0
U
UG
UG
U
0
0
0
0
0
0
0
0
0
0
0
0
eth0
eth0
eth0
lo
Genmask
255.255.255.0
255.255.255.0
255.255.255.0
255.255.255.0
255.0.0.0
Flags
UG
UG
U
UG
U
MSS
0
0
0
0
0
Window
0
0
0
0
0
irtt
0
0
0
0
0
Iface
eth0
eth0
eth0
eth0
lo
Genmask
255.255.255.0
255.255.255.0
255.255.255.0
255.255.255.0
255.0.0.0
Flags
UG
UG
UG
U
U
MSS
0
0
0
0
0
Window
0
0
0
0
0
irtt
0
0
0
0
0
Iface
eth0
eth0
eth0
eth0
lo
Genmask
255.255.255.0
255.255.255.0
255.255.255.0
255.255.255.0
255.0.0.0
Flags
U
UG
UG
UG
U
MSS
0
0
0
0
0
Window
0
0
0
0
0
irtt
0
0
0
0
0
Iface
eth0
eth0
eth0
eth0
lo
Genmask
255.255.255.0
255.255.255.0
255.255.255.0
255.255.255.0
255.0.0.0
Flags
UG
U
UG
UG
U
MSS
0
0
0
0
0
Window
0
0
0
0
0
irtt
0
0
0
0
0
Iface
eth0
eth0
eth0
eth0
lo
Genmask
255.255.255.0
255.255.255.0
255.255.255.0
255.255.255.0
255.0.0.0
Flags
UG
UG
U
UG
U
MSS
0
0
0
0
0
Window
0
0
0
0
0
irtt
0
0
0
0
0
Iface
eth0
eth0
eth0
eth0
lo
Genmask
255.255.255.0
255.255.255.0
255.255.255.0
255.255.255.0
255.0.0.0
Flags
UG
UG
UG
U
U
MSS
0
0
0
0
0
Window
0
0
0
0
0
irtt
0
0
0
0
0
Iface
eth0
eth0
eth0
eth0
lo
‘netstat –rn’ for PC2
Kernel IP routing table
Destination
Gateway
10.0.4.0
10.0.2.2
10.0.1.0
10.0.2.1
10.0.2.0
0.0.0.0
10.0.3.0
10.0.2.2
127.0.0.0
0.0.0.0
‘netstat –rn’ for PC3
Kernel IP routing table
Destination
Gateway
10.0.4.0
10.0.3.3
10.0.1.0
10.0.3.2
10.0.2.0
10.0.3.2
10.0.3.0
0.0.0.0
127.0.0.0
0.0.0.0
‘netstat –rn’ for PC4
Kernel IP routing table
Destination
Gateway
10.0.4.0
0.0.0.0
10.0.1.0
10.0.4.3
10.0.2.0
10.0.4.3
10.0.3.0
10.0.4.3
127.0.0.0
0.0.0.0
Output from Step 5
‘netstat –rn’ for PC1
Kernel IP routing table
Destination
Gateway
10.0.4.0
10.0.1.1
10.0.1.0
0.0.0.0
10.0.2.0
10.0.1.1
10.0.3.0
10.0.1.1
127.0.0.0
0.0.0.0
‘netstat –rn’ for PC2
Kernel IP routing table
Destination
Gateway
10.0.4.0
10.0.2.2
10.0.1.0
10.0.2.1
10.0.2.0
0.0.0.0
10.0.3.0
10.0.2.2
127.0.0.0
0.0.0.0
‘netstat –rn’ for PC3
Kernel IP routing table
Destination
Gateway
10.0.4.0
10.0.3.3
10.0.1.0
10.0.3.2
10.0.2.0
10.0.3.2
10.0.3.0
0.0.0.0
127.0.0.0
0.0.0.0
7
‘netstat –rn’ for PC4
Kernel IP routing table
Destination
Gateway
10.0.4.0
0.0.0.0
10.0.1.0
10.0.4.3
10.0.2.0
10.0.4.3
10.0.3.0
10.0.4.3
127.0.0.0
0.0.0.0
Genmask
255.255.255.0
255.255.255.0
255.255.255.0
255.255.255.0
255.0.0.0
Flags
U
UG
UG
UG
U
MSS
0
0
0
0
0
Window
0
0
0
0
0
irtt
0
0
0
0
0
Iface
eth0
eth0
eth0
eth0
lo
The time it took to update the routing tables was not too long. (few seconds!)
Questions from EXERCISE 3(B):
--- 10.0.1.10 ping statistics --196 packets transmitted, 24 received, +113 errors, 87% packet loss, time 195235ms
rtt min/avg/max/mdev = 1.057/1.808/6.620/1.333 ms, pipe 3
The number of lost packets = 172.
The time it took RIP to update the routing tables is approximately 172 seconds (2 minutes
and 52 seconds).
Questions from EXERCISE 4(B):
After disconnecting PC3, the network became unreachable for a very long time. The
metric in ethereal was 16 hops, which means the cost is infinity.
RIP packet starting from Frame 76 reached count-to-infinity:
Routing Information Protocol
Command: Response (2)
Version: RIPv2 (2)
Routing Domain: 0
IP Address: 10.0.1.0, Metric: 16
Address Family: IP (2)
Route Tag: 0
IP Address: 10.0.1.0 (10.0.1.0)
Netmask: 255.255.255.0 (255.255.255.0)
Next Hop: 0.0.0.0 (0.0.0.0)
Metric: 16
Questions from EXERCISE 4(C):
In Exercise 4b, the time of convergence was slow. In Exercise 4c, the routers converged a
lot faster.
Exercies 4b without flash update:
[root@PC2 root]# ping 10.0.1.10
PING 10.0.1.10 (10.0.1.10) 56(84) bytes of data.
64 bytes from 10.0.1.10: icmp_seq=1 ttl=62 time=1.16 ms
64 bytes from 10.0.1.10: icmp_seq=2 ttl=62 time=1.05 ms
64 bytes from 10.0.1.10: icmp_seq=3 ttl=62 time=1.06 ms
64 bytes from 10.0.1.10: icmp_seq=4 ttl=62 time=1.07 ms
64 bytes from 10.0.1.10: icmp_seq=5 ttl=62 time=0.998 ms
64 bytes from 10.0.1.10: icmp_seq=6 ttl=62 time=1.00 ms
64 bytes from 10.0.1.10: icmp_seq=7 ttl=62 time=1.08 ms
64 bytes from 10.0.1.10: icmp_seq=8 ttl=62 time=1.10 ms
64 bytes from 10.0.1.10: icmp_seq=9 ttl=62 time=1.10 ms
64 bytes from 10.0.1.10: icmp_seq=10 ttl=62 time=1.10 ms
64 bytes from 10.0.1.10: icmp_seq=11 ttl=62 time=1.02 ms
64 bytes from 10.0.1.10: icmp_seq=12 ttl=62 time=1.04 ms
64 bytes from 10.0.1.10: icmp_seq=13 ttl=62 time=1.05 ms
8
64 bytes from 10.0.1.10: icmp_seq=14 ttl=62 time=1.24 ms
64 bytes from 10.0.1.10: icmp_seq=15 ttl=62 time=0.983 ms
64 bytes from 10.0.1.10: icmp_seq=16 ttl=62 time=1.07 ms
64 bytes from 10.0.1.10: icmp_seq=17 ttl=62 time=1.08 ms
64 bytes from 10.0.1.10: icmp_seq=18 ttl=62 time=1.08 ms
64 bytes from 10.0.1.10: icmp_seq=19 ttl=62 time=0.999 ms
From 10.0.3.10 icmp_seq=20 Destination Net Unreachable
From 10.0.3.10 icmp_seq=21 Destination Net Unreachable
From 10.0.3.10 icmp_seq=22 Destination Net Unreachable
From 10.0.3.10 icmp_seq=23 Destination Net Unreachable
ping: sendmsg: Network is unreachable
ping: sendmsg: Network is unreachable
ping: sendmsg: Network is unreachable
ping: sendmsg: Network is unreachable
ping: sendmsg: Network is unreachable
ping: sendmsg: Network is unreachable
ping: sendmsg: Network is unreachable
ping: sendmsg: Network is unreachable
ping: sendmsg: Network is unreachable
ping: sendmsg: Network is unreachable
ping: sendmsg: Network is unreachable
ping: sendmsg: Network is unreachable
ping: sendmsg: Network is unreachable
ping: sendmsg: Network is unreachable
ping: sendmsg: Network is unreachable
ping: sendmsg: Network is unreachable
ping: sendmsg: Network is unreachable
ping: sendmsg: Network is unreachable
ping: sendmsg: Network is unreachable
64 bytes from 10.0.1.10: icmp_seq=178 ttl=63 time=2.26 ms
64 bytes from 10.0.1.10: icmp_seq=179 ttl=63 time=0.768 ms
64 bytes from 10.0.1.10: icmp_seq=180 ttl=63 time=0.775 ms
64 bytes from 10.0.1.10: icmp_seq=181 ttl=63 time=0.681 ms
64 bytes from 10.0.1.10: icmp_seq=182 ttl=63 time=0.685 ms
64 bytes from 10.0.1.10: icmp_seq=183 ttl=63 time=0.759 ms
64 bytes from 10.0.1.10: icmp_seq=184 ttl=63 time=0.763 ms
64 bytes from 10.0.1.10: icmp_seq=185 ttl=63 time=0.747 ms
64 bytes from 10.0.1.10: icmp_seq=186 ttl=63 time=0.730 ms
64 bytes from 10.0.1.10: icmp_seq=187 ttl=63 time=0.728 ms
64 bytes from 10.0.1.10: icmp_seq=188 ttl=63 time=0.714 ms
64 bytes from 10.0.1.10: icmp_seq=189 ttl=63 time=0.702 ms
64 bytes from 10.0.1.10: icmp_seq=190 ttl=63 time=0.691 ms
64 bytes from 10.0.1.10: icmp_seq=191 ttl=63 time=0.773 ms
64 bytes from 10.0.1.10: icmp_seq=192 ttl=63 time=0.759 ms
64 bytes from 10.0.1.10: icmp_seq=193 ttl=63 time=0.753 ms
64 bytes from 10.0.1.10: icmp_seq=194 ttl=63 time=0.749 ms
64 bytes from 10.0.1.10: icmp_seq=195 ttl=63 time=0.734 ms
64 bytes from 10.0.1.10: icmp_seq=196 ttl=63 time=0.733 ms
64 bytes from 10.0.1.10: icmp_seq=197 ttl=63 time=0.713 ms
64 bytes from 10.0.1.10: icmp_seq=198 ttl=63 time=0.704 ms
64 bytes from 10.0.1.10: icmp_seq=199 ttl=63 time=0.748 ms
64 bytes from 10.0.1.10: icmp_seq=200 ttl=63 time=0.773 ms
64 bytes from 10.0.1.10: icmp_seq=201 ttl=63 time=0.748 ms
64 bytes from 10.0.1.10: icmp_seq=202 ttl=63 time=0.749 ms
64 bytes from 10.0.1.10: icmp_seq=203 ttl=63 time=0.743 ms
64 bytes from 10.0.1.10: icmp_seq=204 ttl=63 time=1.44 ms
64 bytes from 10.0.1.10: icmp_seq=205 ttl=63 time=0.757 ms
64 bytes from 10.0.1.10: icmp_seq=206 ttl=63 time=0.737 ms
64 bytes from 10.0.1.10: icmp_seq=207 ttl=63 time=0.723 ms
64 bytes from 10.0.1.10: icmp_seq=208 ttl=63 time=0.723 ms
64 bytes from 10.0.1.10: icmp_seq=209 ttl=63 time=0.712 ms
64 bytes from 10.0.1.10: icmp_seq=210 ttl=63 time=0.708 ms
--- 10.0.1.10 ping statistics ---
9
210 packets transmitted, 52 received, +4 errors, 75% packet loss, time 209248ms
rtt min/avg/max/mdev = 0.681/0.901/2.262/0.265 ms
Exercise 4c with flash update:
[root@PC2 root]# ping 10.0.1.10
PING 10.0.1.10 (10.0.1.10) 56(84) bytes of data.
64 bytes from 10.0.1.10: icmp_seq=1 ttl=62 time=4.10 ms
64 bytes from 10.0.1.10: icmp_seq=2 ttl=62 time=1.08 ms
64 bytes from 10.0.1.10: icmp_seq=3 ttl=62 time=1.11 ms
64 bytes from 10.0.1.10: icmp_seq=4 ttl=62 time=1.02 ms
64 bytes from 10.0.1.10: icmp_seq=5 ttl=62 time=1.10 ms
64 bytes from 10.0.1.10: icmp_seq=6 ttl=62 time=1.06 ms
64 bytes from 10.0.1.10: icmp_seq=7 ttl=62 time=1.09 ms
64 bytes from 10.0.1.10: icmp_seq=8 ttl=62 time=1.00 ms
64 bytes from 10.0.1.10: icmp_seq=9 ttl=62 time=0.976 ms
64 bytes from 10.0.1.10: icmp_seq=10 ttl=62 time=1.19 ms
64 bytes from 10.0.1.10: icmp_seq=11 ttl=62 time=1.10 ms
64 bytes from 10.0.1.10: icmp_seq=12 ttl=62 time=1.11 ms
64 bytes from 10.0.1.10: icmp_seq=13 ttl=62 time=0.945 ms
64 bytes from 10.0.1.10: icmp_seq=14 ttl=62 time=1.05 ms
64 bytes from 10.0.1.10: icmp_seq=15 ttl=62 time=1.06 ms
64 bytes from 10.0.1.10: icmp_seq=16 ttl=62 time=1.07 ms
64 bytes from 10.0.1.10: icmp_seq=17 ttl=62 time=1.09 ms
64 bytes from 10.0.1.10: icmp_seq=18 ttl=62 time=1.18 ms
64 bytes from 10.0.1.10: icmp_seq=19 ttl=62 time=1.27 ms
64 bytes from 10.0.1.10: icmp_seq=20 ttl=62 time=1.04 ms
64 bytes from 10.0.1.10: icmp_seq=21 ttl=62 time=1.03 ms
64 bytes from 10.0.1.10: icmp_seq=22 ttl=62 time=1.12 ms
64 bytes from 10.0.1.10: icmp_seq=23 ttl=62 time=0.964 ms
64 bytes from 10.0.1.10: icmp_seq=24 ttl=62 time=0.978 ms
64 bytes from 10.0.1.10: icmp_seq=25 ttl=62 time=1.07 ms
64 bytes from 10.0.1.10: icmp_seq=26 ttl=62 time=1.08 ms
64 bytes from 10.0.1.10: icmp_seq=27 ttl=62 time=1.18 ms
64 bytes from 10.0.1.10: icmp_seq=28 ttl=62 time=1.19 ms
64 bytes from 10.0.1.10: icmp_seq=29 ttl=62 time=1.19 ms
64 bytes from 10.0.1.10: icmp_seq=30 ttl=62 time=1.10 ms
64 bytes from 10.0.1.10: icmp_seq=31 ttl=62 time=1.12 ms
64 bytes from 10.0.1.10: icmp_seq=32 ttl=62 time=1.05 ms
64 bytes from 10.0.1.10: icmp_seq=33 ttl=62 time=1.04 ms
64 bytes from 10.0.1.10: icmp_seq=34 ttl=62 time=1.05 ms
64 bytes from 10.0.1.10: icmp_seq=35 ttl=62 time=1.06 ms
64 bytes from 10.0.1.10: icmp_seq=36 ttl=62 time=1.07 ms
64 bytes from 10.0.1.10: icmp_seq=37 ttl=62 time=1.07 ms
64 bytes from 10.0.1.10: icmp_seq=38 ttl=62 time=1.08 ms
64 bytes from 10.0.1.10: icmp_seq=39 ttl=62 time=1.08 ms
64 bytes from 10.0.1.10: icmp_seq=40 ttl=62 time=1.01 ms
64 bytes from 10.0.1.10: icmp_seq=41 ttl=62 time=1.01 ms
64 bytes from 10.0.1.10: icmp_seq=42 ttl=62 time=1.01 ms
64 bytes from 10.0.1.10: icmp_seq=43 ttl=62 time=1.02 ms
64 bytes from 10.0.1.10: icmp_seq=44 ttl=62 time=1.04 ms
From 10.0.3.10 icmp_seq=45 Destination Net Unreachable
From 10.0.3.10 icmp_seq=46 Destination Net Unreachable
ping: sendmsg: Network is unreachable
ping: sendmsg: Network is unreachable
ping: sendmsg: Network is unreachable
ping: sendmsg: Network is unreachable
ping: sendmsg: Network is unreachable
ping: sendmsg: Network is unreachable
ping: sendmsg: Network is unreachable
ping: sendmsg: Network is unreachable
64 bytes from 10.0.1.10: icmp_seq=204 ttl=63 time=1.51 ms
64 bytes from 10.0.1.10: icmp_seq=205 ttl=63 time=0.728 ms
64 bytes from 10.0.1.10: icmp_seq=206 ttl=63 time=0.724 ms
10
64 bytes from 10.0.1.10: icmp_seq=207 ttl=63 time=0.731 ms
64 bytes from 10.0.1.10: icmp_seq=208 ttl=63 time=0.725 ms
64 bytes from 10.0.1.10: icmp_seq=209 ttl=63 time=0.714 ms
64 bytes from 10.0.1.10: icmp_seq=210 ttl=63 time=0.691 ms
64 bytes from 10.0.1.10: icmp_seq=211 ttl=63 time=0.693 ms
64 bytes from 10.0.1.10: icmp_seq=212 ttl=63 time=0.688 ms
64 bytes from 10.0.1.10: icmp_seq=213 ttl=63 time=0.685 ms
64 bytes from 10.0.1.10: icmp_seq=214 ttl=63 time=0.677 ms
64 bytes from 10.0.1.10: icmp_seq=215 ttl=63 time=0.682 ms
64 bytes from 10.0.1.10: icmp_seq=216 ttl=63 time=0.674 ms
64 bytes from 10.0.1.10: icmp_seq=217 ttl=63 time=0.756 ms
64 bytes from 10.0.1.10: icmp_seq=218 ttl=63 time=0.748 ms
64 bytes from 10.0.1.10: icmp_seq=219 ttl=63 time=0.741 ms
64 bytes from 10.0.1.10: icmp_seq=220 ttl=63 time=0.732 ms
64 bytes from 10.0.1.10: icmp_seq=221 ttl=63 time=0.730 ms
64 bytes from 10.0.1.10: icmp_seq=222 ttl=63 time=0.728 ms
64 bytes from 10.0.1.10: icmp_seq=223 ttl=63 time=0.723 ms
64 bytes from 10.0.1.10: icmp_seq=224 ttl=63 time=0.712 ms
64 bytes from 10.0.1.10: icmp_seq=225 ttl=63 time=0.730 ms
64 bytes from 10.0.1.10: icmp_seq=226 ttl=63 time=0.715 ms
64 bytes from 10.0.1.10: icmp_seq=227 ttl=63 time=0.696 ms
64 bytes from 10.0.1.10: icmp_seq=228 ttl=63 time=0.703 ms
64 bytes from 10.0.1.10: icmp_seq=229 ttl=63 time=0.704 ms
64 bytes from 10.0.1.10: icmp_seq=230 ttl=63 time=0.698 ms
64 bytes from 10.0.1.10: icmp_seq=231 ttl=63 time=0.693 ms
64 bytes from 10.0.1.10: icmp_seq=232 ttl=63 time=0.676 ms
64 bytes from 10.0.1.10: icmp_seq=233 ttl=63 time=0.752 ms
64 bytes from 10.0.1.10: icmp_seq=234 ttl=63 time=0.753 ms
--- 10.0.1.10 ping statistics --234 packets transmitted, 75 received, +2 errors, 67% packet loss, time 233531ms
rtt min/avg/max/mdev = 0.674/0.978/4.104/0.414 ms
Questions from EXERCISE 5(C):
1.) 30 packets, 30 seconds.
2.) Asdf (still looking for ethereal output from other people in class)
Hello Packet:
Internet Protocol, Src Addr: 10.0.1.1 (10.0.1.1), Dst Addr: 224.0.0.5 (224.0.0.5)
Version: 4
Header length: 20 bytes
Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00)
0000 00.. = Differentiated Services Codepoint: Default (0x00)
.... ..0. = ECN-Capable Transport (ECT): 0
.... ...0 = ECN-CE: 0
Total Length: 68
Identification: 0x3555 (13653)
Flags: 0x00
.0.. = Don't fragment: Not set
..0. = More fragments: Not set
Fragment offset: 0
Time to live: 1
Protocol: OSPF (0x59)
Header checksum: 0x9906 (correct)
Source: 10.0.1.1 (10.0.1.1)
Destination: 224.0.0.5 (224.0.0.5)
Open Shortest Path First
OSPF Header
OSPF Version: 2
Message Type: Hello Packet (1)
Packet Length: 48
Source OSPF Router: 10.0.1.1 (10.0.1.1)
Area ID: 0.0.0.1
Packet Checksum: 0xd093 (correct)
Auth Type: Null
Auth Data (none)
11
OSPF Hello Packet
Network Mask: 255.255.255.0
Hello Interval: 10 seconds
Options: 0x2 (E)
Router Priority: 1
Router Dead Interval: 40 seconds
Designated Router: 10.0.1.2
Backup Designated Router: 10.0.1.1
Active Neighbor: 10.0.1.2
Update Packet:
Internet Protocol, Src Addr: 10.0.1.2 (10.0.1.2), Dst Addr: 224.0.0.5 (224.0.0.5)
Version: 4
Header length: 20 bytes
Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00)
0000 00.. = Differentiated Services Codepoint: Default (0x00)
.... ..0. = ECN-Capable Transport (ECT): 0
.... ...0 = ECN-CE: 0
Total Length: 84
Identification: 0x3706 (14086)
Flags: 0x00
.0.. = Don't fragment: Not set
..0. = More fragments: Not set
Fragment offset: 0
Time to live: 1
Protocol: OSPF (0x59)
Header checksum: 0x9744 (correct)
Source: 10.0.1.2 (10.0.1.2)
Destination: 224.0.0.5 (224.0.0.5)
Open Shortest Path First
OSPF Header
OSPF Version: 2
Message Type: LS Update (4)
Packet Length: 64
Source OSPF Router: 10.0.1.2 (10.0.1.2)
Area ID: 0.0.0.1
Packet Checksum: 0x4563 (correct)
Auth Type: Null
Auth Data (none)
LS Update Packet
Number of LSAs: 1
LS Type: Router-LSA
LS Age: 2 seconds
Options: 0x22 (E/DC)
Link-State Advertisement Type: Router-LSA (1)
Link State ID: 10.0.4.4
Advertising Router: 10.0.4.4 (10.0.4.4)
LS Sequence Number: 0x80000016
LS Checksum: cef5
Length: 36
Flags: 0x00
Number of Links: 1
Type: Transit ID: 10.0.5.6
Data: 10.0.5.8
Metric: 10
IP address of Designated Router: 10.0.5.6
Link Data: 10.0.5.8
Link Type: 2 - Connection to a transit network
Number of TOS metrics: 0
TOS 0 metric: 10
Acknowledge Packet:
Internet Protocol, Src Addr: 10.0.1.1 (10.0.1.1), Dst Addr: 224.0.0.5 (224.0.0.5)
Version: 4
Header length: 20 bytes
Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00)
0000 00.. = Differentiated Services Codepoint: Default (0x00)
.... ..0. = ECN-Capable Transport (ECT): 0
.... ...0 = ECN-CE: 0
Total Length: 64
12
Identification: 0x355c (13660)
Flags: 0x00
.0.. = Don't fragment: Not set
..0. = More fragments: Not set
Fragment offset: 0
Time to live: 1
Protocol: OSPF (0x59)
Header checksum: 0x9903 (correct)
Source: 10.0.1.1 (10.0.1.1)
Destination: 224.0.0.5 (224.0.0.5)
Open Shortest Path First
OSPF Header
OSPF Version: 2
Message Type: LS Acknowledge (5)
Packet Length: 44
Source OSPF Router: 10.0.1.1 (10.0.1.1)
Area ID: 0.0.0.1
Packet Checksum: 0x6591 (correct)
Auth Type: Null
Auth Data (none)
LSA Header
LS Age: 2 seconds
Options: 0x22 (E/DC)
Link-State Advertisement Type: Router-LSA (1)
Link State ID: 10.0.4.4
Advertising Router: 10.0.4.4 (10.0.4.4)
LS Sequence Number: 0x80000016
LS Checksum: cef5
Length: 36
3.) Link state database of PC2 output:
PC2# show ip ospf database
OSPF Router with ID (10.0.1.2)
Router Link States (Area 0.0.0.1)
Link ID
10.0.1.1
10.0.1.2
10.0.3.1
10.0.3.2
10.0.3.4
10.0.4.3
10.0.4.4
10.0.6.7
ADV Router
10.0.1.1
10.0.1.2
10.0.3.1
10.0.3.2
10.0.3.4
10.0.4.3
10.0.4.4
10.0.6.7
Age
691
669
1120
878
622
1549
565
536
Seq#
0x800000dc
0x8000000b
0x80000011
0x8000000f
0x80000008
0x8000000b
0x80000016
0x8000000e
CkSum
0x8681
0x0fbd
0xccd8
0x8459
0x16c0
0x7b1c
0xcef5
0x6353
Link count
2
2
2
1
2
2
1
2
Net Link States (Area 0.0.0.1)
Link ID
10.0.1.2
10.0.2.3
10.0.3.4
10.0.5.6
10.0.6.6
ADV Router
10.0.1.2
10.0.3.1
10.0.3.4
10.0.4.3
10.0.4.3
Age
690
1885
643
1804
1549
Seq#
0x80000006
0x8000000e
0x80000006
0x8000000c
0x80000005
CkSum
0x59c8
0x449e
0x5db6
0x567e
0xb531
4.) Updated packet contains numbers of LSA and the time that the LSA entries stay
there. In addition, it also showed the number of links which are Stub and Transit.
5.) Answers from Step 5 and Step 9
1. 19 seconds for OSPF "update" message
2. 15 OSPF messages including "Hello" and "Update & Acknowledge" messages before it's
connected
3. OSPF Update message
13
4. Periodically, each router broadcast LSA to surrounding hosts by using OSPF update and hosts
which got updated, will use "acknowledge" OSPF to acknowledge that it got updated.
5. It is using IP (internet Protocol) |IP | OSPF in Data|
6. broadcast address
7. 30 packets 19 secs
8. Yes; all of the OSPF databases are all the same because it's flooded.
Questions from EXERCISE 6:
1.) Asdf (still looking for ethereal output from other people in class)
Different types of OSPF packets that we did not see in part 5 are LS request and DB
Descr.
Open Shortest Path First
OSPF Header
OSPF Version: 2
Message Type: DB Descr. (2)
Packet Length: 32
Source OSPF Router: 10.0.1.2 (10.0.1.2)
Area ID: 0.0.0.0 (Backbone)
Packet Checksum: 0xbc2d (correct)
Auth Type: Null
Auth Data (none)
OSPF DB Description
Interface MTU: 1500
Options: 0x2 (E)
Flags: 0x7 (MS/M/I)
DD Sequence: 1109126319
Open Shortest Path First
OSPF Header
OSPF Version: 2
Message Type: LS Request (3)
Packet Length: 36
Source OSPF Router: 10.0.1.1 (10.0.1.1)
Area ID: 0.0.0.0 (Backbone)
Packet Checksum: 0xdcd2 (correct)
Auth Type: Null
Auth Data (none)
Link State Request
Link-State Advertisement Type: Router-LSA (1)
Link State ID: 10.0.1.2
Advertising Router: 10.0.1.2 (10.0.1.2)
2.) All link state databases:
PC1 ospfd# show ip ospf database
OSPF Router with ID (10.0.1.1)
Router Link States (Area 0.0.0.0)
Link ID
10.0.1.1
10.0.1.2
ADV Router
10.0.1.1
10.0.1.2
Age Seq#
CkSum Link count
583 0x80000003 0x53c3 1
571 0x80000003 0x51c2 1
Net Link States (Area 0.0.0.0)
Link ID
10.0.1.1
ADV Router
10.0.1.1
Age Seq#
CkSum
583 0x80000001 0x73b5
Summary Link States (Area 0.0.0.0)
Link ID
10.0.2.0
10.0.3.0
10.0.4.0
10.0.5.0
10.0.6.0
ADV Router
10.0.1.1
10.0.1.1
10.0.1.1
10.0.1.2
10.0.1.2
Age
273
273
242
571
138
Seq#
0x80000001
0x80000001
0x80000004
0x80000001
0x80000004
CkSum
0xcf6b
0xce6a
0xbd77
0xa88e
0xa190
Route
10.0.2.0/24
10.0.3.0/24
10.0.4.0/24
10.0.5.0/24
10.0.6.0/24
14
10.0.7.0
10.0.1.2
551 0x80000001 0x9c97 10.0.7.0/24
PC2 ospfd# show ip ospf database
OSPF Router with ID (10.0.1.2)
Router Link States (Area 0.0.0.0)
Link ID
10.0.1.1
10.0.1.2
ADV Router
10.0.1.1
10.0.1.2
Age Seq#
CkSum Link count
918 0x80000003 0x53c3 1
904 0x80000003 0x51c2 1
Net Link States (Area 0.0.0.0)
Link ID
10.0.1.1
ADV Router
10.0.1.1
Age Seq#
CkSum
918 0x80000001 0x73b5
Summary Link States (Area 0.0.0.0)
Link ID
10.0.2.0
10.0.3.0
10.0.4.0
10.0.5.0
10.0.6.0
10.0.7.0
ADV Router
10.0.1.1
10.0.1.1
10.0.1.1
10.0.1.2
10.0.1.2
10.0.1.2
Age
608
608
577
904
471
884
Seq#
0x80000001
0x80000001
0x80000004
0x80000001
0x80000004
0x80000001
CkSum
0xcf6b
0xce6a
0xbd77
0xa88e
0xa190
0x9c97
Route
10.0.2.0/24
10.0.3.0/24
10.0.4.0/24
10.0.5.0/24
10.0.6.0/24
10.0.7.0/24
Router Link States (Area 0.0.0.2)
Link ID
10.0.1.2
10.0.6.6
10.0.6.7
10.0.7.8
ADV Router
10.0.1.2
10.0.6.6
10.0.6.7
10.0.7.8
Age
480
475
482
788
Seq#
0x80000006
0x80000006
0x80000007
0x80000003
CkSum
0xe918
0x6728
0x5e3f
0x6f16
Link count
1
2
2
2
Net Link States (Area 0.0.0.2)
Link ID
10.0.5.8
10.0.6.7
10.0.7.8
ADV Router
10.0.7.8
10.0.6.7
10.0.7.8
Age
478
476
788
Seq#
0x80000004
0x80000002
0x80000001
CkSum
0x8e38
0x9d60
0xb81f
Summary Link States (Area 0.0.0.2)
Link ID
10.0.1.0
10.0.2.0
10.0.3.0
10.0.4.0
ADV Router
10.0.1.2
10.0.1.2
10.0.1.2
10.0.1.2
Age
904
602
602
571
Seq#
0x80000001
0x80000001
0x80000001
0x80000004
CkSum
0xd466
0x2e02
0x2d01
0x1c0e
Route
10.0.1.0/24
10.0.2.0/24
10.0.3.0/24
10.0.4.0/24
PC3 ospfd# show ip ospf database
OSPF Router with ID (10.0.3.4)
Router Link States (Area 0.0.0.1)
Link ID
10.0.1.1
10.0.3.3
10.0.3.4
10.0.4.5
ADV Router
10.0.1.1
10.0.3.3
10.0.3.4
10.0.4.5
Age
646
669
646
640
Seq#
0x8000000c
0x80000007
0x8000000b
0x80000005
CkSum
0x57b4
0x9d19
0x01bd
0xedbe
Link count
1
2
2
2
Net Link States (Area 0.0.0.1)
Link ID
10.0.2.1
10.0.3.4
10.0.4.4
ADV Router
10.0.1.1
10.0.3.4
10.0.3.4
Age
646
748
645
Seq#
0x80000004
0x80000002
0x80000002
CkSum
0xc743
0x799c
0x937e
Summary Link States (Area 0.0.0.1)
15
Link ID
10.0.1.0
10.0.5.0
10.0.6.0
10.0.7.0
ADV Router
10.0.1.1
10.0.1.1
10.0.1.1
10.0.1.1
Age
1179
962
528
942
Seq#
0x80000001
0x80000001
0x80000004
0x80000001
CkSum
0xda61
0x131b
0x0c1d
0x0724
Route
10.0.1.0/24
10.0.5.0/24
10.0.6.0/24
10.0.7.0/24
PC4 ospfd# show ip ospf database
OSPF Router with ID (10.0.6.7)
Router Link States (Area 0.0.0.2)
Link ID
10.0.1.2
10.0.6.6
10.0.6.7
10.0.7.8
ADV Router
10.0.1.2
10.0.6.6
10.0.6.7
10.0.7.8
Age
608
600
606
913
Seq#
0x80000006
0x80000006
0x80000007
0x80000003
CkSum
0xe918
0x6728
0x5e3f
0x6f16
Link count
1
2
2
2
Net Link States (Area 0.0.0.2)
Link ID
10.0.5.8
10.0.6.7
10.0.7.8
ADV Router
10.0.7.8
10.0.6.7
10.0.7.8
Age
603
600
913
Seq#
0x80000004
0x80000002
0x80000001
CkSum
0x8e38
0x9d60
0xb81f
Summary Link States (Area 0.0.0.2)
Link ID
10.0.1.0
10.0.2.0
10.0.3.0
10.0.4.0
ADV Router
10.0.1.2
10.0.1.2
10.0.1.2
10.0.1.2
Age
1032
729
729
698
Seq#
0x80000001
0x80000001
0x80000001
0x80000004
CkSum
0xd466
0x2e02
0x2d01
0x1c0e
Route
10.0.1.0/24
10.0.2.0/24
10.0.3.0/24
10.0.4.0/24
Router1#show ip ospf database
OSPF Router with ID (10.0.3.3) (Process ID 1)
Router Link States (Area 1)
Link ID
10.0.1.1
10.0.3.3
10.0.3.4
10.0.4.5
ADV Router
10.0.1.1
10.0.3.3
10.0.3.4
10.0.4.5
Age
467
490
469
463
Seq#
0x8000000C
0x80000007
0x8000000B
0x80000005
Checksum
0x57B4
0x9D19
0x1BD
0xEDBE
Seq#
0x80000004
0x80000002
0x80000002
Checksum
0xC743
0x799C
0x937E
Link count
1
2
2
2
Net Link States (Area 1)
Link ID
10.0.2.1
10.0.3.4
10.0.4.4
ADV Router
10.0.1.1
10.0.3.4
10.0.3.4
Age
467
571
468
Summary Net Link States (Area 1)
Link ID
10.0.1.0
10.0.5.0
10.0.6.0
10.0.7.0
ADV Router
10.0.1.1
10.0.1.1
10.0.1.1
10.0.1.1
Age
1002
785
349
766
Seq#
0x80000001
0x80000001
0x80000004
0x80000001
Checksum
0xDA61
0x131B
0xC1D
0x724
Router2#show ip ospf database
OSPF Router with ID (10.0.4.5) (Process ID 1)
Router Link States (Area 1)
Link ID
10.0.1.1
10.0.3.3
10.0.3.4
10.0.4.5
ADV Router
10.0.1.1
10.0.3.3
10.0.3.4
10.0.4.5
Age
430
455
433
426
Seq#
0x8000000C
0x80000007
0x8000000B
0x80000005
Checksum
0x57B4
0x9D19
0x1BD
0xEDBE
Link count
1
2
2
2
16
Net Link States (Area 1)
Link ID
10.0.2.1
10.0.3.4
10.0.4.4
ADV Router
10.0.1.1
10.0.3.4
10.0.3.4
Age
430
534
432
Seq#
0x80000004
0x80000002
0x80000002
Checksum
0xC743
0x799C
0x937E
Summary Net Link States (Area 1)
Link ID
10.0.1.0
10.0.5.0
10.0.6.0
10.0.7.0
ADV Router
10.0.1.1
10.0.1.1
10.0.1.1
10.0.1.1
Age
965
748
313
730
Seq#
0x80000001
0x80000001
0x80000004
0x80000001
Checksum
0xDA61
0x131B
0xC1D
0x724
Router3#show ip ospf database
OSPF Router with ID (10.0.6.6) (Process ID 1)
Router Link States (Area 2)
Link ID
10.0.1.2
10.0.6.6
10.0.6.7
10.0.7.8
ADV Router
10.0.1.2
10.0.6.6
10.0.6.7
10.0.7.8
Age
212
205
212
519
Seq#
0x80000006
0x80000006
0x80000007
0x80000003
Checksum
0xE918
0x6728
0x5E3F
0x6F16
Seq#
0x80000004
0x80000002
0x80000001
Checksum
0x8E38
0x9D60
0xB81F
Link count
1
2
2
2
Net Link States (Area 2)
Link ID
10.0.5.8
10.0.6.7
10.0.7.8
ADV Router
10.0.7.8
10.0.6.7
10.0.7.8
Age
209
206
519
Summary Net Link States (Area 2)
Link ID
10.0.1.0
10.0.2.0
10.0.3.0
10.0.4.0
ADV Router
10.0.1.2
10.0.1.2
10.0.1.2
10.0.1.2
Age
636
333
333
304
Seq#
0x80000001
0x80000001
0x80000001
0x80000004
Checksum
0xD466
0x2E02
0x2D01
0x1C0E
Router4#show ip ospf database
OSPF Router with ID (10.0.7.8) (Process ID 1)
Router Link States (Area 2)
Link ID
10.0.1.2
10.0.6.6
10.0.6.7
10.0.7.8
ADV Router
10.0.1.2
10.0.6.6
10.0.6.7
10.0.7.8
Age
294
288
294
599
Seq#
0x80000006
0x80000006
0x80000007
0x80000003
Checksum
0xE918
0x6728
0x5E3F
0x6F16
Seq#
0x80000004
0x80000002
0x80000001
Checksum
0x8E38
0x9D60
0xB81F
Link count
1
2
2
2
Net Link States (Area 2)
Link ID
10.0.5.8
10.0.6.7
10.0.7.8
ADV Router
10.0.7.8
10.0.6.7
10.0.7.8
Age
289
288
599
Summary Net Link States (Area 2)
Link ID
10.0.1.0
10.0.2.0
10.0.3.0
10.0.4.0
ADV Router
10.0.1.2
10.0.1.2
10.0.1.2
10.0.1.2
Age
718
416
416
386
Seq#
0x80000001
0x80000001
0x80000001
0x80000004
Checksum
0xD466
0x2E02
0x2D01
0x1C0E
17
3.) Answers to questions from Step 4:
1. Instead of knowing all network connections, hosts only know the hosts in their own areas,
relying on the border gateways to reach other areas.
2. Routers in Area 1 do not know about routers in Area 2. They know only up the the border-line
router that sits between their area and the backbone area.
3. The border-line router between Area 1 and Area 0 knows all the routers in Area 1 and the
border-line router between Area 2 and Area 0. The border-line router between Area 2 and Area 0
knows all the routers in Area 2 and the border-line router between Area 1 and Area 0.
4. IP routers in areas 1 and 2 will just send datagrams through their respective gateways, PC1
and PC2.
4.) The output of the command is the border router PC1 that lies between Area 1 and
the backbone area.
Output of Router1#show ip ospf border-routers:
OSPF Process 1 internal Routing Table
Codes: i - Intra-area route, I - Inter-area route
i 10.0.1.1 [10] via 10.0.2.1, FastEthernet0/1, ABR, Area 1, SPF 11
Questions from EXERCISE 7(A):
1.) Answers to Step 7:
1.) KeepAlive - Message sent by one network device to inform another network device
that the virtual circuit between the two is still active.
Open - open soft connection
Update - Routing table update
2.) BGP uses TCP to establish a reliable connection between two BGP speakers on port
179. Exactly one TCP session is established between each peer for each BGP session.
No routing information can be exchanged until the TCP session has been established.
This implies that each BGP speaker must have working IP connectivity between them
first, which is usually provided by a directly connected interface or the IGP. For added
security, MD5 signatures can be used to authenticate each TCP segment.
3.) 10.0.4.1/28
4.) Router1 10.0.4.1, Router2 10.0.4.2, and Router3 10.0.4.3
2.) BGP update messages contain the AS-PATHBorder Gateway Protocol
Border Gateway Protocol
UPDATE Message
Marker: 16 bytes
Length: 52 bytes
Type: UPDATE Message (2)
Unfeasible routes length: 0 bytes
Total path attribute length: 25 bytes
Path attributes
ORIGIN: IGP (4 bytes)
Flags: 0x40 (Well-known, Transitive, Complete)
0... .... = Well-known
.1.. .... = Transitive
..0. .... = Complete
...0 .... = Regular length
Type code: ORIGIN (1)
Length: 1 byte
Origin: IGP (0)
AS_PATH: 100 (7 bytes)
Flags: 0x40 (Well-known, Transitive, Complete)
0... .... = Well-known
.1.. .... = Transitive
..0. .... = Complete
...0 .... = Regular length
Type code: AS_PATH (2)
Length: 4 bytes
AS path: 100
AS path segment: 100
18
Path segment type: AS_SEQUENCE (2)
Path segment length: 1 AS
Path segment value: 100...
3.) They constantly exchange AS-PATH information, which contains the next hop to get
to other destinations.
...
NEXT_HOP: 10.0.4.1 (7 bytes)
Flags: 0x40 (Well-known, Transitive, Complete)
0... .... = Well-known
.1.. .... = Transitive
..0. .... = Complete
...0 .... = Regular length
Type code: NEXT_HOP (3)
Length: 4 bytes
Next hop: 10.0.4.1 (10.0.4.1)
MULTI_EXIT_DISC: 0 (7 bytes)
Flags: 0x80 (Optional, Non-transitive, Complete)
1... .... = Optional
.0.. .... = Non-transitive
..0. .... = Complete
...0 .... = Regular length
Type code: MULTI_EXIT_DISC (4)
Length: 4 bytes
Multiple exit discriminator: 0
Network layer reachability information: 4 bytes
10.0.1.0/24
NLRI prefix length: 24
NLRI prefix: 10.0.1.0 (10.0.1.0)
...
Questions from EXERCISE 7(B):
Step 4 Answers:
1.) From the only notification message of BGP packets, we found out that there is Error
Code stated that Hold Timer is expired. Here, routers must maintain a TCP session with
their neighbors since we were using BGP and AS topology. If a TCP session is
terminated for any reason, the routing information learnt from that session is deleted. All
routing updates contain the originating AS number. In our lab result, it seems like
AS200 tried to keep TCP session with AS100 but since AS100 was disconnected, it was
notified and it sent update to AS300.
2.) BGP Update message and notification message.
Border Gateway Protocol
UPDATE Message
Marker: 16 bytes
Length: 52 bytes
Type: UPDATE Message (2)
Unfeasible routes length: 0 bytes
Total path attribute length: 25 bytes
Path attributes
ORIGIN: IGP (4 bytes)
Flags: 0x40 (Well-known, Transitive, Complete)
0... .... = Well-known
.1.. .... = Transitive
..0. .... = Complete
...0 .... = Regular length
Type code: ORIGIN (1)
Length: 1 byte
Origin: IGP (0)
AS_PATH: 200 (7 bytes)
Flags: 0x40 (Well-known, Transitive, Complete)
0... .... = Well-known
.1.. .... = Transitive
..0. .... = Complete
...0 .... = Regular length
19
Type code: AS_PATH (2)
Length: 4 bytes
AS path: 200
AS path segment: 200
Path segment type: AS_SEQUENCE (2)
Path segment length: 1 AS
Path segment value: 200
NEXT_HOP: 10.0.4.2 (7 bytes)
Flags: 0x40 (Well-known, Transitive, Complete)
0... .... = Well-known
.1.. .... = Transitive
..0. .... = Complete
...0 .... = Regular length
Type code: NEXT_HOP (3)
Length: 4 bytes
Next hop: 10.0.4.2 (10.0.4.2)
MULTI_EXIT_DISC: 0 (7 bytes)
Flags: 0x80 (Optional, Non-transitive, Complete)
1... .... = Optional
.0.. .... = Non-transitive
..0. .... = Complete
...0 .... = Regular length
Type code: MULTI_EXIT_DISC (4)
Length: 4 bytes
Multiple exit discriminator: 0
Network layer reachability information: 4 bytes
10.0.2.0/24
NLRI prefix length: 24
NLRI prefix: 10.0.2.0 (10.0.2.0)CHECKLIST
FORM FOR LAB 4
Prelab 4 question sheet
Checkoff for Part 1
Checkoff for Part 2
Checkoff for Part 3
Checkoff for Part 4
Checkoff for Part 5
Checkoff for Part 6
Checkoff for Part 7
Feedback sheet
Lab report
FEEDBACK FORM FOR LAB 4
Part 1
Configuring RIP on
a Cisco router
Part 2
Configuring RIP on
a Linux PC
Part 3
Reconfiguring the
topology in RIP
Part 4
Count-to-infinity
problem in RIP
Difficulty
1
Interest Level
2
Time to Complete
63 minutes
1
2
50 minutes
1
0
40 minutes
1
1
40 minutes
20
Part 5
Configuring Open
Shortest Path First
(OSPF)
Part 6
Hierarchical routing
in OSPF
Part 7
Configuring the
Border Gateway
Protocol (BGP)
-1
-1
40 minutes
0
1
37 minutes
1
1
45 minutes
What I liked about this lab:
-I liked the fact that it showed us how static IP routes are made and how routers
are configured using IOS.
What I disliked about this lab:
-The report questions were a little long and required extra research.
My suggestion to improve this lab:
-Make clearer questions and maybe a standard of what data to show since some of
the captures are huge but I am not sure what parts they want to see even though I know
which ones are relevant to my answers.
21