Information About the Unicast RIB and FIB
The unicast RIB (IPv4 RIB and IPv6 RIB) and FIB are part of the Cisco NX-OS forwarding architecture,
Layer 3 Consistency Checker
In rare instances, an inconsistency can occur between the unicast RIB and the FIB on each module. Cisco NX-OS supports the Layer 3 consistency checker. This feature detects inconsistencies between the unicast IPv4 RIB on the supervisor module and the FIB on each interface module. Inconsistencies include the following:
- Missing prefix
- Extra prefix
- Wrong next-hop address
- Incorrect Layer 2 rewrite string in the ARP or neighbor discovery (ND) cache
The Layer 3 consistency checker compares the FIB entries to the latest adjacency information from the Adjacency Manager (AM) and logs any inconsistencies. The consistency checker then compares the unicast RIB prefixes to the module FIB and logs any inconsistencies.
Dynamic TCAM Allocation
Dynamic TCAM allocation reallocates unused TCAM blocks on M1 Series non-XL modules to an adjacent region when all existing blocks in that region are full. Dynamic TCAM allocation allows more flexibility in the number of routes that the FIB can allocate for a route type.
Cisco NX-OS divides the FIB to support multiple address families. The FIB TCAM for M1 Series non-XL modules has 128K physical entries.
Region | Default Number of Routes | Number of TCAM Blocks | Entry Size |
---|---|---|---|
IPv4 Unicast Routes |
56,000 |
7 |
72 bits |
IPv4 Multicast Routes or IPv6 Unicast Routes |
32,000 |
8 |
144 bits |
IPv6 Multicast Routes |
2,000 |
1 |
288 bits |
Maximum TCAM Entries and FIB Scale Limits
The FIB TCAM entries are system wide resources that are shared across virtual device contexts (VDC) configured on the module. Table 16-2 describes the supported maximum FIB scale entries on the Nexus 7000 system configuration per route-type.
Module Type in a VDC | Maximum TCAM Physical Entries in a VDC | Maximum Supported IPv4 Unicast Routes | Maximum Supported IPv4 Multicast Routes | Maximum Supported IPv6 Unicast Routes | Maximum Supported IPv6 Multicast Routes |
---|---|---|---|---|---|
Only non-XL modules in a VDC |
128,000 |
112,000 |
32,000 mroutes |
56,000 routes |
2,000 routes |
Only XL modules in a VDC |
900,000 |
900,000 |
32,000 mroutes |
350,000 routes |
2,000 routes |
Mix of XL/non-XL modules in the same VDC |
128,000 |
112,000 |
32,000 mroutes |
56,000 routes |
2,000 routes |
Only F2 Series modules in a VDC1 |
32,000 |
32,768 |
16,384 mroutes |
16,384 routes |
8,192 routes |
Note |
The table above captures the scale limits in a VDC. In a Cisco Nexus 7000 system, the total memory on the supervisor module restricts the actual route scale limits across all VDCs in the system. |
Note |
Do not exceed the maximum route limits for non-XL modules in a VDC that contains both XL modules and non-XL modules. |
Note |
The actual FIB TCAM can scale to a higher scale number from a hardware perspective. The table above captures the currently supported FIB sizes. |
Note |
The maximum routes are individual route-type maximum values and these values are not cumulative across each route-type. |
You must install the Scalable Services License (see the Cisco NX-OS Licensing Guide) and configure the higher shared memory sizes (see the Cisco Nexus 7000 Series NX-OS Virtual Device Context Configuration Guide, Release 5.x) for the routing table to enable the higher FIB scale on the XL modules. See the Cisco Nexus 7000 Series Hardware Installation and Reference Guide for more information on the XL modules.
Note |
M3 cards have larger FIB limits and they do not require the XL license to reach their maximum FIB sizes. |
When you install the Scalable Services license, you may see the following system message:
"2011 Mar 30 12:38:13 switch
%PLTFM_CONFIG-4-XL_LICENSE_MIX_NOTIFY: Mixed use of non-XL with XL modules in
the same VDC may limit common resources to non-XL capacity."
This message occurs if you install the Scalable Services license in a system with non-XL modules or when non-XL modules come on line after you install this license.
Note |
The full IPv4 Internet route tables currently have more than 500,000 routes and require the XL modules. |
The unicast RIB and FIB support virtual routing and forwarding (VRF) instances. VRF exists within VDCs. By default, Cisco NX-OS places you in the default VDC and default VRF unless you specifically configure another VDC and VRF. For more information, see the Cisco Nexus 7000 Series NX-OS Virtual Device Context Configuration Guide.