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Date: Mon, 22 Jun 2015 23:51:02 -0400
From: Stephen Hemminger <stephen@networkplumber.org>
To: Matthew Hall <mhall@mhcomputing.net>
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Cc: "<dev@dpdk.org>" <dev@dpdk.org>
Subject: Re: [dpdk-dev] rte_lpm with larger nexthops or another method?
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In order to make Vyatta/Brocade router work with LPM code
I ended up redoing the layout. It is:


/** Tbl24 entry structure. */
struct rte_lpm_tbl24_entry {
	/* Using single uint8_t to store 3 values. */
	uint8_t valid       :1; /**< Validation flag. */
	uint8_t ext_entry   :1; /**< external entry? */
	uint8_t depth;	      /**< Rule depth. */
	/* Stores Next hop or group index (i.e. gindex)into tbl8. */
	union {
		uint16_t next_hop;
		uint16_t tbl8_gindex;
	};
};

/** Tbl8 entry structure. */
struct rte_lpm_tbl8_entry {
	uint16_t next_hop;	/**< next hop. */
	uint8_t  depth;	/**< Rule depth. */
	uint8_t valid       :1; /**< Validation flag. */
	uint8_t valid_group :1; /**< Group validation flag. */
};

And also several other scalability improvements (plus IPv6)
and the correct handling of /32.

Unfortunately, this is such a big binary change that I was
reluctant to break any tests or applications using existing code
and therefore never submitted the patches.