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Configuring the Unified Forwarding Table

Configuring an Address-Storage Profile

You configure the mix that best meets your needs by choosing the appropriate profile. Table 1 lists the profiles you can choose and the maximum values for the MAC address and host table entries.

Note that if the host table stores the maximum number of entries for any given type, the entire table is full and is unable to accommodate any entries of any other type. For example, an IPv6 unicast address occupies twice as much memory as an IPv4 unicast address, and an IPv6 multicast address occupies four times as much memory as an IPv4 unicast address. For more information about valid combinations of table entries see Understanding the Unified Forwarding Table.

Note: When you configure and commit a profile, the PFE process restarts and all the data interfaces on the switch go down and come back up.

The settings for l2-profile-three are configured by default. That is, if you do not enter a set forwarding–options chassis profile-name statement, these settings are configured.

Configuring the LPM Allocation

In addition to choosing a profile, you can further optimize memory allocation for LPM table entries by configuring how many IPv6 prefixes in the range /65 through /127 you want the switch to store. The switch uses LPM entries during address lookup to match addresses to the most-specific (longest) applicable prefix. The procedures for configuring the LPM table are different depending on which version of Junos OS you are using.

• Configuring the LPM Table With Junos OS 13.2X51-D10 and 13.2X52-D10
• Configuring the LPM Table With Junos OS 13.2x51-D15

Configuring the LPM Table With Junos OS 13.2X51-D10 and 13.2X52-D10

With Junos OS 13.2x51-D10 and 13.2X52-D10, the switch allocates memory for 16 IPv6 prefixes in the range /65 through /127 by default. If you want to use more than 16 IPv6 prefixes in this range, you must enter and commit the following statement:

Each increment adds support for 16 IPv6 prefixes between /65 and /127, for a maximum of 2048 such prefixes (16 x 128 = 2048). The system supports 16 of these prefixes by default, so to increase the number of supported prefixes, you must enter a value of 2 or greater. For example, if you enter 2, the system will support 32 IPv6 prefixes in the range /65 through /127.

Note: When you configure and commit the num-65-127-prefix value, all the data interfaces on the switch restart. The management interfaces are unaffected.

The LPM table is shared, and each increment that you add for IPv6 prefixes in the range /65 through /127 reduces the number of table entries that are available for IPv4 prefixes and IPv6 prefixes shorter than /65. Note that IPv6 prefixes /65 and longer consume twice as much memory as shorter IPv6 prefixes and four times as much memory as IPv4 prefixes. So, for example, entering the following statement

provides for 16 additional IPv6 prefixes /65 or longer (for a total of 32 such prefixes) and reduces the numbers of other prefixes that can be stored, as indicated:

• 32 fewer IPv6 prefixes shorter than /65 (16 IPv6 prefixes /65 or longer consume the same amount of memory as 32 IPv6 prefixes shorter than /65), or
• 64 fewer IPv4 prefixes (16 IPv6 prefixes /65 or longer consume the same amount of memory as 64 IPv4 prefixes)

Table 2 provides examples of valid combinations that the LPM table can store using the l2 and l3 profiles. Once again, each row in the table represents a case in which the table is full and cannot accommodate any more entries.

Note: With Junos OS 13.2X51-D10 and 13.2X52-D10, the lpm-profile does not support IPv6 prefixes. If you use this version of Junos OS and also use the lpm-profile, do not configure the num-65-127-prefix statement. That is, leave it at its default value of 1, which allows for as many as 128K IPv4 prefixes (the maximum possible).

Configuring the LPM Table With Junos OS 13.2x51-D15

With Junos OS 13.2X51-D15, you can configure the memory allocation for the LPM table for the lpm-profile profile independently of the other profiles. In addition, Junos OS 13.2x51-D15 offers twice as much storage for IPv6 prefixes /65 through /127 (4K instead of 2K) for the l2 and l3 profiles.

• Configuring the l2 and l3 profiles With Junos OS 13.2x51-D15
• Configuring The lpm-profile With Junos OS 13.2x51-D15

Configuring the l2 and l3 profiles With Junos OS 13.2x51-D15

With Junos OS 13.2x51-D15, you can configure the switch to support as many as 4K IPv6 prefixes /65 through /127 if you are using any profile other than the lpm-profile profile. To do so, enter and commit the following statement:

Each increment adds support for 1K IPv6 prefixes between /65 and /127, for a maximum of 4K such prefixes. The default value is 1, which allocates memory for 1K of IPv6 prefixes in this range. Each increment that you add for IPv6 prefixes in the range /65 through /127 reduces the number of table entries that are available for IPv6 prefixes shorter than /65 and IPv4 prefixes. Table 3 shows the numbers of entries that you can allocate by using the num-65-127-prefix statement with Junos OS 13.2X51-D15. Once again, each row represents a case in which the table is full and cannot accommodate any more entries.

Note: When you configure the num-65-127-prefix value, the PFE process restarts and all the data interfaces on the switch go down and come back up. The management interfaces are unaffected.

Configuring The lpm-profile With Junos OS 13.2x51-D15

If you use the lpm-profile profile with Junos OS 13.2x51-D15, you can control whether the switch allocates any memory for IPv6 prefixes /65 through /127. By default, the switch supports the following with this profile:

• 128K IPv4 prefixes
• 16K IPv6 prefixes (all lengths)

You can disable support for IPv6 prefixes /65 through /127 with the lpm-profile profile so that there is more memory for IPv6 prefixes shorter than /65. To do so, enter and commit the following statement:

If you enter this statement, the switch allocates memory for the following:

• 128K IPv4 and IPv6 prefixes shorter than /65
• 0K IPv6 prefixes /65 through /127

For example, if you use the prefix-65-127-disable statement, each of the following combinations are valid:

• 100K IPv4 and 28K IPv6 /64 prefixes
• 64K IPv4 and 64K IPv6 /64 prefixes
• 128K IPv4 and 0K IPv6 /64 prefixes
• 0K IPv4 and 128K IPv6 /64 prefixes