uart는 8bit 7bit만 있는줄 알았는데 9bit도 있다고 한다.
근데 PC에 달린녀석이나 USB to Serial 등으로는 안되는것 같기도 하고..
[링크 : https://community.st.com/t5/stm32-mcus-products/9-bit-uart-receive-stm32f103/td-p/336998]
| DHCP option (0) | 2026.03.13 |
|---|---|
| DHCP option 82 relay (0) | 2025.01.23 |
| multicast (0) | 2023.08.26 |
| cobs (0) | 2023.05.25 |
| PAM4 (0) | 2023.01.16 |
예전에 찾아봤던 신기한 녀석의 후속글.. 이라고 해야하나?
2025.01.23 - [이론 관련/네트워크 관련] - DHCP option 82 relay
0~255 총 256개의 옵션이 존재하며 BOOTP 에서 유래하거나 DHCP에서 추가된 것들이 있는 것 같은데..
dhcp 서버 설정을 해본적이 없는것 같네.. dhcpd.conf 뒤져보면 나오려나?
RFC 1497 (BOOTP Vendor Information Extensions) vendor extensions[13]: Section 3 CodeNameLengthNotes
| 0 | Pad | 0 octets | Can be used to pad other options so that they are aligned to the word boundary; is not followed by length byte |
| 1 | Subnet mask | 4 octets | Client's subnet mask as per RFC 950. If both the subnet mask and the router option (option 3) are included, the subnet mask option must be first. |
| 2 | Time offset | 4 octets | Time offset of the client's subnet in seconds from Coordinated Universal Time (UTC). The offset is expressed as a two's complement 32-bit integer. A positive offset indicates a location east of the zero meridian and a negative offset indicates a location west of the zero meridian. |
| 3 | Router | Multiples of 4 octets | Available routers, should be listed in order of preference |
| 4 | Time server | Multiples of 4 octets | Available Time Protocol servers to synchronise with, should be listed in order of preference |
| 5 | Name server | Multiples of 4 octets | Available IEN 116 name servers, should be listed in order of preference |
| 6 | Domain name server | Multiples of 4 octets | Available DNS servers, should be listed in order of preference |
| 7 | Log server | Multiples of 4 octets | Available log servers, should be listed in order of preference |
| 8 | Cookie server | Multiples of 4 octets | Cookie in this case means "fortune cookie" or "quote of the day", a pithy or humorous anecdote often sent as part of a logon process on large computers; it has nothing to do with cookies sent by websites. |
| 9 | LPR Server | Multiples of 4 octets | A list of Line Printer Daemon protocol servers available to the client, should be listed in order of preference |
| 10 | Impress server | Multiples of 4 octets | A list of Imagen Impress servers available to the client, should be listed in order of preference |
| 11 | Resource location server | Multiples of 4 octets | A list of Resource Location Protocol servers available to the client, should be listed in order of preference |
| 12 | Host name | Minimum of 1 octet | Name of the client. The name may be qualified with the local domain name. |
| 13 | Boot file size | 2 octets | Length of the boot image in 512B blocks |
| 14 | Merit dump file | Minimum of 1 octet | Path where crash dumps should be stored |
| 15 | Domain name | Minimum of 1 octet | |
| 16 | Swap server | 4 octets | The IP address of a server where a swap service (e.g., swap over NFS) is provided for diskless workstations[14] |
| 17 | Root path | Minimum of 1 octet | The path in the remote filesystem specified by siaddr or sname that the client should mount as its root filesystem (e.g, over NFS) |
| 18 | Extensions path | Minimum of 1 octet | |
| 255 | End | 0 octets | Used to mark the end of the vendor option field |
[링크 : https://en.wikipedia.org/wiki/Dynamic_Host_Configuration_Protocol#Options]
| This appendix contains DHCP options and BOOTP vendor extensions from RFC 2132, and includes the validation type for each option, as indicated in Table 10: DHCPv4 Options by Number , on page 23. The following sections describe the DHCP options in detail: • RFC 1497 Vendor Extensions, on page 1 |
| DHCP option 43 / 25DHCP (Dynamic Host Configuration Protocol) 에는 클라이언트가 DHCP 서버로부터 정보를 요청할 때 클라이언트에게 송신할 수 있는 많은 구성 옵션이 있습니다. 검색 도구를 사용하여 모든 DHCP 옵션을 볼 수 있습니다. DHCP 옵션은 DHCP 서버가 IP 주소와 함께 클라이언트에게 전달하는 추가적인 구성 데이터를 정의합니다. 일반적인 옵션에는 서브네트 마스크, 도메인명, 라우터 IP 주소, 도메인명 서버 IP 주소 및 정적 라우트가 포함됩니다. RFC 2132: DHCP 옵션 및 BOOTP 공급업체 확장의 정의를 기반으로 하는 표준 DHCP 옵션이 다음 표에 설명되어 있습니다. IBM Navigator FOR I의 DHCP 옵션 표시를 사용하여 사용자 지정 옵션을 구성할 수도 있습니다. |
[링크 : https://www.ibm.com/docs/ko/i/7.5.0?topic=concepts-dhcp-options-lookup]
[링크 : http://www.ktword.co.kr/test/view/view.php?no=1925]
윈도우 서버 DHCP 설정
[링크 : https://undefinedmaster.tistory.com/23] 43
linux dhcpd 설정
| host x41 { hardware ethernet 00:0a:e4:2f:66:38; fixed-address 10.0.0.201; option subnet-mask 255.255.255.0; option domain-name-servers 10.0.0.20; option domain-name "site"; option vendor-class-identifier "PXEClient"; vendor-option-space PXE; option PXE.discovery-control 7; option PXE.boot-server 15 1 10.0.0.20; option PXE.boot-menu 15 15 "Tpm for OSd 7.1"; option PXE.menu-prompt 0 "Tpm for Osd"; } |
[링크 : https://www.ibm.com/docs/en/tpmfod/7.1.1.14?topic=configuration-dhcpdconf-example]
[링크 : https://manpages.ubuntu.com/manpages/bionic/man5/dhcp-options.5.html]
[링크 : https://y7712.tistory.com/entry/Ubuntu-DHCP]
dhcp 옵션에서 1번이 subnet 3번이 router 인데 아래 옵션이 그 옵션인가?
| default-lease-time 600; max-lease-time 7200; subnet 10.0.0.0 netmask 255.255.255.0 { option subnet-mask 255.255.255.0; option routers 10.0.0.1; range 10.0.0.5 10.0.0.15; } subnet 172.16.0.0 netmask 255.255.255.0 { option subnet-mask 255.255.255.0; option routers 172.16.0.1; range 172.16.0.5 172.16.0.15; } |
| uart 9bit multidrop (0) | 2026.03.17 |
|---|---|
| DHCP option 82 relay (0) | 2025.01.23 |
| multicast (0) | 2023.08.26 |
| cobs (0) | 2023.05.25 |
| PAM4 (0) | 2023.01.16 |
물리적 포트에 특정 ip를 할당하는게 어떤 기술일까 하고 찾아보는데
이걸 기반으로 포트에 꽂히면 인증을 해주어서 DHCP option 82를 설정해주고
그럼 그 값에 따라 DHCP 서버에서 특정 ip를 주도록 구성을 해둔 듯?
[링크 : http://nstco.co.kr/sub/view.php?idx=95]
[링크 : https://patents.google.com/patent/KR20140062387A/ko]
[링크 : https://serverfault.com/questions/350446/how-to-bind-an-ip-to-a-specific-switch-port-with-dhcp]
+
2026.03.13
하나만 설정하면 되는게 아니라 4개의 옵션이 다 설정되어야 DHCP option 82 relay 가 적용되나 보다.
| option agent.circuit-id string; The circuit-id suboption encodes an agent-local identifier of the circuit from which a DHCP client-to- server packet was received. It is intended for use by agents in relaying DHCP responses back to the proper circuit. The format of this option is currently defined to be vendor-dependent, and will probably remain that way, although the current draft allows for the possibility of standardizing the format in the future. option agent.remote-id string; The remote-id suboption encodes information about the remote host end of a circuit. Examples of what it might contain include caller ID information, username information, remote ATM address, cable modem ID, and similar things. In principal, the meaning is not well-specified, and it should generally be assumed to be an opaque object that is administratively guaranteed to be unique to a particular remote end of a circuit. option agent.DOCSIS-device-class uint32; The DOCSIS-device-class suboption is intended to convey information about the host endpoint, hardware, and software, that either the host operating system or the DHCP server may not otherwise be aware of (but the relay is able to distinguish). This is implemented as a 32-bit field (4 octets), each bit representing a flag describing the host in one of these ways. So far, only bit zero (being the least significant bit) is defined in RFC3256. If this bit is set to one, the host is considered a CPE Controlled Cable Modem (CCCM). All other bits are reserved. option agent.link-selection ip-address; The link-selection suboption is provided by relay agents to inform servers what subnet the client is actually attached to. This is useful in those cases where the giaddr (where responses must be sent to the relay agent) is not on the same subnet as the client. When this option is present in a packet from a relay agent, the DHCP server will use its contents to find a subnet declared in configuration, and from here take one step further backwards to any shared-network the subnet may be defined within; the client may be given any address within that shared network, as normally appropriate. |
| uart 9bit multidrop (0) | 2026.03.17 |
|---|---|
| DHCP option (0) | 2026.03.13 |
| multicast (0) | 2023.08.26 |
| cobs (0) | 2023.05.25 |
| PAM4 (0) | 2023.01.16 |
iptime 공유기를 보는데 iptv 사용이라는 항목에
이런 주소가 보여서 multicast 주소 같은데 왜 뜬금없이 iptv라고 해둔거야? 하면서 보는데
의외로 저 주소에 추가된 ip들이 꽤 있어서 조사해 보는 중
| 233.233.233.233 (01:00:5e:69:e9:e9) 224.3.1.200 (01:00:5e:03:01:c8) 239.5.6.11 (01:00:5e:05:06:0b) 239.5.6.10 (01:00:5e:05:06:0a) 239.5.6.15 (01:00:5e:05:06:0f) 239.255.255.253 (01:00:5e:7f:ff:fd) 239.255.102.18 (01:00:5e:7f:66:12) |
| * 한편, IP 멀티캐스트 주소 변환용으로, 01-00-5E-00-00-00 ~ 01-00-5E-7F-FF-FF 범위가 예약됨 (RFC 1112 : Host Extensions for IP Multicasting) |
[링크 : http://www.ktword.co.kr/test/view/view.php?m_temp1=2294]
ip multicast와 ethernet multicast라.. 무슨 차이지?
[링크 : http://www.ktword.co.kr/test/view/view.php?m_temp1=5390&id=708]
| - 주소 범위 : 224.0.0.0 ~ 239.255.255.255 |
[링크 : http://www.ktword.co.kr/test/view/view.php?m_temp1=3607]
| DHCP option (0) | 2026.03.13 |
|---|---|
| DHCP option 82 relay (0) | 2025.01.23 |
| cobs (0) | 2023.05.25 |
| PAM4 (0) | 2023.01.16 |
| nrz encoding/decoding (0) | 2022.08.24 |
bit stuffing 등을 포함하는 상위개념
[링크 : https://en.m.wikipedia.org/wiki/Consistent_Overhead_Byte_Stuffing]
| DHCP option 82 relay (0) | 2025.01.23 |
|---|---|
| multicast (0) | 2023.08.26 |
| PAM4 (0) | 2023.01.16 |
| nrz encoding/decoding (0) | 2022.08.24 |
| 광 케이블 DAC, AOC (0) | 2022.06.30 |
디지털이 이제 다시 아날로그로 돌아가는 시대인가...
[링크 : https://www.rambus.com/blogs/future-nrz-pam4/]
| 400 기가비트 이더넷(GE) 표준은 4개 수준의 PAM(PAM4) 다중 레벨 시그널링을 권장 변조 형식으로 정의하여 시리얼 400GE 데이터 센터 인터페이스를 구현합니다. 이는 100GE에서 사용되던 2개 상태 영비복귀(NRZ) 변조로부터 발전한 것입니다 |
64 QAM
[링크 : https://www.everythingrf.com/community/what-is-64-qam-modulation\
| multicast (0) | 2023.08.26 |
|---|---|
| cobs (0) | 2023.05.25 |
| nrz encoding/decoding (0) | 2022.08.24 |
| 광 케이블 DAC, AOC (0) | 2022.06.30 |
| CRC-16 / X-25 (0) | 2021.12.07 |
[링크 : https://www.oguchi-rd.com/technology/nrzi.pdf]
[링크 : https://github.com/illusionic/NRZ_i-and-NRZ_L-_encoding]
python
[링크 : https://github.com/jncraton/nrz-decode]
online
| cobs (0) | 2023.05.25 |
|---|---|
| PAM4 (0) | 2023.01.16 |
| 광 케이블 DAC, AOC (0) | 2022.06.30 |
| CRC-16 / X-25 (0) | 2021.12.07 |
| RS485 오실로스코프 파형 (0) | 2021.11.04 |
DAC - Direct Attach Copper Cable
AOC - Active Optical Cable
[링크 : https://m.blog.naver.com/panoptics/220875130979]
[링크 : http://ko.3rd-party-transceiver.com/info/difference-between-aoc-dac-cables-27652925.html]
| PAM4 (0) | 2023.01.16 |
|---|---|
| nrz encoding/decoding (0) | 2022.08.24 |
| CRC-16 / X-25 (0) | 2021.12.07 |
| RS485 오실로스코프 파형 (0) | 2021.11.04 |
| EtherCAT - Ethernet for Control Automation Technology (0) | 2021.11.01 |
아래가 정확하게 맞는건진 모르겠지만..
비슷하면서도 초기값과 xor 값 그리고 비트 시프트 하는 것이 전혀 다르다.
| uint16_t crc16_ccitt_false(char* pData, int length) { int i; uint16_t wCrc = 0xffff; while (length--) { wCrc ^= *(unsigned char *)pData++ << 8; for (i=0; i < 8; i++) wCrc = wCrc & 0x8000 ? (wCrc << 1) ^ 0x1021 : wCrc << 1; } return wCrc; } uint16_t crc16_x25(char* pData, int length) { int i; uint16_t wCrc = 0xffff; while (length--) { wCrc ^= *(unsigned char *)pData++ << 0; for (i=0; i < 8; i++) wCrc = wCrc & 0x0001 ? (wCrc >> 1) ^ 0x8408 : wCrc >> 1; } return wCrc ^ 0xffff; } |
| nrz encoding/decoding (0) | 2022.08.24 |
|---|---|
| 광 케이블 DAC, AOC (0) | 2022.06.30 |
| RS485 오실로스코프 파형 (0) | 2021.11.04 |
| EtherCAT - Ethernet for Control Automation Technology (0) | 2021.11.01 |
| WiFi 프로토콜, cipher (0) | 2021.09.27 |
RS485는 LSB 부터 전송하게 되는 듯?
일단 예제는 아래와 같은데
[링크 : https://www.best-microcontroller-projects.com/how-rs232-works.html]
대문자 J는 0x4A 이고
2진수로 계산하면 0b01001010 이고
실제로 찍은걸 보면 0이 Low고 1이 High로 매핑되고
LSB 부터니까 01010010 순서고
레벨을 바꾸어서 보면 10101101 인데
start bit 1개 들어가니 110101101 으로 보인다.
오호.. 신기해라(!)
| 광 케이블 DAC, AOC (0) | 2022.06.30 |
|---|---|
| CRC-16 / X-25 (0) | 2021.12.07 |
| EtherCAT - Ethernet for Control Automation Technology (0) | 2021.11.01 |
| WiFi 프로토콜, cipher (0) | 2021.09.27 |
| wake on patern matching (0) | 2021.06.10 |
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