Re: Peering best practices advice needed.
On 8-dec-04, at 18:03, Rolo Tomassi wrote: Now someone mentioned that we could use AS-LOOP-IN feature which will overcome this problem and allow us to route to each other via EBGP. Some gear doesn't send updates with AS X in the path to AS X. So depending on the type of routers your upstreams have, you may not see the routing information from the other instance of your AS.
Re: Peering best practices advice needed.
On Wed, 2004-12-08 at 17:03 +, Rolo Tomassi wrote: > Hi all, > > Please forgive the simplistic nature of the query.. > > Basically my company is multi-homed with 2 different providers in the UK, > and advertising a /18. Now some colleaguges in another part of the world > want to break that /18 into two /19's and advertise one /19 and we advertise > the other. This is fine, however we are NOT running IBGP in the core, > therefore the UK customers in the /19 will not be able to reach the other > /19 as there would be a loop detected through EBGP. > > Now someone mentioned that we could use AS-LOOP-IN feature which will > overcome this problem and allow us to route to each other via EBGP. I really > think this is a bad idea but until we get an internal link - I dont see a > way forward. So... anyone doing this currently in their network or have any > "best practices" way round this. I want our company to be good Netizens but > still be able to pass traffic between the 2 /19's. Well another way for solve this problem is that both parts advertise their /19. From the transit provider take your normal routing table and a default route. The default route allows the two /19's to reach each other over the transit provider(s). -- Cheers Dg
Re: Peering best practices advice needed.
Rich LOL !! thanks for your input :) From: Richard Irving <[EMAIL PROTECTED]> To: Rolo Tomassi <[EMAIL PROTECTED]> CC: [EMAIL PROTECTED] Subject: Re: Peering best practices advice needed. Date: Wed, 08 Dec 2004 12:56:13 -0500 Rolo Tomassi wrote: Hi all, Please forgive the simplistic nature of the query.. Basically my company is multi-homed with 2 different providers in the UK, and advertising a /18. Now some colleaguges in another part of the world want to break that /18 into two /19's and advertise one /19 and we advertise the other. This is fine, however we are NOT running IBGP in the core, therefore the UK customers in the /19 will not be able to reach the other /19 as there would be a loop detected through EBGP. Pardon my simplistic solution, try dropping the /18, and -only- advertise the corresponding /19 from each region. Now someone mentioned that we could use AS-LOOP-IN feature which will overcome this problem and allow us to route to each other via EBGP. I really think this is a bad idea but until we get an internal link - I dont see a way forward. So... anyone doing this currently in their network or have any "best practices" way round this. I want our company to be good Netizens but still be able to pass traffic between the 2 /19's. See above. K.I.S.S. (No offense intended ;) Any help would be greatly appreciated. Rolo ! _ Stay in touch with absent friends - get MSN Messenger http://www.msn.co.uk/messenger _ It's fast, it's easy and it's free. Get MSN Messenger today! http://www.msn.co.uk/messenger
RE: Peering best practices advice needed.
Hello. Three options. 1. Acquire a second ASN, and announce each site's /19 from a different asn. 2. Announce each locations /19 from it's respective location, using the same asn. Use the cisco BGP command Allow-as-in to permit each AS to hear the remote site's network advertisement. 3. If the remote site will not be multihomed, ask their ISP to announce the /19 for you. My gut says that if you are advertising a block in the territory of another RIR, your irr entries will need to be correct to save filtering issues. Good Luck, Ejay > -Original Message- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On > Behalf Of Rolo Tomassi > Sent: Wednesday, December 08, 2004 11:04 AM > To: [EMAIL PROTECTED] > Subject: Peering best practices advice needed. > > > Hi all, > > Please forgive the simplistic nature of the query.. > > Basically my company is multi-homed with 2 different > providers in the UK, > and advertising a /18. Now some colleaguges in another part > of the world > want to break that /18 into two /19's and advertise one /19 > and we advertise > the other. This is fine, however we are NOT running IBGP in the core, > therefore the UK customers in the /19 will not be able to > reach the other > /19 as there would be a loop detected through EBGP. > > Now someone mentioned that we could use AS-LOOP-IN feature which will > overcome this problem and allow us to route to each other via > EBGP. I really > think this is a bad idea but until we get an internal link - > I dont see a > way forward. So... anyone doing this currently in their > network or have any > "best practices" way round this. I want our company to be > good Netizens but > still be able to pass traffic between the 2 /19's. > > Any help would be greatly appreciated. > > Rolo ! > > _ > Stay in touch with absent friends - get MSN Messenger > http://www.msn.co.uk/messenger
Re: Peering best practices advice needed.
[EMAIL PROTECTED] wrote: That is what he is doing, however if he is advertising the two /19's, >from two disconnected sites with the same ASN, > they will not be able to reach each other as BGP will >interpret this as a path loop. Yup. I would presume, as they aren't connected, nor running iBGP, they would be running different ASN's. Anything else hurts. On Wed, Dec 08, 2004 at 12:56:13PM -0500, Richard Irving wrote: Rolo Tomassi wrote: Hi all, Please forgive the simplistic nature of the query.. Basically my company is multi-homed with 2 different providers in the UK, and advertising a /18. Now some colleaguges in another part of the world want to break that /18 into two /19's and advertise one /19 and we advertise the other. This is fine, however we are NOT running IBGP in the core, therefore the UK customers in the /19 will not be able to reach the other /19 as there would be a loop detected through EBGP. Pardon my simplistic solution, try dropping the /18, and -only- advertise the corresponding /19 from each region. Now someone mentioned that we could use AS-LOOP-IN feature which will overcome this problem and allow us to route to each other via EBGP. I really think this is a bad idea but until we get an internal link - I dont see a way forward. So... anyone doing this currently in their network or have any "best practices" way round this. I want our company to be good Netizens but still be able to pass traffic between the 2 /19's. See above. K.I.S.S. (No offense intended ;) Any help would be greatly appreciated. Rolo ! _ Stay in touch with absent friends - get MSN Messenger http://www.msn.co.uk/messenger
Re: Peering best practices advice needed.
Hi there, If I understand your predicament correctly, our company has a similar situation. We have two locations from which we need to advertise routes from our AS, but our internal link between these two locations is a very high cost satellite link. This means we can not afford to advertise our whole IP allocation equally from both locations. We have a /19 allocated, and we advertise both the /19 from each location, and the more specific /20 particular to each location. To circumvent the loop detection, we use the hidden Cisco command, neighbour x.x.x.x allow-as in. This allows each location to accept the remote's advertised /20 to be inserted into the routing table. Should connectivity ever be lost across the public networks in between, there is a higher cost static route over the satellite link. Perhaps in a more complex and more meshed AS, this loop dodging would be a bad thing(tm). In our simple two location, semi-discontiguous network layout, it has been a problem-free solution. Hope this helps in some way. Regards, Graham Blake SSI Micro Network Services At 10:03 AM 08/12/2004, Rolo Tomassi wrote: Hi all, Please forgive the simplistic nature of the query.. Basically my company is multi-homed with 2 different providers in the UK, and advertising a /18. Now some colleaguges in another part of the world want to break that /18 into two /19's and advertise one /19 and we advertise the other. This is fine, however we are NOT running IBGP in the core, therefore the UK customers in the /19 will not be able to reach the other /19 as there would be a loop detected through EBGP. Now someone mentioned that we could use AS-LOOP-IN feature which will overcome this problem and allow us to route to each other via EBGP. I really think this is a bad idea but until we get an internal link - I dont see a way forward. So... anyone doing this currently in their network or have any "best practices" way round this. I want our company to be good Netizens but still be able to pass traffic between the 2 /19's. Any help would be greatly appreciated. Rolo ! _ Stay in touch with absent friends - get MSN Messenger http://www.msn.co.uk/messenger
Re: Peering best practices advice needed.
On Dec 8, 2004, at 12:56 PM, Richard Irving wrote: Please forgive the simplistic nature of the query.. Actually, it is refreshing to see _operational_ questions on the list. :-) Basically my company is multi-homed with 2 different providers in the UK, and advertising a /18. Now some colleaguges in another part of the world want to break that /18 into two /19's and advertise one /19 and we advertise the other. This is fine, however we are NOT running IBGP in the core, therefore the UK customers in the /19 will not be able to reach the other /19 as there would be a loop detected through EBGP. Pardon my simplistic solution, try dropping the /18, and -only- advertise the corresponding /19 from each region. This will only work if you have separate ASNs, which would be my suggested solution. In fact, even if you announce the /18 + both /19s, as long as each site as a separate ASN, it will work. If they must have the same ASN for some reason, have your upstreams send you default route as well as a full table. You will not see the "other" /19, but you will send traffic to the upstream because of the default and they will route it properly. Now someone mentioned that we could use AS-LOOP-IN feature which will overcome this problem and allow us to route to each other via EBGP. I really think this is a bad idea but until we get an internal link - I dont see a way forward. So... anyone doing this currently in their network or have any "best practices" way round this. I want our company to be good Netizens but still be able to pass traffic between the 2 /19's. I've never used AS-LOOP-IN. Sorry. :( But I have used the above solution (and static defaults), and it works fine. -- TTFN, patrick
Re: Peering best practices advice needed.
Rolo Tomassi wrote: Hi all, Please forgive the simplistic nature of the query.. Basically my company is multi-homed with 2 different providers in the UK, and advertising a /18. Now some colleaguges in another part of the world want to break that /18 into two /19's and advertise one /19 and we advertise the other. This is fine, however we are NOT running IBGP in the core, therefore the UK customers in the /19 will not be able to reach the other /19 as there would be a loop detected through EBGP. Pardon my simplistic solution, try dropping the /18, and -only- advertise the corresponding /19 from each region. Now someone mentioned that we could use AS-LOOP-IN feature which will overcome this problem and allow us to route to each other via EBGP. I really think this is a bad idea but until we get an internal link - I dont see a way forward. So... anyone doing this currently in their network or have any "best practices" way round this. I want our company to be good Netizens but still be able to pass traffic between the 2 /19's. See above. K.I.S.S. (No offense intended ;) Any help would be greatly appreciated. Rolo ! _ Stay in touch with absent friends - get MSN Messenger http://www.msn.co.uk/messenger
Peering best practices advice needed.
Hi all, Please forgive the simplistic nature of the query.. Basically my company is multi-homed with 2 different providers in the UK, and advertising a /18. Now some colleaguges in another part of the world want to break that /18 into two /19's and advertise one /19 and we advertise the other. This is fine, however we are NOT running IBGP in the core, therefore the UK customers in the /19 will not be able to reach the other /19 as there would be a loop detected through EBGP. Now someone mentioned that we could use AS-LOOP-IN feature which will overcome this problem and allow us to route to each other via EBGP. I really think this is a bad idea but until we get an internal link - I dont see a way forward. So... anyone doing this currently in their network or have any "best practices" way round this. I want our company to be good Netizens but still be able to pass traffic between the 2 /19's. Any help would be greatly appreciated. Rolo ! _ Stay in touch with absent friends - get MSN Messenger http://www.msn.co.uk/messenger
