Differences

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--- hints:routing [2020/09/22 21:07] – [Default Originate in IS-IS] philip
+++ hints:routing [2020/09/22 21:12] (current) – [Complete Configuration] philip
@@ Line 78: / Line 78: @@
 route-map EBGP-in permit 5
  description Do not propagate default route
- match ip address prefix-list default
+ match ip address prefix-list DEFAULT
  set community no-advertise
 !
@@ Line 88: / Line 88: @@
  address-family ipv4
   neighbor 10.10.10.1 route-map EBGP-in in
+  distance bgp 20 200 200
 !
 </code>
-The no-advertise community will make sure that the matched route will not be announced to any other BGP speaker.
+The ''no-advertise'' community will make sure that the matched route will not be announced to any other BGP speaker.
 ==== Conclusion ====
@@ Line 97: / Line 98: @@
 With the configuration applied to both Border Routers now, the rest of the routers will see a default route via IS-IS only. There will be no default route in BGP apart from at the Border Routers. Each Border Router will see the default route being learned from the attached external neighbour. And the best path to the default route will be determined by the IS-IS metric attached to the default being propagated by IS-IS.
+==== Complete Configuration ====
+For BR1 (making BR1 the //main// default gateway):
+<code>
+router isis ISP
+ ...
+ default-information originate route-map DEFAULT-ORIG
+!
+router bgp 64512
+ address-family ipv4
+  neighbor 10.10.10.1 route-map EBGP-in in
+  distance bgp 20 200 200
+!
+ip access-list standard BGP-NH
+ remark External BGP speaker
+ permit 10.10.10.1
+!
+ip prefix-list DEFAULT permit 0.0.0.0/0
+!
+route-map DEFAULT-ORIG permit 5
+ match ip address prefix-list DEFAULT
+ match ip next-hop BGP-NH
+!
+route-map EBGP-in permit 5
+ description Do not propagate default route
+ match ip address prefix-list DEFAULT
+ set community no-advertise
+!
+route-map EBGP-in permit 10
+ description Other policy
+ ...
+!
+</code>
+For BR2 (making BR2 the //backup// default gateway):
+<code>
+router isis ISP
+ ...
+ default-information originate route-map DEFAULT-ORIG
+!
+router bgp 64512
+ address-family ipv4
+  neighbor 10.10.20.1 route-map EBGP-in in
+  distance bgp 20 200 200
+!
+ip access-list standard BGP-NH
+ remark External BGP speaker
+ permit 10.10.20.1
+!
+ip prefix-list DEFAULT permit 0.0.0.0/0
+!
+route-map DEFAULT-ORIG permit 5
+ match ip address prefix-list DEFAULT
+ match ip next-hop BGP-NH
+ set metric 10
+!
+route-map EBGP-in permit 5
+ description Do not propagate default route
+ match ip address prefix-list DEFAULT
+ set community no-advertise
+!
+route-map EBGP-in permit 10
+ description Other policy
+ ...
+!
+</code>
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