Ccna routing and Switching Complete Study Guide

R1

R2

S1

S2

2001:db8:3c4d:1:21a:6dff:fe37:a443

Fe80::21a:6dff:fe64:9b2

2001:db8:3c4d:2:21a:6dff:fe64:9b3

Fe80::21a:6dff:fe64:9b3

2001:db8:3c4d:3:21a:6dff:fe37:a44e

Fe80::21a:6dff:fe37:a44e

2001:db8:3c4d:2:21a:6dff:fe37:a44f

Fe80::21a:6dff:fe37:a44f

Fa0/1

Fa0/0

Fa0/1

Fa0/0

2001:db8:3c4d:3:ac3b:2ef:1823:8938

2001:db8:3c4d:2::64

2001:db8:3c4d:1:a14c:8c33:2d1:be3d

PC1

Server1

I want to point out that this is not an “introduction to IPv6” chapter, so I’m assuming 

you’ve got some IPv6 fundamentals down.

Notice that I documented both the link-local and global addresses assigned to each 

router interface in Figure 20.4. We need both in order to troubleshoot, so right away, you 

can see that things get a bit more complicated because of the longer addresses and the fact 

that there are multiple addresses per interface involved!

But before we start troubleshooting the IPv6 network in Figure 20.4, I want to refresh your 

memory on the ICMPv6 protocol, which is an important protocol in our troubleshooting arsenal.

ICMPv6

IPv4 used the ICMP workhorse for lots of tasks, including error messages like destination 

unreachable and troubleshooting functions like Ping and Traceroute. ICMPv6 still does 

those things for us, but unlike its predecessor, the v6 flavor isn’t implemented as a separate 

layer 3 protocol. Instead, it’s an integrated part of IPv6 and is carried after the basic IPv6 

header information as an extension header.

ICMPv6 is used for router solicitation and advertisement, for neighbor solicitation and 

advertisement (i.e., finding the MAC addresses for IPv6 neighbors), and for redirecting the 

host to the best router (default gateway).

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Troubleshooting IPv6 Network Connectivity