From 543427d2b7bacdbb0e061d8fa405070a93238357 Mon Sep 17 00:00:00 2001 From: Jet Hughes Date: Tue, 18 Oct 2022 11:54:16 +1300 Subject: [PATCH] vault backup: 2022-10-18 11:54:16 --- content/notes/19-network-layer-data-plane.md | 51 +++++++++++++++++++- 1 file changed, 49 insertions(+), 2 deletions(-) diff --git a/content/notes/19-network-layer-data-plane.md b/content/notes/19-network-layer-data-plane.md index 5d964cbbc..47ba2fc42 100644 --- a/content/notes/19-network-layer-data-plane.md +++ b/content/notes/19-network-layer-data-plane.md @@ -117,7 +117,54 @@ header - offset - offset of the fragment in the packets data field (units of 8 bytes) -![example](https://i.imgur.com/eENmMTd.png) +![frag example](https://i.imgur.com/eENmMTd.png) +what needs to change in the header of fragment +- flag +- offset +- length +- ttl +- checksum + +## special IPv4 Adresses and NAT +special addresses +- 127.0.0.1 localhost/loopback +- 10.0.0.0/8 private use +- 192.168.0.0/16 private use + +NAT (network address translation): all devices in local network share just one IPv4 address +- allow multiple devices to share the same adresses +- help preserve the limited amount of IP address +- translate from private IP to public IP +- ![NAT diagram](https://i.imgur.com/fU7hTbO.png) + +# IPv6 +- inital motivation: IPv4 mostly used up +- additional motivation + - speed prcessing/forwarding: 40 byte fixed length header + - enable different network-layer treatment of "flows" + - better support for host mobility + - better support for security + +datagram format![](https://i.imgur.com/6O7jPQg.png) + +adressses +- 128 bits +- hexadecimal colon notation + - 12AB:0000:0000:CD30:0000:0000:0000:0000 +- adress compression + - consecutive sections of seros are replaced with :: + - can be used only once per address + - e.g., 12AB:0000:0000:CD30:: + +CIDR +- classless interdomain routing +- method for allocating IP addresses and IP routing +- notation + - based of variable length subnet mask (VLSM) + - address format: IP address/x, where x is number of bits from left to right as network part + - ![](https://i.imgur.com/n681AV1.png) + +extension headers: ![](https://i.imgur.com/8rM3clb.png) +differencees: ![](https://i.imgur.com/cWKDpEY.png) -# IPv6 \ No newline at end of file