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Merge pull request #17234 from FRRouting/mergify/bp/dev/10.2/pr-17199

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bgpd: compare aigp after local route check in bgp_path_info_cmp() (backport #17199)
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Donatas Abraitis 2024-10-25 13:10:24 +03:00 committed by GitHub
commit 6b6422899b
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5 changed files with 83 additions and 33 deletions
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55
bgpd/bgp_route.c
View File

@ -1064,7 +1064,32 @@ int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
}
}
/* Tie-breaker - AIGP (Metric TLV) attribute */
/* 3. Local route check. We prefer:
* - BGP_ROUTE_STATIC
* - BGP_ROUTE_AGGREGATE
* - BGP_ROUTE_REDISTRIBUTE
*/
new_origin = !(new->sub_type == BGP_ROUTE_NORMAL || new->sub_type == BGP_ROUTE_IMPORTED);
exist_origin = !(exist->sub_type == BGP_ROUTE_NORMAL ||
exist->sub_type == BGP_ROUTE_IMPORTED);
if (new_origin && !exist_origin) {
*reason = bgp_path_selection_local_route;
if (debug)
zlog_debug("%s: %s wins over %s due to preferred BGP_ROUTE type", pfx_buf,
new_buf, exist_buf);
return 1;
}
if (!new_origin && exist_origin) {
*reason = bgp_path_selection_local_route;
if (debug)
zlog_debug("%s: %s loses to %s due to preferred BGP_ROUTE type", pfx_buf,
new_buf, exist_buf);
return 0;
}
/* 3.5. Tie-breaker - AIGP (Metric TLV) attribute */
if (CHECK_FLAG(newattr->flag, ATTR_FLAG_BIT(BGP_ATTR_AIGP)) &&
CHECK_FLAG(existattr->flag, ATTR_FLAG_BIT(BGP_ATTR_AIGP)) &&
CHECK_FLAG(bgp->flags, BGP_FLAG_COMPARE_AIGP)) {
@ -1094,34 +1119,6 @@ int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
}
}
/* 3. Local route check. We prefer:
* - BGP_ROUTE_STATIC
* - BGP_ROUTE_AGGREGATE
* - BGP_ROUTE_REDISTRIBUTE
*/
new_origin = !(new->sub_type == BGP_ROUTE_NORMAL ||
new->sub_type == BGP_ROUTE_IMPORTED);
exist_origin = !(exist->sub_type == BGP_ROUTE_NORMAL ||
exist->sub_type == BGP_ROUTE_IMPORTED);
if (new_origin && !exist_origin) {
*reason = bgp_path_selection_local_route;
if (debug)
zlog_debug(
"%s: %s wins over %s due to preferred BGP_ROUTE type",
pfx_buf, new_buf, exist_buf);
return 1;
}
if (!new_origin && exist_origin) {
*reason = bgp_path_selection_local_route;
if (debug)
zlog_debug(
"%s: %s loses to %s due to preferred BGP_ROUTE type",
pfx_buf, new_buf, exist_buf);
return 0;
}
/* Here if these are imported routes then get ultimate pi for
* path compare.
*/

8
doc/user/bgp.rst
View File

@ -160,16 +160,16 @@ bottom until one of the factors can be used.
Prefer higher local preference routes to lower.
3. **Local route check**
Prefer local routes (statics, aggregates, redistributed) to received routes.
If ``bgp bestpath aigp`` is enabled, and both paths that are compared have
AIGP attribute, BGP uses AIGP tie-breaking unless both of the paths have the
AIGP metric attribute. This means that the AIGP attribute is not evaluated
during the best path selection process between two paths when one path does
not have the AIGP attribute.
3. **Local route check**
Prefer local routes (statics, aggregates, redistributed) to received routes.
4. **AS path length check**
Prefer shortest hop-count AS_PATHs.

5
tests/topotests/bgp_aigp_rr/r1/bgpd.conf
View File

@ -18,6 +18,7 @@ router bgp 65001
neighbor 10.0.0.4 timers connect 1
neighbor 10.0.0.4 route-reflector-client
address-family ipv4
network 10.0.1.2/32 route-map set-aigp
neighbor 10.0.0.4 route-map set-nexthop out
exit-address-family
!
@ -25,3 +26,7 @@ route-map set-nexthop permit 10
set ip next-hop peer-address
exit
!
route-map set-aigp permit 10
set aigp 50
set weight 0
!

4
tests/topotests/bgp_aigp_rr/r2/bgpd.conf
View File

@ -7,6 +7,7 @@ router bgp 65001
neighbor 10.0.0.1 timers connect 1
address-family ipv4
redistribute connected route-map connected-to-bgp
network 10.0.1.2/32 route-map set-aigp
neighbor 10.0.0.1 next-hop-self
exit-address-family
!
@ -16,3 +17,6 @@ route-map connected-to-bgp permit 10
match ip address prefix-list p22
set aigp 2
!
route-map set-aigp permit 10
set aigp 10
!

44
tests/topotests/bgp_aigp_rr/test_bgp_aigp_rr.py
View File

@ -101,6 +101,45 @@ def test_bgp_aigp_rr():
expected = {"paths": [{"aigpMetric": aigp, "valid": True}]}
return topotest.json_cmp(output, expected)
def _bgp_check_aigp_bestpath():
output = json.loads(r1.vtysh_cmd("show bgp ipv4 unicast 10.0.1.2/32 json"))
expected = {
"prefix": "10.0.1.2/32",
"paths": [
{
"aigpMetric": 50,
"valid": True,
"sourced": True,
"local": True,
"bestpath": {"overall": True, "selectionReason": "Local Route"},
"nexthops": [
{
"ip": "0.0.0.0",
"hostname": "r1",
"afi": "ipv4",
"metric": 0,
"accessible": True,
"used": True,
}
],
},
{
"aigpMetric": 10,
"valid": True,
"nexthops": [
{
"ip": "10.0.0.2",
"hostname": "r2",
"afi": "ipv4",
"metric": 10,
"accessible": True,
"used": True,
}
],
},
],
}
return topotest.json_cmp(output, expected)
# r2, 10.0.2.2/32 with aigp-metric 2
test_func = functools.partial(_bgp_check_aigp_metric, r2, "10.0.2.2/32", 2)
@ -122,6 +161,11 @@ def test_bgp_aigp_rr():
_, result = topotest.run_and_expect(test_func, None, count=60, wait=1)
assert result is None, "aigp-metric for 10.0.2.2/32 is not 12"
# r1, check if the local route is favored over AIGP comparison
test_func = functools.partial(_bgp_check_aigp_bestpath)
_, result = topotest.run_and_expect(test_func, None, count=60, wait=1)
assert result is None, "Local route is not favored over AIGP in best-path selection"
if __name__ == "__main__":
args = ["-s"] + sys.argv[1:]