Errata

Is:
#config-reg 0x2102
Should be:
#config-reg 0x2142

Without the "login" command users will not be able to logon via telnet even if a
password is set.

Table 5-3 shows three possible Ethernet encapsulation types, but "isol" is incorrect.
Example:
boston#conf t
Enter configuration commands, one per line. End with CNTL/Z.
boston(config)#int e 0
boston(config-if)#encapsulation snap
boston(config-if)#encapsulation isol
^
% Invalid input detected at '^' marker.

boston(config-if)#encapsulation arpa
boston(config-if)#end

Looks like the router will accept "iso" nut not "isol".

The following statement is incorrect "HDLC ... is proprietary to Cisco". HDLC is in
fact an open standard developed by International Organization for
Standardization(ISO). It falls under the ISO standards ISO 3309 and ISO 4335.

Cisco does use a proprietary version of HDLC, but still uses the standards based
framing (just changes the packet contents).

passive-interface serial0
should read:
passive-interface ethernet0

passive-interface serial0
should read:
passive-interface ethernet0

!Define access list 10
should read:
!Define access list 11

The text before the example output should be
"If the reported distance is LESS than the feasible distance, the path becomes the
feasible successor for the route"

The book incorrectly names Type 6 LSAs as NSSA LSA. Truth is that NSSA use type-7
LSAs.

Example, here is a snippet from RFC-1587:

3.3 Type-7 LSAs: NSSA External Link-State Advertisements

External routes are imported into NSSAs as type-7 LSAs by the NSSA's
AS boundary routers. An NSSA AS boundary routers is a router which
has an interface associated with the NSSA and is exchanging routing
information with routers belonging to another AS. As with type-5
LSAs a separate type-7 LSA is originated for each destination
network. To support NSSA areas, the link-state database must
therefore be expanded to contain a type-7 LSA.

Type 7-LSAs are identical to type-5 LSAs except for the following
(see section 12.3.4 "AS external links" in the OSPF
specification).

1. The type field in the LSA header is 7.

2. Type-7 LSAs are only flooded within the NSSA.
The flooding of type-7 LSAs follow the same rules
as the flooding of type 1-4 LSAs.

3. Type-7 LSAs are kept within the NSSA's LSDB (are
area specific) whereas because type-5 LSAs are
flooded to all type-5 capable areas, type-5 LSAs
global scope in the router's LSDB.

4. At the area border router, selected type-7 LSAs are
translated into type 5-LSAs and flooded into the
backbone.

A type-6 OSPF LSA carries Multicast specific information for MOSPF. The definition
in the book is incorrect.

There are two serious flaws with the virtual-link example. First, router1 and
router2 both have their Loopback0 interface assigned to the same subnet (this is
wrong).

Example:
Router1
inteface Loopback0
ip address 10.10.7.4 255.255.255.0

Router2
inteface Loopback0
ip address 10.10.7.5 255.255.255.0

Secondly, neither router is distributing their loopback subnet within OSPF. (i.e.
there is no network statement for the loopback0 subnets)
If the routers don't advertise their loopback0 address, which would become their
router-ID and their virtual-link end point, then the example would fail.

Both issues would have to be corrected before the example would work correctly...

In the example the eigrp timers are adjusted on interface serial 0 but they use the
wrong EIGRP AS number.

Example from the book:
interface Serail1
ip hello-interval eigrp 1 5
ip hold-time eigrp 1 15
!
router eigrp 100

Both of the EIGRP interface timing commands use AS 1 whereas the router is configured
to use AS 100.

Also, the timers picked are incorrect. The default timers for an normal point-to-
point EIGRP interface are hello 5 sec, hold 15 secs. If the author wants to speed up
dialling, then the timers should be adjusted downwards (eg. hello 3 sec, and hold 9
sec for instance).

The dialer list is configured incorrectly.
dialer-list 1 list 110

The example above, taken from the book, shows the incorrect syntax.

Should be:
dialer-list 1 protocol ip list 101

Example:
Router(config)#dialer-list 1 ?
protocol Permit or Deny based on protocols

Router(config)#

The second IP address assigned by the ISP should be 192.168.2.1, not 192.168.10.2.1
(which isn't even a valid IP address.)

The IP address should be 192.168.1.1, not 198.168.1.1.

The IP address should be 192.168.1.1, not 198.168.1.1.

The IP address should be 192.168.2.1, not 198.168.2.1.

The subnet mask should be 255.255.255.0, not 255.255.255.255.

In the "Protect VTYs with an Access List" paragraph, the last line of the example (Users and Authentication) looks like it's part o
f the it but, in fact it should be the title of the next paragraph, isn't it?

The author states that "show ip arp"

"This commmand lists all the machines from which the router has seen packets in the
last 30 minutes"

The above statement is wrong. The default timeout for an ARP entry is 4 hours as the
author correctly notes on page 262.

In fact the entries in "show ip arp" will only timeout if the device responding to
the arp is removed from the network. Just prior to an arp entry timeout the router
performs a unicast arp to refresh the entry. This behavior can be observed with the
"clear arp" in conjunction with "debug arp"

r2#sh ip arp
Protocol Address Age (min) Hardware Addr Type Interface
Internet 181.16.12.1 7 aabb.cc00.1500 ARPA Ethernet0/0
Internet 181.16.12.2 - aa00.0400.0204 ARPA Ethernet0/0
Internet 181.16.24.4 7 aabb.cc00.1802 ARPA Ethernet1/0
Internet 181.16.24.2 - aa00.0400.0204 ARPA Ethernet1/0

r2#debug arp
ARP packet debugging is on

r2#clear arp
r2#
*Mar 3 18:05:50.623: IP ARP: sent req src 181.16.12.2 aa00.0400.0204,
dst 181.16.12.1 aabb.cc00.1500 Ethernet0/0
*Mar 3 18:05:50.623: IP ARP: sent req src 181.16.24.2 aa00.0400.0204,
dst 181.16.24.4 aabb.cc00.1802 Ethernet1/0
*Mar 3 18:05:50.623: IP ARP: sent rep src 181.16.12.2 aa00.0400.0204,
dst 181.16.12.2 ffff.ffff.ffff Ethernet0/0
*Mar 3 18:05:50.623: IP ARP: sent rep src 181.16.24.2 aa00.0400.0204,
dst 181.16.24.2 ffff.ffff.ffff Ethernet1/0
*Mar 3 18:05:50.683: IP ARP: rcvd rep src 181.16.12.1 aabb.cc00.1500, dst
181.16.12.2 Ethernet0/0
*Mar 3 18:05:50.683: IP ARP: creating entry for IP address: 181.16.12.1,hw:
aabb.cc00.1500
*Mar 3 18:05:50.683: IP ARP: rcvd rep src 181.16.24.4 aabb.cc00.1802, dst
181.16.24.2 Ethernet1/0
*Mar 3 18:05:50.683: IP ARP: creating entry for IP address: 181.16.24.4,hw:
aabb.cc00.1802

r2#sh arp
Protocol Address Age (min) Hardware Addr Type Interface
Internet 181.16.12.1 0 aabb.cc00.1500 ARPA Ethernet0/0
Internet 181.16.12.2 - aa00.0400.0204 ARPA Ethernet0/0
Internet 181.16.24.4 0 aabb.cc00.1802 ARPA Ethernet1/0
Internet 181.16.24.2 - aa00.0400.0204 ARPA Ethernet1/0

The description of Passive FTP is incorrect. The statement "With passive FTP, the
file transfer occurs on the same port as the initial [control] connection" is simply
not true. Passive FTP uses separate ports to transfer data then the initial control
session.

A normal FTP data session initiates from the server's port 20 back to the client
(port 1024+) which can confuse Firewalls. However, on a passive FTP session the data
session originate from the client to the server in the same direction as the original
control session. Even though the sessions initiate in the same direction they use
different port numbers (generally 1024+ to 1024+)...

The book omitted the most common type of OSPF network, "point-to-point".

Example:
boston(config-subif)#ip ospf network ?
broadcast Specify OSPF broadcast multi-access network
non-broadcast Specify OSPF NBMA network
point-to-multipoint Specify OSPF point-to-multipoint network
point-to-point Specify OSPF point-to-point network

Missing description of "scheduler allocate" configuration setting. Normally, this is
configured as "no scheduler allocate" to use the default CPU scheduling (allows 5% of
CPU time for low-priority tasks).

The default timers for HSRP are incorrect. The book quotes, "hello seconds, 1; hold
seconds, 3" when in actual fact the default timers are Hello 3 seconds and holdtime
10 seconds.

Example:
Router:66#sh stand
FastEthernet0/0.2 - Group 0
Local state is Listen, priority 100
Hellotime 3 sec, holdtime 10 sec
Virtual IP address is 172.26.2.22 configured
Active router is unknown
Standby router is unknown
0 state changes, last state change never

Regarding the command "tacacs-server attempts", the author incorrectly identifies the
meaning of this command. This command does not modify the number of attempts to
reach the tacacs server before deciding the server is unavailable. Instead, it
modifies the number of incorrect login attempts the router will allow (while using
TACACS) before it terminates the session.

Example:
Router1(config)#tacacs-server ?
attempts Number of login attempts via TACACS

ssh is missing from the valid list of protocols.