Two islands of IPv6 networks that are running ISIS (IPv6 IGP) must be connected using a tunnel over an IPv4 network. Which tunneling method can be used to achieve this goal?

The correct answer is A. GRE tunnels. GRE has a protocol field that identifies the passenger protocol. GRE tunnels allow Intermediate System-to-Intermediate System (IS-IS) or IPv6 to be specified as a passenger protocol, which allows both IS-IS and IPv6 traffic to run over the same tunnel. If GRE did not have a…

Core Technologies

Question

Options

AGRE tunnels
Bautomatic 6 to 4 tunnels
CISATAP tunnels
Dmanual tunnels (RFC 2893)

How the community answered

(34 responses)

A
74% (25)
B
3% (1)
C
15% (5)
D
9% (3)

Explanation

GRE has a protocol field that identifies the passenger protocol. GRE tunnels allow Intermediate System-to-Intermediate System (IS-IS) or IPv6 to be specified as a passenger protocol, which allows both IS-IS and IPv6 traffic to run over the same tunnel. If GRE did not have a protocol field, it would be impossible to distinguish whether the tunnel was carrying IS-IS or IPv6 packets. The GRE protocol field is why it is desirable that you tunnel IS-IS and IPv6 inside GRE

Topics

#IPv6 tunneling#GRE#IS-IS#IPv4 backbone

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