Hi folks, I was hearing that typically BGP4 is run on all routers inside a POP, including access routers connecting to customers, border routers connecting other ISPs and core routers connecting to other POPs in the same network. I can understand why BGP4 is run on access and border routers. But running BGP4 on core routers is beyond my understanding. I thought you don't need to run BGP4 on core routers which are considered to be interior nodes. Can someone shed some light on what is the benefit of running BGP4 on the core routers? Thanks, Hansen
On Sun, Jul 09, 2000 at 07:49:37PM -0400, HANSEN CHAN wrote:
Hi folks,
I was hearing that typically BGP4 is run on all routers inside a POP, including access routers connecting to customers, border routers connecting other ISPs and core routers connecting to other POPs in the same network.
I can understand why BGP4 is run on access and border routers. But running BGP4 on core routers is beyond my understanding. I thought you don't need to run BGP4 on core routers which are considered to be interior nodes.
Can someone shed some light on what is the benefit of running BGP4 on the core routers?
If these routers run "normal" ip routing you have to, as each router does a lookup of the destination ip address of each packet, and forward it accordingly. If you run MPLS, you don't have to, as it uses labels to get to the next-hop router. /Jesper -- Jesper Skriver, jesper(at)skriver(dot)dk - CCIE #5456 Work: Network manager @ AS3292 (Tele Danmark DataNetworks) Private: Geek @ AS2109 (A much smaller network ;-) One Unix to rule them all, One Resolver to find them, One IP to bring them all and in the zone to bind them.
Even with MPLS, you need to run some sort of a routing protocol. ISIS or OSPF with TE extensions would do. One can also use BGP with MPLS Label extensions as well. By the way, how does this work with route reflectors? Bora ----- Original Message ----- From: "Jesper Skriver" <jesper@skriver.dk> To: "HANSEN CHAN" <hansen.chan@alcatel.com> Cc: <nanog@merit.edu> Sent: Sunday, July 09, 2000 8:20 PM Subject: Re: Running BGP4 on a Core Router
On Sun, Jul 09, 2000 at 07:49:37PM -0400, HANSEN CHAN wrote:
Hi folks,
I was hearing that typically BGP4 is run on all routers inside a POP, including access routers connecting to customers, border routers connecting other ISPs and core routers connecting to other POPs in the same network.
I can understand why BGP4 is run on access and border routers. But running BGP4 on core routers is beyond my understanding. I thought you don't need to run BGP4 on core routers which are considered to be interior nodes.
Can someone shed some light on what is the benefit of running BGP4 on the core routers?
If these routers run "normal" ip routing you have to, as each router does a lookup of the destination ip address of each packet, and forward it accordingly.
If you run MPLS, you don't have to, as it uses labels to get to the next-hop router.
/Jesper
-- Jesper Skriver, jesper(at)skriver(dot)dk - CCIE #5456 Work: Network manager @ AS3292 (Tele Danmark DataNetworks) Private: Geek @ AS2109 (A much smaller network ;-)
One Unix to rule them all, One Resolver to find them, One IP to bring them all and in the zone to bind them.
On Sun, Jul 09, 2000 at 09:09:48PM -0700, Bora Akyol wrote:
Even with MPLS, you need to run some sort of a routing protocol. ISIS or OSPF with TE extensions would do.
Yes - did I say any different ? This was specific regarding BGP4 ...
One can also use BGP with MPLS Label extensions as well. By the way, how does this work with route reflectors?
You will need a IGP. /Jesper -- Jesper Skriver, jesper(at)skriver(dot)dk - CCIE #5456 Work: Network manager @ AS3292 (Tele Danmark DataNetworks) Private: Geek @ AS2109 (A much smaller network ;-) One Unix to rule them all, One Resolver to find them, One IP to bring them all and in the zone to bind them.
Jesper Skriver wrote:
On Sun, Jul 09, 2000 at 09:09:48PM -0700, Bora Akyol wrote:
Even with MPLS, you need to run some sort of a routing protocol. ISIS or OSPF with TE extensions would do.
Yes - did I say any different ? This was specific regarding BGP4 ...
Assuming all traffic is MPLS. This is not always the case. However, i'd be interested in knowing any network out there that has been able to achieve 100% MPLS forwarding in the core and has turned BGP-4 off their cores... dave
One can also use BGP with MPLS Label extensions as well. By the way, how does this work with route reflectors?
You will need a IGP.
/Jesper
-- Jesper Skriver, jesper(at)skriver(dot)dk - CCIE #5456 Work: Network manager @ AS3292 (Tele Danmark DataNetworks) Private: Geek @ AS2109 (A much smaller network ;-)
One Unix to rule them all, One Resolver to find them, One IP to bring them all and in the zone to bind them.
we can even imagine some core that is not ip core but, say, atm core and all lsrs are atm-lsrs. actually some providers (like c&w) have exactly this no ip core, overlay model. it's far from being the best one. -- dima.
-----Original Message----- From: owner-nanog@merit.edu [mailto:owner-nanog@merit.edu]On Behalf Of Bora Akyol Sent: Monday, July 10, 2000 12:10 AM To: nanog Subject: Re: Running BGP4 on a Core Router
Even with MPLS, you need to run some sort of a routing protocol.
ISIS or OSPF with TE extensions would do.
One can also use BGP with MPLS Label extensions as well. By the way, how does this work with route reflectors?
Bora
----- Original Message ----- From: "Jesper Skriver" <jesper@skriver.dk> To: "HANSEN CHAN" <hansen.chan@alcatel.com> Cc: <nanog@merit.edu> Sent: Sunday, July 09, 2000 8:20 PM Subject: Re: Running BGP4 on a Core Router
On Sun, Jul 09, 2000 at 07:49:37PM -0400, HANSEN CHAN wrote:
Hi folks,
I was hearing that typically BGP4 is run on all routers inside a POP, including access routers connecting to customers, border routers connecting other ISPs and core routers connecting to other POPs in the same network.
I can understand why BGP4 is run on access and border routers. But running BGP4 on core routers is beyond my understanding. I thought you don't need to run BGP4 on core routers which are considered to be interior nodes.
Can someone shed some light on what is the benefit of running BGP4 on the core routers?
If these routers run "normal" ip routing you have to, as each router does a lookup of the destination ip address of each packet, and forward it accordingly.
If you run MPLS, you don't have to, as it uses labels to get to the next-hop router.
/Jesper
-- Jesper Skriver, jesper(at)skriver(dot)dk - CCIE #5456 Work: Network manager @ AS3292 (Tele Danmark DataNetworks) Private: Geek @ AS2109 (A much smaller network ;-)
One Unix to rule them all, One Resolver to find them, One IP to bring them all and in the zone to bind them.
The atm part is only the layer two core C&W and UUnet, both have ip on all core routers taking full bgp routes. Much like sprint has a POS core, but they still run ip over it. You have to have some kind of layer 2 core to run ip over so if you think about it every one has some kind of overlay model. Chris ----- Original Message ----- From: "Dmitri Krioukov" <dima@krioukov.net> To: "Bora Akyol" <akyol@akyol.org> Cc: "nanog" <nanog@merit.edu> Sent: Tuesday, July 11, 2000 9:54 PM Subject: RE: Running BGP4 on a Core Router
we can even imagine some core that is not ip core but, say, atm core and all lsrs are atm-lsrs.
actually some providers (like c&w) have exactly this no ip core, overlay model. it's far from being the best one. -- dima.
-----Original Message----- From: owner-nanog@merit.edu [mailto:owner-nanog@merit.edu]On Behalf Of Bora Akyol Sent: Monday, July 10, 2000 12:10 AM To: nanog Subject: Re: Running BGP4 on a Core Router
Even with MPLS, you need to run some sort of a routing protocol.
ISIS or OSPF with TE extensions would do.
One can also use BGP with MPLS Label extensions as well. By the way, how does this work with route reflectors?
Bora
----- Original Message ----- From: "Jesper Skriver" <jesper@skriver.dk> To: "HANSEN CHAN" <hansen.chan@alcatel.com> Cc: <nanog@merit.edu> Sent: Sunday, July 09, 2000 8:20 PM Subject: Re: Running BGP4 on a Core Router
On Sun, Jul 09, 2000 at 07:49:37PM -0400, HANSEN CHAN wrote:
Hi folks,
I was hearing that typically BGP4 is run on all routers inside a
including access routers connecting to customers, border routers connecting other ISPs and core routers connecting to other POPs in
POP, the
same network.
I can understand why BGP4 is run on access and border routers. But running BGP4 on core routers is beyond my understanding. I thought you don't need to run BGP4 on core routers which are considered to be interior nodes.
Can someone shed some light on what is the benefit of running BGP4 on the core routers?
If these routers run "normal" ip routing you have to, as each router does a lookup of the destination ip address of each packet, and forward it accordingly.
If you run MPLS, you don't have to, as it uses labels to get to the next-hop router.
/Jesper
-- Jesper Skriver, jesper(at)skriver(dot)dk - CCIE #5456 Work: Network manager @ AS3292 (Tele Danmark DataNetworks) Private: Geek @ AS2109 (A much smaller network ;-)
One Unix to rule them all, One Resolver to find them, One IP to bring them all and in the zone to bind them.
-----Original Message----- From: owner-nanog@merit.edu [mailto:owner-nanog@merit.edu]On Behalf Of Bora Akyol Sent: Monday, July 10, 2000 12:10 AM To: nanog Subject: Re: Running BGP4 on a Core Router
Even with MPLS, you need to run some sort of a routing protocol.
ISIS or OSPF with TE extensions would do.
One can also use BGP with MPLS Label extensions as well. By the way, how does this work with route reflectors?
it should work just fine (as mentioned in the draft). however, if you're looking for any operational experience, then i don't think you'll be able to easily find it...
Bora -- dima.
participants (6)
-
Bora Akyol -
Chris -
Dave Cooper -
Dmitri Krioukov -
HANSEN CHAN -
Jesper Skriver