What is GLBP?

GLBP is a protocol for load balancing routers but make them appear to be a single router to other devices on a network. GLBP stands for gateway load balancing protocol. An example of a situation where this could be used is for balancing between two broadband connections for a small to medium office. As far I as am aware it will only work with cisco routers and nobody else support the GLBP protocol. A full description can be found on the cisco web site for the command reference.

How does it work?

It works the same way as other redundant gateway protocols work. Like HSRP or VRRP. However in GLBP instead of one or other router being the active gateway both routers share an ip address to make them both active in the setup. So as an added benefit of load balancing you can also have the added benefit of redundancy for free. It is possible for the device to share a single ip address because it will only ever advertise one mac / arp address to each host that requests the gateway.

Where is the benefit?

What it will not be able to do is to double an internet connection bandwidth to a single machine when nat is involved. What it will do is spread the load from multiple machines into two or more internet connections. So it is best suited to growing offices where there are too many people for a single internet connection but not yet enough to consider getting a costly leased line.

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I seem to keep running into a problem with a cisco router (a cisco 877) with a virgin media connection. It would appear that part of virgin's network tends to break. I don't know the exact cause but from how I understand it. It is a fault with virgin somehow and some type of compatibility issue with cisco routers.

The problem for me tends to trigger when virgin has an issue inside their network or for some reason I have to disable the internet connection. When I bring the connection back up the cisco router can never successfully get an ip address by dhcp again. Until of course virgin is contacted and something is reset at their end. It will however allocate an ip address to a computer if you plug it directly into the virgin connection.

Here is how I was debugging the issue. To start with put your cisco terminl connection into monitor mode and debug dhcp (after you become an enabled user of course). Like this

Cisco#terminal monitor
Cisco#debug dhcp

This will cause you to see output like the following.

Jun  6 08:51:39.998: DHCP: deleting entry 83D002B8 0.0.0.0 from list
Jun  6 08:52:09.437: DHCP: Try 15 to acquire address for Vlan2
Jun  6 08:52:09.441: DHCP: allocate request
Jun  6 08:52:09.445: DHCP: new entry. add to queue, interface Vlan2
Jun  6 08:52:09.445: DHCP: SDiscover attempt # 1 for entry:
Jun  6 08:52:09.445: DHCP: SDiscover: sending 290 byte length DHCP packet
Jun  6 08:52:09.445: DHCP: SDiscover 290 bytes
Jun  6 08:52:09.445:             B'cast on Vlan2 interface from 0.0.0.0
Jun  6 08:52:13.006: DHCP: SDiscover attempt # 2 for entry:
Jun  6 08:52:13.006: DHCP: SDiscover: sending 290 byte length DHCP packet
Jun  6 08:52:13.006: DHCP: SDiscover 290 bytes
Jun  6 08:52:13.006:             B'cast on Vlan2 interface from 0.0.0.0
Jun  6 08:52:17.006: DHCP: SDiscover attempt # 3 for entry:
Jun  6 08:52:17.006: DHCP: SDiscover: sending 290 byte length DHCP packet
Jun  6 08:52:17.006: DHCP: SDiscover 290 bytes
Jun  6 08:52:17.006:             B'cast on Vlan2 interface from 0.0.0.0
Jun  6 08:52:28.568: DHCP: Received a BOOTREP pkt Not for us..:  xid: 0x3E466ABF%Unknown DHCP problem.. No allocation possible
Jun  6 08:52:29.924: DHCP: Waiting for 60 seconds on interface Vlan2

Unfortunatly the information is not very forthcoming with anything that matters. Since virgin is not actually replying to any dhcp requests with anything! So the next step to try is to reboot the cable modem etc... Of course it will just keep repeating the same output as above and virgin will continue to ignore any dhcp requests for some reason.

The next part of this is to phone virgin. Tell them specificly that the router is not allocating an address. They will then head off do some checks make sure they can talk to the cable modem directly and quitly reset something. Of course on the next attempt you can then expect some sort of success.

Jun  6 08:57:31.489: DHCP: Try 19 to acquire address for Vlan2
Jun  6 08:57:31.493: DHCP: allocate request
Jun  6 08:57:31.497: DHCP: new entry. add to queue, interface Vlan2
Jun  6 08:57:31.497: DHCP: SDiscover attempt # 1 for entry:
Jun  6 08:57:31.497: DHCP: SDiscover: sending 290 byte length DHCP packet
Jun  6 08:57:31.497: DHCP: SDiscover 290 bytes
Jun  6 08:57:31.497:             B'cast on Vlan2 interface from 0.0.0.0
Jun  6 08:57:35.106: DHCP: SDiscover attempt # 2 for entry:
Jun  6 08:57:35.106: DHCP: SDiscover: sending 290 byte length DHCP packet
Jun  6 08:57:35.106: DHCP: SDiscover 290 bytes
Jun  6 08:57:35.106:             B'cast on Vlan2 interface from 0.0.0.0
Jun  6 08:57:39.106: DHCP: SDiscover attempt # 3 for entry:
Jun  6 08:57:39.106: DHCP: SDiscover: sending 290 byte length DHCP packet
Jun  6 08:57:39.106: DHCP: SDiscover 290 bytes
Jun  6 08:57:39.106:             B'cast on Vlan2 interface from 0.0.0.0
Jun  6 08:57:39.154: DHCP: Received a BOOTREP pkt
Jun  6 08:57:39.154: DHCP: offer received from 62.31.64.115
Jun  6 08:57:39.154: DHCP: SRequest attempt # 1 for entry:
Jun  6 08:57:39.154: DHCP: SRequest- Server ID option: 62.31.64.115
Jun  6 08:57:39.154: DHCP: SRequest- Requested IP addr option: x.x.x.x
Jun  6 08:57:39.154: DHCP: SRequest placed lease len option: 603658
Jun  6 08:57:39.154: DHCP: SRequest: 308 bytes
Jun  6 08:57:39.154: DHCP: SRequest: 308 bytes
Jun  6 08:57:39.154:             B'cast on Vlan2 interface from 0.0.0.0
Jun  6 08:57:42.110: DHCP: SRequest attempt # 2 for entry:
Jun  6 08:57:42.110: DHCP: SRequest- Server ID option: 62.31.64.115
Jun  6 08:57:42.110: DHCP: SRequest- Requested IP addr option: x.x.x.x
Jun  6 08:57:42.110: DHCP: SRequest placed lease len option: 603658
Jun  6 08:57:42.110: DHCP: SRequest: 308 bytes
Jun  6 08:57:42.110: DHCP: SRequest: 308 bytes
Jun  6 08:57:42.110:             B'cast on Vlan2 interface from 0.0.0.0
Jun  6 08:57:42.347: DHCP: Received a BOOTREP pkt
Jun  6 08:57:46.347: DHCP Client Pooling: ***Allocated IP address: x.x.x.x
Jun  6 08:57:46.351: Allocated IP address = x.x.x.x  255.255.255.240

Finally it gets an ip address. The reason why I suspect this is a problem inside the virgin network is simple. Evertime I have to take the connection offline I can do it by a shutdown of the interface (the easy method) or by rebooting the cisco or some such. This problem occurs in exactly the same way. However the following at the site end of things never changes.

• The cisco will still manage to get an ip address without being restarted.
• The cisco config has not changed in any way.

To make matters worse. Virgin are not capable of allocating a static ip address to the connection. their definition of static is still allocated by dhcp. So there is no way around this problem.

I guess its just one of thoose things that will never be fixed by virgin media. I think this is a virgin media issue. What do you think?

Coming fromt he UK I have always been a little annoyed about the way broadband is sold to end users. Typically the internet providers tend to attempt to sell their services as unlimited and then have a limit in the small print. Personally I think this is grossly unfair and should not be permitted to continue. I actually think the speed the internet providers is also grossly mis leading along with there connections. Since the more modern connections are now performing at very decent speeds of up to 24 mbits / sec. I have decided to have a look at the figures just to see exactly what the internet providers actually offer in terms of usage.

When I talk about usage I am actually talking about thoughput. Lets face it once you get speeds faster than 5mbits a second you can stream videos from youtube / iplayer and anything else. So lets look at some providers on the bases of how much you can stream and the value for money you are really getting.

I am going to start with plusnet. I used to use them when adsl first arrived inside the UK. Connections were 0.5mbit and it was a real step up from modem speeds at the time. so I decided to look at their top end package of what they could offer me. Though I would point out that they are more honest than most and tell you directly what the limits on the connections are and don't attempt to hide it in the small print. Looking at their website I can figure out the following on their up to 20mbit connection

• Limit - 60GBytes
• Cost - £11.49
• Cost / GByte - £0.19
• Maximum Usage @ 20MBit - 13 Minutes / Day

Now lets look at a massive provider inside the UK called BT. I have used connections from BT in the past and a lot of small companies have used them. I have found their technical support (if you could call it that) to be dreadfull with long wait times. Long response times. Long fix times (eg > 1 Week). Not only that but when you look at their largest package they offer an unlimited service. At first this always seems great. However they apply a fair usage policy to their connection at 100Gb. Though their 40Mbit FTTC service looks great (at first glance). This is what I think of them after some calculations.

• Limit - 100GBytes
• Cost - £28
• Cost / GByte - £0.28
• Maximum Usage @ 40 MBit - 11 Minutes / Day

So already you can see a pattern. First they are actually more expensive than plusnet. What I find most shocking about this unlimited service is that they consider maximum bandwidth usage of 11minutes / day "fair usage".

Now lets look at a smaller provider that I am currently using called BEThere. They are actually the longest provider I have been with which has not applied a "fair usage" policy or I have become so frustrated with. They do have a hidden fair usage policy on their "unlimited" service but I have not been able to find any information to why it was applied. I have seen their connections regularly support downloads of greater than 200GB / Month usage so I for the calculations I am going to put in a guess at 300GB or so. Though I have heard other people who are closer to 300-400GB in usage and still don't have problems. I would also add any support problems have always been corrected within 24-48. Normally within the first 2-4 hours of them occuring.

• Limit - Mayby 300GB?
• Cost - £22 (I think its up to £27 now)
• Cost / GBytes - £0.07
• Maximum Usage @ 24 Mbits - 56 Minutes / Day

So there you have it. A completly different way to look at picking an internet provider. I think the reasons for the cost differences are very obvious as well. Plusnet, BT always seem to offer additional services. BEThere don't offer additional services other than an outbound email relay. They provide an internet connection and almost nothing else. So it would appear the company that offers less actually offers *a lot* more.

Recently I seem to be running into a little bit of a spamming problem with backlink's being submitted to the blog. It looks like the way .net blog engine does post is really easy for the spammer to be able to post lots and lots of comments with bots (I guess the spammers are getting good at this now). This sounds quite bad but everything is being caught by the spam filters so its really not so bad. So this is a bit of a guide to attempt to protect a website from such action coming from abusive computers around the internet. More...

Something I just happened to notice today was that O2 have decided to block some internet access from my iPhone. This isn't something that I asked for when I signed up nor was I aware of it when I took out the contract. so this also means that they are spying on my connection. They kind of have todo this in order for the blocking to work since they have to intercept the connections to the server and see what it is they are requesting.

What I find really stupid about it is that I actually initially though it was a scam since the app I was using had been recently upgraded. The app of course is Othello. The reason for the block according to O2 is because the site contains content for over 18's. I guess it must have been google mobile ad's that are being rated as over 18 for some reason. Or mayby something in the app. More...