BGP - Network subcommand

Daniel333

So I am setting up a basic BGP topology.

Weird thing, it doesn't work when I use the
#network 192.168.1.0 mask 255.255.255.0

but works fine when I do this
#network 192.168.1.0

Any idea why that might be? Shouldn't they mean the same thing?

mikej412

Daniel333 wrote: »

Shouldn't they mean the same thing?

It depends on what you mean by it didn't work and it did work.

It's BGP -- so how it works depends on whether auto summary is enabled or not. Current versions of IOS disable auto summary by default -- so it's a good habit to get into using the mask keyword.

chmorin

mikej412 wrote: »

It depends on what you mean by it didn't work and it did work.

It's BGP -- so how it works depends on whether auto summary is enabled or not. Current versions of IOS disable auto summary by default -- so it's a good habit to get into using the mask keyword.

I also believe the same rule could apply to other routing protocols as well like EIGRP. I remember it being banged into my head that once I first configure the protocol, to type in "no auto-summary" as my next command. Like you said I don't think this is needed in newer IOS versions.

Unless you want auto summary, that is. Most don't now-a-days.

Daniel333

Turns out I just didn't wait long enough. Sorry, kinda embarrassed.

Forsaken_GA

Daniel333 wrote: »

Turns out I just didn't wait long enough. Sorry, kinda embarrassed.

Yeah, BGP route propagation isn't instant like the IGP protocols, sometimes it takes a few for your routes to be announced

deth1k

This is down to BGP Scanner process which verifies next hop of every route in BGP RIB every 60 seconds. You can tune it down to 1 second but that could cause an instability in a live environment network.

command: "bgp scan-time"

HTH

Netwurk

For what it's worth, here's my lab's BGP config


router bgp 65500
no synchronization
bgp log-neighbor-changes
network 10.10.10.0 mask 255.255.255.0
neighbor 192.168.55.5 remote-as 65501

and

router bgp 65501
no synchronization
bgp log-neighbor-changes
network 172.16.7.0 mask 255.255.255.0
neighbor 192.168.55.6 remote-as 65500


Thanks to BGP I can now ping 10.10.10.x from 65501.

From 65501, sh ip route shows

sh ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter are
* - candidate default, U - per-user static route, o - ODR
P - periodic downloaded static route
(unnecessary output not shown)
B 10.10.10.0/24 [20/0] via 192.168.55.6, 1w5d


BGP is of course the EGP everyone uses nowadays. All the other protocols are IGP's.

EGP (the protocol that BGP replaced) is the only other EGP that I know of other than BGP.

I hope this helps D333, happy holidays to you and yours.