Subject: (usr-tc) Cisco router bandwidth

From: [email-masked]
Date: Mon, 15 May 2000 17:21:30 +0000

A few weeks back there was a discussion here on the amount of memory
required for a Cisco router running in a multihomed environment and
BGP4.  The recommendation was 128M of memory.  I am interested in
how much bandwidth into the Internet folks are seeing BGP4 use in
this type of environment.  Is it a significant amount ?  Can someone
put a quantity around it ?

Thanks,

Jeff Binkley
ASA Network Computing

-
 To unsubscribe to usr-tc, send an email to "[email-masked]"
 with "unsubscribe usr-tc" in the body of the message.
 For information on digests or retrieving files and old messages send
 "help" to the same address.  Do not use quotes in your message.

---

From: Jeff Mcadams <[email-masked]>
Date: Mon, 15 May 2000 17:33:47 +0000

Also sprach Jeff Binkley
>BGP4.  The recommendation was 128M of memory.  I am interested in how
>much bandwidth into the Internet folks are seeing BGP4 use in this type
>of environment.  Is it a significant amount ?  Can someone put a
>quantity around it ?

You can run 2 full views in 64megs of ram...its rather tight though, so
128megs is definitely recommended.

You cannot fit a single view in 32megs, you will require at least 64megs
to even take the first full view (unless you get get 48megs or
something, but I don't think any cisco's handle memory in that
increment).
-- 
Jeff McAdams                            Email: [email-masked]
Head Network Administrator              Voice: (502) 966-3848
IgLou Internet Services                        (800) 436-4456

-

---

From: Paul Farber <[email-masked]>
Date: Mon, 15 May 2000 18:13:38 +0000

If you are taking full routes.. then yes.  I did bgp to my upstream (C&W)
with only 48Mb installed.  I only took a few routes though.

Paul Farber
Farber Technology
[email-masked]
Ph  570-628-5303
Fax 570-628-5545

-

---

From: [email-masked]
Date: Mon, 15 May 2000 20:03:09 +0000

Paul,

Thanks.  I was more interested in network bandwidth than router memory.

Jeff Binkley
ASA Network Computing

-> If you are taking full routes.. then yes.  I did bgp to my upstream (C&W)
-> with only 48Mb installed.  I only took a few routes though.
->
-> Paul Farber
-> Farber Technology
-> [email-masked]
-> Ph  570-628-5303
-> Fax 570-628-5545
->
-> On Mon, 15 May 2000, Jeff Binkley wrote:
->
-> >
-> > A few weeks back there was a discussion here on the amount of memory >
-> required for a Cisco router running in a multihomed environment and > BGP4.
-> The recommendation was 128M of memory.  I am interested in > how much
-> bandwidth into the Internet folks are seeing BGP4 use in > this type of
-> environment.  Is it a significant amount ?  Can someone > put a quantity
-> around it ?
-> >
-> > Thanks,
-> >
-> > Jeff Binkley
-> > ASA Network Computing
-> >
-> > -
-> >  To unsubscribe to usr-tc, send an email to "[email-masked]" >
-> with "unsubscribe usr-tc" in the body of the message.
-> >  For information on digests or retrieving files and old messages send >
-> "help" to the same address.  Do not use quotes in your message. >

-

---

From: [email-masked]
Date: Mon, 15 May 2000 20:33:26 +0000

-> >A few weeks back there was a discussion here on the amount of memory
-> >required for a Cisco router running in a multihomed environment and >BGP4.
-> The recommendation was 128M of memory.  I am interested in how >much
-> bandwidth into the Internet folks are seeing BGP4 use in this type >of
-> environment.  Is it a significant amount ?  Can someone put a >quantity
-> around it ?
->
-> You can run 2 full views in 64megs of ram...its rather tight though, so
-> 128megs is definitely recommended.
->
-> You cannot fit a single view in 32megs, you will require at least 64megs to
-> even take the first full view (unless you get get 48megs or
-> something, but I don't think any cisco's handle memory in that
-> increment).

Jeff,

Thanks.  I was really looking for the amount of network bandwidth, not how much
memory it takes.  I've already started the upgrade from 64-128 megs.

Thanks,

Jeff Binkley
ASA Network Computing

-

---

From: Jeff Mcadams <[email-masked]>
Date: Mon, 15 May 2000 21:39:38 +0000

Also sprach Jeff Binkley
>Thanks.  I was really looking for the amount of network bandwidth, not
>how much memory it takes.  I've already started the upgrade from 64-128
>megs.

Once a BGP session is stabilized, it really uses *very* little network
bandwidth.  As a data point, it takes about a minute to a minute and a
half to sync up a full BGP view over a T1 (someone that's checked this
more recently than I might want to correct me if necessary), obviously,
as you drop down bandwidth from there, the time will go up...that should
give you a good data point to start with though.  Once the initial sync
is done, normal operation of BGP uses a miniscule amount of bandwidth.
The only data that is transfered over the BGP session is route updates,
meaning information is only really sent when a route changes, appears or
disappears.  I'm sure you can imagine that for a typical multi-homed ISP
or customer, these changes will not be significant.

FWIW, on my backup T1's (meaning the only traffic on them should *only*
be BGP updates) the traffic rate is almost unmeasurable as far as the
Cisco 5 minute input/output rate is concerned.  I occasionally see them
show 1000 bits/sec, 1 packets/sec, but only very briefly.  It uses
*that* little of traffic.
-- 
Jeff McAdams                            Email: [email-masked]
Head Network Administrator              Voice: (502) 966-3848
IgLou Internet Services                        (800) 436-4456

-

---

From: Mike Andrews <[email-masked]>
Date: Mon, 15 May 2000 22:44:30 +0000

> 128megs is definitely recommended.

We're fitting 3 full views into a 64 meg 3620, but just barely -- only
about 5 meg free, and CPU is running around 40%.  DON'T try this at home,
kids; we're ONLY doing it because the 7206VXR we ordered is backordered
and our UUNET T1 showed up early.  I'm surprised it actually worked,
really.  But at the rate the table's growing, that 5 meg will be gone by
the end of the summer.

A 3640 should be considered the rock bottom minimum these days, and a 3661
or 7100 or 7200 would give a lot more breathing room.  We went 7206VXR to
get away from external CSU/DSU's -- cramming a ton of WIC-1DSU-T1's into a
3661 would have been ugly and not very efficient use of the available
slots... plus we can put T3's into it later as we need them.

BGP itself doesn't take much bandwidth, and bandwidth doesn't affect
memory usage.  It might affect CPU usage, though.  We're pushing about 2
megabits of backbone traffic into that 3620 and back out the other side to
some internal T1/ethernet links.

Mike Andrews (MA12) * [email-masked] * http://www.bit0.com/
VP, sysadmin, & network guy, Digital Crescent Inc, Frankfort KY
Internet services for Frankfort, Lawrenceburg, Owenton, Shelbyville
www.fark.com: If it's not news, it's Fark.  (Or something like that.)

-

---

From: Mike Andrews <[email-masked]>
Date: Mon, 15 May 2000 22:45:40 +0000

> more recently than I might want to correct me if necessary), obviously,

Longer than that if your CPU is slow (i.e. 3620 or 3640) -- it spends more
time processing the routes than it does actually transferring them.  :)
Our poor 3620 takes up to 3 minutes to bring a session up.  Another good
reason to go 366x or 71xx or 720x...

-