BGP IPv6 - Summarization
Summarization
BGP (Border Gateway Protocol) IPv6 summarization is a technique employed to streamline the representation of routing information within BGP networks. This process involves aggregating multiple IPv6 prefixes into a more condensed summary route. IPv6 summarization in BGP helps address scalability challenges by reducing the size and complexity of routing tables. By presenting a summarized view of the network's topology, routers can optimize memory usage and enhance the efficiency of BGP routing operations. However, careful consideration is needed during summarization to ensure that the aggregated prefixes accurately represent the underlying subnets and avoid unnecessary loss of routing details. Proper implementation of IPv6 summarization in BGP contributes to a more scalable, manageable, and streamlined routing infrastructure, particularly crucial in networks with a large number of IPv6 prefixes.
Lab:
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Cisco IOS Software, Linux Software (I86BI_LINUX-ADVENTERPRISEK9-M), Version 15.2(4)M1, DEVELOPMENT TEST SOFTWARE
Task 1: Configure IPv6 BGP Summarization
Step 1: In the configuration mode of router configure loopbacks with network address in sequence
R1:
interface loopback 1
ip address 11:0:1::2/64
interface loopback 2
ip address 11:0:2::2/64
interface loopback 3
ip address 11:0:3::2/64
exit
Step 2: Summarize BGP routes in router mode
R1:
router bgp 65100
address-family ipv6
aggregate-address 11::/16
exit
Step 3: Verify receipt of summary route in other router’s BGP table by following command:
R2# clear bgp ipv6 * soft
//it will flush the bgp table and will learn fresh route.
R2#show bgp ipv6 unicast
BGP table version is 14, local router ID is 22.0.3.2
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter, x best-external
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*> 11::/16 11:0:1::1 0 0 65100 i
*> 11:0:1::/64 11:0:1::1 0 0 65100 i
*> 11:0:2::/64 11:0:1::1 0 0 65100 i
*> 11:0:3::/64 11:0:1::1 0 0 65100 i
*> 22:0:1::/64 :: 0 32768 i
*> 22:0:2::/64 :: 0 32768 i
*> 22:0:3::/64 :: 0 32768 i
*>i 33:0:1::/64 33:0:1::3 0 100 0 i
*>i 33:0:2::/64 33:0:1::3 0 100 0 i
*>i 33:0:3::/64 33:0:1::3 0 100 0 i
*>i 44:0:1::/64 44:0:1::4 0 100 0 65200 i
*>i 44:0:2::/64 44:0:1::4 0 100 0 65200 i
*>i 44:0:3::/64 44:0:1::4 0 100 0 65200 i
R4# clear bgp ipv6 * soft
R4#show bgp ipv6 unicast
BGP table version is 62, local router ID is 44.0.3.4
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*> 11::/16 33:0:1::3 0 65000 65100 i
*> 11:0:1::/64 33:0:1::3 0 65000 65100 i
*> 11:0:2::/64 33:0:1::3 0 65000 65100 i
*> 11:0:3::/64 33:0:1::3 0 65000 65100 i
*> 22:0:1::/64 33:0:1::3 0 65000 i
*> 22:0:2::/64 33:0:1::3 0 65000 i
*> 22:0:3::/64 33:0:1::3 0 65000 i
*> 33:0:1::/64 33:0:1::3 0 0 65000 i
*> 33:0:2::/64 33:0:1::3 0 0 65000 i
*> 33:0:3::/64 33:0:1::3 0 0 65000 i
*> 44:0:1::/64 0.0.0.0 0 32768 i
*> 44:0:2::/64 0.0.0.0 0 32768 i
*> 44:0:3::/64 0.0.0.0 0 32768 i
If BGP will send only summary route of an network then the router which is sending summary route will stripped off all previous AS-tag and will send summarized route with fresh originating router, this will lead to Loops in BGP. To avoid loops, BGP send summarized as well as Individual routes to other routers.
Step 4: Configure Summarize only BGP routes in router mode
R3:
router bgp 65000
address-family ipv6
aggregate-address 11::/16 summary-only
exit
Step 5: Verify receipt of summary route in other router’s BGP table by following command
R4# clear bgp ipv6 * soft
R4#show bgp ipv6 unicast
BGP table version is 19, local router ID is 44.0.3.4
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
x best-external, a additional-path, c RIB-compressed,
Origin codes: i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found
Network Next Hop Metric LocPrf Weight Path
*> 11::/16 33:0:1::3 0 0 65000 i
*> 22:0:1::/64 33:0:1::3 0 65000 i
*> 22:0:2::/64 33:0:1::3 0 65000 i
*> 22:0:3::/64 33:0:1::3 0 65000 i
*> 33:0:1::/64 33:0:1::3 0 0 65000 i
*> 33:0:2::/64 33:0:1::3 0 0 65000 i
*> 33:0:3::/64 33:0:1::3 0 0 65000 i
*> 44:0:1::/64 :: 0 32768 i
*> 44:0:2::/64 :: 0 32768 i
*> 44:0:3::/64 :: 0 32768 i
By summary-only command, BGP will send only summary route of network then the router which is sending summary route will stripped off all previous AS-tag and will send summarized route with fresh originating router.
Step 6: Configure Summarize only as-set BGP routes in router mode
R3:
router bgp 65000
address-family ipv6
aggregate-address 11::/16 summary-only as-set
exit
Step 7: Verify receipt of summary route in other router’s BGP table by following command
R4#show bgp ipv6 unicast
BGP table version is 19, local router ID is 44.0.3.4
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
x best-external, a additional-path, c RIB-compressed,
Origin codes: i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found
Network Next Hop Metric LocPrf Weight Path
*> 11::/16 33:0:1::3 0 0 65000 65100 i
*> 22:0:1::/64 33:0:1::3 0 65000 i
*> 22:0:2::/64 33:0:1::3 0 65000 i
*> 22:0:3::/64 33:0:1::3 0 65000 i
*> 33:0:1::/64 33:0:1::3 0 0 65000 i
*> 33:0:2::/64 33:0:1::3 0 0 65000 i
*> 33:0:3::/64 33:0:1::3 0 0 65000 i
*> 44:0:1::/64 :: 0 32768 i
*> 44:0:2::/64 :: 0 32768 i
*> 44:0:3::/64 :: 0 32768 i
By as-set command, only summary route as well as retaining all previous AS-tag is achieved.