Can non-recursive BGP route be used to determine next-hop for recursive BGP route? The Next CEO of Stack OverflowControlling route-map distribution with 'match interface' in EIGRPVyatta static routing does not correctly route to next hopInternal BGP route exchange issueOSPF Route Tagging and BGP AS PrependTraffic preferring iBGP route over static routeJunos BGP physical Next-hopVrf route with global ip as the next hopOSPF NSSA - Type 7 LSA Metric Changes UnexpectedlyBGP Route Dampaning - Not directly connected eBGP peers - EventsHow does BGP decide which prefix to advertise out of the prefixes in the routing table?
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Can non-recursive BGP route be used to determine next-hop for recursive BGP route?
The Next CEO of Stack OverflowControlling route-map distribution with 'match interface' in EIGRPVyatta static routing does not correctly route to next hopInternal BGP route exchange issueOSPF Route Tagging and BGP AS PrependTraffic preferring iBGP route over static routeJunos BGP physical Next-hopVrf route with global ip as the next hopOSPF NSSA - Type 7 LSA Metric Changes UnexpectedlyBGP Route Dampaning - Not directly connected eBGP peers - EventsHow does BGP decide which prefix to advertise out of the prefixes in the routing table?
In BGP recursive scenario, the recursive route is taking an unexpected next-hop. Here is the routing table:
S* 0.0.0.0/0 [10/0] via 10.10.10.1, wan
B 172.16.5.0/24 [20/0] via 172.80.80.1, MPLS, 2d18h20m
B 192.168.250.0/24 [20/0] via 172.16.5.1 (recursive via 10.10.10.1), 1d1h10m
The next-hop of the recursive route should be the second route in the table which is another BGP route. However, it's taking the default route on top.
When adding a static route which is exactly the same as the second BGP route, next-hop is determined correctly:
S* 0.0.0.0/0 [10/0] via 10.10.10.1, wan
S 172.16.5.0/24 [20/0] via 172.80.80.1, MPLS
B 192.168.250.0/24 [20/0] via 172.16.5.1 (recursive via 172.80.80.1), 1d1h10m
Is this an expected behavior?
routing router bgp next-hop
asked Mar 21 at 7:43
onlyforthisonlyforthis
1334
add a comment |
In BGP recursive scenario, the recursive route is taking an unexpected next-hop. Here is the routing table:
S* 0.0.0.0/0 [10/0] via 10.10.10.1, wan
B 172.16.5.0/24 [20/0] via 172.80.80.1, MPLS, 2d18h20m
B 192.168.250.0/24 [20/0] via 172.16.5.1 (recursive via 10.10.10.1), 1d1h10m
The next-hop of the recursive route should be the second route in the table which is another BGP route. However, it's taking the default route on top.
When adding a static route which is exactly the same as the second BGP route, next-hop is determined correctly:
S* 0.0.0.0/0 [10/0] via 10.10.10.1, wan
S 172.16.5.0/24 [20/0] via 172.80.80.1, MPLS
B 192.168.250.0/24 [20/0] via 172.16.5.1 (recursive via 172.80.80.1), 1d1h10m
Is this an expected behavior?
routing router bgp next-hop
asked Mar 21 at 7:43
onlyforthisonlyforthis
1334
add a comment |
In BGP recursive scenario, the recursive route is taking an unexpected next-hop. Here is the routing table:
S* 0.0.0.0/0 [10/0] via 10.10.10.1, wan
B 172.16.5.0/24 [20/0] via 172.80.80.1, MPLS, 2d18h20m
B 192.168.250.0/24 [20/0] via 172.16.5.1 (recursive via 10.10.10.1), 1d1h10m
The next-hop of the recursive route should be the second route in the table which is another BGP route. However, it's taking the default route on top.
When adding a static route which is exactly the same as the second BGP route, next-hop is determined correctly:
S* 0.0.0.0/0 [10/0] via 10.10.10.1, wan
S 172.16.5.0/24 [20/0] via 172.80.80.1, MPLS
B 192.168.250.0/24 [20/0] via 172.16.5.1 (recursive via 172.80.80.1), 1d1h10m
Is this an expected behavior?
routing router bgp next-hop
asked Mar 21 at 7:43
onlyforthisonlyforthis
1334
In BGP recursive scenario, the recursive route is taking an unexpected next-hop. Here is the routing table:
S* 0.0.0.0/0 [10/0] via 10.10.10.1, wan
B 172.16.5.0/24 [20/0] via 172.80.80.1, MPLS, 2d18h20m
B 192.168.250.0/24 [20/0] via 172.16.5.1 (recursive via 10.10.10.1), 1d1h10m
The next-hop of the recursive route should be the second route in the table which is another BGP route. However, it's taking the default route on top.
When adding a static route which is exactly the same as the second BGP route, next-hop is determined correctly:
S* 0.0.0.0/0 [10/0] via 10.10.10.1, wan
S 172.16.5.0/24 [20/0] via 172.80.80.1, MPLS
B 192.168.250.0/24 [20/0] via 172.16.5.1 (recursive via 172.80.80.1), 1d1h10m
Is this an expected behavior?
routing router bgp next-hop
routing router bgp next-hop
asked Mar 21 at 7:43
onlyforthisonlyforthis
1334
asked Mar 21 at 7:43
onlyforthisonlyforthis
1334
edited Mar 21 at 10:54
onlyforthis
asked Mar 21 at 7:43
onlyforthisonlyforthis
1334
asked Mar 21 at 7:43
onlyforthisonlyforthis
1334
asked Mar 21 at 7:43
onlyforthisonlyforthis
1334
1334
add a comment |
add a comment |
1 Answer
1
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oldest
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IOS will not use another BGP route for recursive lookup for a BGP route. This is somewhat hinted at in the "Why Routers Ignore Paths" section of the "BGP Best Path Selection Algorithm" documentation:
[Routers ignore] paths for which the NEXT_HOP is inaccessible.
Be sure that there is an Interior Gateway Protocol (IGP) route to the NEXT_HOP that is associated with the path.
So yes, this is expected behavior on IOS. Other routing platforms may behave differently. There is also an article describing further how the lookup works.
answered Mar 21 at 8:03
SebastianSebastian
6,07322351
Thanks. This was useful. I wonder if this is a standard BGP behavior or vendor specific.
– onlyforthis
Mar 21 at 8:18
@onlyforthis: I suspect it's mostly standard. For example, RouterOS requires the nexthop scope to be lower than the route's own.
– grawity
Mar 21 at 14:01
@onlyforthis It depends on the vendor, Juniper can use BGP routes for recursive lookup. If this answers you question please accept it as answer.
– Sebastian
Mar 21 at 15:14
add a comment |
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1 Answer
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1 Answer
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IOS will not use another BGP route for recursive lookup for a BGP route. This is somewhat hinted at in the "Why Routers Ignore Paths" section of the "BGP Best Path Selection Algorithm" documentation:
[Routers ignore] paths for which the NEXT_HOP is inaccessible.
Be sure that there is an Interior Gateway Protocol (IGP) route to the NEXT_HOP that is associated with the path.
So yes, this is expected behavior on IOS. Other routing platforms may behave differently. There is also an article describing further how the lookup works.
answered Mar 21 at 8:03
SebastianSebastian
6,07322351
Thanks. This was useful. I wonder if this is a standard BGP behavior or vendor specific.
– onlyforthis
Mar 21 at 8:18
@onlyforthis: I suspect it's mostly standard. For example, RouterOS requires the nexthop scope to be lower than the route's own.
– grawity
Mar 21 at 14:01
@onlyforthis It depends on the vendor, Juniper can use BGP routes for recursive lookup. If this answers you question please accept it as answer.
– Sebastian
Mar 21 at 15:14
add a comment |
IOS will not use another BGP route for recursive lookup for a BGP route. This is somewhat hinted at in the "Why Routers Ignore Paths" section of the "BGP Best Path Selection Algorithm" documentation:
[Routers ignore] paths for which the NEXT_HOP is inaccessible.
Be sure that there is an Interior Gateway Protocol (IGP) route to the NEXT_HOP that is associated with the path.
So yes, this is expected behavior on IOS. Other routing platforms may behave differently. There is also an article describing further how the lookup works.
answered Mar 21 at 8:03
SebastianSebastian
6,07322351
Thanks. This was useful. I wonder if this is a standard BGP behavior or vendor specific.
– onlyforthis
Mar 21 at 8:18
@onlyforthis: I suspect it's mostly standard. For example, RouterOS requires the nexthop scope to be lower than the route's own.
– grawity
Mar 21 at 14:01
@onlyforthis It depends on the vendor, Juniper can use BGP routes for recursive lookup. If this answers you question please accept it as answer.
– Sebastian
Mar 21 at 15:14
add a comment |
IOS will not use another BGP route for recursive lookup for a BGP route. This is somewhat hinted at in the "Why Routers Ignore Paths" section of the "BGP Best Path Selection Algorithm" documentation:
[Routers ignore] paths for which the NEXT_HOP is inaccessible.
Be sure that there is an Interior Gateway Protocol (IGP) route to the NEXT_HOP that is associated with the path.
So yes, this is expected behavior on IOS. Other routing platforms may behave differently. There is also an article describing further how the lookup works.
answered Mar 21 at 8:03
SebastianSebastian
6,07322351
IOS will not use another BGP route for recursive lookup for a BGP route. This is somewhat hinted at in the "Why Routers Ignore Paths" section of the "BGP Best Path Selection Algorithm" documentation:
[Routers ignore] paths for which the NEXT_HOP is inaccessible.
Be sure that there is an Interior Gateway Protocol (IGP) route to the NEXT_HOP that is associated with the path.
So yes, this is expected behavior on IOS. Other routing platforms may behave differently. There is also an article describing further how the lookup works.
answered Mar 21 at 8:03
SebastianSebastian
6,07322351
answered Mar 21 at 8:03
SebastianSebastian
6,07322351
answered Mar 21 at 8:03
SebastianSebastian
6,07322351
answered Mar 21 at 8:03
SebastianSebastian
6,07322351
6,07322351
Thanks. This was useful. I wonder if this is a standard BGP behavior or vendor specific.
– onlyforthis
Mar 21 at 8:18
@onlyforthis: I suspect it's mostly standard. For example, RouterOS requires the nexthop scope to be lower than the route's own.
– grawity
Mar 21 at 14:01
@onlyforthis It depends on the vendor, Juniper can use BGP routes for recursive lookup. If this answers you question please accept it as answer.
– Sebastian
Mar 21 at 15:14
add a comment |
Thanks. This was useful. I wonder if this is a standard BGP behavior or vendor specific.
– onlyforthis
Mar 21 at 8:18
@onlyforthis: I suspect it's mostly standard. For example, RouterOS requires the nexthop scope to be lower than the route's own.
– grawity
Mar 21 at 14:01
@onlyforthis It depends on the vendor, Juniper can use BGP routes for recursive lookup. If this answers you question please accept it as answer.
– Sebastian
Mar 21 at 15:14
Thanks. This was useful. I wonder if this is a standard BGP behavior or vendor specific.
– onlyforthis
Mar 21 at 8:18
Thanks. This was useful. I wonder if this is a standard BGP behavior or vendor specific.
– onlyforthis
Mar 21 at 8:18
@onlyforthis: I suspect it's mostly standard. For example, RouterOS requires the nexthop scope to be lower than the route's own.
– grawity
Mar 21 at 14:01
@onlyforthis: I suspect it's mostly standard. For example, RouterOS requires the nexthop scope to be lower than the route's own.
– grawity
Mar 21 at 14:01
@onlyforthis It depends on the vendor, Juniper can use BGP routes for recursive lookup. If this answers you question please accept it as answer.
– Sebastian
Mar 21 at 15:14
@onlyforthis It depends on the vendor, Juniper can use BGP routes for recursive lookup. If this answers you question please accept it as answer.
– Sebastian
Mar 21 at 15:14
add a comment |
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