2. A Class B Network Case
Connected: An Internet Encyclopedia
2. A Class B Network Case
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Requests For Comments
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RFC 950
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2. A Class B Network Case
2. A Class B Network Case
For this case, assume that the requesting host is on class B
network 128.99.0.0, has address 128.99.4.123, that there is a
gateway at 128.99.4.62, and that a 6-bit wide subnet field is in
use, that is, the address mask is 255.255.252.0.
The host sends the ICMP request to 255.255.255.255:
Source address: 128.99.4.123
Destination address: 255.255.255.255
Protocol: ICMP = 1
Type: Address Mask Request = AM1
Code: 0
Mask: 0
The gateway can then respond directly to the requesting host.
Source address: 128.99.4.62
Destination address: 128.99.4.123
Protocol: ICMP = 1
Type: Address Mask Reply = AM2
Code: 0
Mask: 255.255.252.0
In the diskless workstation case the host sends:
Source address: 0.0.0.0
Destination address: 255.255.255.255
Protocol: ICMP = 1
Type: Address Mask Request = AM1
Code: 0
Mask: 0
128.99.4.62 will hear the datagram, and should respond with this
datagram:
Source address: 128.99.4.62
Destination address: 255.255.255.255
Protocol: ICMP = 1
Type: Address Mask Reply = AM2
Code: 0
Mask: 255.255.252.0
If broadcasting is not allowed 128.99.4.123 sends:
Source address: 128.99.4.123
Destination address: 128.99.4.62
Protocol: ICMP = 1
Type: Address Mask Request = AM1
Code: 0
Mask: 0
128.99.4.62 should respond exactly as in the previous case.
Source address: 128.99.4.62
Destination address: 128.99.4.123
Protocol: ICMP = 1
Type: Address Mask Reply = AM2
Code: 0
Mask: 255.255.252.0
Next: 3. A Class C Network Case (illustrating non-contiguous subnet bits)
Connected: An Internet Encyclopedia
2. A Class B Network Case
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