setMTUwithRA - Verify changing MTU w/ received RA
Host
setMTUwithRA.seq [-tooloption ...] -p setMTUwithRA.def
This test evaluate the behavior of NUT when it receive the RA with MTU option. In this test, NUT is a host and TN plays a Roll of Router and other host. Phisical Network configuration --------+---------------+---------- | | NUT TN
Logical Network Configuration
NUT | ----------------+-------+-------- | Router-A | ----------------+-------+-------- | HOST
In this test, NUT receives RA with MTU.
The TN send a RA to assign global address prefix.
TN NUT | | ---+------------+------
===multicast RA===> src=TN's link-local dst=LinkLocal-all-node M=0, O=0, Lifetime=3600, ReachableTime=60000, RetransTimer=1005 Prefix: L=1, A=1, ValidLifetime=3600005, PreferredLifetime=3600005 Prefix=3ffe:501:ffff:100::, PrefixLength=64 option MTU=1400 Wait (5 sec.) Ignoring DAD packets for global address.
"setMTUwithRA" verify NUT's behavior when it receives RA with MTU option.
TN NUT | | ---+------------+------
1. RA (MTU=1400) TN send RA with MTU=1400. TN === RA(MTU=1400) ===> NUT
2. TN Sends Fragmented Echo Request TN send Echo Request. TN ==== echo request(1400) ===> NUT
4. NUT Sends Fragmented Echo Reply NUT send Echo Reply. << JUDGMENT 1 >> TN <=== echo reply(1400) ====== NUT
3. TN Sends Fragmented Echo Request TN send Echo Request. TN === echo request(1/2 of 1500 MTU=1400) ===> NUT TN === echo request(2/2 of 1500 MTU=1400) ===> NUT
4. NUT Sends Fragmented Echo Reply NUT send Echo Reply << JUDGMENT 1 >> TN <=== echo reply(1/2 of 1500 MTU=1400) === NUT TN <=== echo reply(2/2 of 1500 MTU=1400) === NUT
<< JUDGMENT 1 -PASS- >> NUT sends Echo Reply
"PASS" means that NUT set valid MTU in received RA. And fragmented packets are correct. But if the NUT doesn't support PMTU Discovery, the NUT MUST NOT send echo reply greater than Minimum MTU.
<< JUDGMENT 2 -PASS- >> NUT sends Echo Reply
"PASS" means that NUT sets valid MTU in received RA. And fragmented packets are correct. But if the NUT is LCNA, it may not be able to deal with packets greater than Minimum MTU, in this case NUT doesn't transmit echo reply. And also it could not fragment packets, in this case NUT doesn't transmit echo reply. Both cases are allowed in LCNA specification.
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