Enterasys Networks X-PeditionTM manual IP Routing Protocols, Maximum Transmission Unit MTU, Ping

IP Routing Protocols

VRRP & Secondary IP

Multiple virtual IP addresses per Virtual Router (VR) are available to support multiple logical IP subnets on a single LAN segment. Secondary IP interacts with the XSR’s implementation of the Virtual Router Redundancy Protocol (VRRP) as follows:

•The primary physical IP address on an interface will be selected as a VRRP primary IP address, which is used for VRRP advertisement.

•If one of the virtual IP addresses of a VR is the real physical address of the interface, all other virtual IP addresses of that VR must also be the real physical addresses of that interface.

•Conversely, if any virtual IP address is not the real physical address of that interface, all virtual IP address of that VR cannot be the real physical address of that interface.

•The XSR supports 11 IP addresses per VR (1 primary + 10 secondary)

•With four VR's allowed per XSR, you can configure up to 44 virtual IP addresses per XSR.

PPPoE & Secondary IP

Secondary IP is not supported on PPPoE interfaces.

Maximum Transmission Unit (MTU)

MTU is the largest frame size allowed on an interface. It is dictated by the link level limit on a particular port. Examples of link layer types are Ethernet and 802.3 encapsulation. MTU limits the bytes of data that can be sent in an IP packet using the ip mtu command. Datagrams exceeding the link layer's MTU must be fragmented. The default MTU size is 1500 bytes.

Refer to the XSR CLI Reference Guide for more information.

Ping

Ping is an important debugging tool for testing network layer connectivity between a source and destination address. The source represents an IP address on the XSR where the command is executed from. The destination can be any IP address on the network, including an address on the same device where a ping occurs. Ping also allows the packet size to be set.

Refer to the XSR CLI Reference Guide for more information.

Traceroute

Traceroute is a vital debugging tool which reports the route IP datagrams follow to a certain destination. Its output is a complete list of routers that a specific datagram crosses to reach its destination, as well as the round time trip between the XSR where the Traceroute program runs and each of these routers. The traceroute command can be issued by the XSR.

Refer to the XSR CLI Reference Guide for more information.

IP Routing Protocols

Routing is one of the most important functions of IP. Routing information, which is stored in a routing table, is used by the XSR to determine the route for each of the packets that pass through it. The following routing features are supported on the XSR:

•RIP, OSPF, and BGP

5-10 Configuring IP