What will a switch compare in its MAC table to be able to forward a frame?
Understanding Layer 2 Forwarding Tables on Switches, Routers and NFX Series DevicesYou can configure Layer 2 MAC address and VLAN learning and forwarding properties in support of Layer 2 bridging. Unicast media access control (MAC) addresses are learned to avoid flooding the packets to all the ports in a VLAN. A source MAC entry is created in its source and destination MAC tables for each MAC address learned from packets received on ports that belong to the VLAN. Show
When you configure a VLAN, Layer 2 address learning is enabled by default. The VLAN learns unicast media access control (MAC) addresses to avoid flooding the packets to all the ports in the VLAN. Each VLAN creates a source MAC entry in its source and destination MAC tables for each source MAC address learned from packets received on the ports that belong to the VLAN. Note: Traffic is not flooded back onto the interface on which it was received. However, because this “split horizon” occurs at a late stage, the packet statistics displayed by commands such as [edit chassis forwarding-options] user@switch# set custom-profile1 will include flood traffic. You can optionally disable MAC learning either for the entire device or for a specific VLAN or logical interface. You can also configure the following Layer 2 learning and forwarding properties:
Understanding Layer 2 Forwarding Tables on Security DevicesThe SRX Series device maintains forwarding tables that contain MAC addresses and associated interfaces for each Layer 2 VLAN. When a packet arrives with a new source MAC address in its frame header, the device adds the MAC address to its forwarding table and tracks the interface at which the packet arrived. The table also contains the corresponding interface through which the device can forward traffic for a particular MAC address. If the destination MAC address of a packet is unknown to the device (that is, the destination MAC address in the packet does not have an entry in the forwarding table), the device duplicates the packet and floods it on all interfaces in the VLAN other than the interface on which the packet arrived. This is known as packet flooding and is the default behavior for the device to determine the outgoing interface for an unknown destination MAC address. Packet flooding is performed at two levels: packets are flooded to different zones as permitted by configured Layer 2 security policies, and packets are also flooded to different interfaces with the same VLAN identifier within the same zone. The device learns the forwarding interface for the MAC address when a reply with that MAC address arrives at one of its interfaces. You can specify that the SRX Series device use ARP queries and traceroute requests (which are ICMP echo requests with the time-to-live values set to 1) instead of packet flooding to locate an unknown destination MAC address. This method is considered more secure than packet flooding because the device floods ARP queries and traceroute packets—not the initial packet—on all interfaces. When ARP or traceroute flooding is used, the original packet is dropped. The device broadcasts an ARP or ICMP query to all other devices on the same subnetwork, requesting the device at the specified destination IP address to send back a reply. Only the device with the specified IP address replies, which provides the requestor with the MAC address of the responder. ARP allows the device to discover the destination MAC address for a unicast packet if the destination IP address is in the same subnetwork as the ingress IP address. (The ingress IP address refers to the IP address of the last device to send the packet to the device. The device might be the source that sent the packet or a router forwarding the packet.) Traceroute allows the device to discover the destination MAC address even if the destination IP address belongs to a device in a subnetwork beyond that of the ingress IP address. When you enable ARP queries to locate an unknown destination MAC address, traceroute requests are also enabled. You can also optionally specify that traceroute requests not be used; however, the device can then discover destination MAC addresses for unicast packets only if the destination IP address is in the same subnetwork as the ingress IP address. Whether you enable ARP queries and traceroute requests or ARP-only queries to locate unknown destination MAC addresses, the SRX Series device performs the following series of actions:
Benefits of Unified Forwarding TablesTraditionally, forwarding tables have been statically defined and have supported only a fixed number of entries for each type of address. The unified forwarding table (UFT) provides the following benefits:
Using the Unified Forwarding Table to Optimize Address StorageOn the QFX5100, EX4600, EX4650, QFX5110, QFX5200, and QFX5120 switches, you can control the allocation of forwarding table memory available to store the following:
UFT essentially combines the three distinct forwarding tables to create one table with flexible resource allocation. You can select one of five forwarding table profiles that best meets your network needs. Each profile is configured with different maximum values for each type of address. For example, for a switch that handles a great deal of Layer 2 traffic, such as a virtualized network with many servers and virtualized machines, you would likely choose a profile that allocates a higher percentage of memory to MAC addresses. For a switch that operates in the core of a network, participates in an IP fabric, you probably want to maximize the number of routing table entries it can store. In this case, you would choose a profile that allocates a higher percentage of memory to longest match prefixes. The QFX5200 switch supports a custom profile that allows you to partition the four available shared memory banks with a total of 128,000 entries among MAC addresses, Layer 3 host addresses, and LPM prefixes. Note: Support for QFX5200 switches was introduced in Junos OS Release 15.1x53-D30. The QFX5200 switch is not supported on Junos OS Release 16.1R1. Understanding the Allocation of MAC Addresses and Host AddressesAll five profiles are supported, each of which allocates different amounts of memory for Layer 2 or Layer 3 entries, enabling you choose one that best suits the needs of your network. The QFX5200 and QFX5210 switches, however, supports different maximum values for each profile from the other switches. For more information about the custom profile, see . Note: The default profile is [edit chassis forwarding-options] user@switch# set custom-profile4, which allocates equal space for MAC Addresses and Layer 3 host addresses. On QFX5100, EX4600, QFX5110, and QFX5200 switches, the space is equal to 16,000 IPv4 entries for the LPM table, and on QFX5210 switches, the space is equal to 32,000 IPv4 entries for the LPM table. For the [edit chassis forwarding-options] user@switch# set custom-profile5 the LPM table size is equal to 256,000 IPv4 entries. Note: Starting with Junos OS Release 18.1R1 on the QFX5210-64C switch, for all these profiles, except for the [edit chassis forwarding-options] user@switch# set custom-profile5 the longest prefix match (LPM) table size is equal to 32,000 IPv4 entries. Note: Starting with Junos OS Release 18.3R1 on the QFX5120 and EX4650 switches, for all these profiles, except for the [edit chassis forwarding-options] user@switch# set custom-profile5 the longest prefix match (LPM) table size is equal to 32,000 IPv4 entries. Note: On QFX5100, EX4600, EX4650, QFX5110, QFX5200, QFX5120, and QFX5210-64C switches, IPv4 and IPv6 host routes with ECMP next hops are stored in the host table. Best Practice: If the host or LPM table stores the maximum number of entries for any given type of entry, the entire shared table is full and is unable to accommodate any entries of any other type. Different entry types occupy different amounts of memory. 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. lists the profiles you can choose and the associated maximum values for the MAC address and host table entries on QFX5100 and EX4600 switches. Table 1: Unified Forwarding Table Profiles on QFX5100 and EX4600 SwitchesProfile NameMAC TableHost Table (unicast and multicast addresses) MAC AddressesIPv4 unicastIPv6 unicastIPv4 (*, G)IPv4 (S, G)IPv6 (*, G)IPv6 (S, G) [edit chassis forwarding-options] user@switch# set custom-profile8 288K 16K 8K 8K 8K 4K 4K [edit chassis forwarding-options] user@switch# set custom-profile9 224K 80K 40K 40K 40K 20K 20K [edit chassis forwarding-options] user@switch# set custom-profile4 (default) 160K 144K 72K 72K 72K 36K 36K [edit chassis forwarding-options custom-profile] user@switch# set l2-entries num-banks 01 96K 208K 104K 104K 104K 52K 52K [edit chassis forwarding-options] user@switch# set custom-profile5 32K 16K 8K 8K 8K 4K 4K [edit chassis forwarding-options] user@switch# set custom-profile5with [edit chassis forwarding-options custom-profile] user@switch# set l2-entries num-banks 04 option 32K (stored in LPM table) (stored in LPM table) 8K 8K 4K 4K lists the profiles you can choose and the associated maximum values for the MAC address and host table entries on QFX5110 switches. Table 2: Unified Forwarding Table Profiles on QFX5110 SwitchesProfile NameMAC TableHost Table (unicast and multicast addresses) MAC AddressesIPv4 unicastIPv6 unicastIPv4 (*, G)IPv4 (S, G)IPv6 (*, G)IPv6 (S, G) [edit chassis forwarding-options] user@switch# set custom-profile8 288K 16K 8K 8K 8K 4K 4K [edit chassis forwarding-options] user@switch# set custom-profile9 224K 80K 40K 40K 40K 20K 20K [edit chassis forwarding-options] user@switch# set custom-profile4 (default) 160K 144K 72K 72K 72K 36K 36K [edit chassis forwarding-options custom-profile] user@switch# set l2-entries num-banks 01 96K 208K 104K 104K 104K 52K 52K lists the LPM table size variations for the QFX5110 switch depending on the prefix entries. Table 3: LPM Table Size Variations on QFX5110 SwitchesProfile Name Prefix Entries num-65-127-prefixIPv4 LPM<= /32IPv6 LPM <= /64IPv6 LPM > /64[edit chassis forwarding-options custom-profile] user@switch# set l2-entries num-banks 09 16K 8K 0K [edit chassis forwarding-options] user@switch# set custom-profile3 12K 6K 1K [edit chassis forwarding-options custom-profile] user@switch# set l3-entries num-banks 21 8K 4K 2K [edit chassis forwarding-options custom-profile] user@switch# set l3-entries num-banks 22 4K 2K 3K [edit chassis forwarding-options custom-profile] user@switch# set l3-entries num-banks 23 0K 0K 4K lists the profiles you can choose and the associated maximum values for the MAC address and host table entries on QFX5200-32C switches. Table 4: Unified Forwarding Table Profiles on QFX5200-32C SwitchesProfile NameMAC TableHost Table (unicast and multicast addresses) MAC AddressesIPv4 unicastIPv6 unicastIPv4 (*, G)IPv4 (S, G)IPv6 (*, G)IPv6 (S, G)Exact-Match [edit chassis forwarding-options] user@switch# set custom-profile8 136K 8K 4K 4K 4K 2K 2K 0 [edit chassis forwarding-options] user@switch# set custom-profile9 104K 40K 20K 20K 20K 10K 10K 0 [edit chassis forwarding-options] user@switch# set custom-profile4 (default) 72K 72K 36K 36K 36K 18K 18K 0 [edit chassis forwarding-options custom-profile] user@switch# set l2-entries num-banks 01 40K 104K 52K 52K 52K 26K 26K 0 [edit chassis forwarding-options] user@switch# set custom-profile5 8K 8K 4K 4K 4K 2K 2K 0 lists the profiles you can choose and the associated maximum values for the MAC address and host table entries on QFX5200-48Y switches. Table 5: Unified Forwarding Table Profiles on QFX5200-48Y SwitchesProfile NameMAC TableHost Table (unicast and multicast addresses) MAC AddressesIPv4 unicastIPv6 unicastIPv4 (*, G)IPv4 (S, G)IPv6 (*, G)IPv6 (S, G) [edit chassis forwarding-options] user@switch# set custom-profile8 136K 8K 4K 4K 4K 2K 2K [edit chassis forwarding-options] user@switch# set custom-profile9 104K 40K 20K 20K 20K 10K 10K [edit chassis forwarding-options] user@switch# set custom-profile4 (default) 72K 72K 36K 36K 36K 18K 18K [edit chassis forwarding-options custom-profile] user@switch# set l2-entries num-banks 01 40K 104K 52K 52K 52K 26K 26K [edit chassis forwarding-options] user@switch# set custom-profile5 8K 8K 4K 4K 4K 2K 2K lists the LPM table size variations for the QFX5200-48Y switch depending on the prefix entries. Table 6: LPM Table Size Variations on QFX5200-48Y SwitchesProfile Name Prefix Entries num-65-127-prefixIPv4 LPM<= /32IPv6 LPM <= /64IPv6 LPM > /64[edit chassis forwarding-options custom-profile] user@switch# set l2-entries num-banks 09 16K 8K 0K [edit chassis forwarding-options] user@switch# set custom-profile3 12K 6K 1K [edit chassis forwarding-options custom-profile] user@switch# set l3-entries num-banks 21 8K 4K 2K [edit chassis forwarding-options custom-profile] user@switch# set l3-entries num-banks 22 40K 2K 3K [edit chassis forwarding-options custom-profile] user@switch# set l3-entries num-banks 23 0K 0K 4K lists the profiles you can choose and the associated maximum values for the MAC address and host table entries on QFX5210-64C switches. Table 7: Unified Forwarding Table Profiles on QFX5210-64C SwitchesProfile NameMAC TableHost Table (unicast and multicast addresses) MAC AddressesIPv4 unicastIPv6 unicastIPv4 (*, G)IPv4 (S, G)IPv6 (*, G)IPv6 (S, G)Exact Match [edit chassis forwarding-options] user@switch# set custom-profile8 264K 8K 4K 4K 4K 2K 2K 0K [edit chassis forwarding-options] user@switch# set custom-profile9 200K 72K 36K 36K 36K 18K 18K 0K [edit chassis forwarding-options] user@switch# set custom-profile4 (default) 136K 136K 72K 72K 72K 36K 36K 0K [edit chassis forwarding-options custom-profile] user@switch# set l2-entries num-banks 01 72K 200K 100K 100K 100K 50K 50K 0K lists the profiles you can choose and the associated maximum values for the MAC address and host table entries on QFX5120 and EX4650 switches. Table 8: Unified Forwarding Table Profiles on QFX5120 and EX4650 SwitchesProfile NameMAC TableHost Table (unicast and multicast addresses) MAC AddressesIPv4 unicastIPv6 unicastIPv4 (*, G)IPv4 (S, G)IPv6 (*, G)IPv6 (S, G) [edit chassis forwarding-options] user@switch# set custom-profile8 288K 16K 8K 8K 8K 4K 4K [edit chassis forwarding-options] user@switch# set custom-profile9 224K 80K 40K 40K 40K 20K 20K [edit chassis forwarding-options] user@switch# set custom-profile4 (default) 160K 144K 72K 72K 72K 36K 36K [edit chassis forwarding-options custom-profile] user@switch# set l2-entries num-banks 01 96K 208K 104K 104K 104K 52K 52K lists the LPM table size variations for the QFX5210-64C switch depending on the prefix entries. Table 9: LPM Table Size Variations on QFX5210-64C SwitchesProfile Name Prefix Entries num-65-127-prefixIPv4 LPM<= /32IPv6 LPM <= /64IPv6 LPM > /64[edit chassis forwarding-options custom-profile] user@switch# set l2-entries num-banks 09 32K 16K 0K [edit chassis forwarding-options] user@switch# set custom-profile3 28K 14K 1K [edit chassis forwarding-options custom-profile] user@switch# set l3-entries num-banks 21 24K 12K 2K [edit chassis forwarding-options custom-profile] user@switch# set l3-entries num-banks 22 20K 10K 3K [edit chassis forwarding-options custom-profile] user@switch# set l3-entries num-banks 23 0K 0K 4K lists the Layer 3 Defip table size variations for the QFX5120 and EX4650 switches depending on the changing IPv6/128 prefix entries. Table 10: LPM Table Size Variations on QFX5210-64C and EX4650 SwitchesProfile Name Prefix Entries num-65-127-prefixIPv4 LPM<= /32IPv6 LPM <= /64IPv6 LPM > /64[edit chassis forwarding-options custom-profile] user@switch# set l2-entries num-banks 09 32K 16K 0K [edit chassis forwarding-options custom-profile] user@switch# set l3-entries num-banks 21 24K 12K 2K [edit chassis forwarding-options custom-profile] user@switch# set l3-entries num-banks 23 16K 8K 4K user@switch> show chassis forwarding-options UFT Configuration: custom-profile Configured custom scale: Entry type Total scale(K) L2(mac) 8 L3 (unicast & multicast) 72 Exact Match 0 Longest Prefix Match (lpm) 80 num-65-127-prefix = 1K -------------Bank details for various types of entries------------ Entry type Dedicated Bank Size(K) Shared Bank Size(K) L2 (mac) 8 32 * num shared banks L3 (unicast & multicast 8 32 * num shared banks Exact match 0 16 * num shared banks Longest Prefix match(lpm) 16 32 * num shared banks5 8K 4K 6K user@switch> show chassis forwarding-options UFT Configuration: custom-profile Configured custom scale: Entry type Total scale(K) L2(mac) 8 L3 (unicast & multicast) 72 Exact Match 0 Longest Prefix Match (lpm) 80 num-65-127-prefix = 1K -------------Bank details for various types of entries------------ Entry type Dedicated Bank Size(K) Shared Bank Size(K) L2 (mac) 8 32 * num shared banks L3 (unicast & multicast 8 32 * num shared banks Exact match 0 16 * num shared banks Longest Prefix match(lpm) 16 32 * num shared banks6 0K 0K 8K Unified Forwarding Table Profiles on QFX5130 and QFX5700 Switches for Junos OS Evolved ReleasesYou can configure a forwarding-profile for the unified forwarding table on QFX5130 and QFX5700 switches using the user@switch> show chassis forwarding-options UFT Configuration: custom-profile Configured custom scale: Entry type Total scale(K) L2(mac) 8 L3 (unicast & multicast) 72 Exact Match 0 Longest Prefix Match (lpm) 80 num-65-127-prefix = 1K -------------Bank details for various types of entries------------ Entry type Dedicated Bank Size(K) Shared Bank Size(K) L2 (mac) 8 32 * num shared banks L3 (unicast & multicast 8 32 * num shared banks Exact match 0 16 * num shared banks Longest Prefix match(lpm) 16 32 * num shared banks7 configuration statement at the [edit system packet-forwarding-options] hierarchy level for Junos OS Evolved. user@switch#set system packet-forwarding-options forwarding-profile ? Possible completions: + apply-groups Groups from which to inherit configuration data + apply-groups-except Don't inherit configuration data from these groups default-profile MAC: 32K L3-host: 32K LPM: 720K FP-Compression: 18K, restarts PFE host-acl-profile MAC: 160K L3-host: 160K LPM: 65K FP-Compression: 18K, restarts PFE host-profile MAC: 160K L3-host: 160K LPM: 72K FP-Compression: 0, restarts PFE lpm-profile MAC: 32K L3-host: 32K LPM: 1.24M ARP: 61K FP-Compression: 0 Tunnels: 0, restarts PFE Table 11: Unified Forwarding Table Profiles on QFX5130 and QFX5700 SwitchesProfile ApplicationsDefault profileLPM-profileHost-profileHost-ACL-profileFeatureLayer 2-MAC32K32K160K160KLayer 3 Host Unicast -IPv432K32K160K 160K Layer 3 Host Unicast -IPv616K16K80K80KIPv4 LPM720K1.24M72K65KIPv6 LPM <= /64550K868K50K22KIPv6 LPM > /64335K495K22K12KFP-compression18K0018KARP & NDP32K61K32K32KVRFupto 8Kupto 12Kupto 8Kupto 4KLayer 3 Multicast IPv48K8K16K16KLayer 3 Multicast IPv64K4K8K8KTunnels (VXLAN and GRE) SupportedNot SupportedSupportedSupportedNote:
Understanding Ternary Content Addressable Memory (TCAM) and Longest Prefix Match EntriesYou can further customize non-LPM profiles by configuring the space available for ternary content addressable memory (TCAM) to allocate more memory for longest prefix match entries. You can change the number of entries allocated to these IPv6 addresses, essentially allocating more or less space for LPM IPv4 entries with any prefix length or IPv6 entries with prefix lengths of 64 of shorter. For more information about how to change the default parameters of the TCAM memory space for LPM entries, see . Note: The option to adjust TCAM space is not supported on the longest prefix match (LPM) or custom profiles. However, for the LPM profile, you can configure TCAM space not to allocate any memory for IPv6 entries with prefix lengths of 65 or longer, thereby allocating that memory space only for IPv4 routes or IP routes with prefix lengths equal to or less than 64 or a combination of the two types of prefixes. Note: Starting with Junos OS Release 18.1R1 on QFX5210 switches, you can configure TCAM space to allocate a maximum of 8,000 IPv6 entries with prefix lengths of 65 or longer. The default value is 2,000 entries. Starting with Junos OS Release 13.2X51-D15, you can configure TCAM space to allocate a maximum of 4,000 IPv6 entries with prefix lengths of 65 or longer. The default value is 1,000 entries. Previous to Junos OS Release 13.2X51-D15, you could allocate only a maximum of 2,048 entries for IPv6 the IPv6 prefixes with lengths in the range /65 to /127 range. The default value was 16 entries for these types of IPv6 prefixes. On Junos OS Releases 13.2x51-D10 and 13.2x52D10, the procedure to change the default value of 16 entries differs from later releases, where the maximum and default values are higher. For more information about that procedure, see Host Table Example for Profile with Heavy Layer 2 Trafficlists various valid combinations that the host table can store if you use the [edit chassis forwarding-options] user@switch# set custom-profile8 profile on QFX5100 and EX4600 switches. This profile allocates the percentage of memory to Layer 2 addresses. Note that the default values might be different on other switches. Each row in the table represents a case in which the host table is full and cannot accommodate any more entries. Table 12: Example Host Table Combinations Using l2-profile-one on QFX5100 and EX4600 SwitchesIPv4 unicastIPv6 unicastIPv4 multicast (*, G)IPv4 multicast (S, G)IPv6 multicast (*, G)IPv6 multicast (S, G) 16K 0 0 0 0 0 12K 2K 0 0 0 0 12K 0 2K 2K 0 0 8K 4K 0 0 0 0 4K 2K 2K 2K 0 0 0 4K 0 0 1K 1K Traditionally, forwarding tables have been statically defined and have supported only a fixed number of entries for each type of address. The Unified Forwarding Table (UFT) feature enables you to optimize how forwarding-table memory is allocated to best suit the needs of your network. This example shows how to configure a Unified Forwarding Table profile that enables you to partition four shared hash memory banks among three different types of forwarding-table entries: MAC addresses, Layer 3 host addresses, and longest prefix match (LPM). The UFT feature also supports five profiles that each allocate a specific maximum amount of memory for each type of forwarding table entry. Some profiles allocate more memory to Layer 2 entries, while other profiles allocate more memory to Layer 3 or LPM entries. The maximum values for each type of entry are fixed in these profiles. With the custom profile, you can designate one or more shared memory banks to store a specific type of forwarding-table entry. You can configure as few as one or as many as four memory banks in a custom profile. The custom profile thus provides even more flexibility in enabling you to allocate forwarding-table memory for specific types of entries. To configure a custom profile for the Unified Forwarding Table feature on a QFX5200 switch that allocates two shared memory banks for Layer 3 host address and two shared memory banks for LPM entries, perform these tasks: CLI Quick ConfigurationTo quickly configure this example, copy the following commands, paste them into a text file, remove any line breaks, change any details necessary to match your network configuration, copy and paste the commands into the CLI at the user@switch> show chassis forwarding-options UFT Configuration: custom-profile Configured custom scale: Entry type Total scale(K) L2(mac) 8 L3 (unicast & multicast) 72 Exact Match 0 Longest Prefix Match (lpm) 80 num-65-127-prefix = 1K -------------Bank details for various types of entries------------ Entry type Dedicated Bank Size(K) Shared Bank Size(K) L2 (mac) 8 32 * num shared banks L3 (unicast & multicast 8 32 * num shared banks Exact match 0 16 * num shared banks Longest Prefix match(lpm) 16 32 * num shared banks9 hierarchy level, and then enter [edit chassis forwarding-options] user@switch# set profile-name0 from configuration mode. A commit check is performed to ensure that you have allocated forwarding-table space for no more than four memory banks. CAUTION: When you configure and commit a profile, the Packet Forwarding Engine restarts and all the data interfaces on the switch go down and come back up. user@switch# set chassis forwarding-options custom-profile user@switch# set chassis forwarding-options custom-profile l2-entries num-banks 0 user@switch# set chassis forwarding-options custom-profile l3-entries num-banks 2 user@switch# set chassis forwarding-options custom-profile lpm-entries num-banks 2 Configuring the Custom ProfileStep-by-Step ProcedureTo create the custom profile:
Configuring the Allocation of Shared Memory BanksStep-by-Step ProcedureTo allocate memory for specific types of entries for the shared memory banks:
ResultsFrom configuration mode, confirm your configuration by entering the show chassis forwarding-options command. If the output does not display the intended configuration, repeat the instructions in this example to correct the configuration. user@switch# show chassis forwarding-profile
custom-profile {
l2-entries {
num-banks 0;
}
l3-entries {
num-banks 2;
}
lpm-entries {
num-banks 2
}
}
If you are done configuring the switch, enter [edit chassis forwarding-options] user@switch# set profile-name0 from configuration mode CAUTION: The Packet Forwarding Engine will restart and all the data interfaces on the switch will go down and come back up. Confirm that the configuration is working properly. Checking the Parameters of the Custom ProfilePurposeVerify that the custom profile is enabled. Actionuser@switch> show chassis forwarding-options UFT Configuration: custom-profile Configured custom scale: Entry type Total scale(K) L2(mac) 8 L3 (unicast & multicast) 72 Exact Match 0 Longest Prefix Match (lpm) 80 num-65-127-prefix = 1K -------------Bank details for various types of entries------------ Entry type Dedicated Bank Size(K) Shared Bank Size(K) L2 (mac) 8 32 * num shared banks L3 (unicast & multicast 8 32 * num shared banks Exact match 0 16 * num shared banks Longest Prefix match(lpm) 16 32 * num shared banks MeaningThe output shows that the custom profile is enabled as configured with two shared memory banks designated for Layer 3 host entries; two shared memory banks designated for LPM entries; and no shared memory allocated for Layer 2 entries. The total scale(K) field shows the total allocation of memory, that is, the amount allocated through the shared memory banks plus the amount allocated through the dedicated hash tables. The amount allocated through the dedicated hash tables is fixed and cannot be changed. Therefore, Layer 2 entries have 8K of memory allocated only through the dedicated hash table. Layer 3 host entries have 64K of memory allocated through two shared memory banks plus 8K through the dedicated hash table, for a total of 72K of memory. LPM entries have 64K of memory allocated through two shared memory banks plus 16K through the dedicated hash table, for a total of 80K of memory. Traditionally, forwarding tables have been statically defined and have supported only a fixed number of entries for each type of address stored in the tables. The Unified Forwarding Table feature lets you optimize how your switch allocates forwarding-table memory for different types of addresses. You can choose one of five unified forwarding table profiles. Each profile allocates a different maximum amount of memory for Layer 2, Layer 3 host, and longest prefix match (LPM) entries. In addition to selecting a profile, you can also select how much additional memory to allocate for LPM entries. Two profiles allocate higher percentages of memory to Layer 2 addresses. A third profile allocates a higher percentage of memory to Layer 3 host address, while a fourth profile allocates a higher percentage of memory to LPM entries. There is a default profile configured that allocates an equal amount of memory to Layer 2 and Layer 3 host addresses with the remainder allocated to LPM entries. For a switch in a virtualized network that handles a great deal of Layer 2 traffic, you would choose a profile that allocates a higher percentage of memory to Layer 2 addresses. For a switch that operates in the core of the network, you would choose a profile that allocates a higher percentage of memory to LPM entries. On QFX5200 and QFX5210-64C switches only, you can also configure a custom profile that allows you to partition shared memory banks among the different types of forwarding table entries. On QFX5200 switches, these shared memory banks have a total memory equal to 128,000 IPv4 unicast addresses. On QFX5210 switches, these shared memory banks have a total memory equal to 256,000 IPv4 unicast addresses. For more information about configuring the custom profile, see . To configure a unified forwarding table profile: Specify a forwarding-table profile. [edit chassis forwarding-options] user@switch# set profile-name For example, to specify the profile that allocates the highest percentage of memory to Layer 2 traffic: [edit chassis forwarding-options] user@switch# set l2-profile-one CAUTION: When you configure and commit a profile, in most cases the Packet Forwarding Engine automatically restarts and all the data interfaces on the switch go down and come back up (the management interfaces are unaffected). Starting with Junos OS Releases 14.1X53-D40, 15.1R5, and 16.1R3, for a Virtual Chassis or Virtual Chassis Fabric (VCF) comprised of EX4600 or QFX5100 switches, the Packet Forwarding Engine in member switches does not automatically restart upon configuring and committing a unified forwarding table profile change. This behavior avoids Virtual Chassis or VCF instability after the change propagates to member switches and multiple Packet Forwarding Engines automatically restart at the same time. Instead, a message is displayed at the CLI prompt and logged to the switch’s system log to notify you that the profile change does not take effect until the next time you reboot the Virtual Chassis or VCF. We recommend that you plan to make profile changes only when you can perform a Virtual Chassis or VCF system reboot immediately after committing the configuration update. Otherwise, the Virtual Chassis or VCF could become inconsistent if one or more members have a problem and restart with the new configuration before a planned system reboot activates the change on all members. Note: You can configure only one profile for the entire switch. Note: The [edit chassis forwarding-options] user@switch# set custom-profile4 is configured by default. Note: 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. Keep in mind that 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.. In addition to choosing a profile, you can further optimize memory allocation for longest prefix match (LPM) entries by configuring how many IPv6 prefixes to store with lengths from /65 through /127. The switch uses LPM entries during address lookup to match addresses to the most-specific (longest) applicable prefix. Prefixes of this type are stored in the space for ternary content addressable memory (TCAM). Changing the default parameters makes this space available for LPM entries. Increasing the amount of memory available for these IPv6 prefixes reduces by the same amount how much memory is available to store IPv4 unicast prefixes and IPv6 prefixes with lengths equal to or less than 64. The procedures for configuring the LPM table are different, depending on which version of Junos OS you are using. In the initial releases that UFT is supported, Junos OS Releases 13.2X51-D10 and 13.2X52-10, you can only increase the amount of memory allocated to IPv6 prefixes with lengths from /65 through /127 for any profile, except for [edit chassis forwarding-options] user@switch# set custom-profile5. Starting with Junos OS Release 13.2X51-D15, you can also allocate either less or no memory for IPv6 prefixes with lengths in the range /65 through /127, depending on which profile is configured. For the [edit chassis forwarding-options] user@switch# set profile-name5, however, the only change you can make to the default parameters is to allocate no memory for these types of prefixes. In Junos OS Releases 13.2x51-D10 and 13.2X52-D10, by default, the switch allocates memory for 16 IPv6 with prefixes with lengths in the range /65 through /127. You can configure the switch to allocate more memory for IPv6 prefixes with lengths in the range /65 through /127. To allocate more memory for IPv6 prefixes in the range /65 through /127:
Note: When you configure and commit the [edit chassis forwarding-options] user@switch# set profile-name6 statement, all the data interfaces on the switch restart. The management interfaces are unaffected. The [edit chassis forwarding-options] user@switch# set profile-name6 statement is not supported on the [edit chassis forwarding-options] user@switch# set custom-profile5. Starting in Junos OS Release 13.2X51-D15, you can configure the switch to allocate forwarding table memory for as many as 4,000 IPv6 prefixes with lengths in the range /65 through /127 for any profile other than the [edit chassis forwarding-options] user@switch# set custom-profile5 or [edit chassis forwarding-options] user@switch# set profile-name1. You can also specify to allocate no memory for these IPv6 entries. The default is 1,000 entries for IPv6 prefixes with lengths in the range /65 through /127. Previously, the maximum you could configure was for 2,048 entries for IPv6 prefixes with lengths in the range /65 through /127. The minimum number of entries was previously 16, which was the default. To specify how much forwarding table memory to allocate for IPv6 prefixes with length in the range /65 through /127:
Starting with Junos OS Release 13.2X51-D15, you can use the [edit chassis forwarding-options] user@switch# set l2-profile-one1 statement to allocate entries. shows the numbers of entries that you can allocate. Each row represents a case in which the table is full and cannot accommodate any more entries. Table 13: LPM Table Combinations for L2 and L3 profiles With Junos OS 13.2X51-D15 and Laternum-65-127-prefix ValueIPv4 EntriesIPv6 Entries (Prefix <= 64)IPv6 Entries (Prefix >= 65) [edit chassis forwarding-options custom-profile] user@switch# set l2-entries num-banks 09 16K 8K 0K [edit chassis forwarding-options] user@switch# set custom-profile3 (default) 12K 6K 1K [edit chassis forwarding-options custom-profile] user@switch# set l3-entries num-banks 21 8K 4K 2K [edit chassis forwarding-options custom-profile] user@switch# set l3-entries num-banks 22 4K 2K 3K [edit chassis forwarding-options custom-profile] user@switch# set l3-entries num-banks 23 0K 0K 4K CAUTION: When you configure and commit a profile change with the [edit chassis forwarding-options] user@switch# set profile-name6 statement, the Packet Forwarding Engine automatically restarts and all the data interfaces on the switch go down and come back up (the management interfaces are unaffected). However, starting with Junos OS Releases 14.1X53-D40, 15.1R5, and 16.1R3, Packet Forwarding Engines on switches in a Virtual Chassis or Virtual Chassis Fabric (VCF) do not automatically restart upon configuring a unified forwarding table profile change. This behavior avoids Virtual Chassis or VCF instability after the change propagates to member switches and multiple Packet Forwarding Engines automatically restart at the same time. Instead, a message is displayed at the CLI prompt and logged to the switch’s system log to notify you that the profile change does not take effect until the next time you reboot the Virtual Chassis or VCF. We recommend that you plan to make profile changes only when you can perform a Virtual Chassis or VCF system reboot immediately after committing the configuration update. Otherwise, the Virtual Chassis or VCF could become inconsistent if one or more members have a problem and restart with the new configuration before a planned system reboot activates the change on all members. Starting with Junos OS Release 13.2X51-D15 you can configure the [edit chassis forwarding-options] user@switch# set custom-profile5 profile not to allocate any memory for IPv6 entries with prefix lengths from /65 through /127. These are the default maximum values allocated for LPM memory for the [edit chassis forwarding-options] user@switch# set custom-profile5 by address type:
Note: The memory allocated for each address type represents the maximum default value for all LPM memory. To configure the [edit chassis forwarding-options] user@switch# set custom-profile5 not to allocate forwarding-table memory for IPv6 entries with prefixes from /65 through /127, thus allocating more memory for IPv4: Specify to disable forwarding-table memory for IPv6 prefixes with lengths in the range /65 through /127. user@switch# set chassis forwarding-options custom-profile user@switch# set chassis forwarding-options custom-profile l2-entries num-banks 0 user@switch# set chassis forwarding-options custom-profile l3-entries num-banks 2 user@switch# set chassis forwarding-options custom-profile lpm-entries num-banks 28 For example, on the QFX5100 and EX4600 switches only, if you use the user@switch# set chassis forwarding-options custom-profile user@switch# set chassis forwarding-options custom-profile l2-entries num-banks 0 user@switch# set chassis forwarding-options custom-profile l3-entries num-banks 2 user@switch# set chassis forwarding-options custom-profile lpm-entries num-banks 201 option, each of the following combinations are valid:
Note: On the QFX5200 switches, when you configure the user@switch# set chassis forwarding-options custom-profile user@switch# set chassis forwarding-options custom-profile l2-entries num-banks 0 user@switch# set chassis forwarding-options custom-profile l3-entries num-banks 2 user@switch# set chassis forwarding-options custom-profile lpm-entries num-banks 201 statement, the maximum number of IPv6 entries with prefixes equal to or shorter than 64 is 98,000. Starting in Junos OS Release 15.1X53-D30, you can configure the [edit chassis forwarding-options] user@switch# set custom-profile5 profile to store unicast IPv4 and IPv6 host addresses in the LPM table , thereby freeing memory in the host table. Unicast IPv4 and IPv6 addresses are stored in the LPM table instead of the host table, as shown in for QFX5100 and EX4600 switches. (Platform support depends on the Junos OS release in your installation.) You can use this option in conjunction with the option to allocate no memory in the LPM table for IPv6 entries with prefix lengths in the range /65 through /127. Together, these options maximize the amount of memory available for IPv4 unicast entries and IPv6 entries with prefix lengths equal to or less than 64. Table 14: lpm-profile with unicast-in-lpm Option for QFX5100 and EX4600 Switchesprefix-65- 127-disableMAC TableHost Table (multicast addresses)LPM Table unicast addresses) MACIPv4 unicastIPv6 unicastIPv4 (*, G)IPv4 (S, G)IPv6 (*, G)IPv6 (S, G)IPv4 unicastIPv6 unicast (/64) No 32K 0 0 8K 8K 4K 4K 128K 16K 16K Yes 32K 0 0 8K 8K 4K 4K 128K 128K 0 Starting with Junos Release 18.1R1, you cannot set configure a prefix for the [edit chassis forwarding-options] user@switch# set l2-profile-one1 statement on non-LPM profiles. You can only enable or disable the user@switch# set chassis forwarding-options custom-profile user@switch# set chassis forwarding-options custom-profile l2-entries num-banks 0 user@switch# set chassis forwarding-options custom-profile l3-entries num-banks 2 user@switch# set chassis forwarding-options custom-profile lpm-entries num-banks 201 statement for the [edit chassis forwarding-options] user@switch# set custom-profile5. lists the situations in which the user@switch# set chassis forwarding-options custom-profile user@switch# set chassis forwarding-options custom-profile l2-entries num-banks 0 user@switch# set chassis forwarding-options custom-profile l3-entries num-banks 2 user@switch# set chassis forwarding-options custom-profile lpm-entries num-banks 201 statement should be enabled or disabled. Table 15: LPM Table Size Variations on QFX5200-48Y SwitchesProfile Name Prefix Entries num-65-127-prefixIPv4 <= /32IPv6 <= /64IPv6 > /64user@switch# set chassis forwarding-options custom-profile user@switch# set chassis forwarding-options custom-profile l2-entries num-banks 0 user@switch# set chassis forwarding-options custom-profile l3-entries num-banks 2 user@switch# set chassis forwarding-options custom-profile lpm-entries num-banks 208 > 128K (minimum guaranteed) 98K 0K user@switch# set chassis forwarding-options custom-profile user@switch# set chassis forwarding-options custom-profile l2-entries num-banks 0 user@switch# set chassis forwarding-options custom-profile l3-entries num-banks 2 user@switch# set chassis forwarding-options custom-profile lpm-entries num-banks 209 128K 16K 16K On QFX5120 and EX4600 switches, you cannot set configure a prefix for the [edit chassis forwarding-options] user@switch# set l2-profile-one1 statement on non-LPM profiles. You can only enable or disable the user@switch# set chassis forwarding-options custom-profile user@switch# set chassis forwarding-options custom-profile l2-entries num-banks 0 user@switch# set chassis forwarding-options custom-profile l3-entries num-banks 2 user@switch# set chassis forwarding-options custom-profile lpm-entries num-banks 201 statement for the [edit chassis forwarding-options] user@switch# set custom-profile5 lists the situations in which the user@switch# set chassis forwarding-options custom-profile user@switch# set chassis forwarding-options custom-profile l2-entries num-banks 0 user@switch# set chassis forwarding-options custom-profile l3-entries num-banks 2 user@switch# set chassis forwarding-options custom-profile lpm-entries num-banks 201 statement should be enabled or disabled. Table 16: LPM Table Size Variations on QFX5120 and EX4650 SwitchesProfile Name Prefix Entries prefix-65-127-disableIPv4 <= /32IPv6 <= /64IPv6 > /64user@switch# set chassis forwarding-options custom-profile user@switch# set chassis forwarding-options custom-profile l2-entries num-banks 0 user@switch# set chassis forwarding-options custom-profile l3-entries num-banks 2 user@switch# set chassis forwarding-options custom-profile lpm-entries num-banks 208 351K (360,000 approximate) 168K (172,000 approximate) 0K user@switch# set chassis forwarding-options custom-profile user@switch# set chassis forwarding-options custom-profile l2-entries num-banks 0 user@switch# set chassis forwarding-options custom-profile l3-entries num-banks 2 user@switch# set chassis forwarding-options custom-profile lpm-entries num-banks 209 168K (172,000 approximate) 64K (65,524 approximate) 64K (65,524 approximate) Note that all entries in each table share the same memory space. If a table stores the maximum number of entries for any given type, the entire shared table is full and is unable to accommodate any entries of any other type. For example, if you use the the [edit chassis forwarding-options custom-profile] user@switch# set l2-entries num-banks 04 option and there are 128K IPv4 unicast addresses stored in the LPM table, the entire LPM table is full and no IPv6 addresses can be stored. Similarly, if you use the [edit chassis forwarding-options custom-profile] user@switch# set l2-entries num-banks 04 option but do not use the user@switch# set chassis forwarding-options custom-profile user@switch# set chassis forwarding-options custom-profile l2-entries num-banks 0 user@switch# set chassis forwarding-options custom-profile l3-entries num-banks 2 user@switch# set chassis forwarding-options custom-profile lpm-entries num-banks 201 option, and 16K IPv6 addresses with prefixes shorter than /65 are stored, the entire LPM table is full and no additional addresses (IPv4 or IPv6) can be stored. To configure the [edit chassis forwarding-options] user@switch# set custom-profile5 to store unicast IPv4 entries and IPv6 entries with prefix lengths equal to or less than 64 in the LPM table:
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