On 1/Jul/15 16:52, Nick Hilliard wrote:
This is a strange sort of thing really. There's no reason that a compiled prefix list of 250k entries should take up much RAM in a trie structure; there's no reason that a competently written parser shouldn't be able to handle 20 megs of prefix lists / sets in a trivial amount of time and there's no reason that writing a 20 meg configuration file should take long to write to disk / flash / etc.
BIRD handles this in ultraquick time. Even recent versions of Quagga can now suck + parse 10 megs of prefix filters in a second or two and write them out in less.
But Junos / IOS / XR puke horribly. What gives?
Nick, I think the concerns are two-fold: 1. The time it takes to process the trie. 2. How much physical space there is to support the configuration. Remember some high-end Cisco routers only have 2MB of NVRAM. This could get tested with a large prefix-list configuration. Junos may not have much of a space issue since the configuration is stored on the compact flash or HDD. Trie compilation or process will be very OS-dependent, and how the vendor has chosen to optimize that operation. Mark.