Routing

Hello All,

I am trying to advertise the default route to my BGP peers. Router A (ISP) to Router B (University - Non-Juniper) and Router C (WISP - Non-Juniper)

 

I have been looking at different config from various people on these forums and after a month I cannot seem to get the default-route to advertise to the peers.

 

The config is faily simple.

I have removed all the default route information from the config and just listed my current running BGP and policy options.

Any help will be greatly appreciated.

 

Logical Router:

show configuration logical-systems internet protocols bgp

advertise-inactive;
log-updown;
group internal {
type internal;
export next-hop-self;
neighbor X.X.47.254;
}
group internet-peers {
type external;
family inet {
unicast;
multicast;
}
export adv-supernets;
peer-as XXX34;
multipath;
neighbor X.X.46.253 {
description "ISP 1 - 1G";
export AS-prepend-ISP-1;
peer-as XXX81;
}
neighbor X.X.86.173 {
description "ISP 2 - 5G";
peer-as XXX56;
}
neighbor X.X.152.197 {
description "ISP 3 - 2G";
peer-as XXX82;
}
show configuration logical-systems internet policy-options

prefix-list all-supernets {
X.X.224.0/24;
X.X.225.0/24;
X.X.28.0/22;
X.X.32.0/20;

prefix-list external-supernets {
X.X.64.0/24;
X.X.226.0/24;
X.X.227.0/24;
X.X.110.0/24;
X.X.251.0/24;

policy-statement AS-prepend-ISP-1 {
from policy adv-supernets;
then {
as-path-prepend "XXX34 XXX34";
accept;
}
}

policy-statement adv-supernets {
term 10 {
from {
protocol static;
prefix-list-filter all-supernets exact;
}
then accept;
}
term 15 {
from {
protocol bgp;
prefix-list-filter external-supernets exact;
}
then accept;
}
term 20 {
then reject;
}
then {
next-hop self;
}
}
policy-statement redist-default {
from {
protocol static;
route-filter 0.0.0.0/0 exact;
}
then accept;
}

 

 

Router

local-address X.X.47.254;
group internal {
type internal;
export next-hop-self;
neighbor X.X.47.253;
}
group external {
type external;
neighbor X.X.45.145 {
description "Peer C";
local-address X.X.45.150;
export adv-supernets;
peer-as XXX98;
}
neighbor X.X.47.172 {
description "Peer A";
local-address X.X.47.174;
export adv-supernets;
peer-as XXX36;
}
neighbor X.X.44.201 {
description "Peer B";
local-address X.X.44.202;
export adv-supernets;
peer-as XXX35;
}
neighbor X.X.47.237 {
description "Peer D";
local-address X.X.47.238;
export adv-supernets;
peer-as XXXX08;
}
show configuration policy-options

prefix-list all-supernets {
X.X.224.0/24;
X.X.225.0/24;
X.X.28.0/22;
X.X.32.0/20;

policy-statement adv-supernets {
term 10 {
from {
protocol static;
prefix-list-filter all-supernets exact;
}
then accept;
}
term 20 {
then reject;
}
}
policy-statement next-hop-self {
then {
next-hop self;
}
}
policy-statement redist-default {
from {
route-filter 0.0.0.0/0 exact;
}
then accept;
}
policy-statement redist-pppoe {
from protocol [ access-internal access ];
then accept;
}
policy-statement redist-static {
from protocol static;
then accept;
}

 

Hi WNMC Jack Gonzales,

 

I saw that you created the following policy "policy-statement redist-default" but I don't see where it is applied, please let me know if I missed it. 

 

Regards,
Lil Dexx JNCIE-ENT#863

 

If this solves your problem, please mark this post as "Accepted Solution" so we can help others too

Lil Dex,

 

Currently I do not have the policy-statement redist-default being exported in BGP to my peers as it was not coming up or being advertised.

Hi !!

 

Please go ahead and review the config in this example and let me know if this matches your scenario. 

If not please share a simple topology of how yours routers are connected. 

 

https://www.juniper.net/documentation/en_US/junos/topics/example/policy-default-static-route.html 

 

Hope this helps !!

 

 Please accept this as a solution if it answers your question so others can benefit from your post.

 

+++++++++++++++++++++++++++++++++++++++++++++

 

Accept as Solution = cool !

Accept as Solution+Kudo = You are a Star !

 

+++++++++++++++++++++++++++++++++++++++++++++

Hi,

I have attached a basic drawing of my BGP setup.

I have also looked at that sample config, and when ever I add "set routing-options static route 0.0.0.0/0 discard" to the main router config it stops all my traffic.

 

We use a single MX480 with a logical instance to BGP to our ISP's for access and a main config to provide access to our customers.

Between that logical instance and the main router config I have BGP and OSPF.

 

The logical instance router does advertise the default route as I can see it in the received routes from the BGP.

I just can't seem to get it advertised to my BGP peers.

Are you receiving a default route from your ISP peers and looking to pass that on to your downstream network?

 

Or are you getting full tables only from the ISP and looking to generate a default route and send this to your downstream peers?

 

Hi WNMC Jack Gonzales,

Please share the "show route 0.0.0.0/0 exact" output.

 

Based on, from which protocol you are learning the default route we will need to construct the policy which needs to be applied as BGP export policy.

 

set policy-options policy-statement export term 1 from protocol <protocol-name>
set policy-options policy-statement export term 1 from route-filter 0.0.0.0/0 exact
set policy-options policy-statement export term 1 then accept

If you are not learning the default route you will need to configure a default static route and advertise that (use static as protocol-name).

PS: Please accept my response as solution if it answers your query, kudos are appreciated too!

Thanks

Vishal

Hi

 

show route logical systems internet 0.0.0.0/0 exact

+ = Active Route, - = Last Active, * = Both

0.0.0.0/0 *[Static/5] 2w0d 09:43:48
to X.X.46.253 via ge-0/1/0.0
to X.X.86.173 via xe-1/1/0.0
> to X.X.152.197 via xe-1/1/1.0
[BGP/170] 2w0d 09:43:33, localpref 100
AS path: XX881 I, validation-state: unverified
> to X.X.46.253 via ge-0/1/0.0
[BGP/170] 2w0d 09:43:31, localpref 100
AS path: XX782 174 I, validation-state: unverified
> to X.X.152.197 via xe-1/1/1.0

 

show route 0.0.0.0/0 exact

+ = Active Route, - = Last Active, * = Both

0.0.0.0/0 *[OSPF/150] 2w0d 09:39:02, metric 0, tag 0
> to X.X.47.251 via xe-1/0/0.0
[BGP/170] 2w0d 09:38:59, localpref 100, from X.X.47.253
AS path: XX881 I, validation-state: unverified
> to X.X.47.251 via xe-1/0/0.0

 

I do not belive I am generating the default route to send to my peers.

Hello,

 

You have the default route in the logical system:

show route logical systems internet 0.0.0.0/0 exact

+ = Active Route, - = Last Active, * = Both

0.0.0.0/0 *[Static/5] 2w0d 09:43:48
to X.X.46.253 via ge-0/1/0.0
to X.X.86.173 via xe-1/1/0.0

You can apply following policy:

set policy-options policy-statement export term 1 from protocol static
set policy-options policy-statement export term 1 from route-filter 0.0.0.0/0 exact
set policy-options policy-statement export term 1 then accept

PS: Please accpet my response as solution if it answers your query, kudos are appreciated too!

Thanks
Vishal

Hello,

 

I have added that statement and then added to be exported by BGP.

The default route is not being advertsied as of yet. I have also restarted my BGP gracefully with no change.

Your upstream logical system shows that you are getting a default route via bgp from both of your ISPs.

 

And you also have a static default route pointed to only one of those ISP.

 

Was this static route override of the dual BGP routes done on purpose?

I would have expected that you would use the BGP routes combined with local preference if there is a desire to force the traffic to one ISP by default.

 

Downstream it does seem that the default route is being learned by both BGP and OSPF.  

If you remove the static route you might need to make sure the BGP default leaks into OSPF fo redistribution via that protocol.

 

I guess the question here is what are your goals in routing here.  There are lots of options.

 

Hello,

 

The ulimate goal is to advertise the default route 0.0.0.0/0 to my eBGP peers.

The logical system internet has no issues advertising the default route through OSPF and iBGP. Yes I am receiving a default route from 2 of my 3 ISP's upstream providers but I also have a static route for outbound or upstream traffic to one ISP.

 

I just cannot seem to have the eBGP in my downstream to advertised the default route to the eBGP Peers.

Hello,

I checked the default route in the main instance it seems to be learned from OSPF.  Following export policy can be applied on eBGP.

 

set policy-options policy-statement export term 1 from protocol ospf
set policy-options policy-statement export term 1 from route-filter 0.0.0.0/0 exact
set policy-options policy-statement export term 1 then accept

Once you have applied the policy please check following output and see if the route is advertised or not

show route 0.0.0.0/0 exact advertising-protocol bgp <neighbor-addresss>

Route that need to be advertised:

show route 0.0.0.0/0 exact

+ = Active Route, - = Last Active, * = Both

0.0.0.0/0 *[OSPF/150] 2w0d 09:39:02, metric 0, tag 0
> to X.X.47.251 via xe-1/0/0.0
[BGP/170] 2w0d 09:38:59, localpref 100, from X.X.47.253
AS path: XX881 I, validation-state: unverified
> to X.X.47.251 via xe-1/0/0.0

Hello,

 

I have added this to my Adv-Default statement:

term 10 {
from {
protocol ospf;
route-filter 0.0.0.0/0 exact;
}
then accept;
}

 

The route is still not being advertised to my BGP neighbors.

Ok and where do you apply that directly under the neighbor in the bgp group?

Can you do while the export policy with the default route:

>show route advertising-protocol bgp (neighbor ip)

The idea to add the term directly on the adv-supernets is because I am guessing that policy is working and you are advertising those supernets so we know that policy is being evaluated so I was curious if you add it there what do you see

Can you please try this:

set policy-options policy-statement adv-supernets term default-route from protocol ospf
set policy-options policy-statement adv-supernets term default-route from route-filter 0.0.0.0/0 exact
set policy-options policy-statement adv-supernets term default-route then accept
insert policy-options policy-statement adv-supernets term default-route before term 10
commit

The above suggestion would work if you still have following configuration:

Router

group external {
type external;
neighbor X.X.45.145 {
description "Peer C";
local-address X.X.45.150;
export adv-supernets;
peer-as XXX98;
}
neighbor X.X.47.172 {
description "Peer A";
local-address X.X.47.174;
export adv-supernets;
peer-as XXX36;
}
neighbor X.X.44.201 {
description "Peer B";
local-address X.X.44.202;
export adv-supernets;
peer-as XXX35;
}
neighbor X.X.47.237 {
description "Peer D";
local-address X.X.47.238;
export adv-supernets;
peer-as XXXX08;
}

 

show configuration policy-options

policy-statement adv-supernets {
term 10 {
from {
protocol static;
prefix-list-filter all-supernets exact;
}
then accept;
}
term 20 {
then reject;
}
}

PS: Please accpet my answer as solution if it resolves your query, kudos are appreicated too!

Thanks
Vishal

Hello,

 

I was able to finally get the route 0.0.0.0/0 to be advertised to my eBGP peers

 

I had to remove term 20 then reject from:

policy-statement adv-supernets {
term 10
from protocol static;
prefix-list-filter all-supernets exact;
then accept;
term 20
then reject;

 

This is the final config that it is working on:

policy-statement adv-supernets
term 10
from
protocol static;
prefix-list-filter all-supernets exact;
then accept;

 

policy-statement Adv-Default {
term 10
from
protocol ospf;
route-filter 0.0.0.0/0 exact;
then accept;
term 20
then reject;

 

group external
type external;
neighbor X.X.45.145
local-address X.X.45.150;
export adv-supernets;
peer-as XXX98;

neighbor X.X.47.172
local-address X.X.47.174;
export adv-supernets;
peer-as XXX36;

 

neighbor X.X.44.201
local-address X.X.44.202;
export adv-supernets;
peer-as XXX535;

neighbor X.X.47.237
local-address X.X.47.238;
export [ adv-supernets Adv-Default ];
peer-as XXX108;

 

run show route 0.0.0.0/0 advertising-protocol bgp X.X.47.237

inet.0: 782263 destinations, 782265 routes (782263 active, 0 holddown, 0 hidden)
Prefix Nexthop MED Lclpref AS path
* 0.0.0.0/0 Self 0 I
* X.X.224.0/24 Self I
* X.X.225.0/24 Self I
* X.X.28.0/22 Self I
* X.X.32.0/20 Self I

 

Thank you all for all the assistance.

This is a great community to be part of

Hi WNMC Jack Gonzales, 

 

This looks interesting, can you try this (try using incomplete value and export it to other BGP peers)? 

 

https://tools.ietf.org/html/rfc1397 
2. Default Route Advertisement

A default route is advertised in an UPDATE message that carries
reachability information for network 0.0.0.0. A Network field of
such an UPDATE message must contain the IP address 0.0.0.0 as the
indication that it carries a default route. The NEXT_HOP path
attribute of such a message provides the IP address of a border

gateway that can be used as a default next hop to destinations that
are not listed in the BGP peer's routing table. The value of the
ORIGIN attribute should be 2 (INCOMPLETE). The AS_PATH attribute
should be constructed according to the same rules that apply to a
conventional network advertisement.

If multiple default routes are advertised by a BGP speaker, the
INTER-AS-METRIC path attribute can be included in the corresponding
UPDATE messages to express preference levels for entry points to the
same AS.

The UNREACHABLE path attribute is used to indicate that a previously
advertised default route has become unreachable.

UPDATE messages containing the default route advertisements should be
handled according to the rules that apply to all other UPDATE
messages. If multiple default route are acquired by a BGP speaker, a
route is selected according to the local policies adopted by this BGP
speaker.

 

If this solves your problem, please mark this post as "Accepted Solution".
If you think that my answer was helpful, please spend some Kudos.

Hi!

 

can you try just adding a term to export the defult route before term 20 on the policy adv-supernets?