Assessments - 2, GPA: 4
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Forwarding performance is at a full serial line rate and filtering performance is at a full Ethernet rate of 14 kpps for 64-byte frames (minimum size). Spanning Tree Spanning Tree protocol creates a logical topology to overlay a physical network. This overlay disables all loops in the data path. Enabling Spanning Tree ensures a unique, primary path from any node on a network to any other node. Also, if the primary path is lost, Spanning Tree creates a new primary path by enabling links in the physical network that were previously disabled in creating the active topology. The following figure shows an example of Spanning Tree. Campus-REX RS Interface Card User Manual Internetworking and Management Overview Example Physical Network* LAN Bridge 3 Bridge 2 Bridge 1 Bridge 4 Bridge 5 ENET 1 ENET 3 E N E T 2 LAN LAN Bridge 3 Bridge 2 Bridge 1 Bridge 4 Bridge 5 ENET 1 ENET 3 E N E T 2 Loop-free Topology Using Spanning Tree Protocol LAN *This physical configuration is valid only when used with Spanning Tree to eliminate loops. Campus-REX RS Interface Card User Manual Internetworking and Management Overview To enable or disable Spanning Tree, see “Configure the Campus-REX as a Bridge or Router” on page 3-19. The Campus-REX uses the Spanning Tree defaults shown in the table below. These values are user-configurable through SNMP as part of the Spanning Tree group in RFC 1493. Spanning Tree Attribute Default Value ST Bridge Priority Hx0000 ST Max Age 30 seconds ST Hello Time 10 seconds ST Hold Time 10 second ST Forward Delay 10 second ST Port 1 Priority (LAN) 0 ST Port 2 Priority (HDSL) 0 ST Port Path Cost 1 STATIC IP ROUTING Through the static IP routing feature, you can configure the Campus-REX as an IP router with statically programmed route entries. You can enable this function as a security feature to prevent eavesdropping and to provide broadcast filtering, as well as to specify multiple destination gateways. When static IP routing is enabled, you can access only specific remote IP subnets or hosts. Since IP routers make forward or filter decisions based on the network-layer IP address instead of the MAC hardware address, MAC-level broadcast frames are prevented from reaching unwanted destinations in the network. The following example shows a simple Internet Service Provider (ISP) site that uses the static IP routing feature to filter MAC-level broadcast frames sourced by ISP Subscriber A from reaching ISP Subscriber B. In this example, all frames from Subscriber A and Subscriber B are directed to the router at the Network Access Provider site. From there, frames from both subscribers are forwarded directly to the Internet. Campus-REX RS Interface Card User Manual Internetworking and Management Overview The following shows a more complex example of multiple gateways that use static IP routing to route packets sourced from specific users to different destination gateways. In this example, packets from each subscriber are routed through a common hub to a router dedicated to that subscriber. Campus-REX RS Interface Card User Manual Internetworking and Management Overview When you choose to configure the Campus-REX for static IP routing, set the configuration options defined in the following table. To set these options, see “Configuring as a Router” on page 3-23. Campus-REX RS Interface Card User Manual Internetworking and Management Overview Parameter Definition Bridge/Router Mode Select Bridge or Router. Both Campus-REX units connected through the HDSL link must be configured as routers for static routing to work. Packet Encapsulation Select either PPP or HDLC. You must set both Campus-REX units connected through the HDSL link to the same encapsulation option. For static routing, set this option to HDLC. Default Router IP Address Specifies the next hop default router entry. This entry tells the Campus-REX what to do with a packet that has a destination address that is not in the Static IP Routing table. IP Static Routing Table Specify up to three static route entries, where each entry includes: destination Subnet or host IP address, destination Subnet Mask, and the IP address of the next-hop Gateway to which the packet should be sent. When you configure the remote end of a point-to-point HDSL connection, you can leave this table blank and specify a single default router IP address since all packets will be forwarded to the other end of the connection. Or for security, you can choose to fill in the table. LAN IP Address and Enter the IP address and subnet mask for the LAN Port Subnet Mask (10BASE-T port). These must be configured for static IP routing to function properly. Line IP Address and Enter the IP address and subnet mask for the Line Port Subnet Mask (HDSL port). These must be configured for static IP routing to function properly. When you configure a point-to-point system, the Line IP address of both units must belong to the same IP subnet and the Line Subnet Mask parameters for both units must be the same....