BROCADE IP PRIMER

GlossarySource NAT This is a method of SLB which allows the real servers to be physicallydetached from the ServerIron. The real server replies come back throughthe ServerIron because they appear to come from the ServerIron. The sourceaddress is translated to the ServerIron's IP address.Spanning Tree Protocol This is defined in IEEE 802.1d. It is a Layer 2 protocolthat prevents layer 2 loops. It uses BPDUs to discover paths through the layer2 infrastructure. When multiple paths are found, all but one will be shut down.SSH Secure SHell. This is a Layer 7 protocol that provides command lineaccess to a remote host over an encrypted connection.SSL Secure Sockets Layer. This is a protocol that provides encryption for otherLayer 7 protocols. Most commonly, this is used to encrypt HTTP traffic.SSLB Symmetric Server Load Balancing. This is a design involving multipleServerIrons servicing the same virtual servers. The ServerIrons can work witheach other in an active/standby or active/active configuration.Stub area In OSPF, this is an area that does not receive routes from outside ofthe OSPF autonomous system.Stub AS In BGP, this is an AS that has only one path in and one path out. It isnot multihomed. There's no reason for it to receive all of the routes its BGPpeer has to offer. It just needs a default gateway to point out the only way itcan go.Subnet This is a subdivision of a network class. A subnet extends the networkportion of the subnet mask to define the needed number of networks and hostaddresses per network.Subnet mask This is a 32-bit binary number that defines which portion of anIP address is the network portion, and which portion is the host portion. This isoften represented in the same way as IP addresses (e.g., 255.255.255.0).Supernet This is a method of representing a group of consecutive networks. Itis usually represented in CIDR notation. This is never defined as an entity, butis used to summarize routes as they are advertised to different routers.Switch A network device containing multiple interfaces. Traditionally, thisdevice operates only on Layer 2. It provides an intelligent transfer from oneinterface to another. A switch can also be a Layer 3 device, providing routing aswell as switching.SYN Synchronize. This is the first TCP packet sent to start the initial 3-wayhandshake of a session. It is used to synchronize the TCP sequence numbersthat will be used for the session.SYN attack This is performed by starting the TCP 3-way handshake, but notfinishing it. A SYN is sent from many clients, the server properly responds witha SYN/ACK, but the clients never respond with the final ACK. The server is leftwith many open sessions. It will eventually run out of resources to open newsessions.418 Brocade IP Primer