In Figure 263, Router A could choose to advertise all the four routes or one aggregate route. By aggregating the four routes, fewer updates are sent on the link between routers A and B, router B needs to maintain a smaller routing table resulting in better convergence and router B saves on computational resources by evaluating fewer entries in its routing table.
This feature adds a new indirect keyword and associated IP address parameter to the existing aggregate command in these configuration contexts:
config
router
aggregate ip-prefix/ip-prefix-length [summary-only] [as-set] [aggregator as
-number: ip-address] [community comm-id] [black-hole | indirect ip-address]
config
service
vprn
aggregate ip-prefix/ip-prefix-length [summary-only] [as-set] [aggregator as
-number: ip-address] [community comm-id] [black-hole | indirect ip-address]
|
•
|
indirect — This indicates that the aggregate route has an indirect address. Note from this syntax that the indirect option is mutually exclusive with the black-hole option. To change the next-hop type of an aggregate route (for example from black-hole to indirect) the route must be deleted and then re-added with the new next-hop type (however other configuration attributes can generally be changed dynamically).
|
aggregate ip-prefix/ip-prefix-length [
summary-only] [
as-set] [
aggregator as-number: ip-address] [
community comm-id] [
black-hole |
indirect ip-address]
no aggregate ip-
prefix/ip-prefix-length
The no form of the command removes the aggregate.
Values: ipv4-prefix a.b.c.d (host bits must be 0)
ipv4-prefix-length
0 — 32
ipv6-prefix
x:x:x:x:x:x:x:x
x:x:x:x:x:x:d.d.d.d
x: [0 — FFFF]H
d: [0 — 255]D
ipv6-prefix-length 0 — 128
summary-only — This optional parameter suppresses the advertisement of more specific component routes for the aggregate. To remove the summary-only option, enter the same aggregate command without the summary-only parameter.
as-set — This optional parameter is only applicable to BGP and creates an aggregate where the path advertised for this route will be an AS_SET consisting of all elements contained in all paths that are being summarized. Use this feature carefully as it can increase the amount of route churn due to best path changes.
aggregator as-number:ip-address — This optional parameter adds the BGP aggregator path attribute to the aggregate route. When configuring the aggregator, a two-octet AS number used to form the aggregate route must be entered, followed by the IP address of the BGP system that created the aggregate route.
community comm-id — This configuration option associates a BGP community with the aggregate route. The community can be matched in route policies and is automatically added to BGP routes exported from the aggregate route.
Values:
comm-id asn:comm-val |
well-known-comm
asn 0 — 65535
comm-val 0 — 65535
well-known-comm no-advertise, no-export, no-export-subconfed
black-hole — This optional parameter installs the aggregate route, when activated, in the FIB with a black-hole next-hop. Packets matching an aggregate route with a black-hole next hop are discarded.
indirect ip-address — This configuration option specifies that the aggregate route should be installed in the FIB with a next-hop taken from the route used to forward packets to
ip-address.
Values ipv4-prefix a.b.c.d
ipv6-prefix
x:x:x:x:x:x:x:x
x:x:x:x:x:x:d.d.d.d
x: [0 — FFFF]H
d: [0 — 255]D
A:PE-1>config#router aggregate 10.10.10.0/24 community 64496:64497 indirect 192.168.11.11
A:PE-1# show router aggregate
===============================================================================
Aggregates (Router: Base)
===============================================================================
Prefix Aggr IP-Address Aggr AS
Summary AS Set State
NextHop Community NextHopType
-------------------------------------------------------------------------------
10.10.10.0/24 0.0.0.0 0
False False Inactive
192.168.11.11 64496:64497 Indirect
-------------------------------------------------------------------------------
No. of Aggregates: 1
===============================================================================
*A:PE-1# show router route-table
===============================================================================
Route Table (Router: Base)
===============================================================================
Dest Prefix[Flags] Type Proto Age Pref
Next Hop[Interface Name] Metric
-------------------------------------------------------------------------------
10.10.10.0/24 Remote Aggr 00h00m20s 130
Black Hole 0
10.10.10.3/32 Remote Static 00h00m24s 5
10.18.0.89 1
10.10.10.4/32 Remote Static 00h00m24s 5
10.18.0.89 1
10.10.10.5/32 Remote Static 00h00m24s 5
10.18.0.89 1
10.10.10.8/32 Remote Static 00h00m24s 5
10.18.0.89 1
10.12.0.0/24 Local Local 00h00m24s 0
to_PE-2 0
10.18.0.0/24 Local Local 00h00m24s 0
to_Routers 0
10.19.0.0/24 Local Local 00h00m24s 0
to_Tester 0
10.20.1.1/32 Local Local 00h00m24s 0
system 0
-------------------------------------------------------------------------------
No. of Routes: 9
Flags: L = LFA nexthop available B = BGP backup route available
n = Number of times nexthop is repeated
===============================================================================
A:PE-1# show router aggregate
===============================================================================
Aggregates (Router: Base)
===============================================================================
Prefix Aggr IP-Address Aggr AS
Summary AS Set State
NextHop Community NextHopType
-------------------------------------------------------------------------------
10.10.10.0/24 0.0.0.0 0
False False Active
192.168.11.11 64496:64497 Indirect
-------------------------------------------------------------------------------
No. of Aggregates: 1
===============================================================================
A:PE-2# show router route-table
===============================================================================
Route Table (Router: Base)
===============================================================================
Dest Prefix[Flags] Type Proto Age Pref
Next Hop[Interface Name] Metric
-------------------------------------------------------------------------------
10.10.10.0/24 Remote Static 00h00m14s 5
10.29.0.99 1
10.12.0.0/24 Local Local 00h00m14s 0
to_PE-1 0
10.20.1.2/32 Local Local 00h00m14s 0
system 0
10.29.0.0/24 Local Local 00h00m14s 0
to_Tester 0
192.168.11.0/24 Remote Static 00h00m14s 5
10.12.0.2 1
-------------------------------------------------------------------------------
No. of Routes: 5
Flags: L = LFA nexthop available B = BGP backup route available
n = Number of times nexthop is repeated
===============================================================================
*A:PE-2# show router route-table
===============================================================================
Route Table (Router: Base)
===============================================================================
Dest Prefix[Flags] Type Proto Age Pref
Next Hop[Interface Name] Metric
-------------------------------------------------------------------------------
10.10.10.0/24 Remote Aggr 00h00m20s 130
10.12.0.2 0
10.10.10.3/32 Remote Static 00h00m24s 5
10.18.0.89 1
10.10.10.4/32 Remote Static 00h00m24s 5
10.18.0.89 1
10.10.10.5/32 Remote Static 00h00m24s 5
10.18.0.89 1
10.10.10.8/32 Remote Static 00h00m24s 5
10.18.0.89 1
10.12.0.0/24 Local Local 00h00m24s 0
to_PE-2 0
10.18.0.0/24 Local Local 00h00m24s 0
to_Routers 0
10.19.0.0/24 Local Local 00h00m24s 0
to_Tester 0
10.20.1.1/32 Local Local 00h00m24s 0
system 0
192.168.11.0/24 Remote Static 00h00m24s 5
10.12.0.2 1
-------------------------------------------------------------------------------
No. of Routes: 10
Flags: L = LFA nexthop available B = BGP backup route available
n = Number of times nexthop is repeated
===============================================================================
