mirror_iproute2/include/linux/mpls.h
Eric W. Biederman dacc5d4197 add basic mpls support to iproute
- Pull in the uapi mpls.h
- Update rtnetlink.h to include the mpls rtnetlink notification multicast group.
- Define AF_MPLS in utils.h if it is not defined from elsewhere
  as is done with AF_DECnet

The address syntax for multiple mpls labels is a complete invention.
When I looked there seemed to be no wide spread convention for talking
about an mpls label stack in text for.  Sometimes people did:
"{ Label1, Label2, Label3 }", sometimes people would do:
"[ label3, label2, label1 ]", and most of the time label
stacks were not explicitly shown at all.

The syntax I wound up using, so it would not have spaces and so it
would visually distinct from other kinds of addresses is.

label1/label2/label3 Where label1 is the label at the top of the label
stack and label3 is the label at the bottom on the label stack.

When there is a single label this matches what seems to be convention
with other tools.  Just print out the numeric value of the mpls label.

The netlink protocol for labels uses the on the wire format for a
label stack. The ttl and traffic class are expected to be 0.  Using
the on the wire format is common and what happens with other address
types. BGP when passing label stacks also uses this technique with the
exception that the ttl byte is not included making each label in a BGP
label stack 3 bytes instead of 4.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2015-03-24 15:45:23 -07:00

35 lines
978 B
C

#ifndef _MPLS_H
#define _MPLS_H
#include <linux/types.h>
#include <asm/byteorder.h>
/* Reference: RFC 5462, RFC 3032
*
* 0 1 2 3
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Label | TC |S| TTL |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*
* Label: Label Value, 20 bits
* TC: Traffic Class field, 3 bits
* S: Bottom of Stack, 1 bit
* TTL: Time to Live, 8 bits
*/
struct mpls_label {
__be32 entry;
};
#define MPLS_LS_LABEL_MASK 0xFFFFF000
#define MPLS_LS_LABEL_SHIFT 12
#define MPLS_LS_TC_MASK 0x00000E00
#define MPLS_LS_TC_SHIFT 9
#define MPLS_LS_S_MASK 0x00000100
#define MPLS_LS_S_SHIFT 8
#define MPLS_LS_TTL_MASK 0x000000FF
#define MPLS_LS_TTL_SHIFT 0
#endif /* _MPLS_H */