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This chapter describes the switching database manager (SDM) features built into your switch router. This chapter includes the following topics:
The information in this chapter applies to the Catalyst 8540 CSR and Catalyst 8540 MSR with Layer 3 functionality. For further information about the commands used in this chapter, see "Command Reference."
The enhanced Gigabit Ethernet interfaces use the forwarding engine and the ternary content addressable memory (TCAM) to implement the Layer 2 and Layer 3 functionality. The Layer 2 and Layer 3 switching information is maintained in TCAM. The switching database manager (SDM) is the Layer 3 software subsystem that manages the Layer 3 switching information maintained in TCAM.
SDM resides on the central processor and its primary function is to maintain the Layer 3 switching database. SDM maintains the address entries contained in TCAM in an appropriate order. SDM manages TCAM space by partitioning protocol-specific switching information into multiple regions.
The forwarding engine on the enhanced Gigabit Ethernet interfaces performs packet processing on multiple channels simultaneously and extracts the packet header information. It uses this packet header information to issue exact-match or longest-match address searches in the switching information stored in TCAM.
TCAM identifies the location index of the Layer 2 or Layer 3 address and conveys it to the forwarding engine. The forwarding engine uses this location index to further derive information associated with each Layer 2 and Layer 3 address.
The key benefits of SDM in Layer 3 switching are its ability to organize the switching information in TCAM into protocol- specific regions and its ability to configure the size of these protocol regions. SDM enables exact-match and longest-match address searches, which result in high-speed forwarding.
SDM partitions TCAM space into multiple regions. Each region is protocol specific. SDM interacts with the individual protocol control layer to store Layer 3 switching information. SDM consists of the following types of regions:
The enhanced Gigabit Ethernet interface module supports TCAM sizes of 32K, 64K, or 256K. Each entry in TCAM is 32 bits wide. Since SDM is responsible for managing TCAM space, SDM partitions the entire TCAM space for each protocol region based on user configuration. A change in the partition configuration takes effect only during the next system reboot.
Table 9-1 lists default partitioning for each protocol region in TCAM.
| Protocol Region | Lookup Type | Key Size | Default Size | No. of TCAM Entries |
|---|---|---|---|---|
ipx-bvi-network | Exact-match | 32 bits | 32 | 32 |
ip-adjacency | Exact-match | 32 bits | 2048 | 2048 |
ipx-node | Exact-match | 64 bits | 2048 | 4096 |
ip-prefix | Longest-match | 32 bits | 8192 | 8192 |
ipx-network | Exact-match | 32 bits | 6144 | 6144 |
ip-mcast | Longest-match | 64 bits | 3072 | 6144 |
l2-switching | Exact-match | 64 bits | 1024 | 2048 |
udp-flooding | Exact-match | 64 bits | 256 | 512 |
access-list | First-match | 128 bits | 512 | 8192 |
The enhanced Gigabit Ethernet interface module is available with 32K, 64K, or 256K TCAM space. You can configure the various protocol regions in TCAM based on your requirements and on the size of TCAM on your Gigabit Ethernet interface module.
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Note The enhanced Gigabit Ethernet interface module is available with 32K, 64K, or 256K TCAM space. The maximum SDM size is equal to the lowest TCAM size available among the interface modules present at the time of booting up the switch router. For example, if you have two interface modules with 64K and 256K TCAM sizes, then the maximum SDM size is 64K based on the lowest TCAM size available at bootup. |
This section describes the commands necessary to configure SDM. It includes commands necessary to configure the autolearn feature in SDM, commands required to configure the size of the SDM regions, and commands required to configure the size of the access-list region in the TCAM. The commands described in this section are unique to Layer 3 switching software.
SDM groups entries based on their mask lengths into "buckets." The size of each bucket in the protocol region varies. The autolearn feature in SDM automatically saves the mask length distribution (bucket size distribution) for the longest-match region in the switching database. SDM uses this information to set up the partitions, which are effective during the next system reboot.
Layer 3 switching enables the autolearn feature by default. The no form of the sdm autolearn command disables the SDM autolearn feature. You can reenable autolearn by issuing the sdm autolearn command from global configuration mode, as shown in the following example:
Router# configure terminal Router(config)# sdm autolearn Router(config)# end
The protocol region size in SDM is represented by the number of 32-bit or 64-bit entries. The combined size of all the application regions should be calculated in terms of 32-bit TCAM entries and should not exceed the total TCAM size. The enhanced Gigabit Ethernet interface module supports TCAM sizes of 32K, 64K, or 256K.
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Note Although the size of the whole protocol region is configured by default, you can reconfigure it. The reconfigured size of the protocol region is effective only at the next system reboot. |
To configure SDM size for each protocol region, use the following steps, beginning in global configuration mode:
| Command | Purpose | |
|---|---|---|
Step 1 | Router(config)# sdm size | |
Step 2 | Router(config)# end Router# | Returns to privileged EXEC mode. |
Example
The following output is an example of configuring 2048 entries for the ip-prefix region.
Router# configure terminal Router(config)# sdm size ip-prefix k-entries 2 Router(config)# end
The combined size entered for all the protocol regions should not exceed the total TCAM size. To display the supported size of SDM, use the show sdm size command from global configuration mode.
Router# show sdm size
Switching Database Region Sizes :
IPX BVI Network :32 32-bit entries
IP Adjacency :2048 32-bit entries
IPX Node :2048 64-bit entries
IP Prefix :8192 32-bit entries
IPX Network :6144 32-bit entries
IP Multicast :3072 64-bit entries
UDP Flooding :256 64-bit entries
MAC Addr :1024 64-bit entries
Access List :512 128-bit entries
You can use the show sdm internal command to get SDM management information for each protocol region in TCAM.The information includes SDM status, minimum TCAM size available, and the TCAM size required for your current configuration. For each application region, this command also yields information about the logical start and end of the application region in TCAM, lookup type, key size, and statistics about other key operations.
To obtain SDM management information for each protocol region in TCAM, use the following command:
Command | Purpose |
|---|---|
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Example
The following output is an example of SDM management information for the show sdm internal all-region command:
Router# show sdm internal all-region Address Map : Status :Ready TCAM Minimum Size :262144 entries TCAM Required Size :29248 entries SRAM Sz :481280 entries TCAM Start :32 Xinfo Start :262144 Xinfo Size :225536 Name :IPX BVI Network Size :32 MinSize :32 MaxSize :32 FreeKey :0x0 Start :0x20 End :0x3F Entry :32-bit Lookup :Exact-Match Events : Insert :Success 0 Failure 0 Delete :Success 0 Failure 0 Modify :Success 0 Failure 0 IPCs : Insert :Success 0 Failure 0 Delete :Success 0 Failure 0 Modify :Success 0 Failure 0 Move :Success 0 Failure 0 Mask RW :Success 0 Failure 0 Name :IP Adjacency Size :2048 MinSize :32 MaxSize :65536 FreeKey :0xEEEEEEEE Start :0x40 End :0x83F Entry :32-bit Lookup :Exact-Match Events : Insert :Success 5 Failure 0 Delete :Success 0 Failure 0 Modify :Success 0 Failure 0 IPCs : Insert :Success 5 Failure 0 Delete :Success 0 Failure 0 Modify :Success 0 Failure 0 Move :Success 0 Failure 0 Mask RW :Success 0 Failure 0 Name :IPX Node Size :2048 MinSize :32 MaxSize :65536 FreeKey :0xF0000000 Start :0x840 End :0x183E Entry :64-bit Lookup :Exact-Match Events : Insert :Success 0 Failure 0 Delete :Success 0 Failure 0 Modify :Success 0 Failure 0 IPCs : Insert :Success 0 Failure 0 Delete :Success 0 Failure 0 Modify :Success 0 Failure 0 Move :Success 0 Failure 0 Mask RW :Success 0 Failure 0 Name :IP Prefix Size :8192 MinSize :32 MaxSize :262144 FreeKey :0xEEEEEEEEEEEEEEEE Start :0x1840 End :0x383F Entry :32-bit Lookup :Longest-Match Buckets :33 Events : Insert :Success 9 Failure 0 Delete :Success 0 Failure 0 Modify :Success 0 Failure 0 IPCs : Insert :Success 9 Failure 0 Delete :Success 0 Failure 0 Modify :Success 0 Failure 0 Move :Success 0 Failure 0 Mask RW :Success 20 Failure 0 Name :IPX Network Size :6144 MinSize :32 MaxSize :65536 FreeKey :0x0 Start :0x3840 End :0x503F Entry :32-bit Lookup :Exact-Match Events : Insert :Success 2 Failure 0 Delete :Success 0 Failure 0 Modify :Success 0 Failure 0 IPCs : Insert :Success 2 Failure 0 Delete :Success 0 Failure 0 Modify :Success 0 Failure 0 Move :Success 0 Failure 0 Mask RW :Success 0 Failure 0 Name :IP Multicast Size :3072 MinSize :16 MaxSize :65536 FreeKey :0xF0000000F0000000 Start :0x5040 End :0x683E Entry :64-bit Lookup :Longest-Match Buckets :34 Events : Insert :Success 3 Failure 0 Delete :Success 0 Failure 0 Modify :Success 0 Failure 0 IPCs : Insert :Success 3 Failure 0 Delete :Success 0 Failure 0 Modify :Success 0 Failure 0 Move :Success 0 Failure 0 Mask RW :Success 31 Failure 0 Name :UDP Flooding Size :256 MinSize :256 MaxSize :256 FreeKey :0xF0000000 Start :0x6840 End :0x6A3E Entry :64-bit Lookup :Exact-Match Events : Insert :Success 0 Failure 0 Delete :Success 0 Failure 0 Modify :Success 0 Failure 0 IPCs : Insert :Success 0 Failure 0 Delete :Success 0 Failure 0 Modify :Success 0 Failure 0 Move :Success 0 Failure 0 Mask RW :Success 0 Failure 0 Name :MAC Addr Size :1024 MinSize :64 MaxSize :65536 FreeKey :0x0 Start :0x6A40 End :0x723E Entry :64-bit Lookup :Reserved
For additional information on the show sdm internal command syntax, refer to the sdm commands in "Command Reference".
The enhanced Gigabit Ethernet interface module supports TCAM sizes of 32K, 64K, or 256K. The combined size of the protocol regions and access lists should not exceed your TCAM space. The default size of the access lists in a 32K, 64K, or 256K TCAM is 512. You can use the sdm access-list command to partition the TCAM space for access lists.
To partition the TCAM space for access lists, use the following command:
Command | Purpose |
|---|---|
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Before you configure the access-list region in TCAM, make sure that TCAM has enough space to accommodate the access-list region. Use the show internal all-regions command to verify how much space is available in TCAM.
Example
The following output is an example of configuring 8192 entries for the access list region in TCAM:
Router# configure terminal Router(config)# sdm access-list 8192
Router(config)# end
Posted: Tue Sep 26 13:35:22 PDT 2000
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