10
votes
OSPF or iBGP for interior routing protocol?
iBGP requires a full mesh or use of mitigation like confederations or route reflectors, BGP doesn't converge with anything like the speed of OSPF, etc.
Each OSPF router would have a full ...
- 98.3k
10
votes
OSPF or iBGP for interior routing protocol?
First off, I would dispute the assertion that some others have made that OSPF converges faster than BGP, but more on that later. To answer the OP question first.
You want both.
iBGP is designed to ...
- 2,486
9
votes
Accepted
Why does MPLS need an IGP (like OSPF) in order to work?
Why does MPLS need an IGP (like OSPF) in order to work?
In an MPLS network, OSPF is not used to route customer traffic. It is only used to provide routing for the internal provider network so that ...
- 66.9k
6
votes
What are any disadvantages of redistributing eBGP routes into IGP
To answer your specific question: no, there's no "conceptual" or fundamental reason not to redistribute. There are a few practical considerations, but you seem to already be aware of most ...
- 66.9k
6
votes
Accepted
Does one logical router have only one route table?
Yes. One router have one forwarding table (FIB). It filled by routing protocols from their RIB. Often device can have different FIB's for different type of traffic (i.e. unicast and multicast).
Each ...
- 2,774
5
votes
Hot Potato, algorithm of selecting route in router
Is my algorithm correct?
Not exactly. Routing protocols do not route. A router can route without even using a routing protocol. Routing protocols simply exchange routes with other routers. The router ...
- 98.3k
5
votes
BGP - how does IGP know the right route?
Do eBGP routers send their routing tables to all routers (both BGP and
IGP) in one AS?
No, that's the whole point of running a separate protocol. BGP speakers redistribute a very small number of ...
- 66.9k
5
votes
Why does MPLS need an IGP (like OSPF) in order to work?
So, why to use also MPLS if we already had OSPF?
Downsides of IGP
Metric based: There will be a segment underutilized as you can see from the link cost. Traffic for the different networks attached ...
- 1,491
5
votes
Accepted
EIGRP failover - how do i verify it happened?
There is a command made for such checking. Use:
show ip eigrp events
- 651
4
votes
EIGRP failover - how do i verify it happened?
Yes, you can confirm that. Once hold-time expires, the former
feasible successor route immediately becomes the successor route and
is installed in routing table.
I do not think we have a log message ...
- 3,754
4
votes
Accepted
BGP - how does IGP know the right route?
There are multiple ways to do this.
The other ASes could be sending a default route, or the router in AS100 could just have a default route configured.
The other ASes could just advertise their own ...
- 98.3k
4
votes
Accepted
RIPv2 manual subnet mask configuration?
RIPv2 with the no auto-summary option will advertise the specific routes, not the aggregated prefix, unless you you use the ip summary-address rip interface command.
The network statements in RIP are ...
- 98.3k
3
votes
Accepted
How do two clients of a route reflector learn about each other when no IGP/static-route is used?
BGP generally assumes that AS is running an IGP, to interconnect its routers.
When R_Q receives a route that goes through R_P, it will have to lookup a route to R_P route through IGP as a part of BGP ...
- 1,798
3
votes
OSPF or iBGP for interior routing protocol?
While everything @RonMaupin says is true, in your particular case, with only five routers, there is not a lot to be gained by adding another routing protocol.
Since you don't have a full mesh, you ...
- 66.9k
3
votes
BGP - how does IGP know the right route?
BGP protocol is the routing protocol of the INTERNET. IT´s the way that all the autonomus systems are interconnected. The BGP is conformed by 2 types of peers, internal and external peers(from the AS ...
- 2,105
2
votes
Accepted
Do I understand IP Routing correctly?
Hosts contain their own routing tables, and will consult those to determine whether the packet can be delivered directly, or forwarded to a gateway (and if so, which one). Only then does your step 1 ...
- 246
2
votes
Accepted
EIGRP delay summarization?
What your drawing has is one, or both, of the routers overriding the interface delay. Under normal circumstances, the delay of a link is exactly the same on both ends. One of the routers may be doing ...
- 98.3k
2
votes
Routing between branches
I have had also similar situation.
It depends on different factors. I assume that your topology won't scale that much, so I would suggest keep going with BGP as you mentioned good pros for that.
Also,...
- 132
2
votes
One AS, Multiple Site with different physical location and ISP, different prefix
Since you'll be doing eBGP at both locations, any update received will be subject to BGP loop prevention, which is - any prefix received with the local ASN present within its' AS-Path attribute, will ...
- 21
2
votes
Accepted
What are LDP-MPLS advantages?
In todays routers routing lookup is done in hardware, usually in TCAM, which is as fast as ILM lookup.
So no advantage in lookup speed.
So why is it even needed? For tunneling.
If you want to deploy a ...
- 1,591
1
vote
In a PE-CE network, we would redistribute routes between BGP and IGP without `bgp redistribute-internal`. How does redistribution works?
From:
https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/iproute_bgp/command/irg-cr-book/bgp-a1.html?bookSearch=true#wp4270480859
Command Default In releases prior to Cisco IOS Release 15.1(2)S,
15.2(...
- 1,591
1
vote
How do two clients of a route reflector learn about each other when no IGP/static-route is used?
BGP will not install a route to routing table unless its next-hop adress is reachable.
This reachability can be achieved however you like.
Maybe even using BGP itself to advertise this next-hop👀.......
- 1,591
1
vote
Does the Router running multi routing protocol progresses received the routes will store into the Forwarding table?
Routing protocols have a priority value called Administrative Distance(AD). If two routing protocol processes with different AD values send the same route to RIB, the one with the lowest AD will be ...
- 1,591
1
vote
Why does MPLS need an IGP (like OSPF) in order to work?
MPLS is used to tunnel traffic over MPLS core routers to reach BGP NHs of BGP destination networks, since these MPLS core routers probably didn't learn (and probably shouldn't learn) the destination ...
- 1,591
1
vote
Do I understand IP Routing correctly?
Routers don't "ask" each other about routes when deciding where to send a packet. The routes a router knows about are determined in advance, either statically or by routing protocols.
To reduce the ...
- 13k
1
vote
Routing between branches
While I'm not a fan of IGP over WAN circuits (mostly due to the low circuit speeds which could cause convergence problems if there are many branch sites), I have seen this work well. There is no ...
- 98.3k
1
vote
Why use iBGP inside an Autonomous System, if IGP protocols fulfill the need for internal communication
Traffic in a network can be divided into 4 categories.
Ingress: traffic arriving from outside the network, destined for hosts within the network.
Egress: traffic originating inside the network ...
- 13k
Only top scored, non community-wiki answers of a minimum length are eligible