HP 6120XG HP ProCurve Series 6120 Blade Switches Multicast and Routing Guide - Page 53

IP Forwarding Cache, Routing Paths., Administrative Distance.

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IP Routing Features Overview of IP Routing Routing Paths. The IP route table can receive the routing paths from the following sources: ■ A directly-connected destination, which means there are no router hops to the destination ■ A static IP route, which is a user-configured route ■ A route learned through RIP Administrative Distance. The IP route table contains the best path to a destination. When the software receives paths from more than one of the sources listed above, the software compares the administrative distance of each path and selects the path with the lowest administrative distance. The administrative distance is a protocol-independent value from 1 - 255. The IP route table is displayed by entering the CLI command show ip route from any context level in the console CLI. Here is an example of an entry in the IP route table: Destination Gateway VLAN Type Sub-Type Metric Di 10.10.10.1/32 10.10.12.1 connected 1 0 Each IP route table entry contains the destination's IP address and subnet mask and the IP address of the next-hop router interface to the destination. Each entry also indicates route type. The type indicates how the IP route table received the route. To configure a static IP route, see "Configuring a Static IP Route" on page 3-22 IP Forwarding Cache The IP forwarding cache provides a fast-path mechanism for forwarding IP packets. The cache contains entries for IP destinations. When an ProCurve routing switch has completed processing and addressing for a packet and is ready to forward the packet, the device checks the IP forwarding cache for an entry to the packet's destination. ■ If the cache contains an entry with the destination IP address, the device uses the information in the entry to forward the packet out the ports listed in the entry. The destination IP address is the address of the packet's final destination. The port numbers are the ports through which the destination can be reached. ■ If the cache does not contain an entry, the software can create an entry in the forwarding cache. 3-7

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----------------- --------------- ---- --------- ---------- -------- --
IP Routing Features
Overview of IP Routing
Routing Paths.
The IP route table can receive the routing paths from the
following sources:
■
A directly-connected destination, which means there are no router hops
to the destination
■
A static IP route, which is a user-configured route
■
A route learned through RIP
Administrative Distance.
The IP route table contains the best path to a
destination. When the software receives paths from more than one of the
sources listed above, the software compares the administrative distance of
each path and selects the path with the lowest administrative distance. The
administrative distance is a protocol-independent value from 1 – 255.
The IP route table is displayed by entering the CLI command
show ip route
from any context level in the console CLI. Here is an example of an entry in
the IP route table:
Destination
Gateway
VLAN Type
Sub-Type
Metric
Di
10.10.10.1/32
10.10.12.1
connected
1
0
Each IP route table entry contains the destination’s IP address and subnet
mask and the IP address of the next-hop router interface to the destination.
Each entry also indicates route type. The type indicates how the IP route table
received the route.
To configure a static IP route, see “Configuring a Static IP Route” on page 3-22
IP Forwarding Cache
The IP forwarding cache provides a fast-path mechanism for forwarding IP
packets. The cache contains entries for IP destinations. When an ProCurve
routing switch has completed processing and addressing for a packet and is
ready to forward the packet, the device checks the IP forwarding cache for an
entry to the packet’s destination.
■
If the cache contains an entry with the destination IP address, the device
uses the information in the entry to forward the packet out the ports listed
in the entry. The destination IP address is the address of the packet’s final
destination. The port numbers are the ports through which the destination
can be reached.
■
If the cache does not contain an entry, the software can create an entry in
the forwarding cache.
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