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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.
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9 votes
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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 (...
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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 ...
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6 votes
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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 ...
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5 votes
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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 ...
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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 ...
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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 ...
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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 ...
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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
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4 votes
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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 ...
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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 ...
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4 votes
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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 ...
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4 votes
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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 ...
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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 @...
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3 votes
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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 ...
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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 ...
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3 votes
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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 ...
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3 votes
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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 ...
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3 votes
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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 ...
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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 ...
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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 ...
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3 votes
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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 ...
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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 ...
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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 ...
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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.
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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'...
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2 votes
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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 ...
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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....
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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 ...
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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 ...
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