2016-4-18 ICMPV6 Protocol [rfc2463]--Message detailed

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--icmpv6 (Internet Control Message protocol for the IPV6) is one of the underlying protocols of IPV6. defined in RFC2463 .

-Used to pass information or errors generated in message forwarding.

--icmpv6-defined messages are widely used in other protocols. Includes: NDP (Neighbor Discovery Protocol, PATHMTU Path discovery mechanism, MLD protocol [alternative to multicast in IPv4 IGMP protocol], etc.)

ICMPv6 Baotou is a header that belongs to the upper layer protocol. He must be behind all extension headers.

When specifying the ICMPV6 header, the base header or the "Next header=58"[next-header=0x3a]in the extension header, so that the base header or extension header of the IPV6 can be associated with the ICMPV6 header.

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The following message is a ICMPV6 message.

In this, there is a IPv6 of the basic Baotou, Next-header inside the designated is 0X3A. Specifies the protocol header for the ICMPV6.

The attachment is the relevant grab bag.

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ICMPv6 of the type class:

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1, Error class message (Error message), also known as error messages, the highest bit to be 0, also ICMPv6 type=[0-127].

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NOTES: If this is an error message, then the type in the ICMPV6 header will be between 0-127.

Error message:

---1, error Messages (RFC2463)

~ ~ ~ Destination Unreachable (type=1) not to reach

● code=0: no route to target reached

If you are in the network, R1--R2--R3.

R1 Ping "R5" loopback to ensure that this "R5" is not available in all networks.

Then R1 will send ICMP to R2 this default gateway, but R2 will give R1 a response to a error message, Code=0. Indicates a route that does not reach the destination.

R1--r2--r3

Ping 2055::1 above the R1, this loopback port does not have any route with this route.

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By grasping the packet to see, R1 Ping 2,055:1, the ICMPV6 message to R2 e0/0 input, the result because R2 received no routing information, directly R2 to R1 response to ICMPV6 error message. type=1, Code=0, no route.

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● code=1: communication with the target is forbidden by the managed policy

In this case, it is generally in the middle of the link to do an ACL and other policies prohibit ICMP message traffic.

Here is a packet of the policy ping packet that made the ACL.

R1---[E0/0]R2---R3

An ACL is applied to the input direction of the e0/0 above R2. Disables all ICMP packets sent by R1.

The red box below is an ICMP error message that R2 responds to R1, code=1. Communication with the target is forbidden by the managed policy.
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code=2: Not Specified

● code=3: Address not reached

Here first or to say, address unreachable, and code=0, routing unreachable. What's the difference. Code=3, I have a destination route, but the address is not. Code=0 is that there is no route at all.

Simulation process: Here is to say, R1--R2---2023::x/64---R3

Here the R2 and R3 interface addresses are: 2023::2/64 and 2023::3/64

However, on the R1, ping 2023::10/64 this completely nonexistent address. After the data has been dumped from R1 to R2, R2 has routes, but this "2023::10/64" is completely unreachable.

The simulation topology map is: R1---2012::x/64---R2 (2023::2/64)-----(2023::3/64) R3

Ping 2023::10 the non-existent address above the R1.

The information on debug above R1 is as follows:

*APR 16:31:24.045:icmpv6:sent Echo Request, Src=2012::1, Dst=2023::10.

*APR 16:31:27.265:icmpv6:received Unreachable Code 3, Src=2012::2, dst=2012::1

Ps. R2 return ICMP message code=3 time, there will be a certain delay, because R2 received the message, because there is a route, so R2 also take time to address the search, send ns out, waiting for Na back. If Na does not time out, R2 will not be able to respond to ICMPV6 error messages at this time.

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● code=4: ports not up to

With this, you can use the Traceroute tool.

R1---R2---R3

Landed on the R1 above the traceroute R3. This time the corresponding port is unreachable.

R1:traceroute 2033::1

This time on the R1 received ICMP error message, code=4 message.

*APR 17:32:23.110:icmpv6:received Time Exceeded, Src=2012::2, dst=2012::1

*APR 17:32:23.116:icmpv6:received Time Exceeded, Src=2012::2, dst=2012::1

*APR 17:32:23.121:icmpv6:received Time Exceeded, Src=2012::2, dst=2012::1

*APR 17:32:23.127:icmpv6:received Unreachable Code 4, Src=2023::3, dst=2012::1

*APR 17:32:23.132:icmpv6:received Unreachable Code 4, Src=2023::3, dst=2012::1

*APR 17:32:23.137:icmpv6:received Unreachable Code 4, Src=2023::3, dst=2012::1

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~ ~ ~ Packet Extra long packet Too Big (type=2)

Code=0

~ ~ ~ Timeout Time Exceeded (type=3)

Code=0: Exceeded Hop limit in transit (hot-limit timeout, IPv4 ttl timeout)

Code=1: Time-out during Shard reassembly

~ ~ ~ Parameter Problem parameter problem (type=4)

Code=0: Header field with error encountered

Code=1: Encountering an unrecognized next-header

code=2: An unrecognized IPv6 option was encountered

---2, Information class Messages (Information message), also known as message messages , Highest bit to be 1, also ICMPv6 type=[128-255].

NOTES: In the case of messages of the information class, the value of type is between 128-255 .

Information-type messages (RFC2463), we use the most is type=128 echo request and 129, Echo reply.

~~~~ Echo Request message (Echo Request)

type=128, code=0.

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~~~~ Loopback Response Message (Echo Reply)

type=129, code=0.

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Attachment has I do the experiment related ICMP6 grab bag, have the need friend can download contrast to comb the concept.

This article is from the "hank--me, Focus on Principles" blog, be sure to keep this source http://361531.blog.51cto.com/351531/1765168

2016-4-18 ICMPV6 Protocol [rfc2463]--Message detailed