Memory Considerations

One of the main concerns about the number of signatures loaded on a Cisco router is the amount of memory consumed by each signature. Based on tests conducted on Cisco access routers, a platform with 128 MB of memory can support up to 563 signatures. If the platform has 256 MB of memory, it can support 737 signatures.

Table 13-2 estimates the memory required per signature. According to these estimates, Simple Mail Transfer Protocol (SMTP) signatures require the most memory.

Atomic.IP 0.004

Atomic.IPOPTIONS 0.004

Atomic.ICMP 0.005

Atomic.UDP 0.006

Atomic.TCP 0.05

Service.HTTP 0.08

Service.DNS 0.006

Service.RPC 0.006

0 0

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