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hidden bgp route

 

 

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Bosco.Sachanandani at orange

Jan 8, 2004, 1:09 AM

Post #1 of 4 (1605 views)
Permalink
hidden bgp route

Hi all,

Need a small piece of info. I am running BGP with 2 upstream GRX providers. I am recieving all routes correctly from them except the ones mentioned below.

It turns out that these prefixes are the GRX provider's network prefix's itself. Since it does not get installed in the route table, I have to put in static routes to access stuff like the their DNS servers which are part of these subnets, which is not a very nice thing to do.

My query in general is that what are "hidden" routes? I am using an M20 with JunOS , the upstream provider is using a Cisco 7000 series box. There are NO inbound BGP policies at my end.

The GRX guys cannot seem to figure out why this is happening.

thanks.


admin [at] srmum1-re> show route table Gp_VRF hidden

Gp_VRF.inet.0: 514 destinations, 525 routes (513 active, 0 holddown, 2 hidden)
+ = Active Route, - = Last Active, * = Both

202.123.213.80/28 [BGP/170] 23:37:07, MED 0, localpref 100, from 202.123.213.83
AS path: 19440 I
Unusable
213.181.39.0/24 [BGP/170] 23:38:48, localpref 100, from 213.181.39.20
AS path: 6774 I
Unusable


pekkas at netcore

Jan 8, 2004, 5:19 AM

Post #2 of 4 (1577 views)
Permalink
hidden bgp route [In reply to]

On Thu, 8 Jan 2004, Bosco Sachanandani wrote:
> My query in general is that what are "hidden" routes? I am using an
> M20 with JunOS , the upstream provider is using a Cisco 7000 series
> box. There are NO inbound BGP policies at my end.

hidden routes are those which are rejected by inbound policy, or have
unresolvable next-hop.

As you can see, the next-hop is within the advertised prefix itself,
so next-hop isn't considered valid, and the routes aren't installed.


> admin [at] srmum1-re> show route table Gp_VRF hidden
>
> Gp_VRF.inet.0: 514 destinations, 525 routes (513 active, 0 holddown, 2 hidden)
> + = Active Route, - = Last Active, * = Both
>
> 202.123.213.80/28 [BGP/170] 23:37:07, MED 0, localpref 100, from 202.123.213.83
> AS path: 19440 I
> Unusable
> 213.181.39.0/24 [BGP/170] 23:38:48, localpref 100, from 213.181.39.20
> AS path: 6774 I
> Unusable
>
> _______________________________________________
> juniper-nsp mailing list juniper-nsp [at] puck
> http://puck.nether.net/mailman/listinfo/juniper-nsp
>

--
Pekka Savola "You each name yourselves king, yet the
Netcore Oy kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings


Bosco.Sachanandani at orange

Jan 8, 2004, 6:50 AM

Post #3 of 4 (1572 views)
Permalink
hidden bgp route [In reply to]

hi,

As asked by some of you, maybe this is more helpful. Also, do I need to set the next-hop self option in this case on my router?



admin [at] srmum1-re> show route table Gp_VRF hidden extensive

Gp_VRF.inet.0: 513 destinations, 524 routes (512 active, 0 holddown, 2 hidden)
202.123.213.80/28 (2 entries, 1 announced)
TSI:
Page 0 idx 1 Type 1 val 88002d8
Nexthop: 213.181.39.20
AS path: 6774 19440 I
Communities:
Page 0 idx 5 Type 1 val 8a93b7c
Nexthop: 213.181.39.20
Localpref: 100
AS path: 6774 19440 I
Communities:
Path 202.123.213.80 from 213.181.39.20 Vector len 4. Val: 1 5
KRT in-kernel 202.123.213.80/28 -> {indirect(393)}
BGP Preference: 170/-101
Next hop type: Unusable
State: <Hidden Ext>
Inactive reason: Unusable path
Local AS: 64721 Peer AS: 19440
Age: 1d 5:19:26 Metric: 0
Task: BGP_19440_64721.202.123.213.83+179
AS path: 19440 I
Localpref: 100
Router ID: 192.168.4.1
Indirect next hops: 1
Protocol next hop: 202.123.213.83 Indirect next hop: 0 -
202.123.213.80/28 Originating RIB: Gp_VRF.inet.0
Node path count: 1
Indirect nexthops: 1
Protocol Nexthop: 213.181.39.20
Indirect nexthop: 86d1000 393
Indirect path forwarding nexthops: 1
Nexthop: 213.181.39.25 via fe-0/3/1.3
0.0.0.0/0 Originating RIB: Gp_VRF.inet.0
Node path count: 1
Forwarding nexthops: 1
Nexthop: 213.181.39.25 via fe-0/3/1.3

213.181.39.0/24 (1 entry, 0 announced)
BGP Preference: 170/-101
Next hop type: Unusable
State: <Hidden Ext>
Local AS: 64721 Peer AS: 6774
Age: 1d 5:21:07
Task: BGP_6774_64721.213.181.39.20+179
AS path: 6774 I (Atomic)Aggregator: 6774 213.181.59.92
Localpref: 100
Router ID: 213.181.58.132
Indirect next hops: 1
Protocol next hop: 213.181.39.20 Indirect next hop: 0 -
0.0.0.0/0 Originating RIB: Gp_VRF.inet.0
Node path count: 1
Forwarding nexthops: 1
Nexthop: 213.181.39.25 via fe-0/3/1.3





Probably you're not setting next-hop to self for these prefixes...

Please provide extensive info.
>admin [at] srmum1-re> show route table Gp_VRF hidden extensive

cu
Anton

At 11:37 AM 1/8/2004 +0530, you wrote:
>Hi all,
>
>Need a small piece of info. I am running BGP with 2 upstream GRX
>providers. I am recieving all routes correctly from them except the ones
>mentioned below.
>
>It turns out that these prefixes are the GRX provider's network prefix's
>itself. Since it does not get installed in the route table, I have to put
>in static routes to access stuff like the their DNS servers which are part
>of these subnets, which is not a very nice thing to do.
>
>My query in general is that what are "hidden" routes? I am using an M20
>with JunOS , the upstream provider is using a Cisco 7000 series box. There
>are NO inbound BGP policies at my end.
>
>The GRX guys cannot seem to figure out why this is happening.
>
>thanks.
>
>
>admin [at] srmum1-re> show route table Gp_VRF hidden
>
>Gp_VRF.inet.0: 514 destinations, 525 routes (513 active, 0 holddown, 2 hidden)
>+ = Active Route, - = Last Active, * = Both
>
>202.123.213.80/28 [BGP/170] 23:37:07, MED 0, localpref 100, from
>202.123.213.83
> AS path: 19440 I
> Unusable
>213.181.39.0/24 [BGP/170] 23:38:48, localpref 100, from 213.181.39.20
> AS path: 6774 I
> Unusable
>
>_______________________________________________
>juniper-nsp mailing list juniper-nsp [at] puck
>http://puck.nether.net/mailman/listinfo/juniper-nsp


harry at juniper

Jan 8, 2004, 11:42 AM

Post #4 of 4 (1573 views)
Permalink
hidden bgp route [In reply to]

This seems to be in issue of route recursion, where if a route were to be
installed it would deactivate the route's forwarding or protocol next hop by
virtue of being more specific leading to a recursion loop.


For example, it seems that for:

213.181.39.0/24 (1 entry, 0 announced)
. . . .
Protocol next hop: 213.181.39.20 Indirect next hop:
0 -
0.0.0.0/0 Originating RIB: Gp_VRF.inet.0 <<<<<
Node path count: 1
Forwarding nexthops: 1
Nexthop: 213.181.39.25 via fe-0/3/1.3

You are ultimately using a default route for next hop resolution. This is
ok, expect the route you want to install (213.181.39/24) is a longer match
for the protocols next hop (213.181.39.20) then the currently used 0/0
default. As a result, installing the BGP route would resulting in the
protocol next-hop resolving through the BGP route that needs it's protocol
next-hop resolved.

There are several ways to deal with this. Check out the IP prep guide for
some additional discussion. Some folks alter their IGP to leak/advertise the
protocol next hop so that a default is no longer needed. Setting next-hop to
a physical interface address that is carried by the IGP in that Area/Level
is also workable.

HTHs.





> -----Original Message-----
> From: juniper-nsp-bounces [at] puck
> [mailto:juniper-nsp-bounces [at] puck] On Behalf Of
> Bosco Sachanandani
> Sent: Thursday, January 08, 2004 3:49 AM
> To: juniper-nsp [at] puck
> Subject: RE: [j-nsp] hidden bgp route
>
>
> hi,
>
> As asked by some of you, maybe this is more helpful. Also, do
> I need to set the next-hop self option in this case on my router?
>
>
>
> admin [at] srmum1-re> show route table Gp_VRF hidden extensive
>
> Gp_VRF.inet.0: 513 destinations, 524 routes (512 active, 0
> holddown, 2 hidden) 202.123.213.80/28 (2 entries, 1 announced)
> TSI:
> Page 0 idx 1 Type 1 val 88002d8
> Nexthop: 213.181.39.20
> AS path: 6774 19440 I
> Communities:
> Page 0 idx 5 Type 1 val 8a93b7c
> Nexthop: 213.181.39.20
> Localpref: 100
> AS path: 6774 19440 I
> Communities:
> Path 202.123.213.80 from 213.181.39.20 Vector len 4. Val: 1
> 5 KRT in-kernel 202.123.213.80/28 -> {indirect(393)}
> BGP Preference: 170/-101
> Next hop type: Unusable
> State: <Hidden Ext>
> Inactive reason: Unusable path
> Local AS: 64721 Peer AS: 19440
> Age: 1d 5:19:26 Metric: 0
> Task: BGP_19440_64721.202.123.213.83+179
> AS path: 19440 I
> Localpref: 100
> Router ID: 192.168.4.1
> Indirect next hops: 1
> Protocol next hop: 202.123.213.83
> Indirect next hop: 0 -
> 202.123.213.80/28 Originating RIB:
> Gp_VRF.inet.0
> Node path count: 1
> Indirect nexthops: 1
> Protocol Nexthop: 213.181.39.20
> Indirect nexthop: 86d1000 393
> Indirect path forwarding nexthops: 1
> Nexthop:
> 213.181.39.25 via fe-0/3/1.3
> 0.0.0.0/0 Originating RIB:
> Gp_VRF.inet.0
> Node path count: 1
> Forwarding nexthops: 1
> Nexthop:
> 213.181.39.25 via fe-0/3/1.3
>
> 213.181.39.0/24 (1 entry, 0 announced)
> BGP Preference: 170/-101
> Next hop type: Unusable
> State: <Hidden Ext>
> Local AS: 64721 Peer AS: 6774
> Age: 1d 5:21:07
> Task: BGP_6774_64721.213.181.39.20+179
> AS path: 6774 I (Atomic)Aggregator: 6774 213.181.59.92
> Localpref: 100
> Router ID: 213.181.58.132
> Indirect next hops: 1
> Protocol next hop: 213.181.39.20
> Indirect next hop: 0 -
> 0.0.0.0/0 Originating RIB: Gp_VRF.inet.0
> Node path count: 1
> Forwarding nexthops: 1
> Nexthop: 213.181.39.25 via fe-0/3/1.3
>
>
>
>
>
> Probably you're not setting next-hop to self for these prefixes...
>
> Please provide extensive info.
> >admin [at] srmum1-re> show route table Gp_VRF hidden extensive
>
> cu
> Anton
>
> At 11:37 AM 1/8/2004 +0530, you wrote:
> >Hi all,
> >
> >Need a small piece of info. I am running BGP with 2 upstream GRX
> >providers. I am recieving all routes correctly from them
> except the ones
> >mentioned below.
> >
> >It turns out that these prefixes are the GRX provider's network
> >prefix's
> >itself. Since it does not get installed in the route table,
> I have to put
> >in static routes to access stuff like the their DNS servers
> which are part
> >of these subnets, which is not a very nice thing to do.
> >
> >My query in general is that what are "hidden" routes? I am
> using an M20
> >with JunOS , the upstream provider is using a Cisco 7000
> series box. There
> >are NO inbound BGP policies at my end.
> >
> >The GRX guys cannot seem to figure out why this is happening.
> >
> >thanks.
> >
> >
> >admin [at] srmum1-re> show route table Gp_VRF hidden
> >
> >Gp_VRF.inet.0: 514 destinations, 525 routes (513 active, 0
> holddown, 2
> >hidden)
> >+ = Active Route, - = Last Active, * = Both
> >
> >202.123.213.80/28 [BGP/170] 23:37:07, MED 0, localpref 100, from
> >202.123.213.83
> > AS path: 19440 I
> > Unusable
> >213.181.39.0/24 [BGP/170] 23:38:48, localpref 100, from
> 213.181.39.20
> > AS path: 6774 I
> > Unusable
> >
> >_______________________________________________
> >juniper-nsp mailing list juniper-nsp [at] puck
> >http://puck.nether.net/mailman/listinfo/juniper-nsp
>
>
> _______________________________________________
> juniper-nsp mailing list juniper-nsp [at] puck
> http://puck.nether.net/mailman/listinfo/junipe> r-nsp
>

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