Hence, maximum number of 4-byte words is 16. 16x4 = 64 bytes or 512 bits. deduct minimum IP header without options which is 20 bytes and you end up with 44 bytes or 352 bits available for options. I think you confused the IHL field length with its default value of 5. 5 4-byte words makes up to 20 bytes, which is the default IP header length ...

Each Ethernet frame has Ethernet header, then if it is an IP packet inside it, then it also has IP header, then TCP or UDP header. Not every layer has its own header though. Data link, network and transport layers are the ones that have their distinct headers in the packet.

TCP will take a whole bunch of bytes which is our data and encapsulate that into a TCP header. TCP will then pass the data + TCP header down to the IP protocol that will usually add a 20 byte IP header onto the segment making an IP packet. IP adds a header onto the TCP segment to define the final source and destination. Finally the IP packet is ...

Is the dhcp options field in the application layer or ip header? Expand Post. Like Liked Unlike Reply ...

My first thought was also about "ip source route option", but then, rhe sentence "In source-based routing, routers would reference the source address field." does not really make sense. With "ip source-route", the sender specifies the routing based on additional information in the ip header, not based on the source address of the packet.

Protocol used for SSL VPN and EZVPN are different i.e. SSL and IPSec. Both have different features .Imagine you are in Airport , Hotel etc. having an internet connection where they could possibly only allow port 80 and 443 from inside .

IP header fields options and padding go together and usually IP header does not have options field. Not 100% sure about this " Padding is still optional (may not be there) even if you use Option fields in IP packet (not by default)". Padding should show up only if needed. here are 2 examples: 2nd picture shows Options filed used

I don't understand why we need an ip mtu command on GRE tunnel interfaces, since we can just use the ip tcp-adjust mss command to set the mss. I know that the default MTU is 1500 = 20 bytes ip header + 20 bytes tcp header + 1460 payload (mss) with GRE enable original mtu automatically goes to 1476 because of the new ip + gre headers.

Let say I have a GRE tunnel only, no IP SEC or sth will put more header in the front. So, I read in CLN and know that there are 2 type of MTU, the first one is IP MTU, the MTU of the actual packet, default is 1500 bytes". Change this value by: Ip mtu <X>. Below is the picture:

With VPNs, the problem is that sometimes TCP hosts/servers negotiate a 1500 MSS minus the IP and TCP header, but don't consider the GRE or IPSEC headers. IP Fragmentation then occurs. BUT, there's a way to make the router step in and adjust the MSS value during the MSS value "negotiation" stage (technically it's not a true negotiation).