10
votes
BGP vs OSPF path selection with /24 vs /23`
The route with the longest mask (/24) is always preferred regardless of how it’s learned. The protocol doesn’t matter.
- 63k
9
votes
Accepted
How a router know where to send a packet with the exit interface route command?
The second option is something to avoid. It is acceptable for point-to-point interfaces like serial or tunnel interfaces, but on broadcast media (such as Ethernet), it is "close to illegal" to use (...
- 7,748
7
votes
BGP vs OSPF path selection with /24 vs /23`
Most specific match (longest subnet mask match) will win regardless of routing protocol. If the subnet masks are equal, the route with the lowest administrative distance wins. In this case eBGP ...
- 1,783
6
votes
Accepted
Is there a way to determine my network transportation to specific path?
TLDR you can't.
You can use traceroute to see the path a packet will likely take from your computer to a remote one, however, the very nature of the Internet is that a packet can take any path between ...
- 18.4k
5
votes
Accepted
How does a router decide what route to forward a packet when routes come from different routing protocols?
Routers route packets by what is in the routing table, and identical routes will have the one with the best (lowest) AD make it into the routing table, but the other identical routes will not. Then it ...
- 94.1k
4
votes
NAT VLANS with same IP subnets and same IP addresses
NAT happens on a device that can perform NAT, e.g. a router (even layer-3 switches cannot NAT, except for something like the 65xx series). The outside and inside addressing is placed on different ...
- 94.1k
4
votes
How can a IP under a VLAN communicate other VLAN's IP?
The server's address must be part of the subnet it's configured on. Since you have the server on VLAN 501, its IP address has to be in the 10.50.1.0/24 subnet, not as you have it configured.
Set the ...
- 63k
4
votes
Cisco ASA 5505- My subnet mask is different from Show Route
The L route is the local address assigned to the interface, and the C route is the network attached to the interface. That is completely normal (beyond a certain device code version) for interfaces ...
- 94.1k
4
votes
How to flush route cache in fortigate
From the CLI you can issue the following command to restart the routing service.
exec router restart
To restart OSPF, you can use.
exec router clear ospf process
- 536
4
votes
Accepted
Does gateway have a genmask?
The network mask (or prefix) defines the length of the subnet address in a routing table. Each entry in a routing table consists of subnet address and mask and the next-hop gateway.
Each next-hop ...
- 71.5k
4
votes
Testing Secondary Static Route
If all you're looking for is a way to make sure the new connection can pass traffic, you can add a route for something specific that won't interfere with your normal traffic, such as:
ip route 8.8.8.8 ...
- 4,661
4
votes
Accepted
Juniper "show route receive-protocol bgp" output meaning
First, I think it helps to set the baseline for the general process of how BGP routes are processed, this is true for all vendors.
There are 3 main components:
ADJ-RIB-IN: This is the table where all ...
- 6,450
4
votes
Accepted
CCNA | Routing Protocols | Administrative Distance
Yes, if you're careful.
On Cisco routers, the routing table shows the administrative distance (AD) of each route. Since AD is an attribute of routing protocols, it can tell you which protocol was ...
- 63k
4
votes
Accepted
Difference between default routes
A routing table entry requires a prefix length, ie. 0.0.0.0 /1 in your case.
That entry matches only 0.0.0.0 through 127.255.255.255 (with 127.0.0.0/8 being non-routable as loopback range - thx @...
- 71.5k
3
votes
Accepted
Testing Secondary Static Route
Can I add a static route Cisco3750Stack#ip route 0.0.0.0 0.0.0.0 10.6.0.1 10 to the existing static route and be able to test connectivity with the new IP scheme...?
No, you can't. As others have ...
- 63k
3
votes
Show 'all' routes to a given prefix on Juniper Router
show route <ip address> all shows you all routes received for a given destination, not just the one installed in your FIB.
However, if you receive routes from a transit provider, you typically ...
- 15.7k
3
votes
Accepted
ipv6: I can ping only 1 interface within same network even with static route
You need to remember that ping is bidirectional. You send out an ICMP echo request, and you hope to get back an ICMP echo reply. That means that the replying device must also have a route back to the ...
- 94.1k
3
votes
Accepted
Why is this subnet config required by my vlan "snake topology"?
The point of that port/VLAN chaining rig is that you want to force the switch to receive and send in port pairs. Normally, a switch would take the shortcut to the (final) destination port which you ...
- 71.5k
3
votes
Accepted
How to understand the default gateway generally refers to the 0.0.0.0/0 route?
All IPv4 networks are subnets of the 0.0.0.0/0 network, so in a routing table that network matches any IPv4 network, making it a default network.
If the destination address on a packet does not match ...
- 94.1k
3
votes
How to flush route cache in fortigate
This might be a little late, but since the question still pops up on the Google search, I thought I answer it.
The following command works in 6.2.7* and above, but does not show up as an argument when ...
- 31
3
votes
How to know if ISP network have multiple routes
Personally, I do this type of research using a number of different publicly available "route servers" or "looking glasses." Simply do a web search for "public bgp looking glass" and you should find a ...
- 26.8k
3
votes
Accepted
What's the BGP route `active received accepted damped` status meaning?
The Juniper documentation here actually words this well.
In summary, that is a multipurpose field used to display information about BGP peer sessions. The field’s contents depend upon whether a ...
- 1,267
3
votes
How to redirect traffic when one site goes down without downtime and the subnets are different?
There are a few options— which one you choose depends on many details. This is the kind of problem that people hire consultants for. You shouldn’t expect to get a solution for free from strangers on ...
- 63k
3
votes
Difference between default routes
In routing, the more specific route (= the higher netmask value - the number behind the "/") takes precedence over the less specific route (lower netmask value). The default route, as stated ...
- 191
2
votes
how to change a BGP path in juniper?
The selected path is chosen because (all else being equal) the local preference (190) is set highest on this path. To change which path BGP selects you will need to modify the local preference.
- 63k
2
votes
Route Reflector not reflecting BGP-LU (Labelled Unicast) prefixes
To simplify the explanation, let's just pretend that only RR1 and RR3 exist (and let's forget about RR2 and RR4 for a second).
Similarly, let just pretend ASBR1 and ASBR3 are the only ASBRs (and let'...
- 239
2
votes
Accepted
Strict source routing using my own scattered PCs/ routers
Suppose, I can buy/ own different PCs/ routers in specific places (GEO locations). Is it sufficient to fully control and determine the packages path?
Unless all these routers are directly connected ...
- 71.5k
2
votes
What is route leaking?
What roughly I understand is, advertising route from one vrf table to other.
In the context of MPLS, yes. Or, leaking from the global table into one or more VRFs. It is also used in other places, e....
- 63k
2
votes
How to enable Inter-VLAN multicast traffic on a layer 3 Siemens RX1510 Network Switch using IGMP?
You'll likely want to look into something like Protocol Independent Multicast (PIM), which seems to be covered for that platform here. As Ron points out, IGMP is only managing multicast groups within ...
- 6,036
2
votes
Understanding BGP communities
Communities are usually applied to prefixes via route-maps. In your example, RouterA may have something like this:
route-map to-router-b permit 10
description Tag Prefixes with Community
match ip ...
- 1,267
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